C 使用GDB更改for循环条件？

我正在调试一个程序，对（int I=0；I）的行很感兴趣

---

想要更改我gdb无法更改您的代码，它设置为只读…我同意：我认为有一些工具允许您在调试器（Visual Studio？）中实际替换代码…但我怀疑gdb能做到这一点。我想，你可以改变寄存器来翻转跳转条件…嗯，这有点可疑。在这种情况下，可能只有跳转条件被改变，也许..通过编辑代码将

10

移动到一个变量中，然后通过gdb将变量编辑为

11

。

#include <stdio.h>
int main()
{
  for (int i = 0; i < 10; i++)
    printf("%d\n", i);
  return 0;
}

gcc -g -std=c99 t.c && gdb -q ./a.out

gdb) disas main
Dump of assembler code for function main:
   0x000000000040052d <+0>:     push   %rbp
   0x000000000040052e <+1>:     mov    %rsp,%rbp
   0x0000000000400531 <+4>:     sub    $0x10,%rsp
   0x0000000000400535 <+8>:     movl   $0x0,-0x4(%rbp)
   0x000000000040053c <+15>:    jmp    0x400556 <main+41>
   0x000000000040053e <+17>:    mov    -0x4(%rbp),%eax
   0x0000000000400541 <+20>:    mov    %eax,%esi
   0x0000000000400543 <+22>:    mov    $0x4005f4,%edi
   0x0000000000400548 <+27>:    mov    $0x0,%eax
   0x000000000040054d <+32>:    callq  0x400410 <printf@plt>
   0x0000000000400552 <+37>:    addl   $0x1,-0x4(%rbp)
   0x0000000000400556 <+41>:    cmpl   $0x9,-0x4(%rbp)
   0x000000000040055a <+45>:    jle    0x40053e <main+17>
   0x000000000040055c <+47>:    mov    $0x0,%eax
   0x0000000000400561 <+52>:    leaveq 
   0x0000000000400562 <+53>:    retq   
End of assembler dump.

(gdb) b *0x40055a if i == 10
Breakpoint 1 at 0x40055a: file t.c, line 4.
(gdb) run
Starting program: /tmp/a.out 
0
1
2
3
4
5
6
7
8
9

Breakpoint 1, 0x000000000040055a in main () at t.c:4
4             for (int i = 0; i < 10; i++)
(gdb) p i
$1 = 10
(gdb) jump *0x40053e
Continuing at 0x40053e.
10
[Inferior 1 (process 22210) exited normally]

(gdb) disas/r 0x400556,0x400557
Dump of assembler code from 0x400556 to 0x400557:
   0x0000000000400556 <main+41>:        83 7d fc 09     cmpl   $0x9,-0x4(%rbp)
End of assembler dump.

(gdb) start

Starting program: /tmp/a.out 

Temporary breakpoint 1, main () at t.c:4
4             for (int i = 0; i < 10; i++)

(gdb) set *(char*)0x400559 = 10
(gdb) disas/r 0x400556,0x400557
Dump of assembler code from 0x400556 to 0x400557:
   0x0000000000400556 <main+41>:        83 7d fc 0a     cmpl   $0xa,-0x4(%rbp)
End of assembler dump.

(gdb) c
Continuing.
0
1
2
3
4
5
6
7
8
9
10
[Inferior 1 (process 23131) exited normally]