通过匿名管道获取CMD运行结果

#include <iostream>
#include <string>
#include <Windows.h>

using namespace std;

/*
获取CMD执行结果
cmdLine:要执行的命令
*/
char *GetCmdRet(char *cmdLine);

int main(void)
{
    char *ret = GetCmdRet("ipconfig");
    cout << ret << endl;
    free(ret);
    cout << "
====================换个命令玩玩====================
" << endl;
    ret = GetCmdRet("dir");
    cout << ret << endl;
    free(ret);
    system("pause");
    return 0;
}

char *GetCmdRet(char *cmdLine)
{
    HANDLE hRead = NULL, hWrite = NULL;
    PROCESS_INFORMATION pInfo = { 0 };
    SECURITY_ATTRIBUTES se = { 0 };
    STARTUPINFO sInfo = { 0 };
    char tmpCmd[1000000] = { 0 }, *retStr = NULL;
    DWORD dwLen = 0;
    string ret;

    se.nLength = sizeof(se);
    se.lpSecurityDescriptor = NULL;
    se.bInheritHandle = TRUE;

    // 创建一个匿名管道
    CreatePipe(&hRead, &hWrite, &se, 0);

    sInfo.cb = sizeof(sInfo);
    sInfo.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES; // 这两个常量分别用于设置隐藏窗口+输出目标
    sInfo.wShowWindow = SW_HIDE; // 隐藏窗口运行
    sInfo.hStdOutput = hWrite;    // 让其输出到这个管道去而不是输出到控制台
    sInfo.hStdError = hWrite;    // 错误信息也是输出到该管道
    sprintf_s(tmpCmd, MAX_PATH, "cmd.exe /c %s", cmdLine);
    CreateProcess(NULL, tmpCmd, NULL, NULL, TRUE, NULL, NULL, NULL, &sInfo, &pInfo);
    CloseHandle(hWrite);

    while (dwLen != -1)
    {
        // 查看管道中是否有数据
        PeekNamedPipe(hRead, NULL, NULL, NULL, &dwLen, NULL);
        if (dwLen)
        {
            memset(tmpCmd, 0, MAX_PATH);
            // 读取管道数据
            ReadFile(hRead, tmpCmd, dwLen, &dwLen, NULL);
            ret += tmpCmd;
        }
        else
        {
            DWORD dwExit = 0;
            GetExitCodeProcess(pInfo.hProcess, &dwExit);
            // 避免程序已经退出,但管道仍有数据的情况
            if (dwExit != STILL_ACTIVE)
            {
                CloseHandle(hRead);
                break;
            }
        }
        // 一定要加个延时,否则可能有重复数据
        Sleep(1);
    }
    retStr = (char *)malloc(sizeof(char)*ret.length() + 1);
    memset(retStr, 0, ret.length() + 1);
    lstrcpyn(retStr, ret.c_str(), ret.length() + 1);
    return retStr;
}