From cca2f8fa0eee370e1b75de198dc755c9a4a23bf2 Mon Sep 17 00:00:00 2001
From: Niels Provos <provos@gmail.com>
Date: Fri, 25 Jul 2008 01:29:54 +0000
Subject: [PATCH] make event_add not change any state if it fails; repoted by
 Ian Bell

svn:r923
---
 ChangeLog |  1 +
 event.c   | 37 ++++++++++++++++++++++++++-----------
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e9b61f48..2038a761 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -120,6 +120,7 @@ Changes in current version:
  o Support multiple events listening on the same signal; make signals regular events that go on the same event queue; problem report by Alexander Drozdov.
  o Fix a problem with epoll() and reinit; problem report by Alexander Drozdov.	
  o Fix off-by-one errors in devpoll; from Ian Bell
+ o Make event_add not change any state if it fails; reported by Ian Bell.
 	
 Changes in 1.4.0:
  o allow \r or \n individually to separate HTTP headers instead of the standard "\r\n"; from Charles Kerr.
diff --git a/event.c b/event.c
index e7ed5236..77d2f1de 100644
--- a/event.c
+++ b/event.c
@@ -1027,14 +1027,36 @@ event_add_internal(struct event *ev, const struct timeval *tv)
 
 	assert(!(ev->ev_flags & ~EVLIST_ALL));
 
-	if (tv != NULL) {
+	/*
+	 * prepare for timeout insertion further below, if we get a
+	 * failure on any step, we should not change any state.
+	 */
+	if (tv != NULL && !(ev->ev_flags & EVLIST_TIMEOUT)) {
+		if (min_heap_reserve(&base->timeheap,
+			1 + min_heap_size(&base->timeheap)) == -1)
+			return (-1);  /* ENOMEM == errno */
+	}
+
+	if ((ev->ev_events & (EV_READ|EV_WRITE|EV_SIGNAL)) &&
+	    !(ev->ev_flags & (EVLIST_INSERTED|EVLIST_ACTIVE))) {
+		res = evsel->add(evbase, ev);
+		if (res != -1)
+			event_queue_insert(base, ev, EVLIST_INSERTED);
+	}
+
+	/* 
+	 * we should change the timout state only if the previous event
+	 * addition succeeded.
+	 */
+	if (res != -1 && tv != NULL) {
 		struct timeval now;
 
+		/* 
+		 * we already reserved memory above for the case where we
+		 * are not replacing an exisiting timeout.
+		 */
 		if (ev->ev_flags & EVLIST_TIMEOUT)
 			event_queue_remove(base, ev, EVLIST_TIMEOUT);
-		else if (min_heap_reserve(&base->timeheap,
-			1 + min_heap_size(&base->timeheap)) == -1)
-				return (-1);  /* ENOMEM == errno */
 			    
 		/* Check if it is active due to a timeout.  Rescheduling
 		 * this timeout before the callback can be executed
@@ -1064,13 +1086,6 @@ event_add_internal(struct event *ev, const struct timeval *tv)
 		event_queue_insert(base, ev, EVLIST_TIMEOUT);
 	}
 
-	if ((ev->ev_events & (EV_READ|EV_WRITE|EV_SIGNAL)) &&
-	    !(ev->ev_flags & (EVLIST_INSERTED|EVLIST_ACTIVE))) {
-		res = evsel->add(evbase, ev);
-		if (res != -1)
-			event_queue_insert(base, ev, EVLIST_INSERTED);
-	}
-
 	/* if we are not in the right thread, we need to wake up the loop */
 	if (res != -1 && !EVTHREAD_IN_THREAD(base))
 		send(base->th_notify_fd[1], "", 1, 0);