Client: Don't crash with long window titles using UTF-16 characters

Previously, we set the max length in QString character length, which means
UTF-16 characters (of potentially three bytes) counts as one character. The max
limit of libwayland, however, is in bytes (and the string itself is converted
to UTF-8).

Fix it by dividing the character limit by three because in the worst case each
UTF-16 character will use three bytes when UTF-8 encoded.

Fixes: QTBUG-78478
Change-Id: Idf4721894e0fe6f3cd92bdc6ada7b0ea4199ea63
(cherry picked from commit 1ed0782e93dafb0a3d5ef3a02c9c3999825817ee)
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/auto/client/client/tst_client.cpp b/tests/auto/client/client/tst_client.cpp
index 470db25a4..82ec30510 100644
--- a/tests/auto/client/client/tst_client.cpp
+++ b/tests/auto/client/client/tst_client.cpp
@@ -183,6 +183,7 @@ private slots:
     void hiddenPopupParent();
     void glWindow();
     void longWindowTitle();
+    void longWindowTitleWithUtf16Characters();
 
 private:
     MockCompositor *compositor = nullptr;
@@ -610,6 +611,16 @@ void tst_WaylandClient::longWindowTitle()
     QTRY_VERIFY(compositor->surface());
 }
 
+void tst_WaylandClient::longWindowTitleWithUtf16Characters()
+{
+    QWindow window;
+    QString absurdlyLongTitle = QString("三").repeated(10000);
+    Q_ASSERT(absurdlyLongTitle.length() == 10000); // just making sure the test isn't broken
+    window.setTitle(absurdlyLongTitle);
+    window.show();
+    QTRY_VERIFY(compositor->surface());
+}
+
 int main(int argc, char **argv)
 {
     setenv("XDG_RUNTIME_DIR", ".", 1);