fixed issue where pop_alerts() could return old, invalid alerts

ChangeLog

@@ -1,3 +1,4 @@
+	* fixed issue where pop_alerts() could return old, invalid alerts
 	* fix issue when receiving have-all message before the metadata
 	* don't leave lingering part files handles open
 	* disallow calling add_piece() during checking

src/alert_manager.cpp

@@ -106,7 +106,11 @@ namespace libtorrent {
 	{
 		std::lock_guard<std::recursive_mutex> lock(m_mutex);
 
-		if (m_alerts[m_generation].empty()) return;
+		if (m_alerts[m_generation].empty())
+		{
+			alerts.clear();
+			return;
+		}
 
 		if (m_dropped.any()) {
 			emplace_alert<alerts_dropped_alert>(m_dropped);

test/test_alert_manager.cpp

@@ -281,6 +281,16 @@ TORRENT_TEST(alert_mask)
 	TEST_CHECK(!mgr.should_post<torrent_paused_alert>());
 }
 
+TORRENT_TEST(get_all_empty)
+{
+	alert_manager mgr(100, alert_category::all);
+	std::vector<alert*> alerts(10);
+
+	mgr.get_all(alerts);
+
+	TEST_CHECK(alerts.empty());
+}
+
 TORRENT_TEST(dropped_alerts)
 {
 	alert_manager mgr(1, alert_category::all);

test/test_session.cpp

@@ -424,6 +424,22 @@ TORRENT_TEST(save_state_peer_id)
 	TEST_EQUAL(ses.get_settings().get_str(settings_pack::peer_fingerprint), "foobar");
 }
 
+TORRENT_TEST(pop_alert_clear)
+{
+	session s;
+
+	// make sure the vector is cleared if there are no alerts to be popped
+	std::vector<alert*> alerts(100);
+
+	for (int i = 0; i < 10; ++i)
+	{
+		alerts.resize(100);
+		s.pop_alerts(&alerts);
+		if (alerts.empty()) break;
+	}
+	TEST_CHECK(alerts.empty());
+}
+
 #if !defined TORRENT_DISABLE_LOGGING
 
 #if !defined TORRENT_DISABLE_DHT