BlackBerry: Restore proper BPS channel in event dispatcher

This change ensures that BPS events are delivered to the proper
channel even if the application code would change the channel.

Change-Id: Id44efbdd99350c639e391161dd89b8d422c4b330
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Jeff Kehres <jkehres@rim.com>
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>

1 files changed, 36 insertions, 8 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_blackberry.cpp b/src/corelib/kernel/qeventdispatcher_blackberry.cpp
index 4be1d73b7a..2252b73ad4 100644
--- a/src/corelib/kernel/qeventdispatcher_blackberry.cpp
+++ b/src/corelib/kernel/qeventdispatcher_blackberry.cpp
@@ -55,7 +55,29 @@
 #define qEventDispatcherDebug QT_NO_QDEBUG_MACRO()
 #endif
 
-struct bpsIOHandlerData {
+class BpsChannelScopeSwitcher
+{
+public:
+    BpsChannelScopeSwitcher(int scopeChannel) : innerChannel(scopeChannel)
+    {
+        outerChannel = bps_channel_get_active();
+        if (outerChannel != innerChannel)
+            bps_channel_set_active(innerChannel);
+    }
+
+    ~BpsChannelScopeSwitcher()
+    {
+        if (outerChannel != innerChannel)
+            bps_channel_set_active(outerChannel);
+    }
+
+private:
+    int innerChannel;
+    int outerChannel;
+};
+
+struct bpsIOHandlerData
+{
     bpsIOHandlerData()
         : count(0), readfds(0), writefds(0), exceptfds(0)
     {
@@ -101,7 +123,7 @@ static int bpsIOHandler(int fd, int io_events, void *data)
     // but this only needs to happen once if multiple files become ready at the same time
     if (firstReady) {
         qEventDispatcherDebug << "Sending bpsIOReadyDomain event";
-        // create IO ready event
+        // create unblock event
         bps_event_t *event;
         int result = bps_event_create(&event, bpsUnblockDomain, 0, NULL, NULL);
         if (result != BPS_SUCCESS) {
@@ -109,7 +131,8 @@ static int bpsIOHandler(int fd, int io_events, void *data)
             return BPS_FAILURE;
         }
 
-        // post unblock event to our thread
+        // post unblock event to our thread; in this callback the bps channel is
+        // guarenteed to be the same that was active when bps_add_fd was called
         result = bps_push_event(event);
         if (result != BPS_SUCCESS) {
             qWarning("QEventDispatcherBlackberryPrivate::QEventDispatcherBlackberry: bps_push_event() failed");
@@ -175,6 +198,9 @@ QEventDispatcherBlackberry::~QEventDispatcherBlackberry()
 void QEventDispatcherBlackberry::registerSocketNotifier(QSocketNotifier *notifier)
 {
     Q_ASSERT(notifier);
+    Q_D(QEventDispatcherBlackberry);
+
+    BpsChannelScopeSwitcher channelSwitcher(d->bps_channel);
 
     // Register the fd with bps
     int sockfd = notifier->socket();
@@ -205,8 +231,6 @@ void QEventDispatcherBlackberry::registerSocketNotifier(QSocketNotifier *notifie
         break;
     }
 
-    Q_D(QEventDispatcherBlackberry);
-
     errno = 0;
     int result = bps_add_fd(sockfd, io_events, &bpsIOHandler, d->ioData.data());
 
@@ -216,6 +240,10 @@ void QEventDispatcherBlackberry::registerSocketNotifier(QSocketNotifier *notifie
 
 void QEventDispatcherBlackberry::unregisterSocketNotifier(QSocketNotifier *notifier)
 {
+    Q_D(QEventDispatcherBlackberry);
+
+    BpsChannelScopeSwitcher channelSwitcher(d->bps_channel);
+
     // Allow the base Unix implementation to unregister the fd too
     QEventDispatcherUNIX::unregisterSocketNotifier(notifier);
 
@@ -236,8 +264,6 @@ void QEventDispatcherBlackberry::unregisterSocketNotifier(QSocketNotifier *notif
     if (!io_events)
         return;
 
-    Q_D(QEventDispatcherBlackberry);
-
     errno = 0;
     result = bps_add_fd(sockfd, io_events, &bpsIOHandler, d->ioData.data());
     if (result != BPS_SUCCESS) {
@@ -249,12 +275,14 @@ int QEventDispatcherBlackberry::select(int nfds, fd_set *readfds, fd_set *writef
                                        timeval *timeout)
 {
     Q_UNUSED(nfds);
+    Q_D(QEventDispatcherBlackberry);
+
+    BpsChannelScopeSwitcher channelSwitcher(d->bps_channel);
 
     // Make a note of the start time
     timeval startTime = qt_gettime();
 
     // prepare file sets for bps callback
-    Q_D(QEventDispatcherBlackberry);
     d->ioData->count = 0;
     d->ioData->readfds = readfds;
     d->ioData->writefds = writefds;