VCS[git]: Handle stderr in SynchronousProcess::readDataFromProcess

Timeout handling cannot rely on bytesAvailable(), which applies to
stdout only in the normal case. For 'git pull', which output its
progress on stderr, stderr needs to be checked separately.

Task-number: QTCREATORBUG-777

src/libs/utils/synchronousprocess.cpp

@@ -28,6 +28,7 @@
 **************************************************************************/
 
 #include "synchronousprocess.h"
+#include <qtcassert.h>
 
 #include <QtCore/QDebug>
 #include <QtCore/QTimer>
@@ -41,6 +42,7 @@
 #include <limits.h>
 
 enum { debug = 0 };
+enum { syncDebug = 0 };
 
 enum { defaultMaxHangTimerCount = 10 };
 
@@ -403,25 +405,39 @@ void SynchronousProcess::processStdErr(bool emitSignals)
 bool SynchronousProcess::readDataFromProcess(QProcess &p, int timeOutMS,
                                              QByteArray *stdOut, QByteArray *stdErr)
 {
+    if (syncDebug)
+        qDebug() << ">readDataFromProcess" << timeOutMS;
     if (p.state() != QProcess::Running) {
         qWarning("readDataFromProcess: Process in non-running state passed in.");
         return false;
     }
 
+    QTC_ASSERT(p.readChannel() == QProcess::StandardOutput, return false)
+
     // Keep the process running until it has no longer has data
     bool finished = false;
     bool hasData = false;
     do {
         finished = p.waitForFinished(timeOutMS);
-        if ( (hasData = p.bytesAvailable()) ) {
+        hasData = false;
+        // First check 'stdout'
+        if (p.bytesAvailable()) { // applies to readChannel() only
+            hasData = true;
             const QByteArray newStdOut = p.readAllStandardOutput();
-            const QByteArray newStdErr = p.readAllStandardError();
             if (stdOut)
                 stdOut->append(newStdOut);
+        }
+        // Check 'stderr' separately. This is a special handling
+        // for 'git pull' and the like which prints its progress on stderr.
+        const QByteArray newStdErr = p.readAllStandardError();
+        if (!newStdErr.isEmpty()) {
+            hasData = true;
             if (stdErr)
                 stdErr->append(newStdErr);
         }
     } while (hasData && !finished);
+    if (syncDebug)
+        qDebug() << "<readDataFromProcess" << finished;
     return finished;
 }