Parse ramdisk tar file

kernel/ramdisk/tar.c

@@ -0,0 +1,68 @@
+/*
+Copyright 2025 Kamil Kowalczyk
+
+Redistribution and use in source and binary forms, with or
+without modification, are permitted provided that the following
+conditions are met:
+
+1. Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+“AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <libk/types.h>
+#include <ramdisk/tar.h>
+
+static struct tar_header *ramdisk_tar_headers[TAR_MAX];
+
+usize_t tar_get_size(const byte_t *input) {
+  usize_t size = 0;
+  usize_t j;
+  usize_t count = 1;
+
+  for (j = 11; j > 0; j--, count *= 8)
+    size += ((input[j - 1] - '0') * count);
+
+  return size;
+}
+
+usize_t tar_parse(uptr_t addr) {
+  usize_t i;
+
+  for (i = 0; ; i++) {
+    struct tar_header *header = (struct tar_header *)addr;
+
+    if (header->filename[i] == '\0')
+      break;
+
+    usize_t size = tar_get_size(header->size);
+
+    ramdisk_tar_headers[i] = header;
+
+    addr += ((size / 512) + 1) * 512;
+
+    if (size % 512)
+      addr += 512;
+  }
+
+  return i;
+}