centos下valgrind的安装与使用

一、valgrind基础知识介绍

Valgrind通常用来成分析程序性能及程序中的内存泄露错误。

1、 Valgrind工具集简绍

Valgrind包含下列工具：

1、memcheck：检查程序中的内存问题，如泄漏、越界、非法指针等。

2、callgrind：检测程序代码的运行时间和调用过程，以及分析程序性能。

3、cachegrind：分析CPU的cache命中率、丢失率，用于进行代码优化。

4、helgrind：用于检查多线程程序的竞态条件。

5、massif：堆栈分析器，指示程序中使用了多少堆内存等信息。

6、lackey：

7、nulgrind：

这几个工具的使用是通过命令：valgrind --tool=name 程序名来分别调用的，当不指定tool参数时默认是 --tool=memcheck

如果要检查内存泄漏，只需要增加--leak-check=yes就可以了，命令如下：

valgrind --tool=memcheck --leak-check=yes ./文件名   #这个是全写valgrind --leak-check=yes ./文件名      #可以简写如下

不同工具间加入的代码变化非常的大。在每个作用域的末尾，memcheck加入代码检查每一片内存的访问和进行值计算，代码大小至少增加12倍，运行速度要比平时慢25到50倍。valgrind模拟程序中的每一条指令执行，因此，检查工具和剖析工具不仅仅是对你的应用程序，还有对共享库，GNU C库，X的客户端库都起作用。

2、 Valgrind工具详解

（1）Memcheck

最常用的工具，用来检测程序中出现的内存问题，所有对内存的读写都会被检测到，一切对malloc、free、new、delete的调用都会被捕获。所以，它能检测以下问题：

1、对未初始化内存的使用；

2、读/写释放后的内存块；

3、读/写超出malloc分配的内存块；

4、读/写不适当的栈中内存块；

5、内存泄漏，指向一块内存的指针永远丢失；

6、不正确的malloc/free或new/delete匹配；

7、memcpy()相关函数中的dst和src指针重叠。

这些问题往往是C/C++程序员最头疼的问题，Memcheck能在这里帮上大忙。

二、valgrind的安装：

第一步：获取Valgrind 包可以先使用浏览器访问http://valgrind.org/downloads/查看当前版本。valgrind-3.11.0.tar.bz2

wget http://valgrind.org/downloads/valgrind-3.11.0.tar.bz2

我是直接在windows下载下来然后rz到centos虚拟机的。

第二步：将下载的文件解压

tar -jxvf valgrind-3.11.0.tar.bz2

第三步：安装和配置

./autogen.sh
./configure
make
make install

注意1：执行./autogen.sh的时候可能存在如下报错。

原因与解决：丢失的aclocal是automake包的一部分，因此，要修复该错误，请安装以下包。

（1）在CentOS，Fedora或RHEL上：

sudo yum install automake

（2）在Debian，Ubuntu或Linux Mint上：

sudo apt-get install automake

注意2：我在两个虚拟机下都进了测试。安装当前最新版本valgrind-3.13.0.tar.bz2每次检测到的error都是0，也就是说检测不到错误。卸载后换成valgrind-3.11.0.tar.bz2才可以正常的检测到内存泄漏！！卸载方法

三、valgrind的使用

实例一：

1、首先建立如下a.c文件（存在一个内存泄漏和一个内存错误）。

#include <stdlib.h>
void f(void)
{int*x = (int *)malloc(10 * sizeof(int));x[10]= 0;//problem 1: heap block overrun
}        //problem 2: memory leak -- x not freedint main(void)
{f();return 0;
}

2、执行如下指令

gcc -g a.c -o a    #先编译
valgrind --leak-check=yes ./a   #再检查

3、执行结果如下：

[root@init1 testfile]# valgrind --leak-check=yes ./a
==29936== Memcheck, a memory error detector
==29936== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==29936== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==29936== Command: ./a
==29936==
==29936== Invalid write of size 4
==29936==    at 0x40054E: f (a.c:5)
==29936==    by 0x40055E: main (a.c:10)
==29936==  Address 0x5203068 is 0 bytes after a block of size 40 alloc'd
==29936==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29936==    by 0x400541: f (a.c:4)
==29936==    by 0x40055E: main (a.c:10)
==29936==
==29936==
==29936== HEAP SUMMARY:
==29936==     in use at exit: 40 bytes in 1 blocks
==29936==   total heap usage: 1 allocs, 0 frees, 40 bytes allocated
==29936==
==29936== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==29936==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29936==    by 0x400541: f (a.c:4)
==29936==    by 0x40055E: main (a.c:10)
==29936==
==29936== LEAK SUMMARY:
==29936==    definitely lost: 40 bytes in 1 blocks
==29936==    indirectly lost: 0 bytes in 0 blocks
==29936==      possibly lost: 0 bytes in 0 blocks
==29936==    still reachable: 0 bytes in 0 blocks
==29936==         suppressed: 0 bytes in 0 blocks
==29936==
==29936== For counts of detected and suppressed errors, rerun with: -v
==29936== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)

实例二：

1、建立如下file5.文件

#include <string.h>int main(int argc, char *argv[])
{char *ptr;ptr = (char*) malloc(10);strcpy(ptr, "01234567890");return 0;
}

2、执行如下指令

gcc -g file5.c -o file5    #先编译
valgrind --leak-check=yes ./file5   #再检查

3、结果如下：

[root@init1 testfile]# valgrind --leak-check=yes ./file5
==29976== Memcheck, a memory error detector
==29976== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==29976== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==29976== Command: ./file5
==29976==
==29976== Invalid write of size 4
==29976==    at 0x40055E: main (file5.c:7)
==29976==  Address 0x5203048 is 8 bytes inside a block of size 10 alloc'd
==29976==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29976==    by 0x400548: main (file5.c:6)
==29976==
==29976==
==29976== HEAP SUMMARY:
==29976==     in use at exit: 10 bytes in 1 blocks
==29976==   total heap usage: 1 allocs, 0 frees, 10 bytes allocated
==29976==
==29976== 10 bytes in 1 blocks are definitely lost in loss record 1 of 1
==29976==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29976==    by 0x400548: main (file5.c:6)
==29976==
==29976== LEAK SUMMARY:
==29976==    definitely lost: 10 bytes in 1 blocks
==29976==    indirectly lost: 0 bytes in 0 blocks
==29976==      possibly lost: 0 bytes in 0 blocks
==29976==    still reachable: 0 bytes in 0 blocks
==29976==         suppressed: 0 bytes in 0 blocks
==29976==
==29976== For counts of detected and suppressed errors, rerun with: -v
==29976== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)

实例三：

1、建立如下file2.c文件

#include <stdlib.h>
#include <malloc.h>
#include <string.h>
void test()  {  int *ptr = malloc(sizeof(int)*10);  ptr[10] = 7; // 内存越界  memcpy(ptr +1, ptr, 5); // 踩内存  free(ptr);   free(ptr);// 重复释放  int *p1;  *p1 = 1; // 非法指针
}  int main(void)
{  test();  return 0;
}

2、执行如下指令：

gcc -g file2.c -o file2
valgrind --leak-check=yes ./file2

3、结果如下：

[root@init1 testfile]# valgrind --leak-check=yes ./file2
==29992== Memcheck, a memory error detector
==29992== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==29992== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==29992== Command: ./file2
==29992==
==29992== Invalid write of size 4
==29992==    at 0x4005FE: test (file2.c:6)
==29992==    by 0x400651: main (file2.c:16)
==29992==  Address 0x5203068 is 0 bytes after a block of size 40 alloc'd
==29992==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29992==    by 0x4005F1: test (file2.c:5)
==29992==    by 0x400651: main (file2.c:16)
==29992==
==29992== Source and destination overlap in memcpy(0x5203044, 0x5203040, 5)
==29992==    at 0x4C2E21C: memcpy@@GLIBC_2.14 (vg_replace_strmem.c:1018)
==29992==    by 0x40061F: test (file2.c:7)
==29992==    by 0x400651: main (file2.c:16)
==29992==
==29992== Invalid free() / delete / delete[] / realloc()
==29992==    at 0x4C2AD57: free (vg_replace_malloc.c:530)
==29992==    by 0x400637: test (file2.c:9)
==29992==    by 0x400651: main (file2.c:16)
==29992==  Address 0x5203040 is 0 bytes inside a block of size 40 free'd
==29992==    at 0x4C2AD57: free (vg_replace_malloc.c:530)
==29992==    by 0x40062B: test (file2.c:8)
==29992==    by 0x400651: main (file2.c:16)
==29992==  Block was alloc'd at
==29992==    at 0x4C29C3D: malloc (vg_replace_malloc.c:299)
==29992==    by 0x4005F1: test (file2.c:5)
==29992==    by 0x400651: main (file2.c:16)
==29992==
==29992== Use of uninitialised value of size 8
==29992==    at 0x40063C: test (file2.c:11)
==29992==    by 0x400651: main (file2.c:16)
==29992==
==29992==
==29992== Process terminating with default action of signal 11 (SIGSEGV)
==29992==  Bad permissions for mapped region at address 0x400660
==29992==    at 0x40063C: test (file2.c:11)
==29992==    by 0x400651: main (file2.c:16)
==29992==
==29992== HEAP SUMMARY:
==29992==     in use at exit: 0 bytes in 0 blocks
==29992==   total heap usage: 1 allocs, 2 frees, 40 bytes allocated
==29992==
==29992== All heap blocks were freed -- no leaks are possible
==29992==
==29992== For counts of detected and suppressed errors, rerun with: -v
==29992== Use --track-origins=yes to see where uninitialised values come from
==29992== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 6 from 6)
段错误(吐核)