From 88eacb2e27ab6e7486ce79fb9048a2a59a51f9bd Mon Sep 17 00:00:00 2001
From: Mark Michelson <mmichelson@digium.com>
Date: Wed, 2 Apr 2008 17:37:52 +0000
Subject: [PATCH] Merged revisions 112469 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/trunk

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r112469 | mmichelson | 2008-04-02 12:36:49 -0500 (Wed, 02 Apr 2008) | 21 lines

Merged revisions 112468 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.4

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r112468 | mmichelson | 2008-04-02 12:36:04 -0500 (Wed, 02 Apr 2008) | 13 lines

Fix a race condition in the manager. It is possible that a new manager event
could be appended during a brief time when the manager is not waiting for input.
If an event comes during this period, we need to set an indicator that there is an
event pending so that the manager doesn't attempt to wait forever for an event that
already happened.

(closes issue #12354)
Reported by: bamby
Patches:
      manager_race_condition.diff uploaded by bamby (license 430)
	  (comments added by me)


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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.0@112470 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 main/manager.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/main/manager.c b/main/manager.c
index 4ef298ddb0..5be4cec1cf 100644
--- a/main/manager.c
+++ b/main/manager.c
@@ -167,6 +167,7 @@ struct mansession {
 	int send_events;	/*!<  XXX what ? */
 	struct eventqent *last_ev;	/*!< last event processed. */
 	int writetimeout;	/*!< Timeout for ast_carefulwrite() */
+	int pending_event;         /*!< Pending events indicator in case when waiting_thread is NULL */
 	AST_LIST_ENTRY(mansession) list;
 };
 
@@ -2753,6 +2754,11 @@ static int get_input(struct mansession *s, char *output)
 	while (res == 0) {
 		/* XXX do we really need this locking ? */
 		ast_mutex_lock(&s->__lock);
+		if (s->pending_event) {
+			s->pending_event = 0;
+			ast_mutex_unlock(&s->__lock);
+			return 0;
+		}
 		s->waiting_thread = pthread_self();
 		ast_mutex_unlock(&s->__lock);
 
@@ -2993,6 +2999,13 @@ int __manager_event(int category, const char *event,
 		ast_mutex_lock(&s->__lock);
 		if (s->waiting_thread != AST_PTHREADT_NULL)
 			pthread_kill(s->waiting_thread, SIGURG);
+		else
+			/* We have an event to process, but the mansession is
+			 * not waiting for it. We still need to indicate that there
+			 * is an event waiting so that get_input processes the pending
+			 * event instead of polling.
+			 */
+			s->pending_event = 1;
 		ast_mutex_unlock(&s->__lock);
 	}
 	AST_LIST_UNLOCK(&sessions);