请教：android linker 加载so字节数组

Question

我根据android5.0的linker源码，自己实现了一个加载64位so的功能，将加载so文件换成了加载so的字节数组，不过有一个问题

for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
        if (d->d_tag == DT_NEEDED) {
            const char* library_name = si->strtab + d->d_un.d_val;
            DEBUG("%s needs %s", si->name, library_name);
            soinfo* lsi = find_library(library_name, 0, NULL);
            if (lsi == NULL) {
                strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf));
                DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",
                       library_name, si->name, tmp_err_buf);
                return false;
            }

            si->add_child(lsi);
            *pneeded++ = lsi;
        }
    }

我看网上有人将 soinfo lsi = find_library(library_name, 0, NULL)*; 修改为了dlopen，并且因为7.0后没有返回soinfo，它这里就没有做 si->add_child(lsi);处理

soinfo_relocate中：

  if (sym != 0) {
      sym_name = reinterpret_cast<const char*>(si->strtab + si->symtab[sym].st_name);
     _ s = soinfo_do_lookup(si, sym_name, &lsi, needed);_
      if (s == NULL) {
        // We only allow an undefined symbol if this is a weak reference...
        s = &si->symtab[sym];
        if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
          DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name);
          return -1;
        }

s = soinfo_do_lookup(si, sym_name, &lsi, needed); 这里，直接用dlsym返回地址

我参考的是这个地址：https://blog.csdn.net/u010559109/article/details/120460886

请问有没有试过内存加载so字节数组的。代码修改完成后，经常闪退，找不到原因

Fatal signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0x7058ce0760 in tid 8737 (pool-1-thread-1), pid 8686 (com.test.loader)

Android5.0源码：http://aospxref.com/android-5.0.2_r3/xref/bionic/linker/
附部分我结合linker5.0源码修改后的代码

bool ElfReader::ReadElfHeader() {
    memcpy(&header_, elfData_, sizeof(header_));
    return true;
}




void *mmap_result = mmap(NULL, phdr_size_, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS,
                             -1, 0);
    if (mmap_result == MAP_FAILED) {
        DL_ERR("\"%s\" phdr mmap failed: %s", name_, strerror(errno));
        return false;
    }
    memcpy(mmap_result, elfData_ + page_min, phdr_size_);

    phdr_mmap_ = mmap_result;
    phdr_table_ = reinterpret_cast<ElfW(Phdr) *>(reinterpret_cast<char *>(mmap_result) +
                                                 page_offset);



  mprotect(reinterpret_cast<void *>(seg_page_start), seg_page_end - seg_page_start,
                 PROT_WRITE);

        if (file_length != 0) {
            memcpy(reinterpret_cast<void *>(seg_page_start), elfData_ + file_page_start,
                   file_length);
        }


 if (sym != 0) {

            bool isNeed = false;

            sym_name = reinterpret_cast<const char *>(si->strtab + si->symtab[sym].st_name);

            unsigned elf_hash = elfhash(sym_name);
            //先从本si拿
            ElfW(Sym) *s = soinfo_elf_lookup(si, elf_hash, sym_name);
            if (s != NULL) {
                sym_addr = static_cast<ElfW(Addr)>(s->st_value + si->load_bias);
            } else {
                //再从依赖里面拿
                for (int i = 0; i < needed_count; i++) {
                    uintptr_t value = needed[i];
                    void *handle = reinterpret_cast<void *>(value);
                    sym_addr = reinterpret_cast<ElfW(Addr)>(dlsym(handle, sym_name));
                    if (sym_addr) {
                        isNeed = true;
                        break;
                    }
                }
            }
            if (s == NULL && !isNeed) {
                // We only allow an undefined symbol if this is a weak reference...
                s = &si->symtab[sym];
                if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
                    DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name,
                           si->name);
                    return -1;
                }

Answer 1

每行都加日志，看看哪里发生的踩内存