Don't destroy Qt's internal pthread_key_t if it was not initialized

The destructor function destroy_current_thread_data_key() was always
called on library unload, even if the pthread_key_t was not initialized.
This can cause us to destroy a key that doesn't belong to us, as pointed
out in the task below.

Fix this by creating a function static instance of a class whose
destructor will destroy the key.

Task-number: QTBUG-10861
Reviewed-by: Morten Sørvig

1 files changed, 9 insertions, 7 deletions

diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index f7e80fd..87979c4 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -150,15 +150,17 @@ static void destroy_current_thread_data(void *p)
 static void create_current_thread_data_key()
 {
     pthread_key_create(&current_thread_data_key, destroy_current_thread_data);
+    static class destroy_current_thread_data_key
+    {
+    public:
+        ~destroy_current_thread_data_key()
+        {
+            pthread_key_delete(current_thread_data_key);
+        }
+    } d;
+    Q_UNUSED(d);
 }
 
-static void destroy_current_thread_data_key()
-{
-    pthread_key_delete(current_thread_data_key);
-}
-Q_DESTRUCTOR_FUNCTION(destroy_current_thread_data_key)
-
-
 // Utility functions for getting, setting and clearing thread specific data.
 // In Symbian, TLS access is significantly faster than pthread_getspecific.
 // However Symbian does not have the thread destruction cleanup functionality