After testing under windows, it is found that QT program will kill the process created by CreateProcess when it exits again

legahero

MinGW32，After testing under windows, it is found that QT program will kill the process created by CreateProcess when it exits again，I tested the following situations, but there were no exceptions（windows下经过测试发现QT编写的程序再退出的时候会把CreateProcess创建的进程杀死，我测试了以下各种情况但都没有例外），following code:
#include "bccmainwindow.h"
#include "ui_bccmainwindow.h"
#include <QProcess>
#include <QDebug>
#include <QDir>
//#include <windows.h>
#include "qsystemlibrary.h"

static QString qt_create_commandline(const QString &program, const QStringList &arguments);
static bool startDetachedUacPrompt(const QString &programIn, const QStringList &arguments,
const QString &workingDir, qint64 *pid);
bool startDetached(const QString &program, const QStringList &arguments, const QString &workingDir, qint64 *pid);

using namespace std;
BccMainWindow::BccMainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::BccMainWindow)
{
ui->setupUi(this);
}

BccMainWindow::~BccMainWindow()
{
delete ui;
}

void BccMainWindow::on_pushButton_clicked()
{

QProcess* process  = new QProcess;
//QString strpath = qApp->applicationDirPath();
//process->setWorkingDirectory(strpath + QString("/softwares/com2tcp"));
//QString str_exePath = "\"" + str_exePath + "\"";
QStringList arguments;

arguments << "-new" << "http://www.qq.com";



if (process->state() != QProcess::Running)
{   /// 只允许开启一个进程
     process->startDetached("C:\\Program Files (x86)\\Internet Explorer\\iexplore.exe ", arguments);     // 将以阻塞的方式启动
     //process->start("C:\\Program Files (x86)\\Internet Explorer\\iexplore.exe ", arguments);
     if(!process->waitForStarted())
     {
         qDebug() << "waitForStarted false";
     }
     //process->waitForFinished(5000);
     QString strResult = QString::fromLocal8Bit(process->readAllStandardOutput());
     qDebug() << strResult;
}


if(process)
{
    //process->close();
    delete process;
    process = NULL;
}

}

void BccMainWindow::on_pushButton_2_clicked()
{
QDir::setCurrent("C:\Program Files (x86)\Internet Explorer\");

QStringList arguments;
arguments << "-new" << "http://www.qq.com";
if(!QProcess::startDetached("iexplore.exe",arguments))
{
    qDebug() << "startDetached false";
}

}

void BccMainWindow::on_pushButton_3_clicked()
{
/*
QDir::setCurrent("C:\Program Files (x86)\Internet Explorer\");
int code=QProcess::execute("iexplore.exe -new www.qq.com");

qDebug() << "execute code "<<code;
*/
/*

#define SW_NORMAL 1 //普通方式运行
#define SW_SHOWMINIMIZED 2 //运行时最小化显示
#define SW_SHOWMAXIMIZED 3 //运行时最大化显示
#define SW_MAXIMIZE 3 //最大化运行
*/
WinExec(""C:\Program Files (x86)\Internet Explorer\iexplore.exe" -new www.qq.com",1);

}

void BccMainWindow::on_pushButton_4_clicked()
{
QDir::setCurrent("C:\Program Files (x86)\Internet Explorer\");

QStringList arguments;
arguments << "-new" << "http://www.qq.com";

if(!QProcess::execute("iexplore.exe",arguments))
{
    qDebug() << "execute false";
}

}
/*
QProcess ps;

connect(&ps,SIGNAL(readyReadStandardOutput()),this,SLOT(readProcessStandardOutput()));

QStringList args;

args<<"-c";

args<<"ps | grep 'processName";

ps.start("sh",args);

readProcessStandardOutput()

{
ps.readAllStandardOutput() // 得到sh -c "ps | grep 'processName‘“ 的输出结果，查看这个结果就可以得到这个结果是否在运行。

}
*/

void BccMainWindow::on_pushButton_cmd_clicked()
{
QDir::setCurrent("C:\Program Files (x86)\Internet Explorer\");

QStringList arguments;
arguments<<"/c"<<"iexplore.exe -new \"http://www.qq.com\"";

qint64 pid;
//if(!QProcess::startDetached("cmd",arguments,"C:\\Program Files (x86)\\Internet Explorer\\",&pid))
if(!startDetached("cmd",arguments,"C:\\Program Files (x86)\\Internet Explorer\\",&pid))
{
    qDebug() << "startDetached false";
}

/*
qint64 ProcessId;

HANDLE hProcess = OpenProcess(PROCESS_TERMINATE, FALSE, pid);
if (hProcess == NULL)
{
    //return FALSE;
}
if (!TerminateProcess(hProcess, 0))
{
    //return FALSE;
}
*/
//return TRUE;

}

static QString qt_create_commandline(const QString &program, const QStringList &arguments)
{
QString args;
if (!program.isEmpty()) {
QString programName = program;
if (!programName.startsWith(QLatin1Char('"')) && !programName.endsWith(QLatin1Char('"')) && programName.contains(QLatin1Char(' ')))
programName = QLatin1Char('"') + programName + QLatin1Char('"');
programName.replace(QLatin1Char('/'), QLatin1Char('\'));

    // add the prgram as the first arg ... it works better
    args = programName + QLatin1Char(' ');
}

for (int i=0; i<arguments.size(); ++i) {
    QString tmp = arguments.at(i);
    // Quotes are escaped and their preceding backslashes are doubled.
    tmp.replace(QRegExp(QLatin1String("(\\\\*)\"")), QLatin1String("\\1\\1\\\""));
    if (tmp.isEmpty() || tmp.contains(QLatin1Char(' ')) || tmp.contains(QLatin1Char('\t'))) {
        // The argument must not end with a \ since this would be interpreted
        // as escaping the quote -- rather put the \ behind the quote: e.g.
        // rather use "foo"\ than "foo\"
        int i = tmp.length();
        while (i > 0 && tmp.at(i - 1) == QLatin1Char('\\'))
            --i;
        tmp.insert(i, QLatin1Char('"'));
        tmp.prepend(QLatin1Char('"'));
    }
    args += QLatin1Char(' ') + tmp;
}
return args;

}

// Use ShellExecuteEx() to trigger an UAC prompt when CreateProcess()fails
// with ERROR_ELEVATION_REQUIRED.
static bool startDetachedUacPrompt(const QString &programIn, const QStringList &arguments,
const QString &workingDir, qint64 *pid)
{
typedef BOOL (WINAPI *ShellExecuteExType)(SHELLEXECUTEINFOW *);

static const ShellExecuteExType shellExecuteEx = // XP ServicePack 1 onwards.
    reinterpret_cast<ShellExecuteExType>(QSystemLibrary::resolve(QLatin1String("shell32"),
                                                                 "ShellExecuteExW"));
if (!shellExecuteEx)
    return false;

const QString args = qt_create_commandline(QString(), arguments); // needs arguments only
SHELLEXECUTEINFOW shellExecuteExInfo;
memset(&shellExecuteExInfo, 0, sizeof(SHELLEXECUTEINFOW));
shellExecuteExInfo.cbSize = sizeof(SHELLEXECUTEINFOW);
shellExecuteExInfo.fMask = SEE_MASK_NOCLOSEPROCESS | SEE_MASK_UNICODE | SEE_MASK_FLAG_NO_UI;
shellExecuteExInfo.lpVerb = L"runas";
const QString program = QDir::toNativeSeparators(programIn);
shellExecuteExInfo.lpFile = reinterpret_cast<LPCWSTR>(program.utf16());
if (!args.isEmpty())
    shellExecuteExInfo.lpParameters = reinterpret_cast<LPCWSTR>(args.utf16());
if (!workingDir.isEmpty())
    shellExecuteExInfo.lpDirectory = reinterpret_cast<LPCWSTR>(workingDir.utf16());
shellExecuteExInfo.nShow = SW_SHOWNORMAL;

if (!shellExecuteEx(&shellExecuteExInfo))
    return false;
if (pid)
    *pid = qint64(GetProcessId(shellExecuteExInfo.hProcess));
CloseHandle(shellExecuteExInfo.hProcess);
return true;

}

bool startDetached(const QString &program, const QStringList &arguments, const QString &workingDir, qint64 *pid)
{
static const DWORD errorElevationRequired = 740;

QString args = qt_create_commandline(program, arguments);
bool success = false;
PROCESS_INFORMATION pinfo;

DWORD dwCreationFlags = (GetConsoleWindow() ? 0 : CREATE_NO_WINDOW);
dwCreationFlags |= CREATE_UNICODE_ENVIRONMENT;
dwCreationFlags |= DETACHED_PROCESS;
STARTUPINFOW startupInfo = { sizeof( STARTUPINFO ), 0, 0, 0,
                             (ulong)CW_USEDEFAULT, (ulong)CW_USEDEFAULT,
                             (ulong)CW_USEDEFAULT, (ulong)CW_USEDEFAULT,
                             0, 0, 0, 0, 0, 0, 0, 0, 0, 0
                           };
success = CreateProcess(0, (wchar_t*)args.utf16(),
                        0, 0, FALSE, dwCreationFlags, 0,
                        workingDir.isEmpty() ? 0 : (wchar_t*)workingDir.utf16(),
                        &startupInfo, &pinfo);

if (success) {
    CloseHandle(pinfo.hThread);
    CloseHandle(pinfo.hProcess);
    if (pid)
        *pid = pinfo.dwProcessId;
} else if (GetLastError() == errorElevationRequired) {
    success = startDetachedUacPrompt(program, arguments, workingDir, pid);
}

return success;

}

void BccMainWindow::on_pushButton_CreateP_clicked()
{
char cWindowsDirectory[MAX_PATH] = { 0 };

    //LPTSTR 与 wchar_t* 等价(Unicode环境下)
    LPTSTR cWinDir = new TCHAR[MAX_PATH];
    memset(cWinDir, MAX_PATH, 0);
    //GetCurrentDirectory(MAX_PATH, cWinDir);

    
    wcscpy_s(cWinDir, MAX_PATH, L"D:\\Tool\\DevMng.exe");
    LPTSTR sConLin = cWinDir;

    STARTUPINFO si;
    PROCESS_INFORMATION pi;

    ZeroMemory(&si, sizeof(si));
    ZeroMemory(&pi, sizeof(pi));

    //创建一个新进程
    if (CreateProcess(
        NULL,   //  指向一个NULL结尾的、用来指定可执行模块的宽字节字符串
        sConLin, // 命令行字符串
        NULL, //    指向一个SECURITY_ATTRIBUTES结构体，这个结构体决定是否返回的句柄可以被子进程继承。
        NULL, //    如果lpProcessAttributes参数为空（NULL），那么句柄不能被继承。<同上>
        false,//    指示新进程是否从调用进程处继承了句柄。
        0,  //  指定附加的、用来控制优先类和进程的创建的标
            //  CREATE_NEW_CONSOLE  新控制台打开子进程
            //  CREATE_SUSPENDED    子进程创建后挂起，直到调用ResumeThread函数
        NULL, //    指向一个新进程的环境块。如果此参数为空，新进程使用调用进程的环境
        NULL, //    指定子进程的工作路径
        &si, // 决定新进程的主窗体如何显示的STARTUPINFO结构体
        &pi  // 接收新进程的识别信息的PROCESS_INFORMATION结构体
    ))
    {
        qDebug() << "create process success" << endl;

        //下面两行关闭句柄，解除本进程和新进程的关系，不然有可能不小心调用TerminateProcess函数关掉子进程
//      CloseHandle(pi.hProcess);
//      CloseHandle(pi.hThread);
    }
    else {
        qDebug() << "failed to create process" << endl;
    }
    ::GetCurrentProcess();
    Sleep(1000);

    //终止子进程
    //TerminateProcess(pi.hProcess, 300);

    //终止本进程，状态码
    //ExitProcess(1001);

    //return 0;

}

legahero

I hope that when the main process exits, it does not exit other processes it started，It's useful in some scenarios, such as program upgrades（我希望主进程退出时不会退出它启动的其它进程，在某些场景下还是有用的，比如程序升级），Now I have to use other development tools to finish it.

JKSH

@legahero said in After testing under windows, it is found that QT program will kill the process created by CreateProcess when it exits again:

I hope that when the main process exits, it does not exit other processes it started

Then your other child process must be detached.

Anyway, I see that your code contains both QProcess and CreateProcess. It doesn't make sense to mix both in the same application, so you should just choose one. (I think QProcess is a lot simpler to use)

If you have further questions, please clean up and simplify your code.

legahero

@JKSH ,thanks,I find that this happens when debugging, not when publishing。