Don't ask libwayland to set absurdly long window titles

It will cause libwayland to terminate the application.

Task-number: QTBUG-68715
Change-Id: I1d1830453da224bec8bf4c5d6ab087c0e05328a8
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index fdfd66688..5d658f675 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -287,7 +287,18 @@ void QWaylandWindow::setWindowTitle(const QString &title)
 {
     if (mShellSurface) {
         const QString separator = QString::fromUtf8(" \xe2\x80\x94 "); // unicode character U+2014, EM DASH
-        mShellSurface->setTitle(formatWindowTitle(title, separator));
+        const QString formatted = formatWindowTitle(title, separator);
+
+        const int libwaylandMaxBufferSize = 4096;
+        // Some parts of the buffer is used for metadata, so subtract 100 to be on the safe side
+        const int maxLength = libwaylandMaxBufferSize - 100;
+
+        auto truncated = QStringRef(&formatted).left(maxLength);
+        if (truncated.length() < formatted.length()) {
+            qCWarning(lcQpaWayland) << "Window titles longer than" << maxLength << "characters are not supported."
+                                    << "Truncating window title (from" << formatted.length() << "chars)";
+        }
+        mShellSurface->setTitle(truncated.toString());
     }
 
     if (mWindowDecoration && window()->isVisible())