dmalloc用法快速入门

dmalloc能够检查出直到程序运行结束还没有释放的内存，并且能够精确指出在
哪个源文件的第几行。

dmalloc 主页： http://dmalloc.com

支持的平台：AIX, BSD/OS, DG/UX, Free/Net/OpenBSD, GNU/Hurd, HPUX, Irix, Linux, MS-DOG, NeXT, OSF, SCO, Solaris, SunOS, Ultrix, Unixware, Windoze, and even Unicos on a Cray T3E

最新版本： 5.5.2

安装：下载 http://dmalloc.com/releases/dmalloc-5.5.2.tgz

[code type="bash"]
tar zxvf dmalloc-5.5.2.tgz
cd dmalloc-5.5.2
./configure
make
make install
[/code]

设置环境变量：
对于 Bash, ksh, and zsh (http://www.zsh.org/), 在 `.bashrc', `.profile', or `.zshrc'
文件中加入一行 ( -b 参数表示针对Bash的输出):

function dmalloc { eval `command dmalloc -b $*`; }

然后重新登陆用户，或者执行: source ~/.bashrc 或 source ~/.profile

接下面执行:
[code type="bash"]
dmalloc -l logfile -i 100 low
[/code]

在源文件中添加下面的C代码：

#ifdef DMALLOC
#include "dmalloc.h"
#endif

编译使用的CFLAGS: -DDMALLOC -DDMALLOC_FUNC_CHECK

如： gcc -DDMALLOC -DDMALLOC_FUNC_CHECK dm_test.c

执行:
./a.out

运行上面的命令会在当前目录下生成 logfile文件，查看logfile的内容如下：

cat logfile
[code type="text"]
1214894489: 2: Dmalloc version '5.5.2' from 'http://dmalloc.com/'
1214894489: 2: flags = 0x4e48503, logfile 'logfile'
1214894489: 2: interval = 100, addr = 0, seen # = 0, limit = 0
1214894489: 2: starting time = 1214894489
1214894489: 2: process pid = 9560
1214894489: 2: Dumping Chunk Statistics:
1214894489: 2: basic-block 4096 bytes, alignment 8 bytes
1214894489: 2: heap address range: 0xb8020000 to 0xb8029000, 36864 bytes
1214894489: 2: user blocks: 1 blocks, 4043 bytes (10%)
1214894489: 2: admin blocks: 8 blocks, 32768 bytes (89%)
1214894489: 2: total blocks: 9 blocks, 36864 bytes
1214894489: 2: heap checked 1
1214894489: 2: alloc calls: malloc 2, calloc 0, realloc 0, free 0
1214894489: 2: alloc calls: recalloc 0, memalign 0, valloc 0
1214894489: 2: alloc calls: new 0, delete 0
1214894489: 2: current memory in use: 11 bytes (2 pnts)
1214894489: 2: total memory allocated: 11 bytes (2 pnts)
1214894489: 2: max in use at one time: 11 bytes (2 pnts)
1214894489: 2: max alloced with 1 call: 6 bytes
1214894489: 2: max unused memory space: 53 bytes (82%)
1214894489: 2: top 10 allocations:
1214894489: 2: total-size count in-use-size count source
1214894489: 2: 6 1 6 1 dm_test.c:71
1214894489: 2: 5 1 5 1 dm_test.c:69
1214894489: 2: 11 2 11 2 Total of 2
1214894489: 2: Dumping Not-Freed Pointers Changed Since Start:
1214894489: 2: not freed: '0xb8028fc8|s1' (6 bytes) from 'dm_test.c:71'
1214894489: 2: not freed: '0xb8028fe8|s1' (5 bytes) from 'dm_test.c:69'
1214894489: 2: total-size count source
1214894489: 2: 6 1 dm_test.c:71
1214894489: 2: 5 1 dm_test.c:69
1214894489: 2: 11 2 Total of 2
1214894489: 2: ending time = 1214894489, elapsed since start = 0:00:00
[/code]

那么，哪个地方的内存leak就一目了然了。

//====== dm_test.c 源代码 =============
[code type="c"]
#include
#include
#include

#ifdef DMALLOC
#include
#endif

int main(int argc, char **argv)
{

char *str;

str = malloc(5);

str = malloc(6);

return 0;
}

[/code]