X11: Check for XRandR extension before usage

It happens in practice that XRandR is enabled in the build but is not available
at runtime, particularly with X11 forwarding over SSH.  This properly queries
the extension first to avoid crashing in such situations.

1 files changed, 9 insertions, 6 deletions

diff --git a/src/x11.c b/src/x11.c
index 57dbea5..455ee20 100644
--- a/src/x11.c
+++ b/src/x11.c
@@ -366,12 +366,15 @@ puglRealize(PuglView* const view)
   }
 
 #ifdef HAVE_XRANDR
-  // Set refresh rate hint to the real refresh rate
-  XRRScreenConfiguration* conf         = XRRGetScreenInfo(display, parent);
-  short                   current_rate = XRRConfigCurrentRate(conf);
-
-  view->hints[PUGL_REFRESH_RATE] = current_rate;
-  XRRFreeScreenConfigInfo(conf);
+  int ignored = 0;
+  if (XRRQueryExtension(display, &ignored, &ignored)) {
+    // Set refresh rate hint to the real refresh rate
+    XRRScreenConfiguration* conf         = XRRGetScreenInfo(display, parent);
+    short                   current_rate = XRRConfigCurrentRate(conf);
+
+    view->hints[PUGL_REFRESH_RATE] = current_rate;
+    XRRFreeScreenConfigInfo(conf);
+  }
 #endif
 
   updateSizeHints(view);