valgrind 使用

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[1]分析内存泄露和内存越界

test.c

1 #include <stdio.h>

2
3 void f(void)
4 {
5     int *x = malloc(sizeof(int) * 10);
6     x[10] = 0;
7 }
8
9 int main(void)
10 {
11     f();
12     return 0;
13 }
lengmian@ubuntu:~/akaedu/hwp/search$ valgrind --tool=memcheck --leak-check=full ./val_test==7465== Memcheck, a memory error detector
==7465== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==7465== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info
==7465== Command: ./val_test
==7465==
==7465== Invalid write of size 4              // 这一段数组越界， Invalid write of size 4 表示这个意思？？？固定的说明形式？？

---- 写入的内存大小不对应，发生了内存越界

==7465==    at 0x80483FF: f (val_test.c:6)      // 错误位置
==7465==    by 0x8048411: main (val_test.c:11)
==7465== Address 0x4194050 is 0 bytes after a block of size 40 alloc'd
==7465==    at 0x4024F20: malloc (vg_replace_malloc.c:236)
==7465==    by 0x80483F5: f (val_test.c:5)                ---- 第5行漏了40个字节的内存

==7465==    by 0x8048411: main (val_test.c:11)
==7465==
==7465==
==7465== HEAP SUMMARY:                                  //动态申请空间，没有释放
==7465==     in use at exit: 40 bytes in 1 blocks
==7465==   total heap usage: 1 allocs, 0 frees, 40 bytes allocated
==7465==
==7465== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==7465==    at 0x4024F20: malloc (vg_replace_malloc.c:236)
==7465==    by 0x80483F5: f (val_test.c:5)                    //错误位置
==7465==    by 0x8048411: main (val_test.c:11)
==7465==
==7465== LEAK SUMMARY:
==7465==    definitely lost: 40 bytes in 1 blocks
==7465==    indirectly lost: 0 bytes in 0 blocks
==7465==      possibly lost: 0 bytes in 0 blocks
==7465==    still reachable: 0 bytes in 0 blocks
==7465==         suppressed: 0 bytes in 0 blocks
==7465==
==7465== For counts of detected and suppressed errors, rerun with: -v
==7465== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 13 from 8)