程序人生

   它的官方网址是 http://www.valgrind.org/

   下载最新版本的Valgrind，目前是3.2.0。 wget http://www.valgrind.org/downloads/valkyrie-1.2.0.tar.bz2

   执行常规的安装步骤：./confgure && make && make install。注意： 系统必须安装QT的开发包。即便这样在make 时还是出现qplatformdefs.h这个文件找不到的情况，导致make失败。查找系统中的qplatformdefs.h 之后，发现没有存在于qt的标准头文件目录/usr/lib/qt-3.3/include。如是将/usr/lib/qt-3.3/mkspecs/linux-g++/ 目录下该头文件复制标准头文件目录，重新make ，后面一切OK。

初次使用

    编译如下代码:  gcc -Wall example.c -g -o example 

#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; }

     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。

 

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

==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)