[gvfs] dnssd: Fix crashes when mount failed

[Ondrej Holy <oholy src gnome org>]

commit 8398c16b048ad39bd35ecadfed5c2e8f38770125
Author: Ondrej Holy <oholy redhat com>
Date:   Fri Jul 29 12:48:19 2016 +0200

    dnssd: Fix crashes when mount failed
    
    Mount operation might fail if you run multiple mount operations
    concurrently. Backend memory is released consequently. Unfortunatelly
    AvahiServiceResolvers are not freed and thus resolve_callback might
    be called after backend finalize, which causes segmentation faults.
    This patch fixes this and also some other memory leaks.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=631023

 daemon/gvfsbackenddnssd.c |   29 +++++++++++++++++------------
 1 files changed, 17 insertions(+), 12 deletions(-)
---
diff --git a/daemon/gvfsbackenddnssd.c b/daemon/gvfsbackenddnssd.c
index 51eac9b..31bf54c 100644
--- a/daemon/gvfsbackenddnssd.c
+++ b/daemon/gvfsbackenddnssd.c
@@ -131,6 +131,7 @@ struct _GVfsBackendDnsSd
   GList *files; /* list of LinkFiles */
 
   GList *browsers;
+  GList *resolvers;
 };
 
 typedef struct _GVfsBackendDnsSd GVfsBackendDnsSd;
@@ -566,19 +567,19 @@ resolve_callback (AvahiServiceResolver *r,
   char *path;
 
   if (event == AVAHI_RESOLVER_FAILURE)
-    return;
-  
+    goto out;
+
   /* Link-local ipv6 address, can't make a uri from this, ignore */
   if (address->proto == AVAHI_PROTO_INET6 &&
       address->data.ipv6.address[0] == 0xfe &&
       address->data.ipv6.address[1] == 0x80)
-    return;
-  
+    goto out;
+
   file = lookup_link_file_by_name_and_type (backend,
                                            name, type);
 
   if (file != NULL)
-    return;
+    goto out;
 
   file = link_file_new (name, type, domain, host_name, protocol,
                        address, port, txt);
@@ -591,6 +592,10 @@ resolve_callback (AvahiServiceResolver *r,
                            path,
                            NULL);
   g_free (path);
+
+ out:
+  backend->resolvers = g_list_remove (backend->resolvers, r);
+  avahi_service_resolver_free (r);
 }
 
 static void
@@ -617,18 +622,15 @@ browse_callback (AvahiServiceBrowser *b,
       
     case AVAHI_BROWSER_NEW:
       client = get_global_avahi_client ();
-      
-      /* We ignore the returned resolver object. In the callback
-        function we free it. If the server is terminated before
-        the callback function is called the server will free
-        the resolver for us. */
-      
+
       sr = avahi_service_resolver_new (client, interface, protocol,
                                       name, type, domain, AVAHI_PROTO_UNSPEC, 0, resolve_callback, backend);
 
       if (sr == NULL) 
        g_warning ("Failed to resolve service name '%s': %s\n", name, avahi_strerror (avahi_client_errno 
(client)));
-      
+      else
+       backend->resolvers = g_list_prepend (backend->resolvers, sr);
+
       break;
       
     case AVAHI_BROWSER_REMOVE:
@@ -799,6 +801,9 @@ g_vfs_backend_dns_sd_finalize (GObject *object)
 
   dnssd_backends = g_list_remove (dnssd_backends, backend);
 
+  remove_browsers (backend);
+  g_list_free_full (backend->resolvers, (GDestroyNotify)avahi_service_resolver_free);
+
   if (backend->mount_spec)
     g_mount_spec_unref (backend->mount_spec);