Don't crash by modifying read-only shared_null

Functions that modify the d-pointer must detach or otherwise take
measures to not modify the const, read-only shared_null.

The setSharable(bool) function takes care to detach when setting
sharable to false, but should avoid setting the sharable data member
unless d is not the shared null.

Similarly, QMap<Key, T>::setInsertInOrder() needs to detach if it is
shared with the shared_null (the logic has been updated to be the same
as setSharable()).

Change-Id: Ida5cb9818b86695f1b9f0264418b955c56424898
Reviewed-on: http://codereview.qt-project.org/5929
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Jan-Arve Sæther <jan-arve.saether@nokia.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qhash/tst_qhash.cpp b/tests/auto/corelib/tools/qhash/tst_qhash.cpp
index 16fb123256..fc669628b5 100644
--- a/tests/auto/corelib/tools/qhash/tst_qhash.cpp
+++ b/tests/auto/corelib/tools/qhash/tst_qhash.cpp
@@ -79,6 +79,8 @@ private slots:
     void iterators(); // sligthly modified from tst_QMap
     void keys_values_uniqueKeys(); // slightly modified from tst_QMap
     void noNeedlessRehashes();
+
+    void const_shared_null();
 };
 
 struct Foo {
@@ -1237,5 +1239,16 @@ void tst_QHash::noNeedlessRehashes()
     }
 }
 
+void tst_QHash::const_shared_null()
+{
+    QHash<int, QString> hash1;
+    hash1.setSharable(false);
+    QVERIFY(hash1.isDetached());
+
+    QHash<int, QString> hash2;
+    hash2.setSharable(true);
+    QVERIFY(!hash2.isDetached());
+}
+
 QTEST_APPLESS_MAIN(tst_QHash)
 #include "tst_qhash.moc"