如何修复双重释放或损坏错误

Question

打开不存在的打印机时遇到错误。当找到打印机时，我的应用程序工作正常。但是当找不到打印机时，我会遇到双重释放或损坏错误。下面是我的代码：

#define BUFSIZE 200

FILE *pPortFile = NULL;

void Printer::closePrinter()
{
    if (pPortFile != NULL)
    {
        fclose(pPortFile);
        pPortFile = NULL;
    }
}

void Printer::openPrinter(string sPortName)
{
    struct stat tFilest;
    int iFileDescriptor = 0, i = 0;
    char aResponse[BUFSIZE] = {0}, aFName[BUFSIZE];

    ePrinterType_ = UNKNOWN;

    closePrinter();

    pPortFile = popen("find /sys/devices/platform -name lp0 -print", "r");

    if (pPortFile != NULL)
    {
        i = fread(aResponse, sizeof(char), BUFSIZE - 1, pPortFile);

        aResponse[i] = '\0';

        if(i != 0)
        {
            pclose(pPortFile);
            strcpy(aFName, dirname(aResponse));
            strcat(aFName, "/../../idProduct");
            pPortFile = fopen(aFName, "r");            

            if (i != 0 && pPortFile != NULL)
            {
                i = fread(aResponse, sizeof(char), BUFSIZE - 1, pPortFile);
                aResponse[i] = '\0';

                if (strstr(aResponse,"3538"))
                    ePrinterType_ = PRINTER_1;
                else if (strstr(aResponse,"2305"))
                    ePrinterType_ = PRINTER_2;
            }

            fclose(pPortFile);
        }

        pclose(pPortFile);

    }

    if(ePrinterType_ == UNKNOWN)
    {
        cout << "printer not found" << endl;
        throw Exception("Printer not found");
    }
    else
    {
        pPortFile = fopen(sPortName.c_str(), "r+");
        iFileDescriptor = fileno(pPortFile);
    }
}

我在以下行之后遇到双重释放或损坏(!prev)错误：

if(ePrinterType == UNKNOWN)
{
    cout << "printer not found" << endl;
    throw Exception("Printer not found");
}

我找不到错误实际发生的位置。请帮帮忙

Answer 1

看看这几行--你真的想把它们都做完吗--解释你为什么要这么做……

        pclose(pPortFile);
        ...
        fclose(pPortFile);
    ...
    pclose(pPortFile);