Fix crash when QSocketNotifier used with an invalid descriptor

select code for open C file/socket descriptors was crashing in FD_SET
if a QSocketNotifier was created with an invalid descriptor.

Added two autotests to QSocketNotifier, one to check notifiers with
bogus socket descriptors don't crash, the other to check that notifiers
with posix socket descriptors do work. (symbian socket engine doesn't
use them so they are not implicitly tested)

Reviewed-by: mread
Task-Number: QTBUG-18138
(cherry picked from commit 8a9a6afcf02f089f932bc81431ab46a60af32134)

1 files changed, 6 insertions, 0 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_symbian.cpp b/src/corelib/kernel/qeventdispatcher_symbian.cpp
index e0eeb0819a..bd12726508 100644
--- a/src/corelib/kernel/qeventdispatcher_symbian.cpp
+++ b/src/corelib/kernel/qeventdispatcher_symbian.cpp
@@ -1111,6 +1111,12 @@ bool QEventDispatcherSymbian::hasPendingEvents()
 
 void QEventDispatcherSymbian::registerSocketNotifier ( QSocketNotifier * notifier )
 {
+    //check socket descriptor is usable
+    if (notifier->socket() >= FD_SETSIZE || notifier->socket() < 0) {
+        //same warning message as the unix event dispatcher for easy testing
+        qWarning("QSocketNotifier: Internal error");
+        return;
+    }
     //note - this is only for "open C" file descriptors
     //for native sockets, an active object in the symbian socket engine handles this
     QSocketActiveObject *socketAO = new QSocketActiveObject(this, notifier);