C 导入地址表和全局偏移表之间的区别是什么？_C_Assembly_Elf_Portable Executable_Got

C 导入地址表和全局偏移表之间的区别是什么？

c assembly

C 导入地址表和全局偏移表之间的区别是什么？,c,assembly,elf,portable-executable,got,C,Assembly,Elf,Portable Executable,Got,我试着分别用谷歌搜索它们，但有一件事最突出。只是IAT是针对PE文件的，而GET是针对ELF的吗在Linux上，可以使用nm命令查看必须从共享库导入的所有符号。我编译了一个名为“main”的小程序。使用nm命令，我可以看到对象的偏移。前缀为“T”的符号是函数，可以在“主”代码中找到，以及逻辑偏移量（全局偏移量表）。前缀为“U”的符号未定义，必须导入（导入地址表）有关详细信息，请将objdump与-x选项一起使用： $ objdump -x main main: file format

我试着分别用谷歌搜索它们，但有一件事最突出。只是IAT是针对PE文件的，而GET是针对ELF的吗

在Linux上，可以使用nm命令查看必须从共享库导入的所有符号。我编译了一个名为“main”的小程序。使用nm命令，我可以看到对象的偏移。前缀为“T”的符号是函数，可以在“主”代码中找到，以及逻辑偏移量（全局偏移量表）。前缀为“U”的符号未定义，必须导入（导入地址表）

有关详细信息，请将objdump与-x选项一起使用：

$ objdump -x main

main:   file format Mach-O 64-bit x86-64

Sections:
Idx Name          Size      Address          Type
  0 __text        0000018a 0000000100000d70 TEXT 
  1 __stubs       00000024 0000000100000efa TEXT 
  2 __stub_helper 0000004c 0000000100000f20 TEXT 
  3 __cstring     00000042 0000000100000f6c DATA 
  4 __unwind_info 00000048 0000000100000fb0 DATA 
  5 __nl_symbol_ptr 00000008 0000000100001000 DATA 
  6 __got         00000010 0000000100001008 DATA 
  7 __la_symbol_ptr 00000030 0000000100001018 DATA 

SYMBOL TABLE:
0000000100000d70 g     F __TEXT,__text  _AddAlbum
0000000100000000 g     F __TEXT,__text  __mh_execute_header
0000000100000e40 g     F __TEXT,__text  _main
0000000000000000         *UND*  ___error
0000000000000000         *UND*  ___stderrp
0000000000000000         *UND*  _fprintf
0000000000000000         *UND*  _malloc
0000000000000000         *UND*  _printf
0000000000000000         *UND*  _realloc
0000000000000000         *UND*  _strerror
0000000000000000         *UND*  dyld_stub_binder
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MH_MAGIC_64  X86_64        ALL LIB64     EXECUTE    15       1296   NOUNDEFS DYLDLINK TWOLEVEL PIE
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只是IAT是针对PE文件的，而GET是针对ELF的吗

这是主要区别

另一个区别是，ELF文件中的GOT也可能包含描述ELF文件本身中定义的符号的条目。这是32位共享库的典型情况

PE文件中的IAT仅包含描述在其他DLL文件中定义的符号的条目。

GOT是否必须有一个在executalbe中定义的符号条目，如

main

？共享库有自己的GOT（因为它们需要能够使用代码中的PIC偏移量来访问），因此主可执行文件的GOT显然不需要为自己的符号创建条目，除非主可执行文件的代码引用了它们的条目。可执行文件中的符号可以假定它们“赢得”符号插入，即使它们是全局的（不隐藏），因此通常直接访问它们，而不是通过GOT。

$ objdump -x main

main:   file format Mach-O 64-bit x86-64

Sections:
Idx Name          Size      Address          Type
  0 __text        0000018a 0000000100000d70 TEXT 
  1 __stubs       00000024 0000000100000efa TEXT 
  2 __stub_helper 0000004c 0000000100000f20 TEXT 
  3 __cstring     00000042 0000000100000f6c DATA 
  4 __unwind_info 00000048 0000000100000fb0 DATA 
  5 __nl_symbol_ptr 00000008 0000000100001000 DATA 
  6 __got         00000010 0000000100001008 DATA 
  7 __la_symbol_ptr 00000030 0000000100001018 DATA 

SYMBOL TABLE:
0000000100000d70 g     F __TEXT,__text  _AddAlbum
0000000100000000 g     F __TEXT,__text  __mh_execute_header
0000000100000e40 g     F __TEXT,__text  _main
0000000000000000         *UND*  ___error
0000000000000000         *UND*  ___stderrp
0000000000000000         *UND*  _fprintf
0000000000000000         *UND*  _malloc
0000000000000000         *UND*  _printf
0000000000000000         *UND*  _realloc
0000000000000000         *UND*  _strerror
0000000000000000         *UND*  dyld_stub_binder
Mach header
      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
MH_MAGIC_64  X86_64        ALL LIB64     EXECUTE    15       1296   NOUNDEFS DYLDLINK TWOLEVEL PIE
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      cmd LC_SEGMENT_64
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      cmd LC_SEGMENT_64
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