Bug 618902 - Crash when viewing/closing messages quickly

Closing an EMailBrowser window causes it to be disposed immediately,
but ongoing async operations still hold an EMailBrowser reference --
in particular, regenerating the internal message list and fetching a
mail message.  The callback functions for these operations were not
equipped to deal with the disposed-but-not-yet-finalized object.

3 files changed, 38 insertions, 23 deletions

diff --git a/mail/e-mail-browser.c b/mail/e-mail-browser.c
index cf5176faf2..cd7ecd32fd 100644
--- a/mail/e-mail-browser.c
+++ b/mail/e-mail-browser.c
@@ -445,7 +445,8 @@ mail_browser_dispose (GObject *object)
 	}
 
 	if (priv->message_list != NULL) {
-		g_object_unref (priv->message_list);
+		/* This will cancel a regen operation. */
+		gtk_widget_destroy (priv->message_list);
 		priv->message_list = NULL;
 	}
 
diff --git a/mail/e-mail-reader.c b/mail/e-mail-reader.c
index 53d45fd2e5..bb668bfdac 100644
--- a/mail/e-mail-reader.c
+++ b/mail/e-mail-reader.c
@@ -52,7 +52,8 @@
 #include "mail/message-list.h"
 
 #define E_MAIL_READER_GET_PRIVATE(obj) \
-	(mail_reader_get_private (G_OBJECT (obj)))
+	((EMailReaderPrivate *) g_object_get_qdata \
+	(G_OBJECT (obj), quark_private))
 
 typedef struct _EMailReaderPrivate EMailReaderPrivate;
 
@@ -92,31 +93,24 @@ static GQuark quark_private;
 static guint signals[LAST_SIGNAL];
 
 static void
-mail_reader_finalize (EMailReaderPrivate *priv)
+mail_reader_destroy (GObject *object)
 {
-	if (priv->message_selected_timeout_id > 0)
-		g_source_remove (priv->message_selected_timeout_id);
-
-	g_free (priv->mark_read_message_uid);
-
-	g_slice_free (EMailReaderPrivate, priv);
+	/* This will free the private struct. */
+	g_object_set_qdata (object, quark_private, NULL);
 }
 
-static EMailReaderPrivate *
-mail_reader_get_private (GObject *object)
+static void
+mail_reader_private_free (EMailReaderPrivate *priv)
 {
-	EMailReaderPrivate *priv;
+	if (priv->message_selected_timeout_id > 0)
+		g_source_remove (priv->message_selected_timeout_id);
 
-	priv = g_object_get_qdata (object, quark_private);
+	if (priv->retrieving_message_operation_id > 0)
+		mail_msg_cancel (priv->retrieving_message_operation_id);
 
-	if (G_UNLIKELY (priv == NULL)) {
-		priv = g_slice_new0 (EMailReaderPrivate);
-		g_object_set_qdata_full (
-			object, quark_private, priv,
-			(GDestroyNotify) mail_reader_finalize);
-	}
+	g_free (priv->mark_read_message_uid);
 
-	return priv;
+	g_slice_free (EMailReaderPrivate, priv);
 }
 
 static void
@@ -1830,6 +1824,14 @@ mail_reader_message_loaded_cb (CamelFolder *folder,
 
 	priv = E_MAIL_READER_GET_PRIVATE (reader);
 
+	/* If the private struct is NULL, the EMailReader was destroyed
+	 * while we were loading the message and we're likely holding the
+	 * last reference.  Nothing to do but drop the reference. */
+	if (priv == NULL) {
+		g_object_unref (reader);
+		return;
+	}
+
 	html_display = e_mail_reader_get_html_display (reader);
 	message_list = e_mail_reader_get_message_list (reader);
 
@@ -2551,7 +2553,7 @@ e_mail_reader_get_type (void)
 		type = g_type_register_static (
 			G_TYPE_INTERFACE, "EMailReader", &type_info, 0);
 
-		g_type_interface_add_prerequisite (type, G_TYPE_OBJECT);
+		g_type_interface_add_prerequisite (type, GTK_TYPE_OBJECT);
 	}
 
 	return type;
@@ -2726,6 +2728,19 @@ e_mail_reader_init (EMailReader *reader)
 	g_signal_connect_swapped (
 		message_list, "selection-change",
 		G_CALLBACK (e_mail_reader_changed), reader);
+
+	/* Install a private struct for storing things like flags and
+	 * timeout and asynchronous operation IDs.  We delete it when
+	 * the EMailReader is destroyed rather than finalized so that
+	 * asynchronous callbacks holding a reference can detect that
+	 * the reader has been destroyed and drop their reference. */
+	g_object_set_qdata_full (
+		G_OBJECT (reader), quark_private,
+		g_slice_new0 (EMailReaderPrivate),
+		(GDestroyNotify) mail_reader_private_free);
+	g_signal_connect (
+		reader, "destroy",
+		G_CALLBACK (mail_reader_destroy), NULL);
 }
 
 void
diff --git a/mail/message-list.c b/mail/message-list.c
index ed1236524c..c7361087b8 100644
--- a/mail/message-list.c
+++ b/mail/message-list.c
@@ -4900,7 +4900,7 @@ mail_regen_list (MessageList *ml, const gchar *search, const gchar *hideexpr, Ca
 #endif
 
 	m = mail_msg_new (&regen_list_info);
-	m->ml = ml;
+	m->ml = g_object_ref (ml);
 	m->search = g_strdup (search);
 	m->hideexpr = g_strdup (hideexpr);
 	m->changes = changes;
@@ -4908,7 +4908,6 @@ mail_regen_list (MessageList *ml, const gchar *search, const gchar *hideexpr, Ca
 	m->hidedel = ml->hidedeleted;
 	m->hidejunk = ml->hidejunk;
 	m->thread_subject = gconf_client_get_bool (gconf, "/apps/evolution/mail/display/thread_subject", NULL);
-	g_object_ref(ml);
 	m->folder = ml->folder;
 	camel_object_ref(m->folder);
 	m->last_row = -1;