static void rcd_perform_rebinding_with_section()

in rcd_fishhook/rcd_fishhook.c [90:143]

• 54 lines of code
• 17 McCabe index (conditional complexity)

static void rcd_perform_rebinding_with_section(struct rcd_rebindings_entry *rebindings,
                                           section_t *section,
                                           intptr_t slide,
                                           nlist_t *symtab,
                                           char *strtab,
                                           uint32_t *indirect_symtab) {
  const bool isDataConst = strcmp(section->segname, "__DATA_CONST") == 0;
  uint32_t *indirect_symbol_indices = indirect_symtab + section->reserved1;
  void **indirect_symbol_bindings = (void **)((uintptr_t)slide + section->addr);
  vm_prot_t oldProtection = VM_PROT_READ;
  if (isDataConst) {
    oldProtection = get_protection(rebindings);
    mprotect(indirect_symbol_bindings, section->size, PROT_READ | PROT_WRITE);
  }
  for (uint i = 0; i < section->size / sizeof(void *); i++) {
    uint32_t symtab_index = indirect_symbol_indices[i];
    if (symtab_index == INDIRECT_SYMBOL_ABS || symtab_index == INDIRECT_SYMBOL_LOCAL ||
        symtab_index == (INDIRECT_SYMBOL_LOCAL   | INDIRECT_SYMBOL_ABS)) {
      continue;
    }
    uint32_t strtab_offset = symtab[symtab_index].n_un.n_strx;
    char *symbol_name = strtab + strtab_offset;
    bool symbol_name_longer_than_1 = symbol_name[0] && symbol_name[1];
    struct rcd_rebindings_entry *cur = rebindings;
    while (cur) {
      for (uint j = 0; j < cur->rebindings_nel; j++) {
        if (symbol_name_longer_than_1 &&
            strcmp(&symbol_name[1], cur->rebindings[j].name) == 0) {
          if (cur->rebindings[j].replaced != NULL &&
              indirect_symbol_bindings[i] != cur->rebindings[j].replacement) {
            *(cur->rebindings[j].replaced) = indirect_symbol_bindings[i];
          }
          indirect_symbol_bindings[i] = cur->rebindings[j].replacement;
          goto symbol_loop;
        }
      }
      cur = cur->next;
    }
  symbol_loop:;
  }
  if (isDataConst) {
    int protection = 0;
    if (oldProtection & VM_PROT_READ) {
      protection |= PROT_READ;
    }
    if (oldProtection & VM_PROT_WRITE) {
      protection |= PROT_WRITE;
    }
    if (oldProtection & VM_PROT_EXECUTE) {
      protection |= PROT_EXEC;
    }
    mprotect(indirect_symbol_bindings, section->size, protection);
  }
}