cairo-util: Clean up more Cairo detritus; almost all of it

Pango, Cairo, and fontconfig, all want to leave thread-global data
hanging around in order to maintain a cache. Try to clean up as much of
it as we possibly can on exit, apart from the Pango language string
which appears to be unfreeable, so has been added to LSan suppressions.

Signed-off-by: Daniel Stone <daniels@collabora.com>

.gitlab-ci/leak-sanitizer.supp

@@ -3,3 +3,6 @@
 # Cairo internal leaks from weston-keyboard
 leak:cairo_select_font_face
 leak:cairo_text_extents
+
+# Pango thread-global state (not destroyable?)
+leak:pango_language_get_default

clients/window.c

@@ -6063,6 +6063,7 @@ display_destroy(struct display *display)
 		theme_destroy(display->theme);
 	destroy_cursors(display);
 
+	cleanup_after_cairo();
 
 	if (display->relative_pointer_manager)
 		zwp_relative_pointer_manager_v1_destroy(display->relative_pointer_manager);

shared/cairo-util.c

@@ -40,6 +40,7 @@
 #include <libweston/config-parser.h>
 
 #ifdef HAVE_PANGO
+#include <fontconfig/fontconfig.h>
 #include <pango/pangocairo.h>
 #endif
 
@@ -681,3 +682,17 @@ theme_get_location(struct theme *t, int x, int y,
 
 	return location;
 }
+
+/** Cleanup static Cairo/Pango data
+ *
+ * Using Cairo, Pango, PangoCairo, and fontconfig, ends up leaving a trail of
+ * thread-cached data behind us. Clean up what we can.
+ */
+void
+cleanup_after_cairo(void)
+{
+	cairo_debug_reset_static_data();
+#ifdef HAVE_PANGO
+	FcFini();
+#endif
+}

shared/cairo-util.h

@@ -234,4 +234,7 @@ frame_double_touch_up(struct frame *frame, void *data, int32_t id);
 void
 frame_repaint(struct frame *frame, cairo_t *cr);
 
+void
+cleanup_after_cairo(void);
+
 #endif

shared/meson.build

@@ -57,10 +57,11 @@ deps_cairo_shared = [
 
 dep_pango = dependency('pango', required: false)
 dep_pangocairo = dependency('pangocairo', required: false)
+dep_fontconfig = dependency('fontconfig', required: false)
 dep_glib = dependency('glib-2.0', version: '>= 2.36', required: false)
 
-if dep_pango.found() and dep_pangocairo.found() and dep_glib.found()
-	deps_cairo_shared += [ dep_pango, dep_pangocairo, dep_glib ]
+if dep_pango.found() and dep_pangocairo.found() and dep_fontconfig.found() and dep_glib.found()
+	deps_cairo_shared += [ dep_pango, dep_pangocairo, dep_fontconfig, dep_glib ]
 	config_h.set('HAVE_PANGO', '1')
 endif