Valgrind 使用

用法: valgrind [options] prog-and-args [options]: 常用选项，适用于所有Valgrind工具

1. -tool=<name> 最常用的选项。运行 valgrind中名为toolname的工具。默认memcheck。
2. h –help 显示帮助信息。
3. -version 显示 valgrind内核的版本，每个工具都有各自的版本。
4. q –quiet 安静地运行，只打印错误信息。
5. v –verbose 更详细的信息, 增加错误数统计。
6. -trace-children=no|yes 跟踪子线程? [no]
7. -track-fds=no|yes 跟踪打开的文件描述？[no]
8. -time-stamp=no|yes 增加时间戳到LOG信息? [no]
9. -log-fd=<number> 输出LOG到描述符文件 [2=stderr]
10. -log-file=<file> 将输出的信息写入到filename.PID的文件里，PID是运行程序的进行ID
11. -log-file-exactly=<file> 输出LOG信息到 file
12. -log-file-qualifier=<VAR> 取得环境变量的值来做为输出信息的文件名。 [none]
13. -log-socket=ipaddr:port 输出LOG到socket ，ipaddr:port

LOG信息输出

1. -xml=yes 将信息以xml格式输出，只有memcheck可用
2. -num-callers=<number> show <number> callers in stack traces [12]
3. -error-limit=no|yes 如果太多错误，则停止显示新错误? [yes]
4. -error-exitcode=<number> 如果发现错误则返回错误代码 [0=disable]
5. -db-attach=no|yes 当出现错误， valgrind会自动启动调试器gdb。[no]
6. -db-command=<command> 启动调试器的命令行选项[gdb -nw %f %p]

适用于Memcheck工具的相关选项：

1. -leak-check=no|summary|full 要求对leak给出详细信息? [summary]
2. -leak-resolution=low|med|high how much bt merging in leak check [low]
3. -show-reachable=no|yes show reachable blocks in leak check? [no]

Valgrind 使用举例

下面是一段有问题的C程序代码test.c

#include <stdlib.h>
void f(void)
{
   int* x = malloc(10 * sizeof(int));
   x[10] = 0;  //问题1: 数组下标越界
}                  //问题2: 内存没有释放

int main(void)
{
   f();
   return 0;
 }

1、 编译程序test.c
gcc -Wall test.c -g -o test
2、 使用Valgrind检查程序BUG
valgrind --tool=memcheck --leak-check=full ./test
3、 分析输出的调试信息
==3908== Memcheck, a memory error detector.
==3908== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==3908== Using LibVEX rev 1732, a library for dynamic binary translation.
==3908== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==3908== Using valgrind-3.2.3, a dynamic binary instrumentation framework.
==3908== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==3908== For more details, rerun with: -v
==3908== 
--3908-- DWARF2 CFI reader: unhandled CFI instruction 0:50
--3908-- DWARF2 CFI reader: unhandled CFI instruction 0:50
/*数组越界错误*/
==3908== Invalid write of size 4      
==3908==    at 0x8048384: f (test.c:6)
==3908==    by 0x80483AC: main (test.c:11)
==3908==  Address 0x400C050 is 0 bytes after a block of size 40 alloc'd
==3908==    at 0x40046F2: malloc (vg_replace_malloc.c:149)
==3908==    by 0x8048377: f (test.c:5)
==3908==    by 0x80483AC: main (test.c:11)
==3908== 
==3908== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 14 from 1)
==3908== malloc/free: in use at exit: 40 bytes in 1 blocks. 
==3908== malloc/free: 1 allocs, 0 frees, 40 bytes allocated.
==3908== For counts of detected errors, rerun with: -v
==3908== searching for pointers to 1 not-freed blocks.
==3908== checked 59,124 bytes.
==3908== 
==3908== 
/*有内存空间没有释放*/
==3908== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==3908==    at 0x40046F2: malloc (vg_replace_malloc.c:149)
==3908==    by 0x8048377: f (test.c:5)
==3908==    by 0x80483AC: main (test.c:11)
==3908== 
==3908== LEAK SUMMARY:
==3908==    definitely lost: 40 bytes in 1 blocks.
==3908==      possibly lost: 0 bytes in 0 blocks.
==3908==    still reachable: 0 bytes in 0 blocks.
==3908==         suppressed: 0 bytes in 0 blocks.