Support standard channel redirection in QProcess::startDetached

[ChangeLog][QtCore][QProcess] Added support for standard channel
redirection using setStandard{Input|Output|Error}File to
QProcess::startDetached.

Task-number: QTBUG-2058
Task-number: QTBUG-37656
Change-Id: Iafb9bd7899f752d0305e3410ad4dcb7ef598dc79
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qprocess_unix.cpp

@@ -915,6 +915,17 @@ bool QProcessPrivate::startDetached(qint64 *pid)
         return false;
     }
 
+    if ((stdinChannel.type == Channel::Redirect && !openChannel(stdinChannel))
+            || (stdoutChannel.type == Channel::Redirect && !openChannel(stdoutChannel))
+            || (stderrChannel.type == Channel::Redirect && !openChannel(stderrChannel))) {
+        closeChannel(&stdinChannel);
+        closeChannel(&stdoutChannel);
+        closeChannel(&stderrChannel);
+        qt_safe_close(startedPipe[0]);
+        qt_safe_close(startedPipe[1]);
+        return false;
+    }
+
     pid_t childPid = fork();
     if (childPid == 0) {
         struct sigaction noaction;
@@ -931,6 +942,18 @@ bool QProcessPrivate::startDetached(qint64 *pid)
         if (doubleForkPid == 0) {
             qt_safe_close(pidPipe[1]);
 
+            // copy the stdin socket if asked to (without closing on exec)
+            if (inputChannelMode != QProcess::ForwardedInputChannel)
+                qt_safe_dup2(stdinChannel.pipe[0], STDIN_FILENO, 0);
+
+            // copy the stdout and stderr if asked to
+            if (processChannelMode != QProcess::ForwardedChannels) {
+                if (processChannelMode != QProcess::ForwardedOutputChannel)
+                    qt_safe_dup2(stdoutChannel.pipe[1], STDOUT_FILENO, 0);
+                if (processChannelMode != QProcess::ForwardedErrorChannel)
+                    qt_safe_dup2(stderrChannel.pipe[1], STDERR_FILENO, 0);
+            }
+
             if (!encodedWorkingDirectory.isEmpty()) {
                 if (QT_CHDIR(encodedWorkingDirectory.constData()) == -1)
                     qWarning("QProcessPrivate::startDetached: failed to chdir to %s", encodedWorkingDirectory.constData());
@@ -992,6 +1015,9 @@ bool QProcessPrivate::startDetached(qint64 *pid)
         ::_exit(1);
     }
 
+    closeChannel(&stdinChannel);
+    closeChannel(&stdoutChannel);
+    closeChannel(&stderrChannel);
     qt_safe_close(startedPipe[1]);
     qt_safe_close(pidPipe[1]);
 

src/corelib/io/qprocess_win.cpp

@@ -462,10 +462,24 @@ bool QProcessPrivate::callCreateProcess(QProcess::CreateProcessArguments *cpargs
 {
     if (modifyCreateProcessArgs)
         modifyCreateProcessArgs(cpargs);
-    return CreateProcess(cpargs->applicationName, cpargs->arguments, cpargs->processAttributes,
+    bool success = CreateProcess(cpargs->applicationName, cpargs->arguments,
-                         cpargs->threadAttributes, cpargs->inheritHandles, cpargs->flags,
+                                 cpargs->processAttributes, cpargs->threadAttributes,
-                         cpargs->environment, cpargs->currentDirectory, cpargs->startupInfo,
+                                 cpargs->inheritHandles, cpargs->flags, cpargs->environment,
-                         cpargs->processInformation);
+                                 cpargs->currentDirectory, cpargs->startupInfo,
+                                 cpargs->processInformation);
+    if (stdinChannel.pipe[0] != INVALID_Q_PIPE) {
+        CloseHandle(stdinChannel.pipe[0]);
+        stdinChannel.pipe[0] = INVALID_Q_PIPE;
+    }
+    if (stdoutChannel.pipe[1] != INVALID_Q_PIPE) {
+        CloseHandle(stdoutChannel.pipe[1]);
+        stdoutChannel.pipe[1] = INVALID_Q_PIPE;
+    }
+    if (stderrChannel.pipe[1] != INVALID_Q_PIPE) {
+        CloseHandle(stderrChannel.pipe[1]);
+        stderrChannel.pipe[1] = INVALID_Q_PIPE;
+    }
+    return success;
 }
 
 void QProcessPrivate::startProcess()
@@ -535,19 +549,6 @@ void QProcessPrivate::startProcess()
         errorString = QProcess::tr("Process failed to start: %1").arg(qt_error_string());
     }
 
-    if (stdinChannel.pipe[0] != INVALID_Q_PIPE) {
-        CloseHandle(stdinChannel.pipe[0]);
-        stdinChannel.pipe[0] = INVALID_Q_PIPE;
-    }
-    if (stdoutChannel.pipe[1] != INVALID_Q_PIPE) {
-        CloseHandle(stdoutChannel.pipe[1]);
-        stdoutChannel.pipe[1] = INVALID_Q_PIPE;
-    }
-    if (stderrChannel.pipe[1] != INVALID_Q_PIPE) {
-        CloseHandle(stderrChannel.pipe[1]);
-        stderrChannel.pipe[1] = INVALID_Q_PIPE;
-    }
-
     if (!success) {
         cleanup();
         setErrorAndEmit(QProcess::FailedToStart, errorString);
@@ -874,6 +875,15 @@ bool QProcessPrivate::startDetached(qint64 *pid)
 {
     static const DWORD errorElevationRequired = 740;
 
+    if ((stdinChannel.type == Channel::Redirect && !openChannel(stdinChannel))
+            || (stdoutChannel.type == Channel::Redirect && !openChannel(stdoutChannel))
+            || (stderrChannel.type == Channel::Redirect && !openChannel(stderrChannel))) {
+        closeChannel(&stdinChannel);
+        closeChannel(&stdoutChannel);
+        closeChannel(&stderrChannel);
+        return false;
+    }
+
     QString args = qt_create_commandline(program, arguments, nativeArguments);
     bool success = false;
     PROCESS_INFORMATION pinfo;
@@ -890,11 +900,18 @@ bool QProcessPrivate::startDetached(qint64 *pid)
     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
+                                 0, 0, 0,
+                                 STARTF_USESTDHANDLES,
+                                 0, 0, 0,
+                                 stdinChannel.pipe[0], stdoutChannel.pipe[1], stderrChannel.pipe[1]
                                };
+
+    const bool inheritHandles = stdinChannel.type == Channel::Redirect
+            || stdoutChannel.type == Channel::Redirect
+            || stderrChannel.type == Channel::Redirect;
     QProcess::CreateProcessArguments cpargs = {
         nullptr, reinterpret_cast<wchar_t *>(const_cast<ushort *>(args.utf16())),
-        nullptr, nullptr, false, dwCreationFlags, envPtr,
+        nullptr, nullptr, inheritHandles, dwCreationFlags, envPtr,
         workingDirectory.isEmpty()
             ? nullptr : reinterpret_cast<const wchar_t *>(workingDirectory.utf16()),
         &startupInfo, &pinfo
@@ -909,10 +926,17 @@ bool QProcessPrivate::startDetached(qint64 *pid)
     } else if (GetLastError() == errorElevationRequired) {
         if (envPtr)
             qWarning("QProcess: custom environment will be ignored for detached elevated process.");
+        if (!stdinChannel.file.isEmpty() || !stdoutChannel.file.isEmpty()
+                || !stderrChannel.file.isEmpty()) {
+            qWarning("QProcess: file redirection is unsupported for detached elevated processes.");
+        }
         success = startDetachedUacPrompt(program, arguments, nativeArguments,
                                          workingDirectory, pid);
     }
 
+    closeChannel(&stdinChannel);
+    closeChannel(&stdoutChannel);
+    closeChannel(&stderrChannel);
     return success;
 }
 

tests/auto/corelib/io/qprocess/testDetached/main.cpp

@@ -40,23 +40,8 @@
 #include <windows.h>
 #endif
 
-int main(int argc, char **argv)
+static void writeStuff(QFile &f)
 {
-    QCoreApplication app(argc, argv);
-
-    QStringList args = app.arguments();
-    if (args.count() != 2) {
-        fprintf(stderr, "Usage: testDetached filename.txt\n");
-        return 128;
-    }
-
-    QFile f(args.at(1));
-    if (!f.open(QIODevice::WriteOnly | QIODevice::Truncate | QIODevice::Text)) {
-        fprintf(stderr, "Cannot open %s for writing: %s\n",
-                qPrintable(f.fileName()), qPrintable(f.errorString()));
-        return 1;
-    }
-
     f.write(QDir::currentPath().toUtf8());
     f.putChar('\n');
 #if defined(Q_OS_UNIX)
@@ -67,7 +52,77 @@ int main(int argc, char **argv)
     f.putChar('\n');
     f.write(qgetenv("tst_QProcess"));
     f.putChar('\n');
+}
 
+struct Args
+{
+    int exitCode = 0;
+    QByteArray errorMessage;
+    QString fileName;
+    FILE *channel = nullptr;
+    QByteArray channelName;
+};
+
+static Args parseArguments(const QStringList &args)
+{
+    Args result;
+    if (args.count() < 2) {
+        result.exitCode = 128;
+        result.errorMessage = "Usage: testDetached [--out-channel={stdout|stderr}] filename.txt\n";
+        return result;
+    }
+    for (const QString &arg : args) {
+        if (arg.startsWith("--")) {
+            if (!arg.startsWith("--out-channel=")) {
+                result.exitCode = 2;
+                result.errorMessage = "Unknown argument " + arg.toLocal8Bit();
+                return result;
+            }
+            result.channelName = arg.mid(14).toLocal8Bit();
+            if (result.channelName == "stdout") {
+                result.channel = stdout;
+            } else if (result.channelName == "stderr") {
+                result.channel = stderr;
+            } else {
+                result.exitCode = 3;
+                result.errorMessage = "Unknown channel " + result.channelName;
+                return result;
+            }
+        } else {
+            result.fileName = arg;
+        }
+    }
+    return result;
+}
+
+int main(int argc, char **argv)
+{
+    QCoreApplication app(argc, argv);
+
+    const Args args = parseArguments(app.arguments());
+    if (args.exitCode) {
+        fprintf(stderr, "testDetached: %s\n", args.errorMessage.constData());
+        return args.exitCode;
+    }
+
+    if (args.channel) {
+        QFile channel;
+        if (!channel.open(args.channel, QIODevice::WriteOnly | QIODevice::Text)) {
+            fprintf(stderr, "Cannot open channel %s for writing: %s\n",
+                    qPrintable(args.channelName), qPrintable(channel.errorString()));
+            return 4;
+        }
+        writeStuff(channel);
+    }
+
+    QFile f(args.fileName);
+    if (!f.open(QIODevice::WriteOnly | QIODevice::Truncate | QIODevice::Text)) {
+        fprintf(stderr, "Cannot open %s for writing: %s\n",
+                qPrintable(f.fileName()), qPrintable(f.errorString()));
+        return 1;
+    }
+
+    writeStuff(f);
     f.close();
 
     return 0;

tests/auto/corelib/io/qprocess/tst_qprocess.cpp

@@ -126,6 +126,7 @@ private slots:
     void systemEnvironment();
     void lockupsInStartDetached();
     void waitForReadyReadForNonexistantProcess();
+    void detachedProcessParameters_data();
     void detachedProcessParameters();
     void startFinishStartFinish();
     void invalidProgramString_data();
@@ -2030,13 +2031,25 @@ void tst_QProcess::fileWriterProcess()
     } while (stopWatch.elapsed() < 3000);
 }
 
+void tst_QProcess::detachedProcessParameters_data()
+{
+    QTest::addColumn<QString>("outChannel");
+    QTest::newRow("none") << QString();
+    QTest::newRow("stdout") << QString("stdout");
+    QTest::newRow("stderr") << QString("stderr");
+}
+
 void tst_QProcess::detachedProcessParameters()
 {
+    QFETCH(QString, outChannel);
     qint64 pid;
 
     QFile infoFile(m_temporaryDir.path() + QLatin1String("/detachedinfo.txt"));
     if (infoFile.exists())
         QVERIFY(infoFile.remove());
+    QFile channelFile(m_temporaryDir.path() + QLatin1String("detachedinfo2.txt"));
+    if (channelFile.exists())
+        QVERIFY(channelFile.remove());
 
     QString workingDir = QDir::currentPath() + "/testDetached";
 
@@ -2054,7 +2067,15 @@ void tst_QProcess::detachedProcessParameters()
     process.setCreateProcessArgumentsModifier(
         [&modifierCalls] (QProcess::CreateProcessArguments *) { modifierCalls++; });
 #endif
-    process.setArguments(QStringList(infoFile.fileName()));
+    QStringList args(infoFile.fileName());
+    if (!outChannel.isEmpty()) {
+        args << QStringLiteral("--out-channel=") + outChannel;
+        if (outChannel == "stdout")
+            process.setStandardOutputFile(channelFile.fileName());
+        else if (outChannel == "stderr")
+            process.setStandardErrorFile(channelFile.fileName());
+    }
+    process.setArguments(args);
     process.setWorkingDirectory(workingDir);
     process.setProcessEnvironment(environment);
     QVERIFY(process.startDetached(&pid));
@@ -2071,9 +2092,22 @@ void tst_QProcess::detachedProcessParameters()
     QString actualWorkingDir = QString::fromUtf8(infoFile.readLine()).trimmed();
     QByteArray processIdString = infoFile.readLine().trimmed();
     QByteArray actualEnvVarValue = infoFile.readLine().trimmed();
+    QByteArray infoFileContent;
+    if (!outChannel.isEmpty()) {
+        infoFile.seek(0);
+        infoFileContent = infoFile.readAll();
+    }
     infoFile.close();
     infoFile.remove();
 
+    if (!outChannel.isEmpty()) {
+        QVERIFY(channelFile.open(QIODevice::ReadOnly | QIODevice::Text));
+        QByteArray channelContent = channelFile.readAll();
+        channelFile.close();
+        channelFile.remove();
+        QCOMPARE(channelContent, infoFileContent);
+    }
+
     bool ok = false;
     qint64 actualPid = processIdString.toLongLong(&ok);
     QVERIFY(ok);