Valgrind安装与memcheck简单使用

安装 valgrind

sudo apt install valgrind

安装后，查看一下版本以确认安装成功

valgrind --version

输出形如以下版本号信息就表示安装成功

1	valgrind-3.11.0

使用 memcheck 检查内存泄漏

memleak.cpp

class A {
public:
    A() {
        a_arr = new int[5];
    }
    ~A() {
        delete[] a_arr;
    }

private:
    int* a_arr;
};

class B : public A {
public:
    B() {
        b_arr = new int[3];
    }
    ~B() {
        delete[] b_arr;
    }

private:
    int* b_arr;
};

int main() {
    A* pa = new B();
    delete pa;
    return 0;
}

1 2	g++ -g memleak.cpp -o memleak valgrind --tool=memcheck ./memleak

其中 --tool=memcheck 可以省略，因为 valgrind 的默认工具就是 memcheck 。
可以检查出类B对象中的12个字节（3个int）内存泄漏（见下方 definitely lost ）：

==7661== Memcheck, a memory error detector
==7661== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==7661== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==7661== Command: ./memleak
==7661==
==7661==
==7661== HEAP SUMMARY:
==7661==     in use at exit: 72,716 bytes in 2 blocks
==7661==   total heap usage: 4 allocs, 2 frees, 72,752 bytes allocated
==7661==
==7661== LEAK SUMMARY:
==7661==    definitely lost: 12 bytes in 1 blocks
==7661==    indirectly lost: 0 bytes in 0 blocks
==7661==      possibly lost: 0 bytes in 0 blocks
==7661==    still reachable: 72,704 bytes in 1 blocks
==7661==         suppressed: 0 bytes in 0 blocks
==7661== Rerun with --leak-check=full to see details of leaked memory
==7661==
==7661== For counts of detected and suppressed errors, rerun with: -v
==7661== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

使用 memcheck 检查 overlap

strncpy.cpp

#include <cstring>
#include <iostream>

using namespace std;

int main() {
    char s[60];
    memset(s, '*', sizeof(s));
    strcpy(s, "abcdefghijklmnopqrstuvwxyz");
    strncpy(s + 26, s, 26);
    for (int i = 0; i < 60; i++) cout << (s[i] ? s[i] : '_');
    cout << '\n';
    strncpy(s + 26, s, 27);
    for (int i = 0; i < 60; i++) cout << (s[i] ? s[i] : '_');
    cout << '\n';
    return 0;
}

1 2	g++ -g strncpy.cpp -o strncpy valgrind --tool=memcheck ./strncpy

此时memcheck会检查出重叠（overlap）错误。输出如下

1
2
3

==7561== Source and destination overlap in strncpy(0xfff0003d5, 0xfff0003bb, 27)
==7561==    at 0x4C31626: __strncpy_sse2_unaligned (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7561==    by 0x400951: main (strncpy.cpp:13)

# Linux, Valgrind, memcheck

Valgrind安装与memcheck简单使用

安装 valgrind

使用 memcheck 检查内存泄漏

使用 memcheck 检查 overlap

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