Print function name and file location when caught a SIGSEGV

.debugusrc1.js

@@ -6,27 +6,27 @@ ler("Test error message");
 var offset = "0x0000000000001169"; // dupa(), objdump -d ./test
 
 // Testing...
-pf();
+// pf();
-ppid();
+// ppid();
-pplo();
+// pplo();
 baddr(offset);
 lsbrk();
 
-lif("1 --------------------------------------------");
+// lif("1 --------------------------------------------");
-dr();
+// dr();
-var r14 = gr("r14");
+// var r14 = gr("r14");
-sr("r14", "0x0");
+// sr("r14", "0x0");
-lif("2 --------------------------------------------");
+// lif("2 --------------------------------------------");
-dr();
+// dr();
-sr("r14", r14);
+// sr("r14", r14);
-lif("3 --------------------------------------------");
+// lif("3 --------------------------------------------");
-dr();
+// dr();
 
-var r14_mem = mrdr("r14");
+// var r14_mem = mrdr("r14");
-lif("Memory at r14 " + r14_mem);
+// lif("Memory at r14 " + r14_mem);
-mwrr("r14", "0x696969");
+// mwrr("r14", "0x696969");
-lif("Memory at r14 " + mrdr("r14"));
+// lif("Memory at r14 " + mrdr("r14"));
-mwrr("r14", r14_mem);
+// mwrr("r14", r14_mem);
-lif("Memory at r14 " + mrdr("r14"));
+// lif("Memory at r14 " + mrdr("r14"));
 
 // cont();

.debugusrc1.js.txt

@@ -6,27 +6,27 @@ ler("Test error message");
 var offset = "@DUPA_ADDR"; // dupa(), objdump -d ./test
 
 // Testing...
-pf();
+// pf();
-ppid();
+// ppid();
-pplo();
+// pplo();
 baddr(offset);
 lsbrk();
 
-lif("1 --------------------------------------------");
+// lif("1 --------------------------------------------");
-dr();
+// dr();
-var r14 = gr("r14");
+// var r14 = gr("r14");
-sr("r14", "0x0");
+// sr("r14", "0x0");
-lif("2 --------------------------------------------");
+// lif("2 --------------------------------------------");
-dr();
+// dr();
-sr("r14", r14);
+// sr("r14", r14);
-lif("3 --------------------------------------------");
+// lif("3 --------------------------------------------");
-dr();
+// dr();
 
-var r14_mem = mrdr("r14");
+// var r14_mem = mrdr("r14");
-lif("Memory at r14 " + r14_mem);
+// lif("Memory at r14 " + r14_mem);
-mwrr("r14", "0x696969");
+// mwrr("r14", "0x696969");
-lif("Memory at r14 " + mrdr("r14"));
+// lif("Memory at r14 " + mrdr("r14"));
-mwrr("r14", r14_mem);
+// mwrr("r14", r14_mem);
-lif("Memory at r14 " + mrdr("r14"));
+// lif("Memory at r14 " + mrdr("r14"));
 
 // cont();

da.h

@@ -7,11 +7,11 @@
     do { \
         if ((da)->count == 0) { \
             (da)->capacity = 1; \
-            (da)->items = malloc(sizeof(item)*sizeof((da)->capacity)); \
+            (da)->items = (typeof((da)->items))malloc(sizeof(item)*sizeof((da)->capacity)); \
         } else { \
             if ((da)->count == (da)->capacity) { \
                 (da)->capacity *= 2; \
-                (da)->items = realloc((da)->items, (da)->capacity * sizeof((item))); \
+                (da)->items = (typeof((da)->items))realloc((da)->items, (da)->capacity * sizeof((item))); \
             } \
         } \
         (da)->items[(da)->count++] = (item); \

debugus.c

@@ -145,6 +145,14 @@ void brk_disable(Brk *brk)
     brk->enabled = false;
 }
 
+void symbols_deinit(Symbols *s)
+{
+    for (int i = 0; i < s->count; i++) {
+        free((char *)s->items[i].name);
+    }
+    da_deinit(s);
+}
+
 typedef struct {
     const char *file;
     pid_t pid;
@@ -152,6 +160,8 @@ typedef struct {
     HashTable brks;
     uintptr_t program_load_offset;
     HashTable js_descs;
+    Symbols symbols;
+    FILE *binfile;
     PLibelfinBinding plibelfin;
 } Dbg;
 
@@ -165,7 +175,26 @@ siginfo_t dbg_get_siginfo(Dbg *dbg)
 void dbg_handle_sigsegv(Dbg *dbg, siginfo_t info)
 {
     unused(dbg);
+    uint64_t dbg_get_rip(Dbg *dbg);
     LOG_ERR("Caught a segfault %d. SKILL ISSUE BRO\n", info.si_code);
+    uintptr_t rip = (uintptr_t)dbg_get_rip(dbg);
+    uintptr_t nearest = rip - dbg->symbols.items[0].addr;
+    for (int i = 0; i < dbg->symbols.count; i++) {
+        if (rip - dbg->symbols.items[i].addr < nearest) {
+            nearest = rip - dbg->symbols.items[i].addr;
+        }
+    }
+    uintptr_t addr = rip - nearest;
+    for (int i = 0; i < dbg->symbols.count; i++) {
+        if (dbg->symbols.items[i].addr == addr) {
+            AddrInfo *ai = libelfin_wrap_info_from_rip(dbg->plibelfin, (uint64_t)(addr - dbg->program_load_offset));
+            if (ai != NULL) {
+                LOG_INF("%s:%zu in function %s()\n", ai->file, (size_t)ai->line, dbg->symbols.items[i].name);
+                libelfin_wrap_free_info(ai);
+            }
+            break;
+        }
+    }
 }
 
 void dbg_handle_sigtrap(Dbg *dbg, siginfo_t info)
@@ -538,17 +567,29 @@ void dbg_load_script(Dbg *dbg, const char *script_path)
     fclose(script);
 }
 
-void dbg_libelfin_wrap_init(Dbg *dbg)
+void dbg_init_bin(Dbg *dbg)
 {
     FILE *bin = fopen(dbg->file, "rb");
     if (bin == NULL) {
         LOG_ERR("could not open file %s: %s\n", dbg->file, strerror(errno));
         return;
     }
+    dbg->binfile = bin;
+}
 
-    dbg->plibelfin = libelfin_wrap_get_binding(fileno(bin));
+void dbg_libelfin_wrap_init(Dbg *dbg)
+{
+    dbg->plibelfin = libelfin_wrap_get_binding(fileno(dbg->binfile), dbg->program_load_offset);
+}
 
-    fclose(bin);
+void dbg_load_symbols(Dbg *dbg)
+{
+    libelfin_wrap_get_syms(dbg->plibelfin, &dbg->symbols);
+
+    for (int i = 0; i < dbg->symbols.count; i++) {
+        Symbol *s = &dbg->symbols.items[i];
+        LOG_INF("Found symbol %s 0x%"PRIxPTR"\n", s->name, s->addr);
+    }
 }
 
 void dbg_init(Dbg *dbg, const char *file, pid_t pid)
@@ -559,7 +600,9 @@ void dbg_init(Dbg *dbg, const char *file, pid_t pid)
     hashtable_init(&dbg->js_descs, MAX_JS_FUNCS);
     dbg_init_js(dbg);
     dbg_init_load_offset(dbg);
+    dbg_init_bin(dbg);
     dbg_libelfin_wrap_init(dbg);
+    dbg_load_symbols(dbg);
     hashtable_init(&dbg->brks, MAX_BRKS);
     dbg_load_script(dbg, INIT_SCRIPT);
 }
@@ -569,7 +612,9 @@ void dbg_deinit(Dbg *dbg)
     js_freestate(dbg->js);
     hashtable_deinit(&dbg->brks);
     hashtable_deinit(&dbg->js_descs);
+    symbols_deinit(&dbg->symbols);
     libelfin_wrap_free_binding(dbg->plibelfin);
+    fclose(dbg->binfile);
 }
 
 void dbg_loop(Dbg *dbg)

libelfin_wrap.cpp

@@ -7,19 +7,41 @@
 class LibelfinBinding
 {
     public:
-        LibelfinBinding(int fd)
+        LibelfinBinding(int fd, uintptr_t _loadoffset)
             : elf(elf::create_mmap_loader(fd)),
-              dwarf(dwarf::elf::create_loader(this->elf))
+              dwarf(dwarf::elf::create_loader(this->elf)),
+              loadoffset(_loadoffset)
         {
         }
 
         elf::elf elf;
         dwarf::dwarf dwarf;
+        uintptr_t loadoffset;
 };
 
-DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd)
+DEBUGUS_EXTERNC void libelfin_wrap_get_syms(PLibelfinBinding *pbind, Symbols *syms)
 {
-    return (PLibelfinBinding)new LibelfinBinding(fd);
+    LibelfinBinding *bind = (LibelfinBinding *)pbind;
+    for (auto &section : bind->elf.sections()) {
+        if (section.get_hdr().type == elf::sht::symtab) {
+            for (auto sym : section.as_symtab()) {
+                auto &d = sym.get_data();
+                if (d.type() == elf::stt::func) {
+                    Symbol s = {
+                        .name = (const char *)malloc(strlen(sym.get_name().c_str())+1),
+                        .addr = bind->loadoffset + (uintptr_t)d.value,
+                    };
+                    strcpy((char*)s.name, sym.get_name().c_str());
+                    da_append(syms, s);
+                }
+            }
+        }
+    }
+}
+
+DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd, uintptr_t loadoffset)
+{
+    return (PLibelfinBinding)new LibelfinBinding(fd, loadoffset);
 }
 
 DEBUGUS_EXTERNC void libelfin_wrap_free_binding(PLibelfinBinding pbind)

libelfin_wrap.h

@@ -12,17 +12,30 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "da.h"
+
 typedef struct {
     ssize_t line;
     const char *file;
     uint64_t addr;
 } AddrInfo;
 
+typedef struct {
+    const char *name;
+    uintptr_t addr;
+} Symbol;
+
+typedef struct {
+    Symbol *items;
+    size_t count, capacity;
+} Symbols;
+
 typedef void * PLibelfinBinding;
 
-DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd);
+DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd, uintptr_t loadoffset);
 DEBUGUS_EXTERNC void libelfin_wrap_free_binding(PLibelfinBinding pbind);
 DEBUGUS_EXTERNC AddrInfo *libelfin_wrap_info_from_rip(PLibelfinBinding pbind, uint64_t rip);
 DEBUGUS_EXTERNC void libelfin_wrap_free_info(AddrInfo *ai);
+DEBUGUS_EXTERNC void libelfin_wrap_get_syms(PLibelfinBinding *pbind, Symbols *syms);
 
 #endif // LIBELFIN_WRAP_H_

test.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <inttypes.h>
+#include <stdlib.h>
 
 void dupa(void) {
     printf("KSKSKKSKSKSK\n");
@@ -15,6 +16,10 @@ int main(void)
             dupa();
         }
     }
+
+    int *a = NULL;
+    *a = 6969;
+
     return 0;
 }