From: Michael Catanzaro <mcatanzaro@redhat.com>
Date: Tue, 26 Sep 2023 23:47:01 +0000 (-0500)
Subject: printoperation: fix case where operation may complete multiple twice
X-Git-Tag: archive/raspbian/4.12.4+ds-3+rpi1^2~21^2~1^2~7
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=29a243e3d78f13e94e25517bf95323c3537a118c;p=gtk4.git

printoperation: fix case where operation may complete multiple twice

If we are the final backend, then after removing ourselves there is no
backend remaining. We will schedule the idle even if it has already been
scheduled. This idle is required to run exactly once and executing it
twices results in a double free that crashes loupe when printing. It
also causes the user callback to execute twice, which could cause
similar problems.

Fixes #6122
---

diff --git a/gtk/print/gtkprintoperation-unix.c b/gtk/print/gtkprintoperation-unix.c
index db4d878e33..7a6fb04254 100644
--- a/gtk/print/gtkprintoperation-unix.c
+++ b/gtk/print/gtkprintoperation-unix.c
@@ -1135,7 +1135,10 @@ printer_list_done_cb (GtkPrintBackend *backend,
   gtk_print_backend_destroy (backend);
   g_object_unref (backend);
 
-  if (finder->backends == NULL)
+  /* If there are no more backends left after removing ourselves from the list
+   * above, then we're finished.
+   */
+  if (finder->backends == NULL && !finder->found_printer)
     g_idle_add (find_printer_idle, finder);
 }