Windows/DebugOutput: Check that only one process reads output

Only one process can attach to the system wide application output
buffer. Re-add checks that makes sure we don't try to attach
as second one.

Change-Id: Ic50b43b8d0ac58d792075b59ecb3e490fdb75df8
Reviewed-on: http://codereview.qt.nokia.com/827
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>

src/plugins/projectexplorer/applicationlauncher.cpp

@@ -117,6 +117,8 @@ ApplicationLauncher::ApplicationLauncher(QObject *parent)
             this, SLOT(processStopped()));
 
 #ifdef Q_OS_WIN
+    connect(WinDebugInterface::instance(), SIGNAL(cannotRetrieveDebugOutput()),
+            this, SLOT(cannotRetrieveDebugOutput()));
     connect(WinDebugInterface::instance(), SIGNAL(debugOutput(qint64,QString)),
             this, SLOT(checkDebugOutput(qint64,QString)));
 #endif
@@ -154,8 +156,6 @@ void ApplicationLauncher::start(Mode mode, const QString &program, const QString
 #ifdef Q_OS_WIN
     if (!WinDebugInterface::instance()->isRunning())
         WinDebugInterface::instance()->start(); // Try to start listener again...
-    if (!WinDebugInterface::instance()->isRunning())
-        emit appendMessage(msgWinCannotRetrieveDebuggingOutput(), Utils::ErrorMessageFormat);
 #endif
 
     d->m_currentMode = mode;
@@ -247,6 +247,11 @@ void ApplicationLauncher::readStandardError()
 }
 
 #ifdef Q_OS_WIN
+void ApplicationLauncher::cannotRetrieveDebugOutput()
+{
+    emit appendMessage(msgWinCannotRetrieveDebuggingOutput(), Utils::ErrorMessageFormat);
+}
+
 void ApplicationLauncher::checkDebugOutput(qint64 pid, const QString &message)
 {
     if (applicationPID() == pid)

src/plugins/projectexplorer/applicationlauncher.h

@@ -83,6 +83,7 @@ private slots:
     void readStandardOutput();
     void readStandardError();
 #ifdef Q_OS_WIN
+    void cannotRetrieveDebugOutput();
     void checkDebugOutput(qint64 pid, const QString &message);
 #endif
     void processDone(int, QProcess::ExitStatus);

src/plugins/projectexplorer/windebuginterface.cpp

@@ -77,7 +77,8 @@ void WinDebugInterface::run()
     m_bufferReadyEvent = 0;
     m_sharedFile = 0;
     m_sharedMem  = 0;
-    runLoop();
+    if (!runLoop())
+        emit cannotRetrieveDebugOutput();
     if (m_sharedMem) {
         UnmapViewOfFile(m_sharedMem);
         m_sharedMem = 0;
@@ -100,21 +101,25 @@ void WinDebugInterface::run()
     }
 }
 
-void WinDebugInterface::runLoop()
+bool WinDebugInterface::runLoop()
 {
     m_waitHandles[TerminateEventHandle] = CreateEvent(NULL, FALSE, FALSE, NULL);
+    if (GetLastError() == ERROR_ALREADY_EXISTS)
+        return false;
     m_waitHandles[DataReadyEventHandle] = CreateEvent(NULL, FALSE, FALSE, L"DBWIN_DATA_READY");
-    if (!m_waitHandles[TerminateEventHandle] || !m_waitHandles[DataReadyEventHandle])
+    if (!m_waitHandles[TerminateEventHandle] || !m_waitHandles[DataReadyEventHandle]
-        return;
+            || GetLastError() == ERROR_ALREADY_EXISTS)
+        return false;
     m_bufferReadyEvent = CreateEvent(NULL, FALSE, FALSE, L"DBWIN_BUFFER_READY");
-    if (!m_bufferReadyEvent)
+    if (!m_bufferReadyEvent
-        return;
+            || GetLastError() == ERROR_ALREADY_EXISTS)
+        return false;
     m_sharedFile = CreateFileMapping((HANDLE)-1, NULL, PAGE_READWRITE, 0, 4096, L"DBWIN_BUFFER");
-    if (!m_sharedFile)
+    if (!m_sharedFile || GetLastError() == ERROR_ALREADY_EXISTS)
-        return;
+        return false;
     m_sharedMem = MapViewOfFile(m_sharedFile, FILE_MAP_READ, 0, 0,  512);
     if (!m_sharedMem)
-        return;
+        return false;
 
     LPSTR  message = reinterpret_cast<LPSTR>(m_sharedMem) + sizeof(DWORD);
     LPDWORD processId = reinterpret_cast<LPDWORD>(m_sharedMem);
@@ -130,6 +135,7 @@ void WinDebugInterface::runLoop()
             SetEvent(m_bufferReadyEvent);
         }
     }
+    return true;
 }
 
 } // namespace Internal

src/plugins/projectexplorer/windebuginterface.h

@@ -50,12 +50,13 @@ public:
 
 signals:
     void debugOutput(qint64 pid, const QString &message);
+    void cannotRetrieveDebugOutput();
 
 private:
     enum Handles { DataReadyEventHandle, TerminateEventHandle, HandleCount };
 
     void run();
-    void runLoop();
+    bool runLoop();
 
     static WinDebugInterface *m_instance;