add a way to modify CreateProcess parameters

[ChangeLog][QtCore][QProcess] Added method
setCreateProcessArgumentsModifier to QProcess on Windows to enable
users to intercept and modify CreateProcess parameters.

With such a modifier, calling code can decide whether to inherit
handles, modify the STARTUPINFO struct, and pass its own
combination of process flags to CreateProcess.

Task-number: QTBUG-390
Task-number: QTBUG-6917
Task-number: QTBUG-9350
Task-number: QTBUG-24619
Change-Id: I14757dbbacfebb1c89f52402d36fba0ba9c45f3a
Reviewed-by: Björn Breitmeyer <bjoern.breitmeyer@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

4 files changed, 111 insertions, 6 deletions

diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index 952116b9db..315142aabe 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -744,6 +744,47 @@ void QProcessPrivate::Channel::clear()
 */
 
 /*!
+    \typedef QProcess::CreateProcessArgumentModifier
+    \note This typedef is only available on desktop Windows and Windows CE.
+
+    On Windows, QProcess uses the Win32 API function \c CreateProcess to
+    start child processes. While QProcess provides a comfortable way to start
+    processes without worrying about platform
+    details, it is in some cases desirable to fine-tune the parameters that are
+    passed to \c CreateProcess. This is done by defining a
+    \c CreateProcessArgumentModifier function and passing it to
+    \c setCreateProcessArgumentsModifier.
+
+    A \c CreateProcessArgumentModifier function takes one parameter: a pointer
+    to a \c CreateProcessArguments struct. The members of this struct will be
+    passed to \c CreateProcess after the \c CreateProcessArgumentModifier
+    function is called.
+
+    The following example demonstrates how to pass custom flags to
+    \c CreateProcess.
+    When starting a console process B from a console process A, QProcess will
+    reuse the console window of process A for process B by default. In this
+    example, a new console window with a custom color scheme is created for the
+    child process B instead.
+
+    \snippet qprocess/qprocess-createprocessargumentsmodifier.cpp 0
+
+    \sa QProcess::CreateProcessArguments
+    \sa setCreateProcessArgumentsModifier()
+*/
+
+/*!
+    \class QProcess::CreateProcessArguments
+    \note This struct is only available on the Windows platform.
+
+    This struct is a representation of all parameters of the Windows API
+    function \c CreateProcess. It is used as parameter for
+    \c CreateProcessArgumentModifier functions.
+
+    \sa QProcess::CreateProcessArgumentModifier
+*/
+
+/*!
     \fn void QProcess::error(QProcess::ProcessError error)
     \obsolete
 
@@ -1563,6 +1604,39 @@ void QProcess::setNativeArguments(const QString &arguments)
     d->nativeArguments = arguments;
 }
 
+/*!
+    \since 5.7
+
+    Returns a previously set \c CreateProcess modifier function.
+
+    \note This function is available only on the Windows platform.
+
+    \sa setCreateProcessArgumentsModifier()
+    \sa QProcess::CreateProcessArgumentModifier
+*/
+QProcess::CreateProcessArgumentModifier QProcess::createProcessArgumentsModifier() const
+{
+    Q_D(const QProcess);
+    return d->modifyCreateProcessArgs;
+}
+
+/*!
+    \since 5.7
+
+    Sets the \a modifier for the \c CreateProcess Win32 API call.
+    Pass \c QProcess::CreateProcessArgumentModifier() to remove a previously set one.
+
+    \note This function is available only on the Windows platform and requires
+    C++11.
+
+    \sa QProcess::CreateProcessArgumentModifier
+*/
+void QProcess::setCreateProcessArgumentsModifier(CreateProcessArgumentModifier modifier)
+{
+    Q_D(QProcess);
+    d->modifyCreateProcessArgs = modifier;
+}
+
 #endif
 
 /*!
diff --git a/src/corelib/io/qprocess.h b/src/corelib/io/qprocess.h
index f95358250e..52e0316857 100644
--- a/src/corelib/io/qprocess.h
+++ b/src/corelib/io/qprocess.h
@@ -38,6 +38,8 @@
 #include <QtCore/qstringlist.h>
 #include <QtCore/qshareddata.h>
 
+#include <functional>
+
 QT_BEGIN_NAMESPACE
 
 
@@ -48,6 +50,8 @@ typedef qint64 Q_PID;
 #else
 QT_END_NAMESPACE
 typedef struct _PROCESS_INFORMATION *Q_PID;
+typedef struct _SECURITY_ATTRIBUTES Q_SECURITY_ATTRIBUTES;
+typedef struct _STARTUPINFOW Q_STARTUPINFO;
 QT_BEGIN_NAMESPACE
 #endif
 
@@ -180,7 +184,23 @@ public:
 #if defined(Q_OS_WIN)
     QString nativeArguments() const;
     void setNativeArguments(const QString &arguments);
-#endif
+    struct CreateProcessArguments
+    {
+        const wchar_t *applicationName;
+        wchar_t *arguments;
+        Q_SECURITY_ATTRIBUTES *processAttributes;
+        Q_SECURITY_ATTRIBUTES *threadAttributes;
+        bool inheritHandles;
+        unsigned long flags;
+        void *environment;
+        const wchar_t *currentDirectory;
+        Q_STARTUPINFO *startupInfo;
+        Q_PID processInformation;
+    };
+    typedef std::function<void(CreateProcessArguments *)> CreateProcessArgumentModifier;
+    CreateProcessArgumentModifier createProcessArgumentsModifier() const;
+    void setCreateProcessArgumentsModifier(CreateProcessArgumentModifier modifier);
+#endif // Q_OS_WIN
 
     QString workingDirectory() const;
     void setWorkingDirectory(const QString &dir);
diff --git a/src/corelib/io/qprocess_p.h b/src/corelib/io/qprocess_p.h
index af88d07a7a..227a583718 100644
--- a/src/corelib/io/qprocess_p.h
+++ b/src/corelib/io/qprocess_p.h
@@ -329,6 +329,7 @@ public:
     QStringList arguments;
 #if defined(Q_OS_WIN)
     QString nativeArguments;
+    QProcess::CreateProcessArgumentModifier modifyCreateProcessArgs;
 #endif
     QProcessEnvironment environment;
 
diff --git a/src/corelib/io/qprocess_win.cpp b/src/corelib/io/qprocess_win.cpp
index 80e6d5bb61..bb5bb4b0a5 100644
--- a/src/corelib/io/qprocess_win.cpp
+++ b/src/corelib/io/qprocess_win.cpp
@@ -497,11 +497,21 @@ void QProcessPrivate::startProcess()
                                  0, 0, 0,
                                  stdinChannel.pipe[0], stdoutChannel.pipe[1], stderrChannel.pipe[1]
     };
-    success = CreateProcess(0, (wchar_t*)args.utf16(),
-                            0, 0, TRUE, dwCreationFlags,
-                            environment.isEmpty() ? 0 : envlist.data(),
-                            workingDirectory.isEmpty() ? 0 : (wchar_t*)QDir::toNativeSeparators(workingDirectory).utf16(),
-                            &startupInfo, pid);
+
+    QProcess::CreateProcessArguments cpargs = {
+        0, (wchar_t*)args.utf16(),
+        0, 0, TRUE, dwCreationFlags,
+        environment.isEmpty() ? 0 : envlist.data(),
+        workingDirectory.isEmpty() ? 0 : (wchar_t*)QDir::toNativeSeparators(workingDirectory).utf16(),
+        &startupInfo, pid
+    };
+    if (modifyCreateProcessArgs)
+        modifyCreateProcessArgs(&cpargs);
+    success = CreateProcess(cpargs.applicationName, cpargs.arguments, cpargs.processAttributes,
+                            cpargs.threadAttributes, cpargs.inheritHandles, cpargs.flags,
+                            cpargs.environment, cpargs.currentDirectory, cpargs.startupInfo,
+                            cpargs.processInformation);
+
     QString errorString;
     if (!success) {
         // Capture the error string before we do CloseHandle below