xcb: Check the check for errors in boilerplate

We have to make sure we received all errors that the X server sent out before we
can be sure there are none. To do so, we just have to send some request and wait
for its reply, because that guarantees that the replies/errors to all previous
requests were received.

_cairo_boilerplate_xcb_synchronize doesn't need this, because the GetImage
request already makes sure we received everything.

Signed-off-by: Uli Schlachter <psychon@znc.in>

1 files changed, 13 insertions, 0 deletions

diff --git a/boilerplate/cairo-boilerplate-xcb.c b/boilerplate/cairo-boilerplate-xcb.c
index 67c8163c0..e45a2dc18 100644
--- a/boilerplate/cairo-boilerplate-xcb.c
+++ b/boilerplate/cairo-boilerplate-xcb.c
@@ -79,6 +79,13 @@ _cairo_boilerplate_xcb_handle_errors (xcb_target_closure_t *xtc)
 }
 
 static void
+_cairo_boilerplate_xcb_sync_server (xcb_target_closure_t *xtc)
+{
+    free (xcb_get_input_focus_reply (xtc->c,
+				     xcb_get_input_focus (xtc->c), NULL));
+}
+
+static void
 _cairo_boilerplate_xcb_cleanup (void *closure)
 {
     xcb_target_closure_t *xtc = closure;
@@ -93,6 +100,9 @@ _cairo_boilerplate_xcb_cleanup (void *closure)
     cairo_device_finish (xtc->device);
     cairo_device_destroy (xtc->device);
 
+    /* First synchronize with the X server to make sure there are no more errors
+     * in-flight which we would miss otherwise */
+    _cairo_boilerplate_xcb_sync_server (xtc);
     status = _cairo_boilerplate_xcb_handle_errors (xtc);
     assert (status == CAIRO_STATUS_SUCCESS);
 
@@ -637,6 +647,9 @@ _cairo_boilerplate_xcb_finish_surface (cairo_surface_t *surface)
     if (cairo_surface_status (surface))
 	return cairo_surface_status (surface);
 
+    /* First synchronize with the X server to make sure there are no more errors
+     * in-flight which we would miss otherwise */
+    _cairo_boilerplate_xcb_sync_server (xtc);
     status = _cairo_boilerplate_xcb_handle_errors (xtc);
     if (status)
 	return status;