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gtkprintbackendcups: Fix a crash in avahi_create_browsers()

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In avahi_request_printer_list() a new connection to the DBus system bus
is started asynchronously, but it's not cancellable and it's not taking
any reference of the GtkPrintBackendCups. This means that when the
callback is called, the object might have been destroyed already. We can
just pass the cancellable created and check for the cancelled error in
the callback before trying to use the GtkPrintBackendCups. The code to
cancel avahi operations and to unsibscribe from the DBus signals has
been moved from finalize to dispose to make sure it happens as soon as
possible.

https://bugzilla.gnome.org/show_bug.cgi?id=696553
This commit is contained in:
Carlos Garcia Campos 2013-03-25 13:01:23 +01:00 committed by Carlos Garcia Campos
parent b29cd63c38
commit 5701681df4
1 changed files with 51 additions and 39 deletions
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90
modules/printbackends/cups/gtkprintbackendcups.c
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@ -787,9 +787,6 @@ static void
gtk_print_backend_cups_finalize (GObject *object)
{
GtkPrintBackendCups *backend_cups;
#ifdef HAVE_CUPS_API_1_6
gint i;
#endif
GTK_NOTE (PRINTING,
g_print ("CUPS Backend: finalizing CUPS backend module\n"));
@ -813,6 +810,37 @@ gtk_print_backend_cups_finalize (GObject *object)
g_object_unref (backend_cups->colord_client);
#endif
#ifdef HAVE_CUPS_API_1_6
g_clear_object (&backend_cups->avahi_cancellable);
g_clear_pointer (&backend_cups->avahi_default_printer, g_free);
g_clear_object (&backend_cups->dbus_connection);
#endif
backend_parent_class->finalize (object);
}
static void
gtk_print_backend_cups_dispose (GObject *object)
{
GtkPrintBackendCups *backend_cups;
#ifdef HAVE_CUPS_API_1_6
gint i;
#endif
GTK_NOTE (PRINTING,
g_print ("CUPS Backend: %s\n", G_STRFUNC));
backend_cups = GTK_PRINT_BACKEND_CUPS (object);
if (backend_cups->list_printers_poll > 0)
g_source_remove (backend_cups->list_printers_poll);
backend_cups->list_printers_poll = 0;
backend_cups->list_printers_attempts = 0;
if (backend_cups->default_printer_poll > 0)
g_source_remove (backend_cups->default_printer_poll);
backend_cups->default_printer_poll = 0;
#ifdef HAVE_CUPS_API_1_6
g_cancellable_cancel (backend_cups->avahi_cancellable);
@ -849,34 +877,8 @@ gtk_print_backend_cups_finalize (GObject *object)
backend_cups->avahi_service_browser_subscription_id);
backend_cups->avahi_service_browser_subscription_id = 0;
}
g_clear_object (&backend_cups->avahi_cancellable);
g_clear_pointer (&backend_cups->avahi_default_printer, g_free);
g_clear_object (&backend_cups->dbus_connection);
#endif
backend_parent_class->finalize (object);
}
static void
gtk_print_backend_cups_dispose (GObject *object)
{
GtkPrintBackendCups *backend_cups;
GTK_NOTE (PRINTING,
g_print ("CUPS Backend: %s\n", G_STRFUNC));
backend_cups = GTK_PRINT_BACKEND_CUPS (object);
if (backend_cups->list_printers_poll > 0)
g_source_remove (backend_cups->list_printers_poll);
backend_cups->list_printers_poll = 0;
backend_cups->list_printers_attempts = 0;
if (backend_cups->default_printer_poll > 0)
g_source_remove (backend_cups->default_printer_poll);
backend_cups->default_printer_poll = 0;
backend_parent_class->dispose (object);
}
@ -2609,7 +2611,7 @@ avahi_service_resolver_cb (GObject *source_object,
gpointer user_data)
{
AvahiConnectionTestData *data;
GtkPrintBackendCups *backend = GTK_PRINT_BACKEND_CUPS (user_data);
GtkPrintBackendCups *backend;
const gchar *name;
const gchar *host;
const gchar *type;
@ -2634,6 +2636,8 @@ avahi_service_resolver_cb (GObject *source_object,
&error);
if (output)
{
backend = GTK_PRINT_BACKEND_CUPS (user_data);
g_variant_get (output, "(ii&s&s&s&si&sq@aayu)",
&interface,
&protocol,
@ -2702,7 +2706,8 @@ avahi_service_resolver_cb (GObject *source_object,
}
else
{
g_warning ("%s", error->message);
if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
g_warning ("%s", error->message);
g_error_free (error);
}
}
@ -2805,7 +2810,7 @@ avahi_service_browser_new_cb (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GtkPrintBackendCups *cups_backend = GTK_PRINT_BACKEND_CUPS (user_data);
GtkPrintBackendCups *cups_backend;
GVariant *output;
GError *error = NULL;
gint i;
@ -2815,6 +2820,7 @@ avahi_service_browser_new_cb (GObject *source_object,
&error);
if (output)
{
cups_backend = GTK_PRINT_BACKEND_CUPS (user_data);
i = cups_backend->avahi_service_browser_paths[0] ? 1 : 0;
g_variant_get (output, "(o)", &cups_backend->avahi_service_browser_paths[i]);
@ -2853,8 +2859,8 @@ avahi_service_browser_new_cb (GObject *source_object,
* The creation of ServiceBrowser fails with G_IO_ERROR_DBUS_ERROR
* if Avahi is disabled.
*/
if (error->domain != G_IO_ERROR ||
error->code != G_IO_ERROR_DBUS_ERROR)
if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_DBUS_ERROR) &&
!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
g_warning ("%s", error->message);
g_error_free (error);
}
@ -2865,17 +2871,23 @@ avahi_create_browsers (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GtkPrintBackendCups *cups_backend = GTK_PRINT_BACKEND_CUPS (user_data);
GDBusConnection *dbus_connection;
GtkPrintBackendCups *cups_backend;
GError *error = NULL;
cups_backend->dbus_connection = g_bus_get_finish (res, &error);
if (!cups_backend->dbus_connection)
dbus_connection = g_bus_get_finish (res, &error);
if (!dbus_connection)
{
g_debug ("Couldn't connect to D-Bus system bus, %s", error->message);
if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
g_warning ("Couldn't connect to D-Bus system bus, %s", error->message);
g_error_free (error);
return;
}
cups_backend = GTK_PRINT_BACKEND_CUPS (user_data);
cups_backend->dbus_connection = dbus_connection;
/*
* We need to subscribe to signals of service browser before
* we actually create it because it starts to emit them right
@ -2937,7 +2949,7 @@ static void
avahi_request_printer_list (GtkPrintBackendCups *cups_backend)
{
cups_backend->avahi_cancellable = g_cancellable_new ();
g_bus_get (G_BUS_TYPE_SYSTEM, NULL, avahi_create_browsers, cups_backend);
g_bus_get (G_BUS_TYPE_SYSTEM, cups_backend->avahi_cancellable, avahi_create_browsers, cups_backend);
}
#endif