Implement storedevs, prepare to port littlefs

kernel/fs/littlefs/tests/test_alloc.toml

@@ -0,0 +1,772 @@
+# allocator tests
+# note for these to work there are a number constraints on the device geometry
+if = 'BLOCK_CYCLES == -1'
+
+# parallel allocation test
+[cases.test_alloc_parallel]
+defines.FILES = 3
+defines.SIZE = '(((BLOCK_SIZE-8)*(BLOCK_COUNT-6)) / FILES)'
+defines.GC = [false, true]
+defines.COMPACT_THRESH = ['-1', '0', 'BLOCK_SIZE/2']
+defines.INFER_BC = [false, true]
+code = '''
+    const char *names[] = {"bacon", "eggs", "pancakes"};
+    lfs_file_t files[FILES];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+    lfs_mount(&lfs, &cfg_) => 0;
+    lfs_mkdir(&lfs, "breakfast") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg_) => 0;
+    for (int n = 0; n < FILES; n++) {
+        char path[1024];
+        sprintf(path, "breakfast/%s", names[n]);
+        lfs_file_open(&lfs, &files[n], path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    }
+    for (int n = 0; n < FILES; n++) {
+        if (GC) {
+            lfs_fs_gc(&lfs) => 0;
+        }
+        size_t size = strlen(names[n]);
+        for (lfs_size_t i = 0; i < SIZE; i += size) {
+            lfs_file_write(&lfs, &files[n], names[n], size) => size;
+        }
+    }
+    for (int n = 0; n < FILES; n++) {
+        lfs_file_close(&lfs, &files[n]) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg_) => 0;
+    for (int n = 0; n < FILES; n++) {
+        char path[1024];
+        sprintf(path, "breakfast/%s", names[n]);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        size_t size = strlen(names[n]);
+        for (lfs_size_t i = 0; i < SIZE; i += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            assert(memcmp(buffer, names[n], size) == 0);
+        }
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# serial allocation test
+[cases.test_alloc_serial]
+defines.FILES = 3
+defines.SIZE = '(((BLOCK_SIZE-8)*(BLOCK_COUNT-6)) / FILES)'
+defines.GC = [false, true]
+defines.COMPACT_THRESH = ['-1', '0', 'BLOCK_SIZE/2']
+defines.INFER_BC = [false, true]
+code = '''
+    const char *names[] = {"bacon", "eggs", "pancakes"};
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+    lfs_mount(&lfs, &cfg_) => 0;
+    lfs_mkdir(&lfs, "breakfast") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    for (int n = 0; n < FILES; n++) {
+        lfs_mount(&lfs, &cfg_) => 0;
+        char path[1024];
+        sprintf(path, "breakfast/%s", names[n]);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+        size_t size = strlen(names[n]);
+        uint8_t buffer[1024];
+        memcpy(buffer, names[n], size);
+        for (int i = 0; i < SIZE; i += size) {
+            if (GC) {
+                lfs_fs_gc(&lfs) => 0;
+            }
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+        }
+        lfs_file_close(&lfs, &file) => 0;
+        lfs_unmount(&lfs) => 0;
+    }
+
+    lfs_mount(&lfs, &cfg_) => 0;
+    for (int n = 0; n < FILES; n++) {
+        char path[1024];
+        sprintf(path, "breakfast/%s", names[n]);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        size_t size = strlen(names[n]);
+        for (int i = 0; i < SIZE; i += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            assert(memcmp(buffer, names[n], size) == 0);
+        }
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# parallel allocation reuse test
+[cases.test_alloc_parallel_reuse]
+defines.FILES = 3
+defines.SIZE = '(((BLOCK_SIZE-8)*(BLOCK_COUNT-6)) / FILES)'
+defines.CYCLES = [1, 10]
+defines.INFER_BC = [false, true]
+code = '''
+    const char *names[] = {"bacon", "eggs", "pancakes"};
+    lfs_file_t files[FILES];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+
+    for (int c = 0; c < CYCLES; c++) {
+        lfs_mount(&lfs, &cfg_) => 0;
+        lfs_mkdir(&lfs, "breakfast") => 0;
+        lfs_unmount(&lfs) => 0;
+
+        lfs_mount(&lfs, &cfg_) => 0;
+        for (int n = 0; n < FILES; n++) {
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_file_open(&lfs, &files[n], path,
+                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+        }
+        for (int n = 0; n < FILES; n++) {
+            size_t size = strlen(names[n]);
+            for (int i = 0; i < SIZE; i += size) {
+                lfs_file_write(&lfs, &files[n], names[n], size) => size;
+            }
+        }
+        for (int n = 0; n < FILES; n++) {
+            lfs_file_close(&lfs, &files[n]) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        lfs_mount(&lfs, &cfg_) => 0;
+        for (int n = 0; n < FILES; n++) {
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+            size_t size = strlen(names[n]);
+            for (int i = 0; i < SIZE; i += size) {
+                uint8_t buffer[1024];
+                lfs_file_read(&lfs, &file, buffer, size) => size;
+                assert(memcmp(buffer, names[n], size) == 0);
+            }
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        lfs_mount(&lfs, &cfg_) => 0;
+        for (int n = 0; n < FILES; n++) {
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_remove(&lfs, path) => 0;
+        }
+        lfs_remove(&lfs, "breakfast") => 0;
+        lfs_unmount(&lfs) => 0;
+    }
+'''
+
+# serial allocation reuse test
+[cases.test_alloc_serial_reuse]
+defines.FILES = 3
+defines.SIZE = '(((BLOCK_SIZE-8)*(BLOCK_COUNT-6)) / FILES)'
+defines.CYCLES = [1, 10]
+defines.INFER_BC = [false, true]
+code = '''
+    const char *names[] = {"bacon", "eggs", "pancakes"};
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+
+    for (int c = 0; c < CYCLES; c++) {
+        lfs_mount(&lfs, &cfg_) => 0;
+        lfs_mkdir(&lfs, "breakfast") => 0;
+        lfs_unmount(&lfs) => 0;
+
+        for (int n = 0; n < FILES; n++) {
+            lfs_mount(&lfs, &cfg_) => 0;
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path,
+                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+            size_t size = strlen(names[n]);
+            uint8_t buffer[1024];
+            memcpy(buffer, names[n], size);
+            for (int i = 0; i < SIZE; i += size) {
+                lfs_file_write(&lfs, &file, buffer, size) => size;
+            }
+            lfs_file_close(&lfs, &file) => 0;
+            lfs_unmount(&lfs) => 0;
+        }
+
+        lfs_mount(&lfs, cfg) => 0;
+        for (int n = 0; n < FILES; n++) {
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+            size_t size = strlen(names[n]);
+            for (int i = 0; i < SIZE; i += size) {
+                uint8_t buffer[1024];
+                lfs_file_read(&lfs, &file, buffer, size) => size;
+                assert(memcmp(buffer, names[n], size) == 0);
+            }
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        lfs_mount(&lfs, cfg) => 0;
+        for (int n = 0; n < FILES; n++) {
+            char path[1024];
+            sprintf(path, "breakfast/%s", names[n]);
+            lfs_remove(&lfs, path) => 0;
+        }
+        lfs_remove(&lfs, "breakfast") => 0;
+        lfs_unmount(&lfs) => 0;
+    }
+'''
+
+# exhaustion test
+[cases.test_alloc_exhaustion]
+defines.INFER_BC = [false, true]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+    lfs_mount(&lfs, &cfg_) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    size_t size = strlen("exhaustion");
+    uint8_t buffer[1024];
+    memcpy(buffer, "exhaustion", size);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+    lfs_file_sync(&lfs, &file) => 0;
+
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    lfs_ssize_t res;
+    while (true) {
+        res = lfs_file_write(&lfs, &file, buffer, size);
+        if (res < 0) {
+            break;
+        }
+
+        res => size;
+    }
+    res => LFS_ERR_NOSPC;
+
+    // note that lfs_fs_gc should not error here
+    lfs_fs_gc(&lfs) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg_) => 0;
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_RDONLY);
+    size = strlen("exhaustion");
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "exhaustion", size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# exhaustion wraparound test
+[cases.test_alloc_exhaustion_wraparound]
+defines.SIZE = '(((BLOCK_SIZE-8)*(BLOCK_COUNT-4)) / 3)'
+defines.INFER_BC = [false, true]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+    lfs_mount(&lfs, &cfg_) => 0;
+
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "padding", LFS_O_WRONLY | LFS_O_CREAT);
+    size_t size = strlen("buffering");
+    uint8_t buffer[1024];
+    memcpy(buffer, "buffering", size);
+    for (int i = 0; i < SIZE; i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_remove(&lfs, "padding") => 0;
+
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    size = strlen("exhaustion");
+    memcpy(buffer, "exhaustion", size);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+    lfs_file_sync(&lfs, &file) => 0;
+
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    lfs_ssize_t res;
+    while (true) {
+        res = lfs_file_write(&lfs, &file, buffer, size);
+        if (res < 0) {
+            break;
+        }
+
+        res => size;
+    }
+    res => LFS_ERR_NOSPC;
+
+    // note that lfs_fs_gc should not error here
+    lfs_fs_gc(&lfs) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg_) => 0;
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_RDONLY);
+    size = strlen("exhaustion");
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "exhaustion", size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_remove(&lfs, "exhaustion") => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# dir exhaustion test
+[cases.test_alloc_dir_exhaustion]
+defines.INFER_BC = [false, true]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    struct lfs_config cfg_ = *cfg;
+    if (INFER_BC) {
+        cfg_.block_count = 0;
+    }
+    lfs_mount(&lfs, &cfg_) => 0;
+
+    // find out max file size
+    lfs_mkdir(&lfs, "exhaustiondir") => 0;
+    size_t size = strlen("blahblahblahblah");
+    uint8_t buffer[1024];
+    memcpy(buffer, "blahblahblahblah", size);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    int count = 0;
+    int err;
+    while (true) {
+        err = lfs_file_write(&lfs, &file, buffer, size);
+        if (err < 0) {
+            break;
+        }
+
+        count += 1;
+    }
+    err => LFS_ERR_NOSPC;
+    // note that lfs_fs_gc should not error here
+    lfs_fs_gc(&lfs) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "exhaustion") => 0;
+    lfs_remove(&lfs, "exhaustiondir") => 0;
+
+    // see if dir fits with max file size
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    for (int i = 0; i < count; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_mkdir(&lfs, "exhaustiondir") => 0;
+    lfs_remove(&lfs, "exhaustiondir") => 0;
+    lfs_remove(&lfs, "exhaustion") => 0;
+
+    // see if dir fits with > max file size
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    for (int i = 0; i < count+1; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_mkdir(&lfs, "exhaustiondir") => LFS_ERR_NOSPC;
+
+    lfs_remove(&lfs, "exhaustion") => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# what if we have a bad block during an allocation scan?
+[cases.test_alloc_bad_blocks]
+in = "lfs.c"
+defines.ERASE_CYCLES = 0xffffffff
+defines.BADBLOCK_BEHAVIOR = 'LFS_EMUBD_BADBLOCK_READERROR'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    // first fill to exhaustion to find available space
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "pacman", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "waka");
+    size_t size = strlen("waka");
+    lfs_size_t filesize = 0;
+    while (true) {
+        lfs_ssize_t res = lfs_file_write(&lfs, &file, buffer, size);
+        assert(res == (lfs_ssize_t)size || res == LFS_ERR_NOSPC);
+        if (res == LFS_ERR_NOSPC) {
+            break;
+        }
+        filesize += size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // now fill all but a couple of blocks of the filesystem with data
+    filesize -= 3*BLOCK_SIZE;
+    lfs_file_open(&lfs, &file, "pacman", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    strcpy((char*)buffer, "waka");
+    size = strlen("waka");
+    for (lfs_size_t i = 0; i < filesize/size; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // also save head of file so we can error during lookahead scan
+    lfs_block_t fileblock = file.ctz.head;
+    lfs_unmount(&lfs) => 0;
+
+    // remount to force an alloc scan
+    lfs_mount(&lfs, cfg) => 0;
+
+    // but mark the head of our file as a "bad block", this is force our
+    // scan to bail early
+    lfs_emubd_setwear(cfg, fileblock, 0xffffffff) => 0;
+    lfs_file_open(&lfs, &file, "ghost", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    strcpy((char*)buffer, "chomp");
+    size = strlen("chomp");
+    while (true) {
+        lfs_ssize_t res = lfs_file_write(&lfs, &file, buffer, size);
+        assert(res == (lfs_ssize_t)size || res == LFS_ERR_CORRUPT);
+        if (res == LFS_ERR_CORRUPT) {
+            break;
+        }
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // now reverse the "bad block" and try to write the file again until we
+    // run out of space
+    lfs_emubd_setwear(cfg, fileblock, 0) => 0;
+    lfs_file_open(&lfs, &file, "ghost", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    strcpy((char*)buffer, "chomp");
+    size = strlen("chomp");
+    while (true) {
+        lfs_ssize_t res = lfs_file_write(&lfs, &file, buffer, size);
+        assert(res == (lfs_ssize_t)size || res == LFS_ERR_NOSPC);
+        if (res == LFS_ERR_NOSPC) {
+            break;
+        }
+    }
+    // note that lfs_fs_gc should not error here
+    lfs_fs_gc(&lfs) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+
+    // check that the disk isn't hurt
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "pacman", LFS_O_RDONLY) => 0;
+    strcpy((char*)buffer, "waka");
+    size = strlen("waka");
+    for (lfs_size_t i = 0; i < filesize/size; i++) {
+        uint8_t rbuffer[4];
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+
+# Below, I don't like these tests. They're fragile and depend _heavily_
+# on the geometry of the block device. But they are valuable. Eventually they
+# should be removed and replaced with generalized tests.
+
+# chained dir exhaustion test
+[cases.test_alloc_chained_dir_exhaustion]
+if = 'ERASE_SIZE == 512'
+defines.ERASE_COUNT = 1024
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // find out max file size
+    lfs_mkdir(&lfs, "exhaustiondir") => 0;
+    for (int i = 0; i < 10; i++) {
+        char path[1024];
+        sprintf(path, "dirwithanexhaustivelylongnameforpadding%d", i);
+        lfs_mkdir(&lfs, path) => 0;
+    }
+    size_t size = strlen("blahblahblahblah");
+    uint8_t buffer[1024];
+    memcpy(buffer, "blahblahblahblah", size);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    int count = 0;
+    int err;
+    while (true) {
+        err = lfs_file_write(&lfs, &file, buffer, size);
+        if (err < 0) {
+            break;
+        }
+
+        count += 1;
+    }
+    err => LFS_ERR_NOSPC;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "exhaustion") => 0;
+    lfs_remove(&lfs, "exhaustiondir") => 0;
+    for (int i = 0; i < 10; i++) {
+        char path[1024];
+        sprintf(path, "dirwithanexhaustivelylongnameforpadding%d", i);
+        lfs_remove(&lfs, path) => 0;
+    }
+
+    // see that chained dir fails
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    for (int i = 0; i < count+1; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_sync(&lfs, &file) => 0;
+
+    for (int i = 0; i < 10; i++) {
+        char path[1024];
+        sprintf(path, "dirwithanexhaustivelylongnameforpadding%d", i);
+        lfs_mkdir(&lfs, path) => 0;
+    }
+
+    lfs_mkdir(&lfs, "exhaustiondir") => LFS_ERR_NOSPC;
+
+    // shorten file to try a second chained dir
+    while (true) {
+        err = lfs_mkdir(&lfs, "exhaustiondir");
+        if (err != LFS_ERR_NOSPC) {
+            break;
+        }
+
+        lfs_ssize_t filesize = lfs_file_size(&lfs, &file);
+        filesize > 0 => true;
+
+        lfs_file_truncate(&lfs, &file, filesize - size) => 0;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    err => 0;
+
+    lfs_mkdir(&lfs, "exhaustiondir2") => LFS_ERR_NOSPC;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# split dir test
+[cases.test_alloc_split_dir]
+if = 'ERASE_SIZE == 512'
+defines.ERASE_COUNT = 1024
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // create one block hole for half a directory
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "bump", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    for (lfs_size_t i = 0; i < cfg->block_size; i += 2) {
+        uint8_t buffer[1024];
+        memcpy(&buffer[i], "hi", 2);
+    }
+    uint8_t buffer[1024];
+    lfs_file_write(&lfs, &file, buffer, cfg->block_size) => cfg->block_size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
+    size_t size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < (cfg->block_count-4)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // remount to force reset of lookahead
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // open hole
+    lfs_remove(&lfs, "bump") => 0;
+
+    lfs_mkdir(&lfs, "splitdir") => 0;
+    lfs_file_open(&lfs, &file, "splitdir/bump",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    for (lfs_size_t i = 0; i < cfg->block_size; i += 2) {
+        memcpy(&buffer[i], "hi", 2);
+    }
+    lfs_file_write(&lfs, &file, buffer, 2*cfg->block_size) => LFS_ERR_NOSPC;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# outdated lookahead test
+[cases.test_alloc_outdated_lookahead]
+if = 'ERASE_SIZE == 512'
+defines.ERASE_COUNT = 1024
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // fill completely with two files
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "exhaustion1",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    size_t size = strlen("blahblahblahblah");
+    uint8_t buffer[1024];
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "exhaustion2",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2+1)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // remount to force reset of lookahead
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // rewrite one file
+    lfs_file_open(&lfs, &file, "exhaustion1",
+            LFS_O_WRONLY | LFS_O_TRUNC) => 0;
+    lfs_file_sync(&lfs, &file) => 0;
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // rewrite second file, this requires lookahead does not
+    // use old population
+    lfs_file_open(&lfs, &file, "exhaustion2",
+            LFS_O_WRONLY | LFS_O_TRUNC) => 0;
+    lfs_file_sync(&lfs, &file) => 0;
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2+1)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# outdated lookahead and split dir test
+[cases.test_alloc_outdated_lookahead_split_dir]
+if = 'ERASE_SIZE == 512'
+defines.ERASE_COUNT = 1024
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // fill completely with two files
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "exhaustion1",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    size_t size = strlen("blahblahblahblah");
+    uint8_t buffer[1024];
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "exhaustion2",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2+1)/2)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // remount to force reset of lookahead
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // rewrite one file with a hole of one block
+    lfs_file_open(&lfs, &file, "exhaustion1",
+            LFS_O_WRONLY | LFS_O_TRUNC) => 0;
+    lfs_file_sync(&lfs, &file) => 0;
+    size = strlen("blahblahblahblah");
+    memcpy(buffer, "blahblahblahblah", size);
+    for (lfs_size_t i = 0;
+            i < ((cfg->block_count-2)/2 - 1)*(cfg->block_size-8);
+            i += size) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // try to allocate a directory, should fail!
+    lfs_mkdir(&lfs, "split") => LFS_ERR_NOSPC;
+
+    // file should not fail
+    lfs_file_open(&lfs, &file, "notasplit",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_write(&lfs, &file, "hi", 2) => 2;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_attrs.toml

@@ -0,0 +1,316 @@
+[cases.test_attrs_get_set]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "hello") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_write(&lfs, &file, "hello", strlen("hello")) => strlen("hello");
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    uint8_t buffer[1024];
+    memset(buffer, 0, sizeof(buffer));
+    lfs_setattr(&lfs, "hello", 'A', "aaaa",   4) => 0;
+    lfs_setattr(&lfs, "hello", 'B', "bbbbbb", 6) => 0;
+    lfs_setattr(&lfs, "hello", 'C', "ccccc",  5) => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => 6;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "bbbbbb", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    lfs_setattr(&lfs, "hello", 'B', "", 0) => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => 0;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",         4) => 0;
+    memcmp(buffer+4,  "\0\0\0\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",        5) => 0;
+
+    lfs_removeattr(&lfs, "hello", 'B') => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => LFS_ERR_NOATTR;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",         4) => 0;
+    memcmp(buffer+4,  "\0\0\0\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",        5) => 0;
+
+    lfs_setattr(&lfs, "hello", 'B', "dddddd", 6) => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => 6;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "dddddd", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    lfs_setattr(&lfs, "hello", 'B', "eee", 3) => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => 3;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "eee\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",     5) => 0;
+
+    lfs_setattr(&lfs, "hello", 'A', buffer, LFS_ATTR_MAX+1) => LFS_ERR_NOSPC;
+    lfs_setattr(&lfs, "hello", 'B', "fffffffff", 9) => 0;
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  6) => 9;
+    lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
+
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    memset(buffer, 0, sizeof(buffer));
+    lfs_getattr(&lfs, "hello", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "hello", 'B', buffer+4,  9) => 9;
+    lfs_getattr(&lfs, "hello", 'C', buffer+13, 5) => 5;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "fffffffff", 9) => 0;
+    memcmp(buffer+13, "ccccc",     5) => 0;
+
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => strlen("hello");
+    memcmp(buffer, "hello", strlen("hello")) => 0;
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_attrs_get_set_root]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "hello") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_write(&lfs, &file, "hello", strlen("hello")) => strlen("hello");
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    uint8_t buffer[1024];
+    memset(buffer, 0, sizeof(buffer));
+    lfs_setattr(&lfs, "/", 'A', "aaaa",   4) => 0;
+    lfs_setattr(&lfs, "/", 'B', "bbbbbb", 6) => 0;
+    lfs_setattr(&lfs, "/", 'C', "ccccc",  5) => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => 6;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "bbbbbb", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    lfs_setattr(&lfs, "/", 'B', "", 0) => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => 0;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",         4) => 0;
+    memcmp(buffer+4,  "\0\0\0\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",        5) => 0;
+
+    lfs_removeattr(&lfs, "/", 'B') => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => LFS_ERR_NOATTR;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",         4) => 0;
+    memcmp(buffer+4,  "\0\0\0\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",        5) => 0;
+
+    lfs_setattr(&lfs, "/", 'B', "dddddd", 6) => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => 6;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "dddddd", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    lfs_setattr(&lfs, "/", 'B', "eee", 3) => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => 3;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "eee\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",     5) => 0;
+
+    lfs_setattr(&lfs, "/", 'A', buffer, LFS_ATTR_MAX+1) => LFS_ERR_NOSPC;
+    lfs_setattr(&lfs, "/", 'B', "fffffffff", 9) => 0;
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  6) => 9;
+    lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    memset(buffer, 0, sizeof(buffer));
+    lfs_getattr(&lfs, "/", 'A', buffer,    4) => 4;
+    lfs_getattr(&lfs, "/", 'B', buffer+4,  9) => 9;
+    lfs_getattr(&lfs, "/", 'C', buffer+13, 5) => 5;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "fffffffff", 9) => 0;
+    memcmp(buffer+13, "ccccc",     5) => 0;
+
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => strlen("hello");
+    memcmp(buffer, "hello", strlen("hello")) => 0;
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_attrs_get_set_file]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "hello") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_write(&lfs, &file, "hello", strlen("hello")) => strlen("hello");
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    uint8_t buffer[1024];
+    memset(buffer, 0, sizeof(buffer));
+    struct lfs_attr attrs1[] = {
+        {'A', buffer,    4},
+        {'B', buffer+4,  6},
+        {'C', buffer+10, 5},
+    };
+    struct lfs_file_config cfg1 = {.attrs=attrs1, .attr_count=3};
+
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1) => 0;
+    memcpy(buffer,    "aaaa",   4);
+    memcpy(buffer+4,  "bbbbbb", 6);
+    memcpy(buffer+10, "ccccc",  5);
+    lfs_file_close(&lfs, &file) => 0;
+    memset(buffer, 0, 15);
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "bbbbbb", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    attrs1[1].size = 0;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memset(buffer, 0, 15);
+    attrs1[1].size = 6;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memcmp(buffer,    "aaaa",         4) => 0;
+    memcmp(buffer+4,  "\0\0\0\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",        5) => 0;
+
+    attrs1[1].size = 6;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1) => 0;
+    memcpy(buffer+4,  "dddddd", 6);
+    lfs_file_close(&lfs, &file) => 0;
+    memset(buffer, 0, 15);
+    attrs1[1].size = 6;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memcmp(buffer,    "aaaa",   4) => 0;
+    memcmp(buffer+4,  "dddddd", 6) => 0;
+    memcmp(buffer+10, "ccccc",  5) => 0;
+
+    attrs1[1].size = 3;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1) => 0;
+    memcpy(buffer+4,  "eee", 3);
+    lfs_file_close(&lfs, &file) => 0;
+    memset(buffer, 0, 15);
+    attrs1[1].size = 6;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "eee\0\0\0", 6) => 0;
+    memcmp(buffer+10, "ccccc",     5) => 0;
+
+    attrs1[0].size = LFS_ATTR_MAX+1;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1)
+        => LFS_ERR_NOSPC;
+
+    struct lfs_attr attrs2[] = {
+        {'A', buffer,    4},
+        {'B', buffer+4,  9},
+        {'C', buffer+13, 5},
+    };
+    struct lfs_file_config cfg2 = {.attrs=attrs2, .attr_count=3};
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDWR, &cfg2) => 0;
+    memcpy(buffer+4,  "fffffffff", 9);
+    lfs_file_close(&lfs, &file) => 0;
+    attrs1[0].size = 4;
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg1) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    memset(buffer, 0, sizeof(buffer));
+    struct lfs_attr attrs3[] = {
+        {'A', buffer,    4},
+        {'B', buffer+4,  9},
+        {'C', buffer+13, 5},
+    };
+    struct lfs_file_config cfg3 = {.attrs=attrs3, .attr_count=3};
+
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_RDONLY, &cfg3) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    memcmp(buffer,    "aaaa",      4) => 0;
+    memcmp(buffer+4,  "fffffffff", 9) => 0;
+    memcmp(buffer+13, "ccccc",     5) => 0;
+
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => strlen("hello");
+    memcmp(buffer, "hello", strlen("hello")) => 0;
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_attrs_deferred_file]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "hello") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "hello/hello", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_write(&lfs, &file, "hello", strlen("hello")) => strlen("hello");
+    lfs_file_close(&lfs, &file);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_setattr(&lfs, "hello/hello", 'B', "fffffffff",  9) => 0;
+    lfs_setattr(&lfs, "hello/hello", 'C', "ccccc",      5) => 0;
+
+    uint8_t buffer[1024];
+    memset(buffer, 0, sizeof(buffer));
+    struct lfs_attr attrs1[] = {
+        {'B', "gggg", 4},
+        {'C', "",     0},
+        {'D', "hhhh", 4},
+    };
+    struct lfs_file_config cfg1 = {.attrs=attrs1, .attr_count=3};
+
+    lfs_file_opencfg(&lfs, &file, "hello/hello", LFS_O_WRONLY, &cfg1) => 0;
+
+    lfs_getattr(&lfs, "hello/hello", 'B', buffer,    9) => 9;
+    lfs_getattr(&lfs, "hello/hello", 'C', buffer+9,  9) => 5;
+    lfs_getattr(&lfs, "hello/hello", 'D', buffer+18, 9) => LFS_ERR_NOATTR;
+    memcmp(buffer,    "fffffffff",          9) => 0;
+    memcmp(buffer+9,  "ccccc\0\0\0\0",      9) => 0;
+    memcmp(buffer+18, "\0\0\0\0\0\0\0\0\0", 9) => 0;
+
+    lfs_file_sync(&lfs, &file) => 0;
+    lfs_getattr(&lfs, "hello/hello", 'B', buffer,    9) => 4;
+    lfs_getattr(&lfs, "hello/hello", 'C', buffer+9,  9) => 0;
+    lfs_getattr(&lfs, "hello/hello", 'D', buffer+18, 9) => 4;
+    memcmp(buffer,    "gggg\0\0\0\0\0",     9) => 0;
+    memcmp(buffer+9,  "\0\0\0\0\0\0\0\0\0", 9) => 0;
+    memcmp(buffer+18, "hhhh\0\0\0\0\0",     9) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_badblocks.toml

@@ -0,0 +1,260 @@
+# bad blocks with block cycles should be tested in test_relocations
+if = '(int32_t)BLOCK_CYCLES == -1'
+
+[cases.test_badblocks_single]
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.ERASE_CYCLES = 0xffffffff
+defines.ERASE_VALUE = [0x00, 0xff, -1]
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+defines.NAMEMULT = 64
+defines.FILEMULT = 1
+code = '''
+    for (lfs_block_t badblock = 2; badblock < BLOCK_COUNT; badblock++) {
+        lfs_emubd_setwear(cfg, badblock-1, 0) => 0;
+        lfs_emubd_setwear(cfg, badblock, 0xffffffff) => 0;
+
+        lfs_t lfs;
+        lfs_format(&lfs, cfg) => 0;
+
+        lfs_mount(&lfs, cfg) => 0;
+        for (int i = 1; i < 10; i++) {
+            uint8_t buffer[1024];
+            for (int j = 0; j < NAMEMULT; j++) {
+                buffer[j] = '0'+i;
+            }
+            buffer[NAMEMULT] = '\0';
+            lfs_mkdir(&lfs, (char*)buffer) => 0;
+
+            buffer[NAMEMULT] = '/';
+            for (int j = 0; j < NAMEMULT; j++) {
+                buffer[j+NAMEMULT+1] = '0'+i;
+            }
+            buffer[2*NAMEMULT+1] = '\0';
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, (char*)buffer,
+                    LFS_O_WRONLY | LFS_O_CREAT) => 0;
+            
+            lfs_size_t size = NAMEMULT;
+            for (int j = 0; j < i*FILEMULT; j++) {
+                lfs_file_write(&lfs, &file, buffer, size) => size;
+            }
+
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        lfs_mount(&lfs, cfg) => 0;
+        for (int i = 1; i < 10; i++) {
+            uint8_t buffer[1024];
+            for (int j = 0; j < NAMEMULT; j++) {
+                buffer[j] = '0'+i;
+            }
+            buffer[NAMEMULT] = '\0';
+            struct lfs_info info;
+            lfs_stat(&lfs, (char*)buffer, &info) => 0;
+            info.type => LFS_TYPE_DIR;
+
+            buffer[NAMEMULT] = '/';
+            for (int j = 0; j < NAMEMULT; j++) {
+                buffer[j+NAMEMULT+1] = '0'+i;
+            }
+            buffer[2*NAMEMULT+1] = '\0';
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, (char*)buffer, LFS_O_RDONLY) => 0;
+            
+            int size = NAMEMULT;
+            for (int j = 0; j < i*FILEMULT; j++) {
+                uint8_t rbuffer[1024];
+                lfs_file_read(&lfs, &file, rbuffer, size) => size;
+                memcmp(buffer, rbuffer, size) => 0;
+            }
+
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+    }
+'''
+
+[cases.test_badblocks_region_corruption] # (causes cascading failures)
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.ERASE_CYCLES = 0xffffffff
+defines.ERASE_VALUE = [0x00, 0xff, -1]
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+defines.NAMEMULT = 64
+defines.FILEMULT = 1
+code = '''
+    for (lfs_block_t i = 0; i < (BLOCK_COUNT-2)/2; i++) {
+        lfs_emubd_setwear(cfg, i+2, 0xffffffff) => 0;
+    }
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 1; i < 10; i++) {
+        uint8_t buffer[1024];
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j] = '0'+i;
+        }
+        buffer[NAMEMULT] = '\0';
+        lfs_mkdir(&lfs, (char*)buffer) => 0;
+
+        buffer[NAMEMULT] = '/';
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j+NAMEMULT+1] = '0'+i;
+        }
+        buffer[2*NAMEMULT+1] = '\0';
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, (char*)buffer,
+                LFS_O_WRONLY | LFS_O_CREAT) => 0;
+        
+        lfs_size_t size = NAMEMULT;
+        for (int j = 0; j < i*FILEMULT; j++) {
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+        }
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 1; i < 10; i++) {
+        uint8_t buffer[1024];
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j] = '0'+i;
+        }
+        buffer[NAMEMULT] = '\0';
+        struct lfs_info info;
+        lfs_stat(&lfs, (char*)buffer, &info) => 0;
+        info.type => LFS_TYPE_DIR;
+
+        buffer[NAMEMULT] = '/';
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j+NAMEMULT+1] = '0'+i;
+        }
+        buffer[2*NAMEMULT+1] = '\0';
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, (char*)buffer, LFS_O_RDONLY) => 0;
+        
+        lfs_size_t size = NAMEMULT;
+        for (int j = 0; j < i*FILEMULT; j++) {
+            uint8_t rbuffer[1024];
+            lfs_file_read(&lfs, &file, rbuffer, size) => size;
+            memcmp(buffer, rbuffer, size) => 0;
+        }
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_badblocks_alternating_corruption] # (causes cascading failures)
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.ERASE_CYCLES = 0xffffffff
+defines.ERASE_VALUE = [0x00, 0xff, -1]
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+defines.NAMEMULT = 64
+defines.FILEMULT = 1
+code = '''
+    for (lfs_block_t i = 0; i < (BLOCK_COUNT-2)/2; i++) {
+        lfs_emubd_setwear(cfg, (2*i) + 2, 0xffffffff) => 0;
+    }
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 1; i < 10; i++) {
+        uint8_t buffer[1024];
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j] = '0'+i;
+        }
+        buffer[NAMEMULT] = '\0';
+        lfs_mkdir(&lfs, (char*)buffer) => 0;
+
+        buffer[NAMEMULT] = '/';
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j+NAMEMULT+1] = '0'+i;
+        }
+        buffer[2*NAMEMULT+1] = '\0';
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, (char*)buffer,
+                LFS_O_WRONLY | LFS_O_CREAT) => 0;
+        
+        lfs_size_t size = NAMEMULT;
+        for (int j = 0; j < i*FILEMULT; j++) {
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+        }
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 1; i < 10; i++) {
+        uint8_t buffer[1024];
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j] = '0'+i;
+        }
+        buffer[NAMEMULT] = '\0';
+        struct lfs_info info;
+        lfs_stat(&lfs, (char*)buffer, &info) => 0;
+        info.type => LFS_TYPE_DIR;
+
+        buffer[NAMEMULT] = '/';
+        for (int j = 0; j < NAMEMULT; j++) {
+            buffer[j+NAMEMULT+1] = '0'+i;
+        }
+        buffer[2*NAMEMULT+1] = '\0';
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, (char*)buffer, LFS_O_RDONLY) => 0;
+        
+        lfs_size_t size = NAMEMULT;
+        for (int j = 0; j < i*FILEMULT; j++) {
+            uint8_t rbuffer[1024];
+            lfs_file_read(&lfs, &file, rbuffer, size) => size;
+            memcmp(buffer, rbuffer, size) => 0;
+        }
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# other corner cases
+[cases.test_badblocks_superblocks] # (corrupt 1 or 0)
+defines.ERASE_CYCLES = 0xffffffff
+defines.ERASE_VALUE = [0x00, 0xff, -1]
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+code = '''
+    lfs_emubd_setwear(cfg, 0, 0xffffffff) => 0;
+    lfs_emubd_setwear(cfg, 1, 0xffffffff) => 0;
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => LFS_ERR_NOSPC;
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''

kernel/fs/littlefs/tests/test_bd.toml

@@ -0,0 +1,248 @@
+# These tests don't really test littlefs at all, they are here only to make
+# sure the underlying block device is working.
+#
+# Note we use 251, a prime, in places to avoid aliasing powers of 2.
+# 
+
+[cases.test_bd_one_block]
+defines.READ = ['READ_SIZE', 'BLOCK_SIZE']
+defines.PROG = ['PROG_SIZE', 'BLOCK_SIZE']
+code = '''
+    uint8_t buffer[lfs_max(READ, PROG)];
+
+    // write data
+    cfg->erase(cfg, 0) => 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+        for (lfs_off_t j = 0; j < PROG; j++) {
+            buffer[j] = (i+j) % 251;
+        }
+        cfg->prog(cfg, 0, i, buffer, PROG) => 0;
+    }
+
+    // read data
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, 0, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (i+j) % 251);
+        }
+    }
+'''
+
+[cases.test_bd_two_block]
+defines.READ = ['READ_SIZE', 'BLOCK_SIZE']
+defines.PROG = ['PROG_SIZE', 'BLOCK_SIZE']
+code = '''
+    uint8_t buffer[lfs_max(READ, PROG)];
+    lfs_block_t block;
+
+    // write block 0
+    block = 0;
+    cfg->erase(cfg, block) => 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+        for (lfs_off_t j = 0; j < PROG; j++) {
+            buffer[j] = (block+i+j) % 251;
+        }
+        cfg->prog(cfg, block, i, buffer, PROG) => 0;
+    }
+
+    // read block 0
+    block = 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+
+    // write block 1
+    block = 1;
+    cfg->erase(cfg, block) => 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+        for (lfs_off_t j = 0; j < PROG; j++) {
+            buffer[j] = (block+i+j) % 251;
+        }
+        cfg->prog(cfg, block, i, buffer, PROG) => 0;
+    }
+
+    // read block 1
+    block = 1;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+
+    // read block 0 again
+    block = 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+'''
+
+[cases.test_bd_last_block]
+defines.READ = ['READ_SIZE', 'BLOCK_SIZE']
+defines.PROG = ['PROG_SIZE', 'BLOCK_SIZE']
+code = '''
+    uint8_t buffer[lfs_max(READ, PROG)];
+    lfs_block_t block;
+
+    // write block 0
+    block = 0;
+    cfg->erase(cfg, block) => 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+        for (lfs_off_t j = 0; j < PROG; j++) {
+            buffer[j] = (block+i+j) % 251;
+        }
+        cfg->prog(cfg, block, i, buffer, PROG) => 0;
+    }
+
+    // read block 0
+    block = 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+
+    // write block n-1
+    block = cfg->block_count-1;
+    cfg->erase(cfg, block) => 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+        for (lfs_off_t j = 0; j < PROG; j++) {
+            buffer[j] = (block+i+j) % 251;
+        }
+        cfg->prog(cfg, block, i, buffer, PROG) => 0;
+    }
+
+    // read block n-1
+    block = cfg->block_count-1;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+
+    // read block 0 again
+    block = 0;
+    for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+        cfg->read(cfg, block, i, buffer, READ) => 0;
+
+        for (lfs_off_t j = 0; j < READ; j++) {
+            LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+        }
+    }
+'''
+
+[cases.test_bd_powers_of_two]
+defines.READ = ['READ_SIZE', 'BLOCK_SIZE']
+defines.PROG = ['PROG_SIZE', 'BLOCK_SIZE']
+code = '''
+    uint8_t buffer[lfs_max(READ, PROG)];
+
+    // write/read every power of 2
+    lfs_block_t block = 1;
+    while (block < cfg->block_count) {
+        // write
+        cfg->erase(cfg, block) => 0;
+        for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+            for (lfs_off_t j = 0; j < PROG; j++) {
+                buffer[j] = (block+i+j) % 251;
+            }
+            cfg->prog(cfg, block, i, buffer, PROG) => 0;
+        }
+
+        // read
+        for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+            cfg->read(cfg, block, i, buffer, READ) => 0;
+
+            for (lfs_off_t j = 0; j < READ; j++) {
+                LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+            }
+        }
+
+        block *= 2;
+    }
+
+    // read every power of 2 again
+    block = 1;
+    while (block < cfg->block_count) {
+        // read
+        for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+            cfg->read(cfg, block, i, buffer, READ) => 0;
+
+            for (lfs_off_t j = 0; j < READ; j++) {
+                LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+            }
+        }
+
+        block *= 2;
+    }
+'''
+
+[cases.test_bd_fibonacci]
+defines.READ = ['READ_SIZE', 'BLOCK_SIZE']
+defines.PROG = ['PROG_SIZE', 'BLOCK_SIZE']
+code = '''
+    uint8_t buffer[lfs_max(READ, PROG)];
+
+    // write/read every fibonacci number on our device
+    lfs_block_t block = 1;
+    lfs_block_t block_ = 1;
+    while (block < cfg->block_count) {
+        // write
+        cfg->erase(cfg, block) => 0;
+        for (lfs_off_t i = 0; i < cfg->block_size; i += PROG) {
+            for (lfs_off_t j = 0; j < PROG; j++) {
+                buffer[j] = (block+i+j) % 251;
+            }
+            cfg->prog(cfg, block, i, buffer, PROG) => 0;
+        }
+
+        // read
+        for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+            cfg->read(cfg, block, i, buffer, READ) => 0;
+
+            for (lfs_off_t j = 0; j < READ; j++) {
+                LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+            }
+        }
+
+        lfs_block_t nblock = block + block_;
+        block_ = block;
+        block = nblock;
+    }
+
+    // read every fibonacci number again
+    block = 1;
+    block_ = 1;
+    while (block < cfg->block_count) {
+        // read
+        for (lfs_off_t i = 0; i < cfg->block_size; i += READ) {
+            cfg->read(cfg, block, i, buffer, READ) => 0;
+
+            for (lfs_off_t j = 0; j < READ; j++) {
+                LFS_ASSERT(buffer[j] == (block+i+j) % 251);
+            }
+        }
+
+        lfs_block_t nblock = block + block_;
+        block_ = block;
+        block = nblock;
+    }
+'''
+
+
+
+

kernel/fs/littlefs/tests/test_entries.toml

@@ -0,0 +1,642 @@
+# These tests are for some specific corner cases with neighboring inline files.
+# Note that these tests are intended for 512 byte inline sizes. They should
+# still pass with other inline sizes but wouldn't be testing anything.
+
+defines.CACHE_SIZE = 512
+if = 'CACHE_SIZE % PROG_SIZE == 0 && CACHE_SIZE == 512'
+
+[cases.test_entries_grow]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 20
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 20;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 20
+    sprintf(path, "hi2"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 20
+    sprintf(path, "hi3"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi0 20
+    sprintf(path, "hi0"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 20
+    sprintf(path, "hi2"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 20
+    sprintf(path, "hi3"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_shrink]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 20
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 20;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 20
+    sprintf(path, "hi2"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 20
+    sprintf(path, "hi3"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi0 20
+    sprintf(path, "hi0"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 20
+    sprintf(path, "hi2"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 20
+    sprintf(path, "hi3"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_spill]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 200
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_push_spill]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 200
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_push_spill_two]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 200
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi4 200
+    sprintf(path, "hi4"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi1 20
+    sprintf(path, "hi1"); size = 20;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi4 200
+    sprintf(path, "hi4"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_drop]
+code = '''
+    uint8_t wbuffer[1024];
+    uint8_t rbuffer[1024];
+
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    // write hi0 200
+    char path[1024];
+    lfs_size_t size;
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi1 200
+    sprintf(path, "hi1"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    // write hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "hi1") => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "hi1", &info) => LFS_ERR_NOENT;
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi2 200
+    sprintf(path, "hi2"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "hi2") => 0;
+    lfs_stat(&lfs, "hi2", &info) => LFS_ERR_NOENT;
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    // read hi3 200
+    sprintf(path, "hi3"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "hi3") => 0;
+    lfs_stat(&lfs, "hi3", &info) => LFS_ERR_NOENT;
+    // read hi0 200
+    sprintf(path, "hi0"); size = 200;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_remove(&lfs, "hi0") => 0;
+    lfs_stat(&lfs, "hi0", &info) => LFS_ERR_NOENT;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_create_too_big]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    char path[1024];
+    memset(path, 'm', 200);
+    path[200] = '\0';
+
+    lfs_size_t size = 400;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    uint8_t wbuffer[1024];
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    size = 400;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    uint8_t rbuffer[1024];
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_entries_resize_too_big]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    char path[1024];
+    memset(path, 'm', 200);
+    path[200] = '\0';
+
+    lfs_size_t size = 40;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    uint8_t wbuffer[1024];
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    size = 40;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    uint8_t rbuffer[1024];
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+
+    size = 400;
+    lfs_file_open(&lfs, &file, path,
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    memset(wbuffer, 'c', size);
+    lfs_file_write(&lfs, &file, wbuffer, size) => size;
+    lfs_file_close(&lfs, &file) => 0;
+
+    size = 400;
+    lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, rbuffer, size) => size;
+    memcmp(rbuffer, wbuffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_evil.toml

@@ -0,0 +1,306 @@
+# Tests for recovering from conditions which shouldn't normally
+# happen during normal operation of littlefs
+
+# invalid pointer tests (outside of block_count)
+
+[cases.test_evil_invalid_tail_pointer]
+defines.TAIL_TYPE = ['LFS_TYPE_HARDTAIL', 'LFS_TYPE_SOFTTAIL']
+defines.INVALSET = [0x3, 0x1, 0x2]
+in = "lfs.c"
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // change tail-pointer to invalid pointers
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_HARDTAIL, 0x3ff, 8),
+                (lfs_block_t[2]){
+                    (INVALSET & 0x1) ? 0xcccccccc : 0,
+                    (INVALSET & 0x2) ? 0xcccccccc : 0}})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that mount fails gracefully
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''
+
+[cases.test_evil_invalid_dir_pointer]
+defines.INVALSET = [0x3, 0x1, 0x2]
+in = "lfs.c"
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // make a dir
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "dir_here") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // change the dir pointer to be invalid
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    // make sure id 1 == our directory
+    uint8_t buffer[1024];
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x700, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_NAME, 1, strlen("dir_here")), buffer)
+                => LFS_MKTAG(LFS_TYPE_DIR, 1, strlen("dir_here"));
+    assert(memcmp((char*)buffer, "dir_here", strlen("dir_here")) == 0);
+    // change dir pointer
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 1, 8),
+                (lfs_block_t[2]){
+                    (INVALSET & 0x1) ? 0xcccccccc : 0,
+                    (INVALSET & 0x2) ? 0xcccccccc : 0}})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that accessing our bad dir fails, note there's a number
+    // of ways to access the dir, some can fail, but some don't
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "dir_here", &info) => 0;
+    assert(strcmp(info.name, "dir_here") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "dir_here") => LFS_ERR_CORRUPT;
+    lfs_stat(&lfs, "dir_here/file_here", &info) => LFS_ERR_CORRUPT;
+    lfs_dir_open(&lfs, &dir, "dir_here/dir_here") => LFS_ERR_CORRUPT;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "dir_here/file_here",
+            LFS_O_RDONLY) => LFS_ERR_CORRUPT;
+    lfs_file_open(&lfs, &file, "dir_here/file_here",
+            LFS_O_WRONLY | LFS_O_CREAT) => LFS_ERR_CORRUPT;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_evil_invalid_file_pointer]
+in = "lfs.c"
+defines.SIZE = [10, 1000, 100000] # faked file size
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // make a file
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "file_here",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // change the file pointer to be invalid
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    // make sure id 1 == our file
+    uint8_t buffer[1024];
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x700, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_NAME, 1, strlen("file_here")), buffer)
+                => LFS_MKTAG(LFS_TYPE_REG, 1, strlen("file_here"));
+    assert(memcmp((char*)buffer, "file_here", strlen("file_here")) == 0);
+    // change file pointer
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_CTZSTRUCT, 1, sizeof(struct lfs_ctz)),
+                &(struct lfs_ctz){0xcccccccc, lfs_tole32(SIZE)}})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that accessing our bad file fails, note there's a number
+    // of ways to access the dir, some can fail, but some don't
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "file_here", &info) => 0;
+    assert(strcmp(info.name, "file_here") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    assert(info.size == SIZE);
+
+    lfs_file_open(&lfs, &file, "file_here", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, SIZE) => LFS_ERR_CORRUPT;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // any allocs that traverse CTZ must unfortunately must fail
+    if (SIZE > 2*BLOCK_SIZE) {
+        lfs_mkdir(&lfs, "dir_here") => LFS_ERR_CORRUPT;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_evil_invalid_ctz_pointer] # invalid pointer in CTZ skip-list test
+defines.SIZE = ['2*BLOCK_SIZE', '3*BLOCK_SIZE', '4*BLOCK_SIZE']
+in = "lfs.c"
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // make a file
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "file_here",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    for (int i = 0; i < SIZE; i++) {
+        char c = 'c';
+        lfs_file_write(&lfs, &file, &c, 1) => 1;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+    // change pointer in CTZ skip-list to be invalid
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    // make sure id 1 == our file and get our CTZ structure
+    uint8_t buffer[4*BLOCK_SIZE];
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x700, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_NAME, 1, strlen("file_here")), buffer)
+                => LFS_MKTAG(LFS_TYPE_REG, 1, strlen("file_here"));
+    assert(memcmp((char*)buffer, "file_here", strlen("file_here")) == 0);
+    struct lfs_ctz ctz;
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x700, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_STRUCT, 1, sizeof(struct lfs_ctz)), &ctz)
+                => LFS_MKTAG(LFS_TYPE_CTZSTRUCT, 1, sizeof(struct lfs_ctz));
+    lfs_ctz_fromle32(&ctz);
+    // rewrite block to contain bad pointer
+    uint8_t bbuffer[BLOCK_SIZE];
+    cfg->read(cfg, ctz.head, 0, bbuffer, BLOCK_SIZE) => 0;
+    uint32_t bad = lfs_tole32(0xcccccccc);
+    memcpy(&bbuffer[0], &bad, sizeof(bad));
+    memcpy(&bbuffer[4], &bad, sizeof(bad));
+    cfg->erase(cfg, ctz.head) => 0;
+    cfg->prog(cfg, ctz.head, 0, bbuffer, BLOCK_SIZE) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that accessing our bad file fails, note there's a number
+    // of ways to access the dir, some can fail, but some don't
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "file_here", &info) => 0;
+    assert(strcmp(info.name, "file_here") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    assert(info.size == SIZE);
+
+    lfs_file_open(&lfs, &file, "file_here", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, SIZE) => LFS_ERR_CORRUPT;
+    lfs_file_close(&lfs, &file) => 0;
+
+    // any allocs that traverse CTZ must unfortunately must fail
+    if (SIZE > 2*BLOCK_SIZE) {
+        lfs_mkdir(&lfs, "dir_here") => LFS_ERR_CORRUPT;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+
+[cases.test_evil_invalid_gstate_pointer]
+defines.INVALSET = [0x3, 0x1, 0x2]
+in = "lfs.c"
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // create an invalid gstate
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_fs_prepmove(&lfs, 1, (lfs_block_t [2]){
+            (INVALSET & 0x1) ? 0xcccccccc : 0,
+            (INVALSET & 0x2) ? 0xcccccccc : 0});
+    lfs_dir_commit(&lfs, &mdir, NULL, 0) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that mount fails gracefully
+    // mount may not fail, but our first alloc should fail when
+    // we try to fix the gstate
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "should_fail") => LFS_ERR_CORRUPT;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# cycle detection/recovery tests
+
+[cases.test_evil_mdir_loop] # metadata-pair threaded-list loop test
+in = "lfs.c"
+code = '''
+    // create littlefs
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // change tail-pointer to point to ourself
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_HARDTAIL, 0x3ff, 8),
+                (lfs_block_t[2]){0, 1}})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that mount fails gracefully
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''
+
+[cases.test_evil_mdir_loop2] # metadata-pair threaded-list 2-length loop test
+in = "lfs.c"
+code = '''
+    // create littlefs with child dir
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // find child
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_block_t pair[2];
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x7ff, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 1, sizeof(pair)), pair)
+                => LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 1, sizeof(pair));
+    lfs_pair_fromle32(pair);
+    // change tail-pointer to point to root
+    lfs_dir_fetch(&lfs, &mdir, pair) => 0;
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_HARDTAIL, 0x3ff, 8),
+                (lfs_block_t[2]){0, 1}})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that mount fails gracefully
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''
+
+[cases.test_evil_mdir_loop_child] # metadata-pair threaded-list 1-length child loop test
+in = "lfs.c"
+code = '''
+    // create littlefs with child dir
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // find child
+    lfs_init(&lfs, cfg) => 0;
+    lfs_mdir_t mdir;
+    lfs_block_t pair[2];
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_get(&lfs, &mdir,
+            LFS_MKTAG(0x7ff, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 1, sizeof(pair)), pair)
+                => LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 1, sizeof(pair));
+    lfs_pair_fromle32(pair);
+    // change tail-pointer to point to ourself
+    lfs_dir_fetch(&lfs, &mdir, pair) => 0;
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_HARDTAIL, 0x3ff, 8), pair})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // test that mount fails gracefully
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''

kernel/fs/littlefs/tests/test_exhaustion.toml

@@ -0,0 +1,505 @@
+# test running a filesystem to exhaustion
+[cases.test_exhaustion_normal]
+defines.ERASE_CYCLES = 10
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.BLOCK_CYCLES = 'ERASE_CYCLES / 2'
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+defines.FILES = 10
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "roadrunner") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    uint32_t cycle = 0;
+    while (true) {
+        lfs_mount(&lfs, cfg) => 0;
+        for (uint32_t i = 0; i < FILES; i++) {
+            // chose name, roughly random seed, and random 2^n size
+            char path[1024];
+            sprintf(path, "roadrunner/test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path,
+                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                lfs_ssize_t res = lfs_file_write(&lfs, &file, &c, 1);
+                assert(res == 1 || res == LFS_ERR_NOSPC);
+                if (res == LFS_ERR_NOSPC) {
+                    int err = lfs_file_close(&lfs, &file);
+                    assert(err == 0 || err == LFS_ERR_NOSPC);
+                    lfs_unmount(&lfs) => 0;
+                    goto exhausted;
+                }
+            }
+
+            int err = lfs_file_close(&lfs, &file);
+            assert(err == 0 || err == LFS_ERR_NOSPC);
+            if (err == LFS_ERR_NOSPC) {
+                lfs_unmount(&lfs) => 0;
+                goto exhausted;
+            }
+        }
+
+        for (uint32_t i = 0; i < FILES; i++) {
+            // check for errors
+            char path[1024];
+            sprintf(path, "roadrunner/test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                char r;
+                lfs_file_read(&lfs, &file, &r, 1) => 1;
+                assert(r == c);
+            }
+
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        cycle += 1;
+    }
+
+exhausted:
+    // should still be readable
+    lfs_mount(&lfs, cfg) => 0;
+    for (uint32_t i = 0; i < FILES; i++) {
+        // check for errors
+        char path[1024];
+        sprintf(path, "roadrunner/test%d", i);
+        struct lfs_info info;
+        lfs_stat(&lfs, path, &info) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    LFS_WARN("completed %d cycles", cycle);
+'''
+
+# test running a filesystem to exhaustion
+# which also requires expanding superblocks
+[cases.test_exhaustion_superblocks]
+defines.ERASE_CYCLES = 10
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.BLOCK_CYCLES = 'ERASE_CYCLES / 2'
+defines.BADBLOCK_BEHAVIOR = [
+    'LFS_EMUBD_BADBLOCK_PROGERROR',
+    'LFS_EMUBD_BADBLOCK_ERASEERROR',
+    'LFS_EMUBD_BADBLOCK_READERROR',
+    'LFS_EMUBD_BADBLOCK_PROGNOOP',
+    'LFS_EMUBD_BADBLOCK_ERASENOOP',
+]
+defines.FILES = 10
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    uint32_t cycle = 0;
+    while (true) {
+        lfs_mount(&lfs, cfg) => 0;
+        for (uint32_t i = 0; i < FILES; i++) {
+            // chose name, roughly random seed, and random 2^n size
+            char path[1024];
+            sprintf(path, "test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path,
+                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                lfs_ssize_t res = lfs_file_write(&lfs, &file, &c, 1);
+                assert(res == 1 || res == LFS_ERR_NOSPC);
+                if (res == LFS_ERR_NOSPC) {
+                    int err = lfs_file_close(&lfs, &file);
+                    assert(err == 0 || err == LFS_ERR_NOSPC);
+                    lfs_unmount(&lfs) => 0;
+                    goto exhausted;
+                }
+            }
+
+            int err = lfs_file_close(&lfs, &file);
+            assert(err == 0 || err == LFS_ERR_NOSPC);
+            if (err == LFS_ERR_NOSPC) {
+                lfs_unmount(&lfs) => 0;
+                goto exhausted;
+            }
+        }
+
+        for (uint32_t i = 0; i < FILES; i++) {
+            // check for errors
+            char path[1024];
+            sprintf(path, "test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                char r;
+                lfs_file_read(&lfs, &file, &r, 1) => 1;
+                assert(r == c);
+            }
+
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        cycle += 1;
+    }
+
+exhausted:
+    // should still be readable
+    lfs_mount(&lfs, cfg) => 0;
+    for (uint32_t i = 0; i < FILES; i++) {
+        // check for errors
+        char path[1024];
+        struct lfs_info info;
+        sprintf(path, "test%d", i);
+        lfs_stat(&lfs, path, &info) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    LFS_WARN("completed %d cycles", cycle);
+'''
+
+# These are a sort of high-level litmus test for wear-leveling. One definition
+# of wear-leveling is that increasing a block device's space translates directly
+# into increasing the block devices lifetime. This is something we can actually
+# check for.
+
+# wear-level test running a filesystem to exhaustion
+[cases.test_exhuastion_wear_leveling]
+defines.ERASE_CYCLES = 20
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.BLOCK_CYCLES = 'ERASE_CYCLES / 2'
+defines.FILES = 10
+code = '''
+    uint32_t run_cycles[2];
+    const uint32_t run_block_count[2] = {BLOCK_COUNT/2, BLOCK_COUNT};
+
+    for (int run = 0; run < 2; run++) {
+        for (lfs_block_t b = 0; b < BLOCK_COUNT; b++) {
+            lfs_emubd_setwear(cfg, b,
+                    (b < run_block_count[run]) ? 0 : ERASE_CYCLES) => 0;
+        }
+
+        lfs_t lfs;
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+        lfs_mkdir(&lfs, "roadrunner") => 0;
+        lfs_unmount(&lfs) => 0;
+
+        uint32_t cycle = 0;
+        while (true) {
+            lfs_mount(&lfs, cfg) => 0;
+            for (uint32_t i = 0; i < FILES; i++) {
+                // chose name, roughly random seed, and random 2^n size
+                char path[1024];
+                sprintf(path, "roadrunner/test%d", i);
+                uint32_t prng = cycle * i;
+                lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+                lfs_file_t file;
+                lfs_file_open(&lfs, &file, path,
+                        LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+                for (lfs_size_t j = 0; j < size; j++) {
+                    char c = 'a' + (TEST_PRNG(&prng) % 26);
+                    lfs_ssize_t res = lfs_file_write(&lfs, &file, &c, 1);
+                    assert(res == 1 || res == LFS_ERR_NOSPC);
+                    if (res == LFS_ERR_NOSPC) {
+                        int err = lfs_file_close(&lfs, &file);
+                        assert(err == 0 || err == LFS_ERR_NOSPC);
+                        lfs_unmount(&lfs) => 0;
+                        goto exhausted;
+                    }
+                }
+
+                int err = lfs_file_close(&lfs, &file);
+                assert(err == 0 || err == LFS_ERR_NOSPC);
+                if (err == LFS_ERR_NOSPC) {
+                    lfs_unmount(&lfs) => 0;
+                    goto exhausted;
+                }
+            }
+
+            for (uint32_t i = 0; i < FILES; i++) {
+                // check for errors
+                char path[1024];
+                sprintf(path, "roadrunner/test%d", i);
+                uint32_t prng = cycle * i;
+                lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+                lfs_file_t file;
+                lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+                for (lfs_size_t j = 0; j < size; j++) {
+                    char c = 'a' + (TEST_PRNG(&prng) % 26);
+                    char r;
+                    lfs_file_read(&lfs, &file, &r, 1) => 1;
+                    assert(r == c);
+                }
+
+                lfs_file_close(&lfs, &file) => 0;
+            }
+            lfs_unmount(&lfs) => 0;
+
+            cycle += 1;
+        }
+
+exhausted:
+        // should still be readable
+        lfs_mount(&lfs, cfg) => 0;
+        for (uint32_t i = 0; i < FILES; i++) {
+            // check for errors
+            char path[1024];
+            struct lfs_info info;
+            sprintf(path, "roadrunner/test%d", i);
+            lfs_stat(&lfs, path, &info) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        run_cycles[run] = cycle;
+        LFS_WARN("completed %d blocks %d cycles",
+                run_block_count[run], run_cycles[run]);
+    }
+
+    // check we increased the lifetime by 2x with ~10% error
+    LFS_ASSERT(run_cycles[1]*110/100 > 2*run_cycles[0]);
+'''
+
+# wear-level test + expanding superblock
+[cases.test_exhaustion_wear_leveling_superblocks]
+defines.ERASE_CYCLES = 20
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.BLOCK_CYCLES = 'ERASE_CYCLES / 2'
+defines.FILES = 10
+code = '''
+    uint32_t run_cycles[2];
+    const uint32_t run_block_count[2] = {BLOCK_COUNT/2, BLOCK_COUNT};
+
+    for (int run = 0; run < 2; run++) {
+        for (lfs_block_t b = 0; b < BLOCK_COUNT; b++) {
+            lfs_emubd_setwear(cfg, b,
+                    (b < run_block_count[run]) ? 0 : ERASE_CYCLES) => 0;
+        }
+
+        lfs_t lfs;
+        lfs_format(&lfs, cfg) => 0;
+
+        uint32_t cycle = 0;
+        while (true) {
+            lfs_mount(&lfs, cfg) => 0;
+            for (uint32_t i = 0; i < FILES; i++) {
+                // chose name, roughly random seed, and random 2^n size
+                char path[1024];
+                sprintf(path, "test%d", i);
+                uint32_t prng = cycle * i;
+                lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+                lfs_file_t file;
+                lfs_file_open(&lfs, &file, path,
+                        LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+                for (lfs_size_t j = 0; j < size; j++) {
+                    char c = 'a' + (TEST_PRNG(&prng) % 26);
+                    lfs_ssize_t res = lfs_file_write(&lfs, &file, &c, 1);
+                    assert(res == 1 || res == LFS_ERR_NOSPC);
+                    if (res == LFS_ERR_NOSPC) {
+                        int err = lfs_file_close(&lfs, &file);
+                        assert(err == 0 || err == LFS_ERR_NOSPC);
+                        lfs_unmount(&lfs) => 0;
+                        goto exhausted;
+                    }
+                }
+
+                int err = lfs_file_close(&lfs, &file);
+                assert(err == 0 || err == LFS_ERR_NOSPC);
+                if (err == LFS_ERR_NOSPC) {
+                    lfs_unmount(&lfs) => 0;
+                    goto exhausted;
+                }
+            }
+
+            for (uint32_t i = 0; i < FILES; i++) {
+                // check for errors
+                char path[1024];
+                sprintf(path, "test%d", i);
+                uint32_t prng = cycle * i;
+                lfs_size_t size = 1 << ((TEST_PRNG(&prng) % 10)+2);
+
+                lfs_file_t file;
+                lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+                for (lfs_size_t j = 0; j < size; j++) {
+                    char c = 'a' + (TEST_PRNG(&prng) % 26);
+                    char r;
+                    lfs_file_read(&lfs, &file, &r, 1) => 1;
+                    assert(r == c);
+                }
+
+                lfs_file_close(&lfs, &file) => 0;
+            }
+            lfs_unmount(&lfs) => 0;
+
+            cycle += 1;
+        }
+
+exhausted:
+        // should still be readable
+        lfs_mount(&lfs, cfg) => 0;
+        for (uint32_t i = 0; i < FILES; i++) {
+            // check for errors
+            char path[1024];
+            struct lfs_info info;
+            sprintf(path, "test%d", i);
+            lfs_stat(&lfs, path, &info) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        run_cycles[run] = cycle;
+        LFS_WARN("completed %d blocks %d cycles",
+                run_block_count[run], run_cycles[run]);
+    }
+
+    // check we increased the lifetime by 2x with ~10% error
+    LFS_ASSERT(run_cycles[1]*110/100 > 2*run_cycles[0]);
+'''
+
+# test that we wear blocks roughly evenly
+[cases.test_exhaustion_wear_distribution]
+defines.ERASE_CYCLES = 0xffffffff
+defines.ERASE_COUNT = 256 # small bd so test runs faster
+defines.BLOCK_CYCLES = [5, 4, 3, 2, 1]
+defines.CYCLES = 100
+defines.FILES = 10
+if = 'BLOCK_CYCLES < CYCLES/10'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "roadrunner") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    uint32_t cycle = 0;
+    while (cycle < CYCLES) {
+        lfs_mount(&lfs, cfg) => 0;
+        for (uint32_t i = 0; i < FILES; i++) {
+            // chose name, roughly random seed, and random 2^n size
+            char path[1024];
+            sprintf(path, "roadrunner/test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << 4; //((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path,
+                    LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                lfs_ssize_t res = lfs_file_write(&lfs, &file, &c, 1);
+                assert(res == 1 || res == LFS_ERR_NOSPC);
+                if (res == LFS_ERR_NOSPC) {
+                    int err = lfs_file_close(&lfs, &file);
+                    assert(err == 0 || err == LFS_ERR_NOSPC);
+                    lfs_unmount(&lfs) => 0;
+                    goto exhausted;
+                }
+            }
+
+            int err = lfs_file_close(&lfs, &file);
+            assert(err == 0 || err == LFS_ERR_NOSPC);
+            if (err == LFS_ERR_NOSPC) {
+                lfs_unmount(&lfs) => 0;
+                goto exhausted;
+            }
+        }
+
+        for (uint32_t i = 0; i < FILES; i++) {
+            // check for errors
+            char path[1024];
+            sprintf(path, "roadrunner/test%d", i);
+            uint32_t prng = cycle * i;
+            lfs_size_t size = 1 << 4; //((TEST_PRNG(&prng) % 10)+2);
+
+            lfs_file_t file;
+            lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+            for (lfs_size_t j = 0; j < size; j++) {
+                char c = 'a' + (TEST_PRNG(&prng) % 26);
+                char r;
+                lfs_file_read(&lfs, &file, &r, 1) => 1;
+                assert(r == c);
+            }
+
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_unmount(&lfs) => 0;
+
+        cycle += 1;
+    }
+
+exhausted:
+    // should still be readable
+    lfs_mount(&lfs, cfg) => 0;
+    for (uint32_t i = 0; i < FILES; i++) {
+        // check for errors
+        char path[1024];
+        struct lfs_info info;
+        sprintf(path, "roadrunner/test%d", i);
+        lfs_stat(&lfs, path, &info) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    LFS_WARN("completed %d cycles", cycle);
+
+    // check the wear on our block device
+    lfs_emubd_wear_t minwear = -1;
+    lfs_emubd_wear_t totalwear = 0;
+    lfs_emubd_wear_t maxwear = 0;
+    // skip 0 and 1 as superblock movement is intentionally avoided
+    for (lfs_block_t b = 2; b < BLOCK_COUNT; b++) {
+        lfs_emubd_wear_t wear = lfs_emubd_wear(cfg, b);
+        printf("%08x: wear %d\n", b, wear);
+        assert(wear >= 0);
+        if (wear < minwear) {
+            minwear = wear;
+        }
+        if (wear > maxwear) {
+            maxwear = wear;
+        }
+        totalwear += wear;
+    }
+    lfs_emubd_wear_t avgwear = totalwear / BLOCK_COUNT;
+    LFS_WARN("max wear: %d cycles", maxwear);
+    LFS_WARN("avg wear: %d cycles", totalwear / (int)BLOCK_COUNT);
+    LFS_WARN("min wear: %d cycles", minwear);
+
+    // find standard deviation^2
+    lfs_emubd_wear_t dev2 = 0;
+    for (lfs_block_t b = 2; b < BLOCK_COUNT; b++) {
+        lfs_emubd_wear_t wear = lfs_emubd_wear(cfg, b);
+        assert(wear >= 0);
+        lfs_emubd_swear_t diff = wear - avgwear;
+        dev2 += diff*diff;
+    }
+    dev2 /= totalwear;
+    LFS_WARN("std dev^2: %d", dev2);
+    assert(dev2 < 8);
+'''
+

kernel/fs/littlefs/tests/test_files.toml

@@ -0,0 +1,539 @@
+
+[cases.test_files_simple]
+defines.INLINE_MAX = [0, -1, 8]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "hello",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    lfs_size_t size = strlen("Hello World!")+1;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "Hello World!");
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "hello", LFS_O_RDONLY) => 0;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    assert(strcmp((char*)buffer, "Hello World!") == 0);
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_large]
+defines.SIZE = [32, 8192, 262144, 0, 7, 8193]
+defines.CHUNKSIZE = [31, 16, 33, 1, 1023]
+defines.INLINE_MAX = [0, -1, 8]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // write
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "avacado",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    uint32_t prng = 1;
+    uint8_t buffer[1024];
+    for (lfs_size_t i = 0; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_rewrite]
+defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
+defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
+defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // write
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    lfs_file_open(&lfs, &file, "avacado",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    uint32_t prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE1;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // rewrite
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_WRONLY) => 0;
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => lfs_max(SIZE1, SIZE2);
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    if (SIZE1 > SIZE2) {
+        prng = 1;
+        for (lfs_size_t b = 0; b < SIZE2; b++) {
+            TEST_PRNG(&prng);
+        }
+        for (lfs_size_t i = SIZE2; i < SIZE1; i += CHUNKSIZE) {
+            lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+            lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+            for (lfs_size_t b = 0; b < chunk; b++) {
+                assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+            }
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_append]
+defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
+defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
+defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // write
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    lfs_file_open(&lfs, &file, "avacado",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    uint32_t prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE1;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // append
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_WRONLY | LFS_O_APPEND) => 0;
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE1 + SIZE2;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_truncate]
+defines.SIZE1 = [32, 8192, 131072, 0, 7, 8193]
+defines.SIZE2 = [32, 8192, 131072, 0, 7, 8193]
+defines.CHUNKSIZE = [31, 16, 1]
+defines.INLINE_MAX = [0, -1, 8]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // write
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    lfs_file_open(&lfs, &file, "avacado",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    uint32_t prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE1;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE1; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE1-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // truncate
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_WRONLY | LFS_O_TRUNC) => 0;
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // read
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE2;
+    prng = 2;
+    for (lfs_size_t i = 0; i < SIZE2; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE2-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_reentrant_write]
+defines.SIZE = [32, 0, 7, 2049]
+defines.CHUNKSIZE = [31, 16, 65]
+defines.INLINE_MAX = [0, -1, 8]
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    err = lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY);
+    assert(err == LFS_ERR_NOENT || err == 0);
+    if (err == 0) {
+        // can only be 0 (new file) or full size
+        lfs_size_t size = lfs_file_size(&lfs, &file);
+        assert(size == 0 || size == SIZE);
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    // write
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    uint32_t prng = 1;
+    for (lfs_size_t i = 0; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_reentrant_write_sync]
+defines = [
+    # append (O(n))
+    {MODE='LFS_O_APPEND',
+        SIZE=[32, 0, 7, 2049],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
+    # truncate (O(n^2))
+    {MODE='LFS_O_TRUNC',
+        SIZE=[32, 0, 7, 200],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
+    # rewrite (O(n^2))
+    {MODE=0,
+        SIZE=[32, 0, 7, 200],
+        CHUNKSIZE=[31, 16, 65],
+        INLINE_MAX=[0, -1, 8]},
+]
+reentrant = true
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    err = lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY);
+    assert(err == LFS_ERR_NOENT || err == 0);
+    if (err == 0) {
+        // with syncs we could be any size, but it at least must be valid data
+        lfs_size_t size = lfs_file_size(&lfs, &file);
+        assert(size <= SIZE);
+        uint32_t prng = 1;
+        for (lfs_size_t i = 0; i < size; i += CHUNKSIZE) {
+            lfs_size_t chunk = lfs_min(CHUNKSIZE, size-i);
+            lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+            for (lfs_size_t b = 0; b < chunk; b++) {
+                assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+            }
+        }
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    // write
+    lfs_file_open(&lfs, &file, "avacado",
+        LFS_O_WRONLY | LFS_O_CREAT | MODE) => 0;
+    lfs_size_t size = lfs_file_size(&lfs, &file);
+    assert(size <= SIZE);
+    uint32_t prng = 1;
+    lfs_size_t skip = (MODE == LFS_O_APPEND) ? size : 0;
+    for (lfs_size_t b = 0; b < skip; b++) {
+        TEST_PRNG(&prng);
+    }
+    for (lfs_size_t i = skip; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            buffer[b] = TEST_PRNG(&prng) & 0xff;
+        }
+        lfs_file_write(&lfs, &file, buffer, chunk) => chunk;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // read
+    lfs_file_open(&lfs, &file, "avacado", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => SIZE;
+    prng = 1;
+    for (lfs_size_t i = 0; i < SIZE; i += CHUNKSIZE) {
+        lfs_size_t chunk = lfs_min(CHUNKSIZE, SIZE-i);
+        lfs_file_read(&lfs, &file, buffer, chunk) => chunk;
+        for (lfs_size_t b = 0; b < chunk; b++) {
+            assert(buffer[b] == (TEST_PRNG(&prng) & 0xff));
+        }
+    }
+    lfs_file_read(&lfs, &file, buffer, CHUNKSIZE) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_many]
+defines.N = 300
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // create N files of 7 bytes
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        char path[1024];
+        sprintf(path, "file_%03d", i);
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        char wbuffer[1024];
+        lfs_size_t size = 7;
+        sprintf(wbuffer, "Hi %03d", i);
+        lfs_file_write(&lfs, &file, wbuffer, size) => size;
+        lfs_file_close(&lfs, &file) => 0;
+
+        char rbuffer[1024];
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(strcmp(rbuffer, wbuffer) == 0);
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_many_power_cycle]
+defines.N = 300
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // create N files of 7 bytes
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        char path[1024];
+        sprintf(path, "file_%03d", i);
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        char wbuffer[1024];
+        lfs_size_t size = 7;
+        sprintf(wbuffer, "Hi %03d", i);
+        lfs_file_write(&lfs, &file, wbuffer, size) => size;
+        lfs_file_close(&lfs, &file) => 0;
+        lfs_unmount(&lfs) => 0;
+
+        char rbuffer[1024];
+        lfs_mount(&lfs, cfg) => 0;
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(strcmp(rbuffer, wbuffer) == 0);
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_files_many_power_loss]
+defines.N = 300
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+    // create N files of 7 bytes
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        char path[1024];
+        sprintf(path, "file_%03d", i);
+        err = lfs_file_open(&lfs, &file, path, LFS_O_WRONLY | LFS_O_CREAT);
+        char wbuffer[1024];
+        lfs_size_t size = 7;
+        sprintf(wbuffer, "Hi %03d", i);
+        if ((lfs_size_t)lfs_file_size(&lfs, &file) != size) {
+            lfs_file_write(&lfs, &file, wbuffer, size) => size;
+        }
+        lfs_file_close(&lfs, &file) => 0;
+
+        char rbuffer[1024];
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(strcmp(rbuffer, wbuffer) == 0);
+        lfs_file_close(&lfs, &file) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_interspersed.toml

@@ -0,0 +1,274 @@
+
+[cases.test_interspersed_files]
+defines.SIZE = [10, 100]
+defines.FILES = [4, 10, 26] 
+code = '''
+    lfs_t lfs;
+    lfs_file_t files[FILES];
+    const char alphas[] = "abcdefghijklmnopqrstuvwxyz";
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_file_open(&lfs, &files[j], path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    }
+
+    for (int i = 0; i < SIZE; i++) {
+        for (int j = 0; j < FILES; j++) {
+            lfs_file_write(&lfs, &files[j], &alphas[j], 1) => 1;
+        }
+    }
+
+    for (int j = 0; j < FILES; j++) {
+        lfs_file_close(&lfs, &files[j]);
+    }
+
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "/") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        assert(strcmp(info.name, path) == 0);
+        assert(info.type == LFS_TYPE_REG);
+        assert(info.size == SIZE);
+    }
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_file_open(&lfs, &files[j], path, LFS_O_RDONLY) => 0;
+    }
+
+    for (int i = 0; i < 10; i++) {
+        for (int j = 0; j < FILES; j++) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &files[j], buffer, 1) => 1;
+            assert(buffer[0] == alphas[j]);
+        }
+    }
+
+    for (int j = 0; j < FILES; j++) {
+        lfs_file_close(&lfs, &files[j]);
+    }
+    
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_interspersed_remove_files]
+defines.SIZE = [10, 100]
+defines.FILES = [4, 10, 26]
+code = '''
+    lfs_t lfs;
+    const char alphas[] = "abcdefghijklmnopqrstuvwxyz";
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        for (int i = 0; i < SIZE; i++) {
+            lfs_file_write(&lfs, &file, &alphas[j], 1) => 1;
+        }
+        lfs_file_close(&lfs, &file);
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "zzz", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    for (int j = 0; j < FILES; j++) {
+        lfs_file_write(&lfs, &file, (const void*)"~", 1) => 1;
+        lfs_file_sync(&lfs, &file) => 0;
+
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_remove(&lfs, path) => 0;
+    }
+    lfs_file_close(&lfs, &file);
+
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "/") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "zzz") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    assert(info.size == FILES);
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+
+    lfs_file_open(&lfs, &file, "zzz", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < FILES; i++) {
+        uint8_t buffer[1024];
+        lfs_file_read(&lfs, &file, buffer, 1) => 1;
+        assert(buffer[0] == '~');
+    }
+    lfs_file_close(&lfs, &file);
+    
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_interspersed_remove_inconveniently]
+defines.SIZE = [10, 100]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t files[3];
+    lfs_file_open(&lfs, &files[0], "e", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &files[1], "f", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    lfs_file_open(&lfs, &files[2], "g", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    for (int i = 0; i < SIZE/2; i++) {
+        lfs_file_write(&lfs, &files[0], (const void*)"e", 1) => 1;
+        lfs_file_write(&lfs, &files[1], (const void*)"f", 1) => 1;
+        lfs_file_write(&lfs, &files[2], (const void*)"g", 1) => 1;
+    }
+
+    lfs_remove(&lfs, "f") => 0;
+
+    for (int i = 0; i < SIZE/2; i++) {
+        lfs_file_write(&lfs, &files[0], (const void*)"e", 1) => 1;
+        lfs_file_write(&lfs, &files[1], (const void*)"f", 1) => 1;
+        lfs_file_write(&lfs, &files[2], (const void*)"g", 1) => 1;
+    }
+
+    lfs_file_close(&lfs, &files[0]);
+    lfs_file_close(&lfs, &files[1]);
+    lfs_file_close(&lfs, &files[2]);
+
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "/") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "e") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    assert(info.size == SIZE);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "g") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    assert(info.size == SIZE);
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+
+    lfs_file_open(&lfs, &files[0], "e", LFS_O_RDONLY) => 0;
+    lfs_file_open(&lfs, &files[1], "g", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < SIZE; i++) {
+        uint8_t buffer[1024];
+        lfs_file_read(&lfs, &files[0], buffer, 1) => 1;
+        assert(buffer[0] == 'e');
+        lfs_file_read(&lfs, &files[1], buffer, 1) => 1;
+        assert(buffer[0] == 'g');
+    }
+    lfs_file_close(&lfs, &files[0]);
+    lfs_file_close(&lfs, &files[1]);
+    
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_interspersed_reentrant_files]
+defines.SIZE = [10, 100]
+defines.FILES = [4, 10, 26] 
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    lfs_file_t files[FILES];
+    const char alphas[] = "abcdefghijklmnopqrstuvwxyz";
+
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_file_open(&lfs, &files[j], path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    }
+
+    for (int i = 0; i < SIZE; i++) {
+        for (int j = 0; j < FILES; j++) {
+            lfs_ssize_t size = lfs_file_size(&lfs, &files[j]);
+            assert(size >= 0);
+            if ((int)size <= i) {
+                lfs_file_write(&lfs, &files[j], &alphas[j], 1) => 1;
+                lfs_file_sync(&lfs, &files[j]) => 0;
+            }
+        }
+    }
+
+    for (int j = 0; j < FILES; j++) {
+        lfs_file_close(&lfs, &files[j]);
+    }
+
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "/") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        assert(strcmp(info.name, path) == 0);
+        assert(info.type == LFS_TYPE_REG);
+        assert(info.size == SIZE);
+    }
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+
+    for (int j = 0; j < FILES; j++) {
+        char path[1024];
+        sprintf(path, "%c", alphas[j]);
+        lfs_file_open(&lfs, &files[j], path, LFS_O_RDONLY) => 0;
+    }
+
+    for (int i = 0; i < 10; i++) {
+        for (int j = 0; j < FILES; j++) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &files[j], buffer, 1) => 1;
+            assert(buffer[0] == alphas[j]);
+        }
+    }
+
+    for (int j = 0; j < FILES; j++) {
+        lfs_file_close(&lfs, &files[j]);
+    }
+    
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_orphans.toml

@@ -0,0 +1,340 @@
+[cases.test_orphans_normal]
+in = "lfs.c"
+if = 'PROG_SIZE <= 0x3fe' # only works with one crc per commit
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "parent") => 0;
+    lfs_mkdir(&lfs, "parent/orphan") => 0;
+    lfs_mkdir(&lfs, "parent/child") => 0;
+    lfs_remove(&lfs, "parent/orphan") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // corrupt the child's most recent commit, this should be the update
+    // to the linked-list entry, which should orphan the orphan. Note this
+    // makes a lot of assumptions about the remove operation.
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "parent/child") => 0;
+    lfs_block_t block = dir.m.pair[0];
+    lfs_dir_close(&lfs, &dir) => 0;
+    lfs_unmount(&lfs) => 0;
+    uint8_t buffer[BLOCK_SIZE];
+    cfg->read(cfg, block, 0, buffer, BLOCK_SIZE) => 0;
+    int off = BLOCK_SIZE-1;
+    while (off >= 0 && buffer[off] == ERASE_VALUE) {
+        off -= 1;
+    }
+    memset(&buffer[off-3], BLOCK_SIZE, 3);
+    cfg->erase(cfg, block) => 0;
+    cfg->prog(cfg, block, 0, buffer, BLOCK_SIZE) => 0;
+    cfg->sync(cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
+    lfs_stat(&lfs, "parent/child", &info) => 0;
+    lfs_fs_size(&lfs) => 8;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
+    lfs_stat(&lfs, "parent/child", &info) => 0;
+    lfs_fs_size(&lfs) => 8;
+    // this mkdir should both create a dir and deorphan, so size
+    // should be unchanged
+    lfs_mkdir(&lfs, "parent/otherchild") => 0;
+    lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
+    lfs_stat(&lfs, "parent/child", &info) => 0;
+    lfs_stat(&lfs, "parent/otherchild", &info) => 0;
+    lfs_fs_size(&lfs) => 8;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERR_NOENT;
+    lfs_stat(&lfs, "parent/child", &info) => 0;
+    lfs_stat(&lfs, "parent/otherchild", &info) => 0;
+    lfs_fs_size(&lfs) => 8;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# test that we only run deorphan once per power-cycle
+[cases.test_orphans_no_orphans]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    // mark the filesystem as having orphans
+    lfs_fs_preporphans(&lfs, +1) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_commit(&lfs, &mdir, NULL, 0) => 0;
+
+    // we should have orphans at this state
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+
+    // mount
+    lfs_mount(&lfs, cfg) => 0;
+    // we should detect orphans
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    // force consistency
+    lfs_fs_forceconsistency(&lfs) => 0;
+    // we should no longer have orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_orphans_one_orphan]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    // create an orphan
+    lfs_mdir_t orphan;
+    lfs_alloc_ckpoint(&lfs);
+    lfs_dir_alloc(&lfs, &orphan) => 0;
+    lfs_dir_commit(&lfs, &orphan, NULL, 0) => 0;
+
+    // append our orphan and mark the filesystem as having orphans
+    lfs_fs_preporphans(&lfs, +1) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_pair_tole32(orphan.pair);
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), orphan.pair})) => 0;
+
+    // we should have orphans at this state
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+
+    // mount
+    lfs_mount(&lfs, cfg) => 0;
+    // we should detect orphans
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    // force consistency
+    lfs_fs_forceconsistency(&lfs) => 0;
+    // we should no longer have orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# test that we can persist gstate with lfs_fs_mkconsistent
+[cases.test_orphans_mkconsistent_no_orphans]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    // mark the filesystem as having orphans
+    lfs_fs_preporphans(&lfs, +1) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_dir_commit(&lfs, &mdir, NULL, 0) => 0;
+
+    // we should have orphans at this state
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+
+    // mount
+    lfs_mount(&lfs, cfg) => 0;
+    // we should detect orphans
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    // force consistency
+    lfs_fs_mkconsistent(&lfs) => 0;
+    // we should no longer have orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+
+    // remount
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    // we should still have no orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_orphans_mkconsistent_one_orphan]
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    // create an orphan
+    lfs_mdir_t orphan;
+    lfs_alloc_ckpoint(&lfs);
+    lfs_dir_alloc(&lfs, &orphan) => 0;
+    lfs_dir_commit(&lfs, &orphan, NULL, 0) => 0;
+
+    // append our orphan and mark the filesystem as having orphans
+    lfs_fs_preporphans(&lfs, +1) => 0;
+    lfs_mdir_t mdir;
+    lfs_dir_fetch(&lfs, &mdir, (lfs_block_t[2]){0, 1}) => 0;
+    lfs_pair_tole32(orphan.pair);
+    lfs_dir_commit(&lfs, &mdir, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), orphan.pair})) => 0;
+
+    // we should have orphans at this state
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+
+    // mount
+    lfs_mount(&lfs, cfg) => 0;
+    // we should detect orphans
+    assert(lfs_gstate_hasorphans(&lfs.gstate));
+    // force consistency
+    lfs_fs_mkconsistent(&lfs) => 0;
+    // we should no longer have orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+
+    // remount
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    // we should still have no orphans
+    assert(!lfs_gstate_hasorphans(&lfs.gstate));
+    lfs_unmount(&lfs) => 0;
+'''
+
+# reentrant testing for orphans, basically just spam mkdir/remove
+[cases.test_orphans_reentrant]
+reentrant = true
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,  DEPTH=1, CYCLES=20},
+    {FILES=26, DEPTH=1, CYCLES=20},
+    {FILES=3,  DEPTH=3, CYCLES=20},
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            // is valid dir?
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // try to delete path in reverse order, ignore if dir is not empty
+            for (int d = DEPTH-1; d >= 0; d--) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_remove(&lfs, path);
+                assert(!err || err == LFS_ERR_NOTEMPTY);
+            }
+
+            lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# non-reentrant testing for orphans, this is the same as reentrant
+# testing, but we test way more states than we could under powerloss
+[cases.test_orphans_nonreentrant]
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,   DEPTH=1, CYCLES=2000},
+    {FILES=26,  DEPTH=1, CYCLES=2000},
+    {FILES=3,   DEPTH=3, CYCLES=2000},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                int err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            // is valid dir?
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // try to delete path in reverse order, ignore if dir is not empty
+            for (int d = DEPTH-1; d >= 0; d--) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                int err = lfs_remove(&lfs, path);
+                assert(!err || err == LFS_ERR_NOTEMPTY);
+            }
+
+            lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+

kernel/fs/littlefs/tests/test_powerloss.toml

@@ -0,0 +1,185 @@
+# There are already a number of tests that test general operations under
+# power-loss (see the reentrant attribute). These tests are for explicitly
+# testing specific corner cases.
+
+# only a revision count
+[cases.test_powerloss_only_rev]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "notebook") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "notebook/paper",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    char buffer[256];
+    strcpy(buffer, "hello");
+    lfs_size_t size = strlen("hello");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    char rbuffer[256];
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // get pair/rev count
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "notebook") => 0;
+    lfs_block_t pair[2] = {dir.m.pair[0], dir.m.pair[1]};
+    uint32_t rev = dir.m.rev;
+    lfs_dir_close(&lfs, &dir) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // write just the revision count
+    uint8_t bbuffer[BLOCK_SIZE];
+    cfg->read(cfg, pair[1], 0, bbuffer, BLOCK_SIZE) => 0;
+
+    memcpy(bbuffer, &(uint32_t){lfs_tole32(rev+1)}, sizeof(uint32_t));
+
+    cfg->erase(cfg, pair[1]) => 0;
+    cfg->prog(cfg, pair[1], 0, bbuffer, BLOCK_SIZE) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+
+    // can read?
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // can write?
+    lfs_file_open(&lfs, &file, "notebook/paper",
+            LFS_O_WRONLY | LFS_O_APPEND) => 0;
+    strcpy(buffer, "goodbye");
+    size = strlen("goodbye");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    strcpy(buffer, "hello");
+    size = strlen("hello");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    strcpy(buffer, "goodbye");
+    size = strlen("goodbye");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# partial prog, may not be byte in order!
+[cases.test_powerloss_partial_prog]
+if = '''
+    PROG_SIZE < BLOCK_SIZE
+        && (DISK_VERSION == 0 || DISK_VERSION >= 0x00020001)
+'''
+defines.BYTE_OFF = ["0", "PROG_SIZE-1", "PROG_SIZE/2"]
+defines.BYTE_VALUE = [0x33, 0xcc]
+in = "lfs.c"
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_mkdir(&lfs, "notebook") => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "notebook/paper",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    char buffer[256];
+    strcpy(buffer, "hello");
+    lfs_size_t size = strlen("hello");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    char rbuffer[256];
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // imitate a partial prog, value should not matter, if littlefs
+    // doesn't notice the partial prog testbd will assert
+
+    // get offset to next prog
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "notebook") => 0;
+    lfs_block_t block = dir.m.pair[0];
+    lfs_off_t off = dir.m.off;
+    lfs_dir_close(&lfs, &dir) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // tweak byte
+    uint8_t bbuffer[BLOCK_SIZE];
+    cfg->read(cfg, block, 0, bbuffer, BLOCK_SIZE) => 0;
+
+    bbuffer[off + BYTE_OFF] = BYTE_VALUE;
+
+    cfg->erase(cfg, block) => 0;
+    cfg->prog(cfg, block, 0, bbuffer, BLOCK_SIZE) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+
+    // can read?
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    // can write?
+    lfs_file_open(&lfs, &file, "notebook/paper",
+            LFS_O_WRONLY | LFS_O_APPEND) => 0;
+    strcpy(buffer, "goodbye");
+    size = strlen("goodbye");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+        lfs_file_sync(&lfs, &file) => 0;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "notebook/paper", LFS_O_RDONLY) => 0;
+    strcpy(buffer, "hello");
+    size = strlen("hello");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    strcpy(buffer, "goodbye");
+    size = strlen("goodbye");
+    for (int i = 0; i < 5; i++) {
+        lfs_file_read(&lfs, &file, rbuffer, size) => size;
+        assert(memcmp(rbuffer, buffer, size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_relocations.toml

@@ -0,0 +1,511 @@
+# specific corner cases worth explicitly testing for
+[cases.test_relocations_dangling_split_dir]
+defines.ITERATIONS = 20
+defines.COUNT = 10
+defines.BLOCK_CYCLES = [8, 1]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // fill up filesystem so only ~16 blocks are left
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "padding", LFS_O_CREAT | LFS_O_WRONLY) => 0;
+    uint8_t buffer[512];
+    memset(buffer, 0, 512);
+    while (BLOCK_COUNT - lfs_fs_size(&lfs) > 16) {
+        lfs_file_write(&lfs, &file, buffer, 512) => 512;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // make a child dir to use in bounded space
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (unsigned j = 0; j < ITERATIONS; j++) {
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_CREAT | LFS_O_WRONLY) => 0;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+
+        lfs_dir_t dir;
+        struct lfs_info info;
+        lfs_dir_open(&lfs, &dir, "child") => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+        lfs_dir_close(&lfs, &dir) => 0;
+
+        if (j == (unsigned)ITERATIONS-1) {
+            break;
+        }
+
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_remove(&lfs, path) => 0;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    struct lfs_info info;
+    lfs_dir_open(&lfs, &dir, "child") => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    for (unsigned i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        strcmp(info.name, path) => 0;
+    }
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+    for (unsigned i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+        lfs_remove(&lfs, path) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_relocations_outdated_head]
+defines.ITERATIONS = 20
+defines.COUNT = 10
+defines.BLOCK_CYCLES = [8, 1]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // fill up filesystem so only ~16 blocks are left
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "padding", LFS_O_CREAT | LFS_O_WRONLY) => 0;
+    uint8_t buffer[512];
+    memset(buffer, 0, 512);
+    while (BLOCK_COUNT - lfs_fs_size(&lfs) > 16) {
+        lfs_file_write(&lfs, &file, buffer, 512) => 512;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // make a child dir to use in bounded space
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    for (unsigned j = 0; j < ITERATIONS; j++) {
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_CREAT | LFS_O_WRONLY) => 0;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+
+        lfs_dir_t dir;
+        struct lfs_info info;
+        lfs_dir_open(&lfs, &dir, "child") => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 0;
+
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
+            lfs_file_write(&lfs, &file, "hi", 2) => 2;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+
+        lfs_dir_rewind(&lfs, &dir) => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 2;
+
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
+            lfs_file_write(&lfs, &file, "hi", 2) => 2;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+
+        lfs_dir_rewind(&lfs, &dir) => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 2;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+        lfs_dir_close(&lfs, &dir) => 0;
+
+        for (unsigned i = 0; i < COUNT; i++) {
+            char path[1024];
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_remove(&lfs, path) => 0;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# reentrant testing for relocations, this is the same as the
+# orphan testing, except here we also set block_cycles so that
+# almost every tree operation needs a relocation
+[cases.test_relocations_reentrant]
+reentrant = true
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,  DEPTH=1, CYCLES=20, BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=20, BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=20, BLOCK_CYCLES=1},
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            // is valid dir?
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // try to delete path in reverse order, ignore if dir is not empty
+            for (unsigned d = DEPTH-1; d+1 > 0; d--) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_remove(&lfs, path);
+                assert(!err || err == LFS_ERR_NOTEMPTY);
+            }
+
+            lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# reentrant testing for relocations, but now with random renames!
+[cases.test_relocations_reentrant_renames]
+reentrant = true
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,  DEPTH=1, CYCLES=20, BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=20, BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=20, BLOCK_CYCLES=1},
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        assert(!res || res == LFS_ERR_NOENT);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // create new random path
+            char new_path[256];
+            for (unsigned d = 0; d < DEPTH; d++) {
+                sprintf(&new_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+            }
+
+            // if new path does not exist, rename, otherwise destroy
+            res = lfs_stat(&lfs, new_path, &info);
+            assert(!res || res == LFS_ERR_NOENT);
+            if (res == LFS_ERR_NOENT) {
+                // stop once some dir is renamed
+                for (unsigned d = 0; d < DEPTH; d++) {
+                    char path[1024];
+                    strcpy(&path[2*d], &full_path[2*d]);
+                    path[2*d+2] = '\0';
+                    strcpy(&path[128+2*d], &new_path[2*d]);
+                    path[128+2*d+2] = '\0';
+                    err = lfs_rename(&lfs, path, path+128);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                    if (!err) {
+                        strcpy(path, path+128);
+                    }
+                }
+
+                for (unsigned d = 0; d < DEPTH; d++) {
+                    char path[1024];
+                    strcpy(path, new_path);
+                    path[2*d+2] = '\0';
+                    lfs_stat(&lfs, path, &info) => 0;
+                    assert(strcmp(info.name, &path[2*d+1]) == 0);
+                    assert(info.type == LFS_TYPE_DIR);
+                }
+                
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            } else {
+                // try to delete path in reverse order,
+                // ignore if dir is not empty
+                for (unsigned d = DEPTH-1; d+1 > 0; d--) {
+                    char path[1024];
+                    strcpy(path, full_path);
+                    path[2*d+2] = '\0';
+                    err = lfs_remove(&lfs, path);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                }
+
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            }
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# non-reentrant testing for orphans, this is the same as reentrant
+# testing, but we test way more states than we could under powerloss
+[cases.test_relocations_nonreentrant]
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,  DEPTH=1, CYCLES=2000, BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=2000, BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=2000, BLOCK_CYCLES=1},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                int err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            // is valid dir?
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // try to delete path in reverse order, ignore if dir is not empty
+            for (unsigned d = DEPTH-1; d+1 > 0; d--) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                int err = lfs_remove(&lfs, path);
+                assert(!err || err == LFS_ERR_NOTEMPTY);
+            }
+
+            lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# non-reentrant testing for relocations, but now with random renames!
+[cases.test_relocations_nonreentrant_renames]
+# TODO fix this case, caused by non-DAG trees
+# NOTE the second condition is required
+if = '!(DEPTH == 3 && CACHE_SIZE != 64) && 2*FILES < BLOCK_COUNT'
+defines = [
+    {FILES=6,  DEPTH=1, CYCLES=2000, BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=2000, BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=2000, BLOCK_CYCLES=1},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    uint32_t prng = 1;
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (unsigned i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (unsigned d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        struct lfs_info info;
+        int res = lfs_stat(&lfs, full_path, &info);
+        assert(!res || res == LFS_ERR_NOENT);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                int err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (unsigned d = 0; d < DEPTH; d++) {
+                char path[1024];
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // create new random path
+            char new_path[256];
+            for (unsigned d = 0; d < DEPTH; d++) {
+                sprintf(&new_path[2*d], "/%c", alpha[TEST_PRNG(&prng) % FILES]);
+            }
+
+            // if new path does not exist, rename, otherwise destroy
+            res = lfs_stat(&lfs, new_path, &info);
+            assert(!res || res == LFS_ERR_NOENT);
+            if (res == LFS_ERR_NOENT) {
+                // stop once some dir is renamed
+                for (unsigned d = 0; d < DEPTH; d++) {
+                    char path[1024];
+                    strcpy(&path[2*d], &full_path[2*d]);
+                    path[2*d+2] = '\0';
+                    strcpy(&path[128+2*d], &new_path[2*d]);
+                    path[128+2*d+2] = '\0';
+                    int err = lfs_rename(&lfs, path, path+128);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                    if (!err) {
+                        strcpy(path, path+128);
+                    }
+                }
+
+                for (unsigned d = 0; d < DEPTH; d++) {
+                    char path[1024];
+                    strcpy(path, new_path);
+                    path[2*d+2] = '\0';
+                    lfs_stat(&lfs, path, &info) => 0;
+                    assert(strcmp(info.name, &path[2*d+1]) == 0);
+                    assert(info.type == LFS_TYPE_DIR);
+                }
+
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            } else {
+                // try to delete path in reverse order,
+                // ignore if dir is not empty
+                for (unsigned d = DEPTH-1; d+1 > 0; d--) {
+                    char path[1024];
+                    strcpy(path, full_path);
+                    path[2*d+2] = '\0';
+                    int err = lfs_remove(&lfs, path);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                }
+
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            }
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_seek.toml

@@ -0,0 +1,662 @@
+
+# simple file seek
+[cases.test_seek_read]
+defines = [
+    {COUNT=132, SKIP=4},
+    {COUNT=132, SKIP=128},
+    {COUNT=200, SKIP=10},
+    {COUNT=200, SKIP=100},
+    {COUNT=4,   SKIP=1},
+    {COUNT=4,   SKIP=2},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    size_t size = strlen("kittycatcat");
+    uint8_t buffer[1024];
+    memcpy(buffer, "kittycatcat", size);
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_write(&lfs, &file, buffer, size);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY) => 0;
+
+    lfs_soff_t pos = -1;
+    size = strlen("kittycatcat");
+    for (int i = 0; i < SKIP; i++) {
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+        pos = lfs_file_tell(&lfs, &file);
+    }
+    assert(pos >= 0);
+
+    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_rewind(&lfs, &file) => 0;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, size, LFS_SEEK_CUR) => 3*size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_CUR) => pos;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_END) >= 0 => 1;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    size = lfs_file_size(&lfs, &file);
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# simple file seek and write
+[cases.test_seek_write]
+defines = [
+    {COUNT=132, SKIP=4},
+    {COUNT=132, SKIP=128},
+    {COUNT=200, SKIP=10},
+    {COUNT=200, SKIP=100},
+    {COUNT=4,   SKIP=1},
+    {COUNT=4,   SKIP=2},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    size_t size = strlen("kittycatcat");
+    uint8_t buffer[1024];
+    memcpy(buffer, "kittycatcat", size);
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_write(&lfs, &file, buffer, size);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
+
+    lfs_soff_t pos = -1;
+    size = strlen("kittycatcat");
+    for (int i = 0; i < SKIP; i++) {
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+        pos = lfs_file_tell(&lfs, &file);
+    }
+    assert(pos >= 0);
+
+    memcpy(buffer, "doggodogdog", size);
+    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+
+    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "doggodogdog", size) => 0;
+
+    lfs_file_rewind(&lfs, &file) => 0;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    lfs_file_seek(&lfs, &file, pos, LFS_SEEK_SET) => pos;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "doggodogdog", size) => 0;
+
+    lfs_file_seek(&lfs, &file, -size, LFS_SEEK_END) >= 0 => 1;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "kittycatcat", size) => 0;
+
+    size = lfs_file_size(&lfs, &file);
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => size;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# boundary seek and reads
+[cases.test_seek_boundary_read]
+defines.COUNT = 132
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    size_t size = strlen("kittycatcat");
+    uint8_t buffer[1024];
+    memcpy(buffer, "kittycatcat", size);
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_write(&lfs, &file, buffer, size);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY) => 0;
+
+    size = strlen("kittycatcat");
+    const lfs_soff_t offsets[] = {
+        512,
+        1024-4,
+        512+1,
+        1024-4+1,
+        512-1,
+        1024-4-1,
+
+        512-strlen("kittycatcat"),
+        1024-4-strlen("kittycatcat"),
+        512-strlen("kittycatcat")+1,
+        1024-4-strlen("kittycatcat")+1,
+        512-strlen("kittycatcat")-1,
+        1024-4-strlen("kittycatcat")-1,
+
+        strlen("kittycatcat")*(COUNT-2)-1,
+    };
+
+    for (unsigned i = 0; i < sizeof(offsets) / sizeof(offsets[0]); i++) {
+        lfs_soff_t off = offsets[i];
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
+                size) => 0;
+        // read after
+        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
+                => off+strlen("kittycatcat")+1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
+                size) => 0;
+        // read before
+        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
+                => off-strlen("kittycatcat")-1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
+                size) => 0;
+
+        // read @ 0
+        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
+                size) => 0;
+        // read after
+        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
+                => off+strlen("kittycatcat")+1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
+                size) => 0;
+        // read before
+        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
+                => off-strlen("kittycatcat")-1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
+                size) => 0;
+
+        // sync
+        lfs_file_sync(&lfs, &file) => 0;
+
+        // read @ 0
+        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[off % strlen("kittycatcat")],
+                size) => 0;
+        // read after
+        lfs_file_seek(&lfs, &file, off+strlen("kittycatcat")+1, LFS_SEEK_SET)
+                => off+strlen("kittycatcat")+1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off+1) % strlen("kittycatcat")],
+                size) => 0;
+        // read before
+        lfs_file_seek(&lfs, &file, off-strlen("kittycatcat")-1, LFS_SEEK_SET)
+                => off-strlen("kittycatcat")-1;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer,
+                &"kittycatcatkittycatcat"[(off-1) % strlen("kittycatcat")],
+                size) => 0;
+    }
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# boundary seek and writes
+[cases.test_seek_boundary_write]
+defines.COUNT = 132
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    size_t size = strlen("kittycatcat");
+    uint8_t buffer[1024];
+    memcpy(buffer, "kittycatcat", size);
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_write(&lfs, &file, buffer, size);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
+
+    size = strlen("hedgehoghog");
+    const lfs_soff_t offsets[] = {
+        512,
+        1024-4,
+        512+1,
+        1024-4+1,
+        512-1,
+        1024-4-1,
+
+        512-strlen("kittycatcat"),
+        1024-4-strlen("kittycatcat"),
+        512-strlen("kittycatcat")+1,
+        1024-4-strlen("kittycatcat")+1,
+        512-strlen("kittycatcat")-1,
+        1024-4-strlen("kittycatcat")-1,
+
+        strlen("kittycatcat")*(COUNT-2)-1,
+    };
+
+    for (unsigned i = 0; i < sizeof(offsets) / sizeof(offsets[0]); i++) {
+        lfs_soff_t off = offsets[i];
+        // write @ offset
+        memcpy(buffer, "hedgehoghog", size);
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_write(&lfs, &file, buffer, size) => size;
+
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "hedgehoghog", size) => 0;
+
+        // read @ 0
+        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "hedgehoghog", size) => 0;
+
+        lfs_file_sync(&lfs, &file) => 0;
+
+        // read @ 0
+        lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "kittycatcat", size) => 0;
+
+        // read @ offset
+        lfs_file_seek(&lfs, &file, off, LFS_SEEK_SET) => off;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        memcmp(buffer, "hedgehoghog", size) => 0;
+    }
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# out of bounds seek
+[cases.test_seek_out_of_bounds]
+defines = [
+    {COUNT=132, SKIP=4},
+    {COUNT=132, SKIP=128},
+    {COUNT=200, SKIP=10},
+    {COUNT=200, SKIP=100},
+    {COUNT=4,   SKIP=2},
+    {COUNT=4,   SKIP=3},
+]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    size_t size = strlen("kittycatcat");
+    uint8_t buffer[1024];
+    memcpy(buffer, "kittycatcat", size);
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_write(&lfs, &file, buffer, size);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
+
+    size = strlen("kittycatcat");
+    lfs_file_size(&lfs, &file) => COUNT*size;
+    lfs_file_seek(&lfs, &file, (COUNT+SKIP)*size,
+            LFS_SEEK_SET) => (COUNT+SKIP)*size;
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    memcpy(buffer, "porcupineee", size);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+
+    lfs_file_seek(&lfs, &file, (COUNT+SKIP)*size,
+            LFS_SEEK_SET) => (COUNT+SKIP)*size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "porcupineee", size) => 0;
+
+    lfs_file_seek(&lfs, &file, COUNT*size,
+            LFS_SEEK_SET) => COUNT*size;
+    lfs_file_read(&lfs, &file, buffer, size) => size;
+    memcmp(buffer, "\0\0\0\0\0\0\0\0\0\0\0", size) => 0;
+
+    lfs_file_seek(&lfs, &file, -((COUNT+SKIP)*size),
+            LFS_SEEK_CUR) => LFS_ERR_INVAL;
+    lfs_file_tell(&lfs, &file) => (COUNT+1)*size;
+
+    lfs_file_seek(&lfs, &file, -((COUNT+2*SKIP)*size),
+            LFS_SEEK_END) => LFS_ERR_INVAL;
+    lfs_file_tell(&lfs, &file) => (COUNT+1)*size;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# inline write and seek
+[cases.test_seek_inline_write]
+defines.SIZE = [2, 4, 128, 132]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "tinykitty",
+            LFS_O_RDWR | LFS_O_CREAT) => 0;
+    int j = 0;
+    int k = 0;
+
+    uint8_t buffer[1024];
+    memcpy(buffer, "abcdefghijklmnopqrstuvwxyz", 26);
+    for (unsigned i = 0; i < SIZE; i++) {
+        lfs_file_write(&lfs, &file, &buffer[j++ % 26], 1) => 1;
+        lfs_file_tell(&lfs, &file) => i+1;
+        lfs_file_size(&lfs, &file) => i+1;
+    }
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+    lfs_file_tell(&lfs, &file) => 0;
+    lfs_file_size(&lfs, &file) => SIZE;
+    for (unsigned i = 0; i < SIZE; i++) {
+        uint8_t c;
+        lfs_file_read(&lfs, &file, &c, 1) => 1;
+        c => buffer[k++ % 26];
+    }
+
+    lfs_file_sync(&lfs, &file) => 0;
+    lfs_file_tell(&lfs, &file) => SIZE;
+    lfs_file_size(&lfs, &file) => SIZE;
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+    for (unsigned i = 0; i < SIZE; i++) {
+        lfs_file_write(&lfs, &file, &buffer[j++ % 26], 1) => 1;
+        lfs_file_tell(&lfs, &file) => i+1;
+        lfs_file_size(&lfs, &file) => SIZE;
+        lfs_file_sync(&lfs, &file) => 0;
+        lfs_file_tell(&lfs, &file) => i+1;
+        lfs_file_size(&lfs, &file) => SIZE;
+        if (i < SIZE-2) {
+            uint8_t c[3];
+            lfs_file_seek(&lfs, &file, -1, LFS_SEEK_CUR) => i;
+            lfs_file_read(&lfs, &file, &c, 3) => 3;
+            lfs_file_tell(&lfs, &file) => i+3;
+            lfs_file_size(&lfs, &file) => SIZE;
+            lfs_file_seek(&lfs, &file, i+1, LFS_SEEK_SET) => i+1;
+            lfs_file_tell(&lfs, &file) => i+1;
+            lfs_file_size(&lfs, &file) => SIZE;
+        }
+    }
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+    lfs_file_tell(&lfs, &file) => 0;
+    lfs_file_size(&lfs, &file) => SIZE;
+    for (unsigned i = 0; i < SIZE; i++) {
+        uint8_t c;
+        lfs_file_read(&lfs, &file, &c, 1) => 1;
+        c => buffer[k++ % 26];
+    }
+
+    lfs_file_sync(&lfs, &file) => 0;
+    lfs_file_tell(&lfs, &file) => SIZE;
+    lfs_file_size(&lfs, &file) => SIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# file seek and write with power-loss
+[cases.test_seek_reentrant_write]
+# must be power-of-2 for quadratic probing to be exhaustive
+defines.COUNT = [4, 64, 128]
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+    lfs_file_t file;
+    uint8_t buffer[1024];
+    err = lfs_file_open(&lfs, &file, "kitty", LFS_O_RDONLY);
+    assert(!err || err == LFS_ERR_NOENT);
+    if (!err) {
+        if (lfs_file_size(&lfs, &file) != 0) {
+            lfs_file_size(&lfs, &file) => 11*COUNT;
+            for (int j = 0; j < COUNT; j++) {
+                memset(buffer, 0, 11+1);
+                lfs_file_read(&lfs, &file, buffer, 11) => 11;
+                assert(memcmp(buffer, "kittycatcat", 11) == 0 ||
+                       memcmp(buffer, "doggodogdog", 11) == 0);
+            }
+        }
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_WRONLY | LFS_O_CREAT) => 0;
+    if (lfs_file_size(&lfs, &file) == 0) {
+        for (int j = 0; j < COUNT; j++) {
+            strcpy((char*)buffer, "kittycatcat");
+            size_t size = strlen((char*)buffer);
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+        }
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    strcpy((char*)buffer, "doggodogdog");
+    size_t size = strlen((char*)buffer);
+
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => COUNT*size;
+    // seek and write using quadratic probing to touch all
+    // 11-byte words in the file
+    lfs_off_t off = 0;
+    for (int j = 0; j < COUNT; j++) {
+        off = (5*off + 1) % COUNT;
+        lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        assert(memcmp(buffer, "kittycatcat", size) == 0 ||
+               memcmp(buffer, "doggodogdog", size) == 0);
+        if (memcmp(buffer, "doggodogdog", size) != 0) {
+            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
+            strcpy((char*)buffer, "doggodogdog");
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            assert(memcmp(buffer, "doggodogdog", size) == 0);
+            lfs_file_sync(&lfs, &file) => 0;
+            lfs_file_seek(&lfs, &file, off*size, LFS_SEEK_SET) => off*size;
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            assert(memcmp(buffer, "doggodogdog", size) == 0);
+        }
+    }
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "kitty", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => COUNT*size;
+    for (int j = 0; j < COUNT; j++) {
+        lfs_file_read(&lfs, &file, buffer, size) => size;
+        assert(memcmp(buffer, "doggodogdog", size) == 0);
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+
+# test possible overflow/underflow conditions
+#
+# note these need -fsanitize=undefined to consistently detect
+# overflow/underflow conditions
+
+[cases.test_seek_filemax]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+
+    // seek with LFS_SEEK_SET
+    lfs_file_seek(&lfs, &file, LFS_FILE_MAX, LFS_SEEK_SET) => LFS_FILE_MAX;
+
+    // seek with LFS_SEEK_CUR
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_CUR) => LFS_FILE_MAX;
+
+    // the file hasn't changed size, so seek end takes us back to the offset=0
+    lfs_file_seek(&lfs, &file, +10, LFS_SEEK_END) => size+10;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_seek_underflow]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+
+    // underflow with LFS_SEEK_CUR, should error
+    lfs_file_seek(&lfs, &file, -(size+10), LFS_SEEK_CUR) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, -LFS_FILE_MAX, LFS_SEEK_CUR) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, -(size+LFS_FILE_MAX), LFS_SEEK_CUR)
+            => LFS_ERR_INVAL;
+
+    // underflow with LFS_SEEK_END, should error
+    lfs_file_seek(&lfs, &file, -(size+10), LFS_SEEK_END) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, -LFS_FILE_MAX, LFS_SEEK_END) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, -(size+LFS_FILE_MAX), LFS_SEEK_END)
+            => LFS_ERR_INVAL;
+
+    // file pointer should not have changed
+    lfs_file_tell(&lfs, &file) => size;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_seek_overflow]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "kitty",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs_file_write(&lfs, &file, buffer, size) => size;
+
+    // seek to LFS_FILE_MAX
+    lfs_file_seek(&lfs, &file, LFS_FILE_MAX, LFS_SEEK_SET) => LFS_FILE_MAX;
+
+    // overflow with LFS_SEEK_CUR, should error
+    lfs_file_seek(&lfs, &file, +10, LFS_SEEK_CUR) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, +LFS_FILE_MAX, LFS_SEEK_CUR) => LFS_ERR_INVAL;
+
+    // LFS_SEEK_SET/END don't care about the current file position, but we can
+    // still overflow with a large offset
+
+    // overflow with LFS_SEEK_SET, should error
+    lfs_file_seek(&lfs, &file,
+            +((uint32_t)LFS_FILE_MAX+10),
+            LFS_SEEK_SET) => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file,
+            +((uint32_t)LFS_FILE_MAX+(uint32_t)LFS_FILE_MAX),
+            LFS_SEEK_SET) => LFS_ERR_INVAL;
+
+    // overflow with LFS_SEEK_END, should error
+    lfs_file_seek(&lfs, &file, +(LFS_FILE_MAX-size+10), LFS_SEEK_END)
+            => LFS_ERR_INVAL;
+    lfs_file_seek(&lfs, &file, +(LFS_FILE_MAX-size+LFS_FILE_MAX), LFS_SEEK_END)
+            => LFS_ERR_INVAL;
+
+    // file pointer should not have changed
+    lfs_file_tell(&lfs, &file) => LFS_FILE_MAX;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_shrink.toml

@@ -0,0 +1,109 @@
+# simple shrink
+[cases.test_shrink_simple]
+defines.BLOCK_COUNT = [10, 15, 20]
+defines.AFTER_BLOCK_COUNT = [5, 10, 15, 19]
+   
+if = "AFTER_BLOCK_COUNT <= BLOCK_COUNT"
+code = '''
+#ifdef LFS_SHRINKNONRELOCATING
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, AFTER_BLOCK_COUNT) => 0;
+    lfs_unmount(&lfs);
+    if (BLOCK_COUNT != AFTER_BLOCK_COUNT) {
+        lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+    }
+    lfs_t lfs2 = lfs;
+    struct lfs_config cfg2 = *cfg;
+    cfg2.block_count = AFTER_BLOCK_COUNT;
+    lfs2.cfg = &cfg2;
+    lfs_mount(&lfs2, &cfg2) => 0;
+    lfs_unmount(&lfs2) => 0;
+#endif
+'''
+
+# shrinking full
+[cases.test_shrink_full]
+defines.BLOCK_COUNT = [10, 15, 20]
+defines.AFTER_BLOCK_COUNT = [5, 7, 10, 12, 15, 17, 20]
+defines.FILES_COUNT = [7, 8, 9, 10]
+if = "AFTER_BLOCK_COUNT <= BLOCK_COUNT && FILES_COUNT + 2 < BLOCK_COUNT"
+code = '''
+#ifdef LFS_SHRINKNONRELOCATING
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    // create FILES_COUNT files of BLOCK_SIZE - 50 bytes (to avoid inlining)
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < FILES_COUNT + 1; i++) {
+        lfs_file_t file;
+        char path[1024];
+        sprintf(path, "file_%03d", i);
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        char wbuffer[BLOCK_SIZE];
+        memset(wbuffer, 'b', BLOCK_SIZE);
+        // Ensure one block is taken per file, but that files are not inlined.
+        lfs_size_t size = BLOCK_SIZE - 0x40;
+        sprintf(wbuffer, "Hi %03d", i);
+        lfs_file_write(&lfs, &file, wbuffer, size) => size;
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    int err = lfs_fs_grow(&lfs, AFTER_BLOCK_COUNT);
+    if (err == 0) {
+        for (int i = 0; i < FILES_COUNT + 1; i++) {
+            lfs_file_t file;
+            char path[1024];
+            sprintf(path, "file_%03d", i);
+            lfs_file_open(&lfs, &file, path,
+                    LFS_O_RDONLY ) => 0;
+            lfs_size_t size = BLOCK_SIZE - 0x40;
+            char wbuffer[size];
+            char wbuffer_ref[size];
+            // Ensure one block is taken per file, but that files are not inlined.
+            memset(wbuffer_ref, 'b', size);
+            sprintf(wbuffer_ref, "Hi %03d", i);
+            lfs_file_read(&lfs, &file, wbuffer, BLOCK_SIZE) => size;
+            lfs_file_close(&lfs, &file) => 0;
+            for (lfs_size_t j = 0; j < size; j++) {
+                wbuffer[j] => wbuffer_ref[j];
+            }
+        }
+    } else {
+        assert(err == LFS_ERR_NOTEMPTY);
+    }
+
+    lfs_unmount(&lfs) => 0;
+    if (err == 0 ) {
+        if ( AFTER_BLOCK_COUNT != BLOCK_COUNT ) {
+            lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+        }
+
+        lfs_t lfs2 = lfs;
+        struct lfs_config cfg2 = *cfg;
+        cfg2.block_count = AFTER_BLOCK_COUNT;
+        lfs2.cfg = &cfg2;
+        lfs_mount(&lfs2, &cfg2) => 0;
+        for (int i = 0; i < FILES_COUNT + 1; i++) {
+            lfs_file_t file;
+            char path[1024];
+            sprintf(path, "file_%03d", i);
+            lfs_file_open(&lfs2, &file, path,
+                    LFS_O_RDONLY ) => 0;
+            lfs_size_t size = BLOCK_SIZE - 0x40;
+            char wbuffer[size];
+            char wbuffer_ref[size];
+            // Ensure one block is taken per file, but that files are not inlined.
+            memset(wbuffer_ref, 'b', size);
+            sprintf(wbuffer_ref, "Hi %03d", i);
+            lfs_file_read(&lfs2, &file, wbuffer, BLOCK_SIZE) => size;
+            lfs_file_close(&lfs2, &file) => 0;
+            for (lfs_size_t j = 0; j < size; j++) {
+                wbuffer[j] => wbuffer_ref[j];
+            }
+        }
+        lfs_unmount(&lfs2);
+    }
+#endif
+'''

kernel/fs/littlefs/tests/test_superblocks.toml

@@ -0,0 +1,660 @@
+# simple formatting test
+[cases.test_superblocks_format]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+'''
+
+# mount/unmount
+[cases.test_superblocks_mount]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# make sure the magic string "littlefs" is always at offset=8
+[cases.test_superblocks_magic]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // check our magic string
+    //
+    // note if we lose power we may not have the magic string in both blocks!
+    // but we don't lose power in this test so we can assert the magic string
+    // is present in both
+    uint8_t magic[lfs_max(16, READ_SIZE)];
+    cfg->read(cfg, 0, 0, magic, lfs_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+    cfg->read(cfg, 1, 0, magic, lfs_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+'''
+
+# mount/unmount from interpretting a previous superblock block_count
+[cases.test_superblocks_mount_unknown_block_count]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    memset(&lfs, 0, sizeof(lfs));
+    struct lfs_config tweaked_cfg = *cfg;
+    tweaked_cfg.block_count = 0;
+    lfs_mount(&lfs, &tweaked_cfg) => 0;
+    assert(lfs.block_count == cfg->block_count);
+    lfs_unmount(&lfs) => 0;
+'''
+
+# reentrant format
+[cases.test_superblocks_reentrant_format]
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+# invalid mount
+[cases.test_superblocks_invalid_mount]
+code = '''
+    lfs_t lfs;
+    lfs_mount(&lfs, cfg) => LFS_ERR_CORRUPT;
+'''
+
+# test we can read superblock info through lfs_fs_stat
+[cases.test_superblocks_stat]
+if = 'DISK_VERSION == 0'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // test we can mount and read fsinfo
+    lfs_mount(&lfs, cfg) => 0;
+
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.disk_version == LFS_DISK_VERSION);
+    assert(fsinfo.name_max == LFS_NAME_MAX);
+    assert(fsinfo.file_max == LFS_FILE_MAX);
+    assert(fsinfo.attr_max == LFS_ATTR_MAX);
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+[cases.test_superblocks_stat_tweaked]
+if = 'DISK_VERSION == 0'
+defines.TWEAKED_NAME_MAX = 63
+defines.TWEAKED_FILE_MAX = '(1 << 16)-1'
+defines.TWEAKED_ATTR_MAX = 512
+code = '''
+    // create filesystem with tweaked params
+    struct lfs_config tweaked_cfg = *cfg;
+    tweaked_cfg.name_max = TWEAKED_NAME_MAX;
+    tweaked_cfg.file_max = TWEAKED_FILE_MAX;
+    tweaked_cfg.attr_max = TWEAKED_ATTR_MAX;
+
+    lfs_t lfs;
+    lfs_format(&lfs, &tweaked_cfg) => 0;
+
+    // test we can mount and read these params with the original config
+    lfs_mount(&lfs, cfg) => 0;
+
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.disk_version == LFS_DISK_VERSION);
+    assert(fsinfo.name_max == TWEAKED_NAME_MAX);
+    assert(fsinfo.file_max == TWEAKED_FILE_MAX);
+    assert(fsinfo.attr_max == TWEAKED_ATTR_MAX);
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# expanding superblock
+[cases.test_superblocks_expand]
+defines.BLOCK_CYCLES = [32, 33, 1]
+defines.N = [10, 100, 1000]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, "dummy",
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        lfs_file_close(&lfs, &file) => 0;
+        struct lfs_info info;
+        lfs_stat(&lfs, "dummy", &info) => 0;
+        assert(strcmp(info.name, "dummy") == 0);
+        assert(info.type == LFS_TYPE_REG);
+        lfs_remove(&lfs, "dummy") => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    // one last check after power-cycle
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "dummy",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "dummy", &info) => 0;
+    assert(strcmp(info.name, "dummy") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    lfs_unmount(&lfs) => 0;
+'''
+
+# make sure the magic string "littlefs" is always at offset=8
+[cases.test_superblocks_magic_expand]
+defines.BLOCK_CYCLES = [32, 33, 1]
+defines.N = [10, 100, 1000]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, "dummy",
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        lfs_file_close(&lfs, &file) => 0;
+        struct lfs_info info;
+        lfs_stat(&lfs, "dummy", &info) => 0;
+        assert(strcmp(info.name, "dummy") == 0);
+        assert(info.type == LFS_TYPE_REG);
+        lfs_remove(&lfs, "dummy") => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+
+    // check our magic string
+    //
+    // note if we lose power we may not have the magic string in both blocks!
+    // but we don't lose power in this test so we can assert the magic string
+    // is present in both
+    uint8_t magic[lfs_max(16, READ_SIZE)];
+    cfg->read(cfg, 0, 0, magic, lfs_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+    cfg->read(cfg, 1, 0, magic, lfs_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+'''
+
+# expanding superblock with power cycle
+[cases.test_superblocks_expand_power_cycle]
+defines.BLOCK_CYCLES = [32, 33, 1]
+defines.N = [10, 100, 1000]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_mount(&lfs, cfg) => 0;
+        // remove lingering dummy?
+        struct lfs_info info;
+        int err = lfs_stat(&lfs, "dummy", &info);
+        assert(err == 0 || (err == LFS_ERR_NOENT && i == 0));
+        if (!err) {
+            assert(strcmp(info.name, "dummy") == 0);
+            assert(info.type == LFS_TYPE_REG);
+            lfs_remove(&lfs, "dummy") => 0;
+        }
+
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, "dummy",
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        lfs_file_close(&lfs, &file) => 0;
+        lfs_stat(&lfs, "dummy", &info) => 0;
+        assert(strcmp(info.name, "dummy") == 0);
+        assert(info.type == LFS_TYPE_REG);
+        lfs_unmount(&lfs) => 0;
+    }
+
+    // one last check after power-cycle
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "dummy", &info) => 0;
+    assert(strcmp(info.name, "dummy") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    lfs_unmount(&lfs) => 0;
+'''
+
+# reentrant expanding superblock
+[cases.test_superblocks_reentrant_expand]
+defines.BLOCK_CYCLES = [2, 1]
+defines.N = 24
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+
+    for (int i = 0; i < N; i++) {
+        // remove lingering dummy?
+        struct lfs_info info;
+        err = lfs_stat(&lfs, "dummy", &info);
+        assert(err == 0 || (err == LFS_ERR_NOENT && i == 0));
+        if (!err) {
+            assert(strcmp(info.name, "dummy") == 0);
+            assert(info.type == LFS_TYPE_REG);
+            lfs_remove(&lfs, "dummy") => 0;
+        }
+
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, "dummy",
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        lfs_file_close(&lfs, &file) => 0;
+        lfs_stat(&lfs, "dummy", &info) => 0;
+        assert(strcmp(info.name, "dummy") == 0);
+        assert(info.type == LFS_TYPE_REG);
+    }
+
+    lfs_unmount(&lfs) => 0;
+
+    // one last check after power-cycle
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_info info;
+    lfs_stat(&lfs, "dummy", &info) => 0;
+    assert(strcmp(info.name, "dummy") == 0);
+    assert(info.type == LFS_TYPE_REG);
+    lfs_unmount(&lfs) => 0;
+'''
+
+
+# mount with unknown block_count
+[cases.test_superblocks_unknown_blocks]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // known block_size/block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = BLOCK_COUNT;
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // unknown block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // do some work
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "test",
+            LFS_O_CREAT | LFS_O_EXCL | LFS_O_WRONLY) => 0;
+    lfs_file_write(&lfs, &file, "hello!", 6) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_file_open(&lfs, &file, "test", LFS_O_RDONLY) => 0;
+    uint8_t buffer[256];
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    assert(memcmp(buffer, "hello!", 6) == 0);
+    lfs_unmount(&lfs) => 0;
+'''
+
+# mount with blocks fewer than the erase_count
+[cases.test_superblocks_fewer_blocks]
+defines.BLOCK_COUNT = ['ERASE_COUNT/2', 'ERASE_COUNT/4', '2']
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    // known block_size/block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = BLOCK_COUNT;
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // incorrect block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = ERASE_COUNT;
+    lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+
+    // unknown block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // do some work
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "test",
+            LFS_O_CREAT | LFS_O_EXCL | LFS_O_WRONLY) => 0;
+    lfs_file_write(&lfs, &file, "hello!", 6) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_file_open(&lfs, &file, "test", LFS_O_RDONLY) => 0;
+    uint8_t buffer[256];
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    assert(memcmp(buffer, "hello!", 6) == 0);
+    lfs_unmount(&lfs) => 0;
+'''
+
+# mount with more blocks than the erase_count
+[cases.test_superblocks_more_blocks]
+defines.FORMAT_BLOCK_COUNT = '2*ERASE_COUNT'
+in = 'lfs.c'
+code = '''
+    lfs_t lfs;
+    lfs_init(&lfs, cfg) => 0;
+    lfs.block_count = BLOCK_COUNT;
+
+    lfs_mdir_t root = {
+        .pair = {0, 0}, // make sure this goes into block 0
+        .rev = 0,
+        .off = sizeof(uint32_t),
+        .etag = 0xffffffff,
+        .count = 0,
+        .tail = {LFS_BLOCK_NULL, LFS_BLOCK_NULL},
+        .erased = false,
+        .split = false,
+    };
+
+    lfs_superblock_t superblock = {
+        .version     = LFS_DISK_VERSION,
+        .block_size  = BLOCK_SIZE,
+        .block_count = FORMAT_BLOCK_COUNT,
+        .name_max    = LFS_NAME_MAX,
+        .file_max    = LFS_FILE_MAX,
+        .attr_max    = LFS_ATTR_MAX,
+    };
+
+    lfs_superblock_tole32(&superblock);
+    lfs_dir_commit(&lfs, &root, LFS_MKATTRS(
+            {LFS_MKTAG(LFS_TYPE_CREATE, 0, 0), NULL},
+            {LFS_MKTAG(LFS_TYPE_SUPERBLOCK, 0, 8), "littlefs"},
+            {LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)),
+                &superblock})) => 0;
+    lfs_deinit(&lfs) => 0;
+
+    // known block_size/block_count
+    cfg->block_size = BLOCK_SIZE;
+    cfg->block_count = BLOCK_COUNT;
+    lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+'''
+
+# mount and grow the filesystem
+[cases.test_superblocks_grow]
+defines.BLOCK_COUNT = ['ERASE_COUNT/2', 'ERASE_COUNT/4', '2']
+defines.BLOCK_COUNT_2 = 'ERASE_COUNT'
+defines.KNOWN_BLOCK_COUNT = [true, false]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    // mount with block_size < erase_size
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // same size is a noop
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // grow to new size
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT_2) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT_2;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    // mounting with the previous size should fail
+    cfg->block_count = BLOCK_COUNT;
+    lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT_2;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    // same size is a noop
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT_2) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    // do some work
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "test",
+            LFS_O_CREAT | LFS_O_EXCL | LFS_O_WRONLY) => 0;
+    lfs_file_write(&lfs, &file, "hello!", 6) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_file_open(&lfs, &file, "test", LFS_O_RDONLY) => 0;
+    uint8_t buffer[256];
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    assert(memcmp(buffer, "hello!", 6) == 0);
+    lfs_unmount(&lfs) => 0;
+'''
+
+
+# mount and grow the filesystem
+[cases.test_superblocks_shrink]
+defines.BLOCK_COUNT = 'ERASE_COUNT'
+defines.BLOCK_COUNT_2 = ['ERASE_COUNT/2', 'ERASE_COUNT/4', '2']
+defines.KNOWN_BLOCK_COUNT = [true, false]
+code = '''
+#ifdef LFS_SHRINKNONRELOCATING
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    // mount with block_size < erase_size
+    lfs_mount(&lfs, cfg) => 0;
+    struct lfs_fsinfo fsinfo;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // same size is a noop
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT);
+    lfs_unmount(&lfs) => 0;
+
+    // grow to new size
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT_2) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT_2;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    // mounting with the previous size should fail
+    cfg->block_count = BLOCK_COUNT;
+    lfs_mount(&lfs, cfg) => LFS_ERR_INVAL;
+
+    if (KNOWN_BLOCK_COUNT) {
+        cfg->block_count = BLOCK_COUNT_2;
+    } else {
+        cfg->block_count = 0;
+    }
+
+    // same size is a noop
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_grow(&lfs, BLOCK_COUNT_2) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_unmount(&lfs) => 0;
+
+    // do some work
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "test",
+            LFS_O_CREAT | LFS_O_EXCL | LFS_O_WRONLY) => 0;
+    lfs_file_write(&lfs, &file, "hello!", 6) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_fs_stat(&lfs, &fsinfo) => 0;
+    assert(fsinfo.block_size == BLOCK_SIZE);
+    assert(fsinfo.block_count == BLOCK_COUNT_2);
+    lfs_file_open(&lfs, &file, "test", LFS_O_RDONLY) => 0;
+    uint8_t buffer[256];
+    lfs_file_read(&lfs, &file, buffer, sizeof(buffer)) => 6;
+    lfs_file_close(&lfs, &file) => 0;
+    assert(memcmp(buffer, "hello!", 6) == 0);
+    lfs_unmount(&lfs) => 0;
+#endif
+'''
+
+# test that metadata_max does not cause problems for superblock compaction
+[cases.test_superblocks_metadata_max]
+defines.METADATA_MAX = [
+    'lfs_max(512, PROG_SIZE)',
+    'lfs_max(BLOCK_SIZE/2, PROG_SIZE)',
+    'BLOCK_SIZE'
+]
+defines.N = [10, 100, 1000]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs_file_t file;
+        char name[256];
+        sprintf(name, "hello%03x", i);
+        lfs_file_open(&lfs, &file, name,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_EXCL) => 0;
+        lfs_file_close(&lfs, &file) => 0;
+        struct lfs_info info;
+        lfs_stat(&lfs, name, &info) => 0;
+        assert(strcmp(info.name, name) == 0);
+        assert(info.type == LFS_TYPE_REG);
+    }
+    lfs_unmount(&lfs) => 0;
+'''

kernel/fs/littlefs/tests/test_truncate.toml

@@ -0,0 +1,503 @@
+# simple truncate
+[cases.test_truncate_simple]
+defines.MEDIUMSIZE = [31, 32, 33, 511, 512, 513, 2047, 2048, 2049]
+defines.LARGESIZE = [32, 33, 512, 513, 2048, 2049, 8192, 8193]
+if = 'MEDIUMSIZE < LARGESIZE'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "baldynoop",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "hair");
+    size_t size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < LARGESIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, LARGESIZE-j))
+                => lfs_min(size, LARGESIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+    
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldynoop", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    lfs_file_truncate(&lfs, &file, MEDIUMSIZE) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldynoop", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    size = strlen("hair");
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "hair", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# truncate and read
+[cases.test_truncate_read]
+defines.MEDIUMSIZE = [31, 32, 33, 511, 512, 513, 2047, 2048, 2049]
+defines.LARGESIZE = [32, 33, 512, 513, 2048, 2049, 8192, 8193]
+if = 'MEDIUMSIZE < LARGESIZE'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "baldyread",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "hair");
+    size_t size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < LARGESIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, LARGESIZE-j))
+                => lfs_min(size, LARGESIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldyread", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    lfs_file_truncate(&lfs, &file, MEDIUMSIZE) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    size = strlen("hair");
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "hair", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldyread", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    size = strlen("hair");
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "hair", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# write, truncate, and read
+[cases.test_truncate_write_read]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "sequence",
+            LFS_O_RDWR | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+    uint8_t buffer[1024];
+    size_t size = lfs_min(lfs.cfg->cache_size, sizeof(buffer)/2);
+    lfs_size_t qsize = size / 4;
+    uint8_t *wb = buffer;
+    uint8_t *rb = buffer + size;
+    for (lfs_off_t j = 0; j < size; ++j) {
+        wb[j] = j;
+    }
+
+    /* Spread sequence over size */
+    lfs_file_write(&lfs, &file, wb, size) => size;
+    lfs_file_size(&lfs, &file) => size;
+    lfs_file_tell(&lfs, &file) => size;
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+    lfs_file_tell(&lfs, &file) => 0;
+
+    /* Chop off the last quarter */
+    lfs_size_t trunc = size - qsize;
+    lfs_file_truncate(&lfs, &file, trunc) => 0;
+    lfs_file_tell(&lfs, &file) => 0;
+    lfs_file_size(&lfs, &file) => trunc;
+
+    /* Read should produce first 3/4 */
+    lfs_file_read(&lfs, &file, rb, size) => trunc;
+    memcmp(rb, wb, trunc) => 0;
+
+    /* Move to 1/4 */
+    lfs_file_size(&lfs, &file) => trunc;
+    lfs_file_seek(&lfs, &file, qsize, LFS_SEEK_SET) => qsize;
+    lfs_file_tell(&lfs, &file) => qsize;
+
+    /* Chop to 1/2 */
+    trunc -= qsize;
+    lfs_file_truncate(&lfs, &file, trunc) => 0;
+    lfs_file_tell(&lfs, &file) => qsize;
+    lfs_file_size(&lfs, &file) => trunc;
+
+    /* Read should produce second quarter */
+    lfs_file_read(&lfs, &file, rb, size) => trunc - qsize;
+    memcmp(rb, wb + qsize, trunc - qsize) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# truncate and write
+[cases.test_truncate_write]
+defines.MEDIUMSIZE = [31, 32, 33, 511, 512, 513, 2047, 2048, 2049]
+defines.LARGESIZE = [32, 33, 512, 513, 2048, 2049, 8192, 8193]
+if = 'MEDIUMSIZE < LARGESIZE'
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "baldywrite",
+            LFS_O_WRONLY | LFS_O_CREAT) => 0;
+
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "hair");
+    size_t size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < LARGESIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, LARGESIZE-j))
+                => lfs_min(size, LARGESIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldywrite", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+
+    /* truncate */
+    lfs_file_truncate(&lfs, &file, MEDIUMSIZE) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    /* and write */
+    strcpy((char*)buffer, "bald");
+    size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldywrite", LFS_O_RDONLY) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    size = strlen("bald");
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "bald", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''
+
+# truncate write under powerloss
+[cases.test_truncate_reentrant_write]
+defines.SMALLSIZE = [4, 512]
+defines.MEDIUMSIZE = [0, 3, 4, 5, 31, 32, 33, 511, 512, 513, 1023, 1024, 1025]
+defines.LARGESIZE = 2048
+reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
+code = '''
+    lfs_t lfs;
+    int err = lfs_mount(&lfs, cfg);
+    if (err) {
+        lfs_format(&lfs, cfg) => 0;
+        lfs_mount(&lfs, cfg) => 0;
+    }
+    lfs_file_t file;
+    err = lfs_file_open(&lfs, &file, "baldy", LFS_O_RDONLY);
+    assert(!err || err == LFS_ERR_NOENT);
+    if (!err) {
+        size_t size = lfs_file_size(&lfs, &file);
+        assert(size == 0 ||
+                size == (size_t)LARGESIZE ||
+                size == (size_t)MEDIUMSIZE ||
+                size == (size_t)SMALLSIZE);
+        for (lfs_off_t j = 0; j < size; j += 4) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, lfs_min(4, size-j))
+                    => lfs_min(4, size-j);
+            assert(memcmp(buffer, "hair", lfs_min(4, size-j)) == 0 ||
+                   memcmp(buffer, "bald", lfs_min(4, size-j)) == 0 ||
+                   memcmp(buffer, "comb", lfs_min(4, size-j)) == 0);
+        }
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    lfs_file_open(&lfs, &file, "baldy",
+            LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+    lfs_file_size(&lfs, &file) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "hair");
+    size_t size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < LARGESIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, LARGESIZE-j))
+                => lfs_min(size, LARGESIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "baldy", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => LARGESIZE;
+    /* truncate */
+    lfs_file_truncate(&lfs, &file, MEDIUMSIZE) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+    /* and write */
+    strcpy((char*)buffer, "bald");
+    size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_file_open(&lfs, &file, "baldy", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+    lfs_file_truncate(&lfs, &file, SMALLSIZE) => 0;
+    lfs_file_size(&lfs, &file) => SMALLSIZE;
+    strcpy((char*)buffer, "comb");
+    size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < SMALLSIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, SMALLSIZE-j))
+                => lfs_min(size, SMALLSIZE-j);
+    }
+    lfs_file_size(&lfs, &file) => SMALLSIZE;
+    lfs_file_close(&lfs, &file) => 0;
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# more aggressive general truncation tests
+[cases.test_truncate_aggressive]
+defines.CONFIG = 'range(6)'
+defines.SMALLSIZE = 32
+defines.MEDIUMSIZE = 2048
+defines.LARGESIZE = 8192
+code = '''
+    lfs_t lfs;
+    #define COUNT 5
+    const struct {
+        lfs_off_t startsizes[COUNT];
+        lfs_off_t startseeks[COUNT];
+        lfs_off_t hotsizes[COUNT];
+        lfs_off_t coldsizes[COUNT];
+    } configs[] = {
+        // cold shrinking
+        {{2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE}},
+        // cold expanding
+        {{2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE}},
+        // warm shrinking truncate
+        {{2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE},
+         {          0,           0,           0,           0,           0}},
+        // warm expanding truncate
+        {{          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE},
+         {          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE}},
+        // mid-file shrinking truncate
+        {{2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {  LARGESIZE,   LARGESIZE,   LARGESIZE,   LARGESIZE,   LARGESIZE},
+         {          0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE, 2*LARGESIZE},
+         {          0,           0,           0,           0,           0}},
+        // mid-file expanding truncate
+        {{          0,   SMALLSIZE,   MEDIUMSIZE,  LARGESIZE, 2*LARGESIZE},
+         {          0,           0,   SMALLSIZE,  MEDIUMSIZE,   LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE},
+         {2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE, 2*LARGESIZE}},
+    };
+
+    const lfs_off_t *startsizes = configs[CONFIG].startsizes;
+    const lfs_off_t *startseeks = configs[CONFIG].startseeks;
+    const lfs_off_t *hotsizes   = configs[CONFIG].hotsizes;
+    const lfs_off_t *coldsizes  = configs[CONFIG].coldsizes;
+
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+
+    for (unsigned i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "hairyhead%d", i);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path,
+                LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC) => 0;
+
+        uint8_t buffer[1024];
+        strcpy((char*)buffer, "hair");
+        size_t size = strlen((char*)buffer);
+        for (lfs_off_t j = 0; j < startsizes[i]; j += size) {
+            lfs_file_write(&lfs, &file, buffer, size) => size;
+        }
+        lfs_file_size(&lfs, &file) => startsizes[i];
+
+        if (startseeks[i] != startsizes[i]) {
+            lfs_file_seek(&lfs, &file,
+                    startseeks[i], LFS_SEEK_SET) => startseeks[i];
+        }
+
+        lfs_file_truncate(&lfs, &file, hotsizes[i]) => 0;
+        lfs_file_size(&lfs, &file) => hotsizes[i];
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+
+    for (unsigned i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "hairyhead%d", i);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path, LFS_O_RDWR) => 0;
+        lfs_file_size(&lfs, &file) => hotsizes[i];
+
+        size_t size = strlen("hair");
+        lfs_off_t j = 0;
+        for (; j < startsizes[i] && j < hotsizes[i]; j += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            memcmp(buffer, "hair", size) => 0;
+        }
+
+        for (; j < hotsizes[i]; j += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            memcmp(buffer, "\0\0\0\0", size) => 0;
+        }
+
+        lfs_file_truncate(&lfs, &file, coldsizes[i]) => 0;
+        lfs_file_size(&lfs, &file) => coldsizes[i];
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, cfg) => 0;
+
+    for (unsigned i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "hairyhead%d", i);
+        lfs_file_t file;
+        lfs_file_open(&lfs, &file, path, LFS_O_RDONLY) => 0;
+        lfs_file_size(&lfs, &file) => coldsizes[i];
+
+        size_t size = strlen("hair");
+        lfs_off_t j = 0;
+        for (; j < startsizes[i] && j < hotsizes[i] && j < coldsizes[i];
+                j += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            memcmp(buffer, "hair", size) => 0;
+        }
+
+        for (; j < coldsizes[i]; j += size) {
+            uint8_t buffer[1024];
+            lfs_file_read(&lfs, &file, buffer, size) => size;
+            memcmp(buffer, "\0\0\0\0", size) => 0;
+        }
+
+        lfs_file_close(&lfs, &file) => 0;
+    }
+
+    lfs_unmount(&lfs) => 0;
+'''
+
+# noop truncate
+[cases.test_truncate_nop]
+defines.MEDIUMSIZE = [32, 33, 512, 513, 2048, 2049, 8192, 8193]
+code = '''
+    lfs_t lfs;
+    lfs_format(&lfs, cfg) => 0;
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_t file;
+    lfs_file_open(&lfs, &file, "baldynoop",
+            LFS_O_RDWR | LFS_O_CREAT) => 0;
+
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "hair");
+    size_t size = strlen((char*)buffer);
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_write(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+
+        // this truncate should do nothing
+        lfs_file_truncate(&lfs, &file, j+lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    lfs_file_seek(&lfs, &file, 0, LFS_SEEK_SET) => 0;
+    // should do nothing again
+    lfs_file_truncate(&lfs, &file, MEDIUMSIZE) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "hair", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+
+    // still there after reboot?
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_file_open(&lfs, &file, "baldynoop", LFS_O_RDWR) => 0;
+    lfs_file_size(&lfs, &file) => MEDIUMSIZE;
+    for (lfs_off_t j = 0; j < MEDIUMSIZE; j += size) {
+        lfs_file_read(&lfs, &file, buffer, lfs_min(size, MEDIUMSIZE-j))
+                => lfs_min(size, MEDIUMSIZE-j);
+        memcmp(buffer, "hair", lfs_min(size, MEDIUMSIZE-j)) => 0;
+    }
+    lfs_file_read(&lfs, &file, buffer, size) => 0;
+    lfs_file_close(&lfs, &file) => 0;
+    lfs_unmount(&lfs) => 0;
+'''