linux valgrind内存检测工具

1.下载地址：http://valgrind.org

 

2.下载的是tar.bz2文件

 

3.用以下命令解压：例如

 

$bzip2   -d    valgrind-3.5.0.tar.dz2

$tar   xvf    valgrind-3.5.0.tar

这时候有一个valgrind-3.5.0的文件夹

 

4.然后安装

 

$cd  valgrind-3.5.0

＃./configure

＃make

＃make install

 

即可...........

 

valgrind是针对Intel x86的工具，它模拟x86型号的CPU处理器来直接地观察所有的内存访问，并且分析数据流

 

简单用法：看一下例子：

$ cat -n test.c
     1    #include<stdio.h>
     2    #include<malloc.h>
     3    #include<string.h>
     4    
     5    int main(int argc,char *argv[])
     6    {
     7        char * str;
     8        str=(char *)malloc(5);
     9        strcpy(str,"1234");
    10        printf("%s",str);
    11        free(str);
    12        return 0;
    13    }

现在我们把它编译一下，

 

$ gcc -g testm.c -o testm

 

我们尝试运行一下这个程序

 

$ valgrind --leak-check=full testm
==5338== Memcheck, a memory error detector
==5338== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==5338== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==5338== Command: testm
==5338==
1234==5338==
==5338== HEAP SUMMARY:
==5338==     in use at exit: 0 bytes in 0 blocks
==5338==   total heap usage: 1 allocs, 1 frees, 5 bytes allocated
==5338==
==5338== All heap blocks were freed -- no leaks are possible
==5338==
==5338== For counts of detected and suppressed errors, rerun with: -v
==5338== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 11 from 6)

 

注意划线部分，然后，我们把这个程序改成错误的：

 

这句    9        strcpy(str,"1234");

改成    9        strcpy(str,"12345");         //这时候已经是缓冲区溢出了

 

然后把 free(str);这句去掉；                 //这时候是内存泄露了

 

然后，我们在编译一次。

$ gcc -g testm.c -o testm

然后，这时候运行./testm也是可以进行的。

 

但，用$ valgrind --leak-check=full testm 会有一下结果：

 

$ valgrind --leak-check=full testm
==5557== Memcheck, a memory error detector
==5557== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==5557== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==5557== Command: testm
==5557==
==5557== Invalid write of size 1
==5557==    at 0x40271A7: memcpy (mc_replace_strmem.c:482)
==5557==    by 0x804845E: main (testm.c:9)
==5557==  Address 0x419f02d is 0 bytes after a block of size 5 alloc'd
==5557==    at 0x4025C1C: malloc (vg_replace_malloc.c:195)
==5557==    by 0x8048440: main (testm.c:8)
==5557==
==5557== Invalid read of size 1
==5557==    at 0x4026BA3: strlen (mc_replace_strmem.c:275)
==5557==    by 0x407E6D7: vfprintf (in /lib/tls/i686/cmov/libc-2.9.so)
==5557==    by 0x4084B5F: printf (in /lib/tls/i686/cmov/libc-2.9.so)
==5557==    by 0x8048471: main (testm.c:10)
==5557==  Address 0x419f02d is 0 bytes after a block of size 5 alloc'd
==5557==    at 0x4025C1C: malloc (vg_replace_malloc.c:195)
==5557==    by 0x8048440: main (testm.c:8)
==5557==
12345==5557==
==5557== HEAP SUMMARY:
==5557==     in use at exit: 5 bytes in 1 blocks
==5557==   total heap usage: 1 allocs, 0 frees, 5 bytes allocated
==5557==
==5557== 5 bytes in 1 blocks are definitely lost in loss record 1 of 1
==5557==    at 0x4025C1C: malloc (vg_replace_malloc.c:195)
==5557==    by 0x8048440: main (testm.c:8)
==5557==
==5557== LEAK SUMMARY:
==5557==    definitely lost: 5 bytes in 1 blocks
==5557==    indirectly lost: 0 bytes in 0 blocks
==5557==      possibly lost: 0 bytes in 0 blocks
==5557==    still reachable: 0 bytes in 0 blocks
==5557==         suppressed: 0 bytes in 0 blocks
==5557==
==5557== For counts of detected and suppressed errors, rerun with: -v
==5557== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 11 from 6)

 

也是注意划线部分，前面的是指示出错地方了。

 

1 allocs, 0 frees, 5 bytes allocated 指明了没有释放内存。。

 

我们可以按着它的提示去修改我们的程序。