Fix incomplete override of QIODevice::open in QProcess and QLocalSocket

The rule for a new override is that it must still work if the old
implementation is called. The catch is that any class that derives from
QProcess and isn't recompiled will still have QIODevice::open in its
virtual table. That is equivalent to overriding open() and calling
QIODevice::open() (like the tests).

In Qt 5.0, QProcess::start() called QIODevice::open directly, not the
virtual open(), so there's no expectation that a user-overridden open()
be called. With that in mind, simply fix QProcess::start to not call the
virtual open at all.

Similarly with QLocalSocket, the calls to open were always non-virtual.

Task-number: QTBUG-32284
Change-Id: I88925f0ba08bc23c849658b54582744997e69a4c
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

1 files changed, 37 insertions, 22 deletions

diff --git a/src/corelib/io/qprocess.cpp b/src/corelib/io/qprocess.cpp
index b1861d8038..d8cd1f5fae 100644
--- a/src/corelib/io/qprocess.cpp
+++ b/src/corelib/io/qprocess.cpp
@@ -1959,7 +1959,7 @@ void QProcess::start(const QString &program, const QStringList &arguments, OpenM
     d->program = program;
     d->arguments = arguments;
 
-    open(mode);
+    d->start(mode);
 }
 
 /*!
@@ -1975,7 +1975,17 @@ void QProcess::start(const QString &program, const QStringList &arguments, OpenM
  */
 void QProcess::start(OpenMode mode)
 {
-    open(mode);
+    Q_D(QProcess);
+    if (d->processState != NotRunning) {
+        qWarning("QProcess::start: Process is already running");
+        return;
+    }
+    if (d->program.isEmpty()) {
+        qWarning("QProcess::start: program not set");
+        return;
+    }
+
+    d->start(mode);
 }
 
 /*!
@@ -2008,34 +2018,39 @@ bool QProcess::open(OpenMode mode)
         return false;
     }
 
+    d->start(mode);
+    return true;
+}
+
+void QProcessPrivate::start(QIODevice::OpenMode mode)
+{
+    Q_Q(QProcess);
 #if defined QPROCESS_DEBUG
     qDebug() << "QProcess::start(" << program << ',' << arguments << ',' << mode << ')';
 #endif
 
-    d->outputReadBuffer.clear();
-    d->errorReadBuffer.clear();
+    outputReadBuffer.clear();
+    errorReadBuffer.clear();
 
-    if (d->stdinChannel.type != QProcessPrivate::Channel::Normal)
-        mode &= ~WriteOnly;     // not open for writing
-    if (d->stdoutChannel.type != QProcessPrivate::Channel::Normal &&
-        (d->stderrChannel.type != QProcessPrivate::Channel::Normal ||
-         d->processChannelMode == MergedChannels))
-        mode &= ~ReadOnly;      // not open for reading
+    if (stdinChannel.type != QProcessPrivate::Channel::Normal)
+        mode &= ~QIODevice::WriteOnly;     // not open for writing
+    if (stdoutChannel.type != QProcessPrivate::Channel::Normal &&
+        (stderrChannel.type != QProcessPrivate::Channel::Normal ||
+         processChannelMode == QProcess::MergedChannels))
+        mode &= ~QIODevice::ReadOnly;      // not open for reading
     if (mode == 0)
-        mode = Unbuffered;
-    QIODevice::open(mode);
+        mode = QIODevice::Unbuffered;
+    q->QIODevice::open(mode);
 
-    d->stdinChannel.closed = false;
-    d->stdoutChannel.closed = false;
-    d->stderrChannel.closed = false;
+    stdinChannel.closed = false;
+    stdoutChannel.closed = false;
+    stderrChannel.closed = false;
 
-    d->exitCode = 0;
-    d->exitStatus = NormalExit;
-    d->processError = QProcess::UnknownError;
-    d->errorString.clear();
-    d->startProcess();
-
-    return true;
+    exitCode = 0;
+    exitStatus = QProcess::NormalExit;
+    processError = QProcess::UnknownError;
+    errorString.clear();
+    startProcess();
 }