Ubuntu C语言检测内存泄漏

检测内存泄漏需利用工具Valgrind，

源码下载地址为:http://www.valgrind.org/downloads/current.html#current

其.deb相应版本的下载地址：http://pkgs.org/download/valgrind

测试的例子：

#include <stdlib.h>

void f(void)
{
   int* x = malloc(10 * sizeof(int));
   x[10] = 0;        // problem 1: heap block overrun
}                    // problem 2: memory leak -- x not freed

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

编译代码:  
gcc -Wall example.c -g -o example

注意：gcc 的-g 选项让Valgrind调试输出时指出相应信息的代码所在的行号。

运行valgrind:
valgrind --tool=memcheck --leak-check=yes ./example

valgrind的执行结果:
==6742== Memcheck, a memory error detector for x86-linux.
==6742== Copyright (C) 2002-2004, and GNU GPL'd, by Julian Seward et al.
==6742== Using valgrind-2.2.0, a program supervision framework for x86-linux.
==6742== Copyright (C) 2000-2004, and GNU GPL'd, by Julian Seward et al.
==6742== For more details, rerun with: -v
==6742==
==6742== Invalid write of size 4
==6742==    at 0x8048384: f (example.c:6)
==6742==    by 0x80483AC: main (example.c:12)
==6742==  Address 0x1B908050 is 0 bytes after a block of size 40 alloc'd
==6742==    at 0x1B904984: malloc (vg_replace_malloc.c:131)
==6742==    by 0x8048377: f (example.c:5)
==6742==    by 0x80483AC: main (example.c:12)
==6742==
==6742== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 12 from 1)
==6742== malloc/free: in use at exit: 40 bytes in 1 blocks.
==6742== malloc/free: 1 allocs, 0 frees, 40 bytes allocated.
==6742== For counts of detected errors, rerun with: -v
==6742== searching for pointers to 1 not-freed blocks.
==6742== checked 1360800 bytes.
==6742==
==6742==
==6742== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==6742==    at 0x1B904984: malloc (vg_replace_malloc.c:131)
==6742==    by 0x8048377: f (example.c:5)
==6742==    by 0x80483AC: main (example.c:12)
==6742==
==6742== LEAK SUMMARY:
==6742==    definitely lost: 40 bytes in 1 blocks.
==6742==    possibly lost:   0 bytes in 0 blocks.
==6742==    still reachable: 0 bytes in 0 blocks.
==6742==         suppressed: 0 bytes in 0 blocks.
==6742== Reachable blocks (those to which a pointer was found) are not shown.
==6742== To see them, rerun with: --show-reachable=yes

上面的C程序存在两个错误：1. 数组下标越界；2. 分配的内存没有释放，存在内存泄露的问题。
对于错误1，看Valgrind的调试信息片断
==6742== Invalid write of size 4
==6742==    at 0x8048384: f (example.c:6)
==6742==    by 0x80483AC: main (example.c:12)
==6742==  Address 0x1B908050 is 0 bytes after a block of size 40 alloc'd
==6742==    at 0x1B904984: malloc (vg_replace_malloc.c:131)
==6742==    by 0x8048377: f (example.c:5)

对于错误2，看这个
==6742== malloc/free: 1 allocs, 0 frees, 40 bytes allocated.
......
==6742== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==6742==    at 0x1B904984: malloc (vg_replace_malloc.c:131)
==6742==    by 0x8048377: f (example.c:5)
==6742==    by 0x80483AC: main (example.c:12)