c++ - 批评我的堆调试器

Question

我编写了以下堆调试器以演示内存泄漏、双重删除和错误的删除形式(即尝试使用 delete p 而不是 delete[] p) 给初级程序员。

我很想从强大的 C++ 程序员那里得到一些反馈，因为我以前从未这样做过，而且我确信我犯了一些愚蠢的错误。谢谢!

#include <cstdlib>
#include <iostream>
#include <new>

namespace
{
    const int ALIGNMENT = 16;
    const char* const ERR = "*** ERROR: ";
    int counter = 0;

    struct heap_debugger
    {
        heap_debugger()
        {
            std::cerr << "*** heap debugger started\n";
        }

        ~heap_debugger()
        {
            std::cerr << "*** heap debugger shutting down\n";
            if (counter > 0)
            {
                std::cerr << ERR << "failed to release memory " << counter << " times\n";
            }
            else if (counter < 0)
            {
                std::cerr << ERR << (-counter) << " double deletes detected\n";
            }
        }
    } instance;

    void* allocate(size_t size, const char* kind_of_memory, size_t token) throw (std::bad_alloc)
    {
        void* raw = malloc(size + ALIGNMENT);
        if (raw == 0) throw std::bad_alloc();

        *static_cast<size_t*>(raw) = token;
        void* payload = static_cast<char*>(raw) + ALIGNMENT;

        ++counter;
        std::cerr << "*** allocated " << kind_of_memory << " at " << payload << " (" << size << " bytes)\n";
        return payload;
    }

    void release(void* payload, const char* kind_of_memory, size_t correct_token, size_t wrong_token) throw ()
    {
        if (payload == 0) return;

        std::cerr << "*** releasing " << kind_of_memory << " at " << payload << '\n';
        --counter;

        void* raw = static_cast<char*>(payload) - ALIGNMENT;
        size_t* token = static_cast<size_t*>(raw);

        if (*token == correct_token)
        {
            *token = 0xDEADBEEF;
            free(raw);
        }
        else if (*token == wrong_token)
        {
            *token = 0x177E6A7;
            std::cerr << ERR << "wrong form of delete\n";
        }
        else
        {
            std::cerr << ERR << "double delete\n";
        }
    }
}

void* operator new(size_t size) throw (std::bad_alloc)
{
    return allocate(size, "non-array memory", 0x5AFE6A8D);
}

void* operator new[](size_t size) throw (std::bad_alloc)
{
    return allocate(size, "    array memory", 0x5AFE6A8E);
}

void operator delete(void* payload) throw ()
{
    release(payload, "non-array memory", 0x5AFE6A8D, 0x5AFE6A8E);
}

void operator delete[](void* payload) throw ()
{
    release(payload, "    array memory", 0x5AFE6A8E, 0x5AFE6A8D);
}

Answer 1

您可以保留所有分配的列表，而不是进行侵入性的记录。然后你可以释放内存而不破坏你自己的数据，并跟踪特定地址被“删除”的次数，还可以找到程序试图删除不匹配地址的地方(即不在列表中)。