Windows QPA: Work around intermittent clipboard copy failures

Repeatedly attempt to open the clipboard in case it is opened
by other applications.

Task-number: QTBUG-27097
Change-Id: Ic1cfec0bb17e34f8c7f744add21a4431dae4f5b7
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

src/plugins/platforms/windows/qwindowsclipboard.cpp

@@ -50,6 +50,7 @@
 #include <QtCore/qdebug.h>
 #include <QtCore/qmimedata.h>
 #include <QtCore/qstringlist.h>
+#include <QtCore/qthread.h>
 #include <QtCore/qvariant.h>
 #include <QtCore/qurl.h>
 
@@ -318,7 +319,15 @@ void QWindowsClipboard::setMimeData(QMimeData *mimeData, QClipboard::Mode mode)
             m_data = new QWindowsOleDataObject(mimeData);
     }
 
-    const HRESULT src = OleSetClipboard(m_data);
+    HRESULT src = S_FALSE;
+    int attempts = 0;
+    for (; attempts < 3; ++attempts) {
+        src = OleSetClipboard(m_data);
+        if (src != CLIPBRD_E_CANT_OPEN || QWindowsContext::isSessionLocked())
+            break;
+        QThread::msleep(100);
+    }
+
     if (src != S_OK) {
         QString mimeDataFormats = mimeData ?
             mimeData->formats().join(QLatin1String(", ")) : QString(QStringLiteral("NULL"));

src/plugins/platforms/windows/qwindowscontext.cpp

@@ -86,6 +86,7 @@
 #include <windowsx.h>
 #include <comdef.h>
 #include <dbt.h>
+#include <wtsapi32.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -754,6 +755,37 @@ QWindowsWindow *QWindowsContext::findPlatformWindowAt(HWND parent,
     return result;
 }
 
+bool QWindowsContext::isSessionLocked()
+{
+    bool result = false;
+    const DWORD sessionId = WTSGetActiveConsoleSessionId();
+    if (sessionId != 0xFFFFFFFF) {
+        LPTSTR buffer = nullptr;
+        DWORD size = 0;
+#if !defined(Q_CC_MINGW)
+        if (WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, sessionId,
+                                       WTSSessionInfoEx, &buffer, &size) == TRUE
+            && size > 0) {
+            const WTSINFOEXW *info = reinterpret_cast<WTSINFOEXW *>(buffer);
+            result = info->Level == 1 && info->Data.WTSInfoExLevel1.SessionFlags == WTS_SESSIONSTATE_LOCK;
+            WTSFreeMemory(buffer);
+        }
+#else   // MinGW as of 7.3 does not have WTSINFOEXW in wtsapi32.h
+        // Retrieve the flags which are at offset 16 due to padding for 32/64bit alike.
+        if (WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, sessionId,
+                                       WTS_INFO_CLASS(25), &buffer, &size) == TRUE
+            && size >= 20) {
+            const DWORD *p = reinterpret_cast<DWORD *>(buffer);
+            const DWORD level = *p;
+            const DWORD sessionFlags = *(p + 4);
+            result = level == 1 && sessionFlags == 1;
+            WTSFreeMemory(buffer);
+        }
+#endif // Q_CC_MINGW
+    }
+    return result;
+}
+
 QWindowsMimeConverter &QWindowsContext::mimeConverter() const
 {
     return d->m_mimeConverter;

src/plugins/platforms/windows/qwindowscontext.h

@@ -224,6 +224,8 @@ public:
     bool useRTLExtensions() const;
     QList<int> possibleKeys(const QKeyEvent *e) const;
 
+    static bool isSessionLocked();
+
     QWindowsMimeConverter &mimeConverter() const;
     QWindowsScreenManager &screenManager();
     QWindowsTabletSupport *tabletSupport() const;

src/plugins/platforms/windows/windows.pri

@@ -7,7 +7,7 @@ qtConfig(opengl):!qtConfig(opengles2):!qtConfig(dynamicgl): LIBS *= -lopengl32
 
 mingw: LIBS *= -luuid
 # For the dialog helpers:
-LIBS += -lshlwapi -lshell32 -ladvapi32
+LIBS += -lshlwapi -lshell32 -ladvapi32 -lwtsapi32
 
 DEFINES *= QT_NO_CAST_FROM_ASCII QT_NO_FOREACH