util: keep track of full GSource object not source ID number

The source ID number is an alternative way to identify a source that has
been added to a GMainContext. Internally when a source ID is given, glib
will lookup the corresponding GSource and use that. The use of a source
ID is racy in some cases though, because it is invalid to continue to
use an ID number after the GSource has been removed. It is thus safer
to use the GSource object directly and have full control over the ref
counting and thus cleanup.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/rpc/virnetclient.c

@@ -826,6 +826,7 @@ virNetClientIOEventTLS(int fd,
 static gboolean
 virNetClientTLSHandshake(virNetClientPtr client)
 {
+    g_autoptr(GSource) source = NULL;
     GIOCondition ev;
     int ret;
 
@@ -840,10 +841,10 @@ virNetClientTLSHandshake(virNetClientPtr client)
     else
         ev = G_IO_OUT;
 
-    virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
-                               ev,
-                               client->eventCtx,
-                               virNetClientIOEventTLS, client, NULL);
+    source = virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
+                                        ev,
+                                        client->eventCtx,
+                                        virNetClientIOEventTLS, client, NULL);
 
     return TRUE;
 }
@@ -882,6 +883,7 @@ int virNetClientSetTLSSession(virNetClientPtr client,
     int ret;
     char buf[1];
     int len;
+    g_autoptr(GSource) source = NULL;
 
 #ifndef WIN32
     sigset_t oldmask, blockedsigs;
@@ -934,10 +936,10 @@ int virNetClientSetTLSSession(virNetClientPtr client,
      * etc.  If we make the grade, it will send us a '\1' byte.
      */
 
-    virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
-                               G_IO_IN,
-                               client->eventCtx,
-                               virNetClientIOEventTLSConfirm, client, NULL);
+    source = virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
+                                        G_IO_IN,
+                                        client->eventCtx,
+                                        virNetClientIOEventTLSConfirm, client, NULL);
 
 #ifndef WIN32
     /* Block SIGWINCH from interrupting poll in curses programs */
@@ -1617,6 +1619,7 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
 #endif /* !WIN32 */
         int timeout = -1;
         virNetMessagePtr msg = NULL;
+        g_autoptr(GSource) source = NULL;
         GIOCondition ev = 0;
         struct virNetClientIOEventData data = {
             .client = client,
@@ -1651,10 +1654,10 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
         if (client->nstreams)
             ev |= G_IO_IN;
 
-        virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
-                                   ev,
-                                   client->eventCtx,
-                                   virNetClientIOEventFD, &data, NULL);
+        source = virEventGLibAddSocketWatch(virNetSocketGetFD(client->sock),
+                                            ev,
+                                            client->eventCtx,
+                                            virNetClientIOEventFD, &data, NULL);
 
         /* Release lock while poll'ing so other threads
          * can stuff themselves on the queue */

src/util/vireventglib.c

@@ -45,7 +45,7 @@ struct virEventGLibHandle
     int fd;
     int events;
     int removed;
-    guint source;
+    GSource *source;
     virEventHandleCallback cb;
     void *opaque;
     virFreeCallback ff;
@@ -56,7 +56,7 @@ struct virEventGLibTimeout
     int timer;
     int interval;
     int removed;
-    guint source;
+    GSource *source;
     virEventTimeoutCallback cb;
     void *opaque;
     virFreeCallback ff;
@@ -210,23 +210,25 @@ virEventGLibHandleUpdate(int watch,
         if (events == data->events)
             goto cleanup;
 
-        if (data->source != 0) {
-            VIR_DEBUG("Removed old handle watch=%d", data->source);
-            g_source_remove(data->source);
+        if (data->source != NULL) {
+            VIR_DEBUG("Removed old handle source=%p", data->source);
+            g_source_destroy(data->source);
+            g_source_unref(data->source);
         }
 
         data->source = virEventGLibAddSocketWatch(
             data->fd, cond, NULL, virEventGLibHandleDispatch, data, NULL);
 
         data->events = events;
-        VIR_DEBUG("Added new handle watch=%d", data->source);
+        VIR_DEBUG("Added new handle source=%p", data->source);
     } else {
-        if (data->source == 0)
+        if (data->source == NULL)
             goto cleanup;
 
-        VIR_DEBUG("Removed old handle watch=%d", data->source);
-        g_source_remove(data->source);
-        data->source = 0;
+        VIR_DEBUG("Removed old handle source=%p", data->source);
+        g_source_destroy(data->source);
+        g_source_unref(data->source);
+        data->source = NULL;
         data->events = 0;
     }
 
@@ -272,9 +274,10 @@ virEventGLibHandleRemove(int watch)
     VIR_DEBUG("Remove handle data=%p watch=%d fd=%d",
               data, watch, data->fd);
 
-    if (data->source != 0) {
-        g_source_remove(data->source);
-        data->source = 0;
+    if (data->source != NULL) {
+        g_source_destroy(data->source);
+        g_source_unref(data->source);
+        data->source = NULL;
         data->events = 0;
     }
 
@@ -309,6 +312,22 @@ virEventGLibTimeoutDispatch(void *opaque)
     return TRUE;
 }
 
+
+static GSource *
+virEventGLibTimeoutCreate(int interval,
+                          struct virEventGLibTimeout *data)
+{
+    GSource *source = g_timeout_source_new(interval);
+
+    g_source_set_callback(source,
+                          virEventGLibTimeoutDispatch,
+                          data, NULL);
+    g_source_attach(source, NULL);
+
+    return source;
+}
+
+
 static int
 virEventGLibTimeoutAdd(int interval,
                        virEventTimeoutCallback cb,
@@ -327,9 +346,7 @@ virEventGLibTimeoutAdd(int interval,
     data->opaque = opaque;
     data->ff = ff;
     if (interval >= 0)
-        data->source = g_timeout_add(interval,
-                                     virEventGLibTimeoutDispatch,
-                                     data);
+        data->source = virEventGLibTimeoutCreate(interval, data);
 
     g_ptr_array_add(timeouts, data);
 
@@ -390,19 +407,20 @@ virEventGLibTimeoutUpdate(int timer,
     VIR_DEBUG("Update timeout data=%p timer=%d interval=%d ms", data, timer, interval);
 
     if (interval >= 0) {
-        if (data->source != 0)
-            g_source_remove(data->source);
+        if (data->source != NULL) {
+            g_source_destroy(data->source);
+            g_source_unref(data->source);
+        }
 
         data->interval = interval;
-        data->source = g_timeout_add(data->interval,
-                                     virEventGLibTimeoutDispatch,
-                                     data);
+        data->source = virEventGLibTimeoutCreate(interval, data);
     } else {
-        if (data->source == 0)
+        if (data->source == NULL)
             goto cleanup;
 
-        g_source_remove(data->source);
-        data->source = 0;
+        g_source_destroy(data->source);
+        g_source_unref(data->source);
+        data->source = NULL;
     }
 
  cleanup:
@@ -448,9 +466,10 @@ virEventGLibTimeoutRemove(int timer)
     VIR_DEBUG("Remove timeout data=%p timer=%d",
               data, timer);
 
-    if (data->source != 0) {
-        g_source_remove(data->source);
-        data->source = 0;
+    if (data->source != NULL) {
+        g_source_destroy(data->source);
+        g_source_unref(data->source);
+        data->source = NULL;
     }
 
     /* since the actual timeout deletion is done asynchronously, a timeoutUpdate call may

src/util/vireventglibwatch.c

@@ -233,17 +233,20 @@ GSource *virEventGLibCreateSocketWatch(int fd,
 #endif /* WIN32 */
 
 
-guint virEventGLibAddSocketWatch(int fd,
-                                 GIOCondition condition,
-                                 GMainContext *context,
-                                 virEventGLibSocketFunc func,
-                                 gpointer opaque,
-                                 GDestroyNotify notify)
+GSource *
+virEventGLibAddSocketWatch(int fd,
+                           GIOCondition condition,
+                           GMainContext *context,
+                           virEventGLibSocketFunc func,
+                           gpointer opaque,
+                           GDestroyNotify notify)
 {
-    g_autoptr(GSource) source = NULL;
+    GSource *source = NULL;
 
     source = virEventGLibCreateSocketWatch(fd, condition);
     g_source_set_callback(source, (GSourceFunc)func, opaque, notify);
 
-    return g_source_attach(source, context);
+    g_source_attach(source, context);
+
+    return source;
 }

src/util/vireventglibwatch.h

@@ -40,9 +40,10 @@ typedef gboolean (*virEventGLibSocketFunc)(int fd,
                                            GIOCondition condition,
                                            gpointer data);
 
-guint virEventGLibAddSocketWatch(int fd,
-                                 GIOCondition condition,
-                                 GMainContext *context,
-                                 virEventGLibSocketFunc func,
-                                 gpointer opaque,
-                                 GDestroyNotify notify);
+GSource *virEventGLibAddSocketWatch(int fd,
+                                    GIOCondition condition,
+                                    GMainContext *context,
+                                    virEventGLibSocketFunc func,
+                                    gpointer opaque,
+                                    GDestroyNotify notify)
+    G_GNUC_WARN_UNUSED_RESULT;