setjmp与longjmp的分析

#include <setjmp.h>
int main(int argc, const char* argv[])
{

    jmp_buf buf = {0,};
    int k = 0;
    setjmp(buf);

    k = 1;

    longjmp(buf, 1);
}

测试代码如上所示， 看一下Disassemble的代码__setjmp3:
69CDFC38  mov         edx,dword ptr [esp+4]
69CDFC3C  mov         dword ptr [edx],ebp
69CDFC3E  mov         dword ptr [edx+4],ebx
69CDFC41  mov         dword ptr [edx+8],edi
69CDFC44  mov         dword ptr [edx+0Ch],esi
69CDFC47  mov         dword ptr [edx+10h],esp
69CDFC4A  mov         eax,dword ptr [esp]
69CDFC4D  mov         dword ptr [edx+14h],eax
69CDFC50  mov         dword ptr [edx+20h],56433230h
69CDFC57  mov         dword ptr [edx+24h],0
69CDFC5E  mov         eax,dword ptr fs:[00000000h]
69CDFC64  mov         dword ptr [edx+18h],eax
69CDFC67  cmp         eax,0FFFFFFFFh
69CDFC6A  jne         _s3_get_count (69CDFC75h)
69CDFC6C  mov         dword ptr [edx+1Ch],0FFFFFFFFh
69CDFC73  jmp         _s3_done (69CDFCB0h)
_s3_get_count:
69CDFC75  mov         ecx,dword ptr [esp+8]
69CDFC79  or          ecx,ecx
69CDFC7B  je          _s3_default_trylevel (69CDFC87h)
69CDFC7D  mov         eax,dword ptr [esp+0Ch]
69CDFC81  mov         dword ptr [edx+24h],eax
69CDFC84  dec         ecx
69CDFC85  jne         _s3_save_trylevel (69CDFC8Fh)
_s3_default_trylevel:
69CDFC87  mov         eax,dword ptr [eax+0Ch]
69CDFC8A  mov         dword ptr [edx+1Ch],eax
69CDFC8D  jmp         _s3_done (69CDFCB0h)
_s3_save_trylevel:
69CDFC8F  mov         eax,dword ptr [esp+10h]
69CDFC93  mov         dword ptr [edx+1Ch],eax
69CDFC96  dec         ecx
69CDFC97  je          _s3_done (69CDFCB0h)
69CDFC99  push        esi
69CDFC9A  push        edi
69CDFC9B  lea         esi,[esp+1Ch]
69CDFC9F  lea         edi,[edx+28h]
69CDFCA2  cmp         ecx,6
69CDFCA5  jbe         _s3_save_data (69CDFCACh)
69CDFCA7  mov         ecx,6
_s3_save_data:
69CDFCAC  rep movs    dword ptr es:[edi],dword ptr [esi]
69CDFCAE  pop         edi
69CDFCAF  pop         esi
_s3_done:
69CDFCB0  sub         eax,eax
69CDFCB2  ret
69CDFCB3  int         3
69CDFCB4  int         3
69CDFCB5  int         3
69CDFCB6  int         3
69CDFCB7  int         3
69CDFCB8  int         3
69CDFCB9  int         3
69CDFCBA  int         3
69CDFCBB  int         3
69CDFCBC  int         3
69CDFCBD  int         3
69CDFCBE  int         3
69CDFCBF  int         3

 

将刚刚压入栈中的buf[esp + 4]赋值给edx，然后分别将线程相关的Context的各个register，以及TEB中的某些字段fs:[00000000h]放到该结构体中。

 

fs:[00000000h]保存的是与SEH相关的信息，参考：http://www.mouseos.com/windows/SEH3.html

参考：http://blog.csdn.net/zhongyh/article/details/1467654

 

总之，一旦调用longjmp，那么包括esp在内的Context可能都会被改变