Fix a crash in QFileDialog when selecting an invalid name filter.

When nameDetailsVisible is set to false and an invalid/empty
string is passed to selectNameFilter(), the regexp used to
strip the filter off the suffixes returns empty and a crash
occurs.

Change-Id: I926ea49514ff25a103977d8121fca1cf83d647f5
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
(cherry picked from qtbase/d0aa81ee104107db1ce41a9bf0f91d4cb144f7de)

2 files changed, 54 insertions, 7 deletions

diff --git a/src/gui/dialogs/qfiledialog.cpp b/src/gui/dialogs/qfiledialog.cpp
index e7b6b22..2dd342a 100644
--- a/src/gui/dialogs/qfiledialog.cpp
+++ b/src/gui/dialogs/qfiledialog.cpp
@@ -1184,9 +1184,11 @@ void QFileDialog::selectNameFilter(const QString &filter)
         d->selectNameFilter_sys(filter);
         return;
     }
-    int i;
+    int i = -1;
     if (testOption(HideNameFilterDetails)) {
-        i = d->qFileDialogUi->fileTypeCombo->findText(qt_strip_filters(qt_make_filter_list(filter)).first());
+        const QStringList filters = qt_strip_filters(qt_make_filter_list(filter));
+        if (!filters.isEmpty())
+            i = d->qFileDialogUi->fileTypeCombo->findText(filters.first());
     } else {
         i = d->qFileDialogUi->fileTypeCombo->findText(filter);
     }
@@ -1793,7 +1795,7 @@ QString QFileDialog::getOpenFileName(QWidget *parent,
 
     // create a qt dialog
     QFileDialog dialog(args);
-    if (selectedFilter)
+    if (selectedFilter && !selectedFilter->isEmpty())
         dialog.selectNameFilter(*selectedFilter);
     if (dialog.exec() == QDialog::Accepted) {
         if (selectedFilter)
@@ -1886,7 +1888,7 @@ QStringList QFileDialog::getOpenFileNames(QWidget *parent,
 
     // create a qt dialog
     QFileDialog dialog(args);
-    if (selectedFilter)
+    if (selectedFilter && !selectedFilter->isEmpty())
         dialog.selectNameFilter(*selectedFilter);
     if (dialog.exec() == QDialog::Accepted) {
         if (selectedFilter)
@@ -1981,7 +1983,7 @@ QString QFileDialog::getSaveFileName(QWidget *parent,
     // create a qt dialog
     QFileDialog dialog(args);
     dialog.setAcceptMode(AcceptSave);
-    if (selectedFilter)
+    if (selectedFilter && !selectedFilter->isEmpty())
         dialog.selectNameFilter(*selectedFilter);
     if (dialog.exec() == QDialog::Accepted) {
         if (selectedFilter)
diff --git a/tests/auto/qfiledialog/tst_qfiledialog.cpp b/tests/auto/qfiledialog/tst_qfiledialog.cpp
index 8e69b3c..795caf6 100644
--- a/tests/auto/qfiledialog/tst_qfiledialog.cpp
+++ b/tests/auto/qfiledialog/tst_qfiledialog.cpp
@@ -138,7 +138,9 @@ private slots:
     void selectFilter();
     void viewMode();
     void proxymodel();
+    void setNameFilter_data();
     void setNameFilter();
+    void setEmptyNameFilter();
     void focus();
     void caption();
     void historyBack();
@@ -1019,11 +1021,54 @@ void tst_QFiledialog::proxymodel()
     QCOMPARE(fd.proxyModel(), (QAbstractProxyModel*)0);
 }
 
+void tst_QFiledialog::setEmptyNameFilter()
+{
+    QNonNativeFileDialog fd;
+    fd.setNameFilter(QString());
+    fd.setNameFilters(QStringList());
+}
+
+void tst_QFiledialog::setNameFilter_data()
+{
+    QTest::addColumn<bool>("nameFilterDetailsVisible");
+    QTest::addColumn<QStringList>("filters");
+    QTest::addColumn<QString>("selectFilter");
+    QTest::addColumn<QString>("expectedSelectedFilter");
+
+    QTest::newRow("namedetailsvisible-empty") << true << QStringList() << QString() << QString();
+    QTest::newRow("namedetailsinvisible-empty") << false << QStringList() << QString() << QString();
+
+    const QString anyFileNoDetails = QLatin1String("Any files");
+    const QString anyFile = anyFileNoDetails + QLatin1String(" (*)");
+    const QString imageFilesNoDetails = QLatin1String("Image files");
+    const QString imageFiles = imageFilesNoDetails + QLatin1String(" (*.png *.xpm *.jpg)");
+    const QString textFileNoDetails = QLatin1String("Text files");
+    const QString textFile = textFileNoDetails + QLatin1String(" (*.txt)");
+
+    QStringList filters;
+    filters << anyFile << imageFiles << textFile;
+
+    QTest::newRow("namedetailsvisible-images") << true << filters << imageFiles << imageFiles;
+    QTest::newRow("namedetailsinvisible-images") << false << filters << imageFiles << imageFilesNoDetails;
+
+    const QString invalid = "foo";
+    QTest::newRow("namedetailsvisible-invalid") << true << filters << invalid << anyFile;
+    // Potential crash when trying to convert the invalid filter into a list and stripping it, resulting in an empty list.
+    QTest::newRow("namedetailsinvisible-invalid") << false << filters << invalid << anyFileNoDetails;
+}
+
 void tst_QFiledialog::setNameFilter()
 {
+    QFETCH(bool, nameFilterDetailsVisible);
+    QFETCH(QStringList, filters);
+    QFETCH(QString, selectFilter);
+    QFETCH(QString, expectedSelectedFilter);
+
     QNonNativeFileDialog fd;
-    fd.setFilter(QString());
-    fd.setFilters(QStringList());
+    fd.setNameFilters(filters);
+    fd.setNameFilterDetailsVisible(nameFilterDetailsVisible);
+    fd.selectNameFilter(selectFilter);
+    QCOMPARE(fd.selectedNameFilter(), expectedSelectedFilter);
 }
 
 void tst_QFiledialog::focus()