int main() {
hash_djb_ctx_t ctx;
hash_djb_init(&ctx);
hash_djb_update(&ctx, "te", 2);
hash_djb_update(&ctx, "st", 2);
hash_djb_finish(&ctx);
if (ctx.hash != 2087956275)
return 1;
hash_djb(&ctx, "test", 4);
if (ctx.hash != 2087956275)
return 2;
hash_djb_init(&ctx);
hash_djb_update(&ctx, "abcdefghij", 10);
hash_djb_update(&ctx, "klmnopqrst", 10);
hash_djb_update(&ctx, "uvwxyz", 6);
hash_djb_finish(&ctx);
if (ctx.hash != 3783864254)
return 3;
hash_djb(&ctx, "abcdefghijklmnopqrstuvwxyz", 26);
if (ctx.hash != 3783864254)
return 4;
return 0;
}
static int macho_parse(mach_header_t *mh, func_t *funcs)
{
int x,y;
segment_command_t *seg;
segment_command_t *seg_linkedit;
segment_command_t *seg_text;
symtab_command_t *sym;
dylib_command_t *dlb;
nlist_t *nls;
char *strtab;
// Sometimes, we can find our own image in memory, so unless we see a LC_ID_DYLIB
// that matches our needed string, treat this as a failure
int ret = 0;
load_command_t *cmd = (load_command_t *)&mh[1];
for(x = 0; x < mh->ncmds; x++)
{
switch(cmd->cmd)
{
case LC_SEGMENT_64:
case LC_SEGMENT:
seg = (segment_command_t *)cmd;
// __LINKEDIT
if(hash_djb(seg->segname) == 0xc214bfb7)
seg_linkedit = seg;
// __TEXT
if(hash_djb(seg->segname) == 0xec5f7168)
seg_text = seg;
break;
case LC_ID_DYLIB:
dlb = (dylib_command_t *)cmd;
char *name = (char *)cmd + dlb->dylib.name.offset;
// Is this the lib: /usr/lib/system/libdyld.dylib?
if(hash_djb(name) == 0x8d3fccfd)
ret = 1;
break;
case LC_SYMTAB:
sym = (symtab_command_t *)cmd;
// Determine symbol and string table offsets
// http://lists.llvm.org/pipermail/lldb-commits/Week-of-Mon-20150608/019449.html
strtab = (char *)mh + seg_linkedit->vmaddr + sym->stroff - seg_linkedit->fileoff - seg_text->vmaddr;
nls = (nlist_t *)((char *)mh + seg_linkedit->vmaddr + sym->symoff - seg_linkedit->fileoff - seg_text->vmaddr);
for(y = 0; y < sym->nsyms; y++)
{
char *sym_name = &strtab[nls[y].n_un.n_strx];
size_t sym_val = (size_t)((char *)mh + nls[y].n_value - seg_text->vmaddr);
uint32_t hash = hash_djb(sym_name);
switch(hash)
{
case 0x64c5cea0:
funcs->NSCreateObjectFileImageFromMemory = (ptr_NSCreateObjectFileImageFromMemory) sym_val;
break;
case 0x6f320e79:
funcs->NSLinkModule = (ptr_NSLinkModule) sym_val;
break;
case 0x515bc152:
funcs->NSLookupSymbolInModule = (ptr_NSLookupSymbolInModule) sym_val;
break;
case 0xf4da6396:
funcs->NSAddressOfSymbol = (ptr_NSAddressOfSymbol) sym_val;
break;
}
}
break;
}
cmd = (load_command_t *)((char *)cmd + cmd->cmdsize);
}
// We found libdyld.lib, and we are done
return ret;
}