工具介绍
官网
http://www.linkdata.se/sourcecode/memwatch/
其功能如下官网介绍，挑选重点整理：
1、 号称功能： 内存泄露检测 （检测未释放内存， 即 动态内存开辟未释放的情况）
2、 检测 多次调用free， 和 free 错误地址
3、 检测内存访问的 上越界 和 下越界
4、 检测对野指针进行的写操作
其他内存检测工具有 mtrace valgrind 参考 http://www.cnblogs.com/honglihua8688/p/3727944.html
A memory leak detection tool. Basically, you add a header file to your souce code files, and compile with MEMWATCH defined or not. The header file MEMWATCH.H contains detailed instructions. This is a list of some of the features present in version 2.71:
- ANSI C
- Logging to file or user function using TRACE() macro
- Fault tolerant, can repair it’s own data structures
- Detects double-frees and erroneous free’s
- Detects unfreed memory
- Detects overflow and underflow to memory buffers
- Can set maximum allowed memory to allocate, to stress-test app
- ASSERT(expr) and VERIFY(expr) macros
- Can detect wild pointer writes
- Support for OS specific address validation to avoid GP’s (segmentation faults)
- Collects allocation statistics on application, module or line level
- Rudimentary support for threads (see FAQ for details)
- Rudimentary support for C++ (disabled by default, use with care!)
工具使用
下载工具后， 解压查看其中主要文件为
memwatch.h
memwatch.c
test.c
Makefile
http://www.linkdata.se/downloads/sourcecode/memwatch/memwatch-2.71.tar.gz
直接执行make命令， 则会报错， 需要注释掉 最后一行， 开发者想让使用者通过 test.c 熟悉注释， 通过注释了解使用方法
/* Comment out the following line to compile.
#error "Hey! Don‘t just compile this program, read the comments first!"
*/
make && ./test 则发现 此文件夹下多了一个log文件
memwatch.log
--------------------------------------------------------------------------------------
可见使用memwatch很方便， 只需要将 memwatch.c 和memwatch.h移植到你的待检测程序代码中
通过makefile将 memwatch编译进去，需要关注的是， 编译时加上-DMEMWATCH -DMW_STDIO
$(CC) -DMEMWATCH -DMW_STDIO test.c memwatch.c -o test
test.c demo
test.c 代码如下
/*
** NOTE: Running this program in a Win32 or Unix environment
** will probably result in a segmentation fault or protection
** error. These errors may be caused by MEMWATCH when it is
** looking at memory to see if it owns it, or may be caused by
** the test program writing to memory it does not own.
**
** MEMWATCH has two functions called ‘mwIsReadAddr()‘ and
** ‘mwIsSafeAddr()‘, which are system-specific.
** If they are implemented for your system, and works
** correctly, MEMWATCH will identify garbage pointers and
** avoid causing segmentation faults, GP‘s etc.
**
** If they are NOT implemented, count on getting the core
** dumped when running this test program! As of this writing,
** the safe-address checking has been implemented for Win32
** and ANSI-C compliant systems. The ANSI-C checking traps
** SIGSEGV and uses setjmp/longjmp to resume processing.
**
** Note for Win95 users: The Win32 IsBadReadPtr() and its
** similar functions can return incorrect values. This has
** not happened under WinNT, though, just Win95.
**
** 991009 Johan Lindh
**
*/
#include <stdio.h>
#include <signal.h>
#include "memwatch.h"
#ifndef SIGSEGV
#error "SIGNAL.H does not define SIGSEGV; running this program WILL cause a core dump/crash!"
#endif
#ifndef MEMWATCH
#error "You really, really don‘t want to run this without memwatch. Trust me."
#endif
#if !defined(MW_STDIO) && !defined(MEMWATCH_STDIO)
#error "Define MW_STDIO and try again, please."
#endif
int main()
{
char *p;
/* Collect stats on a line number basis */
mwStatistics( 2 );
/* Slows things down, but OK for this test prg */
/* mwAutoCheck( 1 ); */
TRACE("Hello world!\n");
p = malloc(210);
free(p);
p = malloc(20);
p = malloc(200); /* causes unfreed error */
p[-1] = 0; /* causes underflow error */
free(p);
p = malloc(100);
p[ -(int)(sizeof(long)*8) ] = -1; /* try to damage MW‘s heap chain */
free( p ); /* should cause relink */
mwSetAriFunc( mwAriHandler );
ASSERT(1==2);
mwLimit(1000000);
mwNoMansLand( MW_NML_ALL );
/* These may cause a general protection fault (segmentation fault) */
/* They‘re here to help test the no-mans-land protection */
if( mwIsSafeAddr(p+50000,1) ) {
TRACE("Killing byte at %p\n", p+50000);
*(p+50000) = 0;
}
if( mwIsSafeAddr(p+30000,1) ) {
TRACE("Killing byte at %p\n", p+30000);
*(p+30000) = 0;
}
if( mwIsSafeAddr(p+1000,1) ) {
TRACE("Killing byte at %p\n", p+1000);
*(p+1000) = 0;
}
if( mwIsSafeAddr(p-100,1) ) {
TRACE("Killing byte at %p\n", p-100);
*(p-100) = 0;
}
/* This may cause a GP fault as well, since MW data buffers */
/* have been damaged in the above killing spree */
CHECK();
p = malloc(12000);
p[-5] = 1;
p[-10] = 2;
p[-15] = 3;
p[-20] = 4;
/* This may cause a GP fault since MW‘s buffer list may have */
/* been damaged by above killing, and it will try to repair it. */
free(p);
p = realloc(p,10); /* causes realloc: free‘d from error */
/* May cause GP since MW will inspect the memory to see if it owns it. */
free( (void*)main );
return 0;
}
/* Comment out the following line to compile.
#error "Hey! Don‘t just compile this program, read the comments first!"
*/
memwatch.log内容， 如下粗体字标注， 有泄露检测结果 和 越界检测结果
============= MEMWATCH 2.71 Copyright (C) 1992-1999 Johan Lindh =============
Started at Wed Jul 15 22:04:06 2015
Modes: __STDC__ 64-bit mwDWORD==(unsigned long)
mwROUNDALLOC==8 sizeof(mwData)==32 mwDataSize==32
statistics: now collecting on a line basis
Hello world!
underflow: <5> test.c(62), 200 bytes alloc‘d at <4> test.c(60)
assert trap: <8> test.c(69), 1==2
assert trap: <8> IGNORED - execution continues
limit: old limit = none, new limit = 1000000 bytes
grabbed: all allowed memory to no-mans-land (976 kb)
Killing byte at 0x84496f0
Killing byte at 0x84448d0
Killing byte at 0x843d788
Killing byte at 0x843d33c
check: <8> test.c(95), checking chain alloc nomansland
check: <8> test.c(95), complete; no errors
internal: <10> test.c(105), checksum for MW-0x85331f8 is incorrect
underflow: <10> test.c(105), 0 bytes alloc‘d at <9> test.c(865)
overflow: <10> test.c(105), 0 bytes alloc‘d at <9> test.c(865)
internal: <10> test.c(107), no-mans-land MW-0x85331f8 is corrupted
realloc: <10> test.c(107), 0x8533220 was freed from test.c(105)
WILD free: <11> test.c(110), unknown pointer 0x8048a3b
Stopped at Wed Jul 15 22:04:21 2015
wild pointer: <11> no-mans-land memory hit at 0x84496f0
wild pointer: <11> no-mans-land memory hit at 0x84448d0
wild pointer: <11> no-mans-land memory hit at 0x843d788
dropped: all no-mans-land memory (976 kb)
unfreed: <3> test.c(59), 20 bytes at 0x843d1d0 {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: 5
L)argest memory usage : 12020
T)otal of all alloc() calls: 12530
U)nfreed bytes totals : 12020
Memory usage statistics (detailed):
Module/Line Number Largest Total Unfreed
%s
0 0 0 -100
64 0 0 0 -100
test.c 5 12120 12530 12120
865 0 0 0 0
97 1 12000 12000 12000
64 1 100 100 100
60 1 200 200 0
59 1 20 20 20
57 1 210 210 0