使用gdb调试链接库中的函数时遇到问题

Question

我正在阅读一些关于gdb的资料，但我在让gdb (我运行的是7.11.1)从库中调试函数时遇到了问题。

用于了解调试器的示例代码非常简单：

#include <stdio.h>
#include <string.h>

int main() {
    char str_a[20];

    strcpy(str_a, "Hello, world!\n");
    printf(str_a);
}

我编译它时启用了调试符号，启动了GDB，并设置了一些断点：

(gdb) list
1   #include <stdio.h>
2   #include <string.h>
3   
4   int main() {
5       char str_a[20];
6   
7       strcpy(str_a, "Hello, world!\n");
8       printf(str_a);
9   }
(gdb) break 7
Breakpoint 1 at 0x4005ad: file char_array2.c, line 7.
(gdb) break strcpy
Function "strcpy" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 2 (strcpy) pending.
(gdb) break 8
Breakpoint 3 at 0x4005cf: file char_array2.c, line 8.
(gdb) run
Starting program: /home/david/hacking_the_art_of_exploitation/Chapter_2/char_array2 

Breakpoint 1, main () at char_array2.c:7
7       strcpy(str_a, "Hello, world!\n");
(gdb) continue
Continuing.

Breakpoint 3, main () at char_array2.c:8
8       printf(str_a);
(gdb) continue
Continuing.
Hello, world!
[Inferior 1 (process 7061) exited normally]

如您所见，调试器永远不会深入到strcpy函数。

我尝试将set stop-on-solib-events 1添加到我的.gdbinit中。这会导致不同但仍然不受欢迎的结果：

(gdb) run
Starting program: /home/david/hacking_the_art_of_exploitation/Chapter_2/char_array2 
Stopped due to shared library event (no libraries added or removed)

我有点不知所措。提前感谢您的帮助。

Answer 1

我相信您需要libc-dbg包和libc源码包来调试libc函数。在Ubuntu上，你可以通过

sudo apt-get install libc6-dbg
mkdir ~/libc ; cd ~/libc
apt-get source libc6