为什么此代码会破坏内存? [英] Why does this code corrupt memory?

问题描述

这是一个相当新手的问题，应该很快就可以回答...

This is a fairly newbie question which should be answerable reasonably quickly...

基本上，在 echo 中第一次调用 Printf 后， args 的内容已损坏.在我看来，我是错误地传递了指针.但是不知道为什么吗?

Basically, after the first call to Printf in echo, the contents of args is corrupted. It sounds to me like i'm passing the pointers around incorrectly. But can't figure out why?

#define MAX_PRINT_OUTPUT 4096

void Echo(char *args[MAX_COMMAND_ARGUMENTS], int argCount)
{
    for (int i = 1; i < argCount; ++i)
    {
        Printf("%s ", args[i]);
        Printf("\n");
    }
};

void Printf(const char *output, ...)
{
    va_list args;
    char formattedOutput[MAX_PRINT_OUTPUT];

    va_start(args, output);
    vsnprintf(formattedOutput, sizeof(formattedOutput), output, args);
    va_end(args);

    g_PlatformDevice->Print(formattedOutput);
};

void RiseWindows::Print(const char *output)
{
    //Corruption appears to occur as soon as this function is entered
    #define CONSOLE_OUTPUT_SIZE 32767

    char buffer[CONSOLE_OUTPUT_SIZE];
    char *pBuffer = buffer;
    const char *pOutput = output;
    int i = 0;

    while (pOutput[i] && ((pBuffer - buffer) < sizeof(buffer) - 1))
    {
        if (pOutput[i] == '\n' && pOutput[i+1] == '\r' )
        {
            pBuffer[0] = '\r';
            pBuffer[1] = '\n';
            pBuffer += 2;
            ++i;
        }
        else if (pOutput[i] == '\r')
        {
            pBuffer[0] = '\r';
            pBuffer[1] = '\n';
            pBuffer += 2;
        }
        else if (pOutput[i] == '\n')
        {
            pBuffer[0] = '\r';
            pBuffer[1] = '\n';
            pBuffer += 2;
        }
        else
        {
            *pBuffer = pOutput[i];
            ++pBuffer;
        }
        ++i;
    }
    *pBuffer = 0;

    SendMessage(this->ConsoleWindow.hwndBuffer, EM_LINESCROLL, 0, 0xffff);
    SendMessage(this->ConsoleWindow.hwndBuffer, EM_SCROLLCARET, 0, 0);
    SendMessage(this->ConsoleWindow.hwndBuffer, EM_REPLACESEL, 0, (LPARAM)buffer);

};

注意这不是生产代码，只是概念证明.
编辑，如果不清楚，则g_PlatformDevice的类型为RiseWindows.
编辑这是在vs2008下运行的Windows XP平台上

NOTE This is not production code, just proof of concept.
EDIT g_PlatformDevice is of type RiseWindows, if that wasn't clear...
EDIT This is on a windows xp platform running under vs2008

更新 对于任何有兴趣的人来说，问题似乎是调用堆栈溢出，然后再向下定义堆栈，再定义另一个大型数组.对此进行重构消除了内存损坏.所以粉刷起来要一连串的打击！

UPDATE For anyone interested, the problem appears to have been an overflowed call stack, further down the stack then this another large array was being defined. Refactoring this eliminated the memory corruption. So chalked up to stack battering!

推荐答案

您还没有提到此代码在什么环境下运行.可能是您在丢钱.您在RiseWindows :: Print中的堆栈上声明了一个32767字节的数组.在我熟悉的某些嵌入式系统环境中，这将是个坏消息.您可以增加堆栈大小和/或在堆上分配该缓冲区只是为了测试该理论吗?您可能想使该缓冲区成为std :: vector或私有成员矢量，以避免每次调用Print时对其进行分配和重新分配.

You haven't mentioned what environment this code runs under. It could be you are blowing your stack. You are declaring a 32767 byte array on the stack in RiseWindows::Print. On some embedded system environments that I am familiar with that would be bad news. Can you increase your stack size and/or allocate that buffer on the heap just to test that theory? You may want to make that buffer a std::vector instead, or possibly a private member vector to avoid allocating and reallocating it every time you call Print.

沿着这些行，MAX_PRINT_OUTPUT有多大?

Along those lines, how big is MAX_PRINT_OUTPUT?

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