我有两个 c 文件:
交流
void main(){
...
getvtable()->function();
}
vtable 指向位于 bc 中的函数:
void function(){
malloc(42);
}
现在,如果我在 valgrind 中跟踪程序,我会得到以下信息:
==29994== 4,155 bytes in 831 blocks are definitely lost in loss record 26 of 28
==29994== at 0x402CB7A: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==29994== by 0x40A24D2: (below main) (libc-start.c:226)
所以对函数的调用在堆栈上完全被省略了!这怎么可能?如果我使用 GDB,则会显示一个正确的堆栈,包括“函数”。
包括调试符号,Linux,32 位。
更新:
回答第一个问题,我在调试 valgrind 的 GDB 服务器时得到以下输出。断点不会到来,而当我直接使用 GDB 调试时会出现断点。
stasik@gemini:~$ gdb -q
(gdb) set confirm off
(gdb) target remote | vgdb
Remote debugging using | vgdb
relaying data between gdb and process 11665
[Switching to Thread 11665]
0x040011d0 in ?? ()
(gdb) file /home/stasik/leak.so
Reading symbols from /home/stasik/leak.so...done.
(gdb) break function
Breakpoint 1 at 0x110c: file ../../source/leakclass.c, line 32.
(gdb) commands
Type commands for breakpoint(s) 1, one per line.
End with a line saying just "end".
>silent
>end
(gdb) continue
Continuing.
Program received signal SIGTRAP, Trace/breakpoint trap.
0x0404efcb in ?? ()
(gdb) source thread-frames.py
Stack level 0, frame at 0x42348a0:
eip = 0x404efcb; saved eip 0x4f2f544c
called by frame at 0x42348a4
Arglist at 0x4234898, args:
Locals at 0x4234898, Previous frame's sp is 0x42348a0
Saved registers:
ebp at 0x4234898, eip at 0x423489c
Stack level 1, frame at 0x42348a4:
eip = 0x4f2f544c; saved eip 0x6e492056
called by frame at 0x42348a8, caller of frame at 0x42348a0
Arglist at 0x423489c, args:
Locals at 0x423489c, Previous frame's sp is 0x42348a4
Saved registers:
eip at 0x42348a0
Stack level 2, frame at 0x42348a8:
eip = 0x6e492056; saved eip 0x205d6f66
called by frame at 0x42348ac, caller of frame at 0x42348a4
Arglist at 0x42348a0, args:
Locals at 0x42348a0, Previous frame's sp is 0x42348a8
Saved registers:
eip at 0x42348a4
Stack level 3, frame at 0x42348ac:
eip = 0x205d6f66; saved eip 0x61746144
---Type <return> to continue, or q <return> to quit---
called by frame at 0x42348b0, caller of frame at 0x42348a8
Arglist at 0x42348a4, args:
Locals at 0x42348a4, Previous frame's sp is 0x42348ac
Saved registers:
eip at 0x42348a8
Stack level 4, frame at 0x42348b0:
eip = 0x61746144; saved eip 0x65736162
called by frame at 0x42348b4, caller of frame at 0x42348ac
Arglist at 0x42348a8, args:
Locals at 0x42348a8, Previous frame's sp is 0x42348b0
Saved registers:
eip at 0x42348ac
Stack level 5, frame at 0x42348b4:
eip = 0x65736162; saved eip 0x70616d20
called by frame at 0x42348b8, caller of frame at 0x42348b0
Arglist at 0x42348ac, args:
Locals at 0x42348ac, Previous frame's sp is 0x42348b4
Saved registers:
eip at 0x42348b0
Stack level 6, frame at 0x42348b8:
eip = 0x70616d20; saved eip 0x2e646570
called by frame at 0x42348bc, caller of frame at 0x42348b4
Arglist at 0x42348b0, args:
---Type <return> to continue, or q <return> to quit---
Locals at 0x42348b0, Previous frame's sp is 0x42348b8
Saved registers:
eip at 0x42348b4
Stack level 7, frame at 0x42348bc:
eip = 0x2e646570; saved eip 0x0
called by frame at 0x42348c0, caller of frame at 0x42348b8
Arglist at 0x42348b4, args:
Locals at 0x42348b4, Previous frame's sp is 0x42348bc
Saved registers:
eip at 0x42348b8
Stack level 8, frame at 0x42348c0:
eip = 0x0; saved eip 0x0
caller of frame at 0x42348bc
Arglist at 0x42348b8, args:
Locals at 0x42348b8, Previous frame's sp is 0x42348c0
Saved registers:
eip at 0x42348bc
(gdb) continue
Continuing.
Program received signal SIGTRAP, Trace/breakpoint trap.
0x0404efcb in ?? ()
(gdb) continue
Continuing.