MEMWATCH 调试动态库2

下面是一个memwatch使用的例子：

1.

# cat test.c

#include
#include
#include "memwatch.h"
int main(void)
{
  char *ptr1;
  char *ptr2;
  ptr1 = malloc(512);
  ptr2 = malloc(512);
  ptr2 = ptr1;
  free(ptr2);
  free(ptr1);
}
2.

# cat Makefile
test:
 gcc -DMEMWATCH -DMEMWATCH_STDIO test.c memwatch.c -o test

3.

make 之后执行 ./test

# ./test
MEMWATCH detected 2 anomalies

查看 log内容：

4.

# cat memwatch.log

============= MEMWATCH 2.71 Copyright (C) 1992-1999 Johan Lindh =============

Started at Thu Feb 24 10:13:41 2011

Modes: __STDC__ 64-bit mwDWORD==(unsigned long)
mwROUNDALLOC==8 sizeof(mwData)==32 mwDataSize==32

double-free: <4> test.c(23), 0x8e444c8 was freed from test.c(22)

Stopped at Thu Feb 24 10:13:41 2011

unfreed: <2> test.c(20), 512 bytes at 0x8e44700   {FE FE FE FE FE FE FE FE FE FE FE FE FE FE FE FE ................}

Memory usage statistics (global):
 N)umber of allocations made: 2
 L)argest memory usage      : 1024
 T)otal of all alloc() calls: 1024
 U)nfreed bytes totals      : 512

可以看出：

double-free: <4> test.c(23), 0x8e444c8 was freed from test.c(22)：test.c的第23行内存双重释放。该内存在22行已被释放过。

unfreed: <2> test.c(20), 512 bytes at 0x8e44700  ： test.c的第20行分配的内存没被释放。

最后是一个统计结果：

动态分配了两次内存。一共分配了1024，未释放512.