From b54d2b2c38d55e00445a11ea70f97c007cfad08f Mon Sep 17 00:00:00 2001
From: Mark Spencer <markster@digium.com>
Date: Tue, 20 Apr 2004 03:16:01 +0000
Subject: [PATCH] Make sure we safely lock both channels when doing a
 masquerade.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@2716 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 channel.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/channel.c b/channel.c
index f0b8e8f9e5..ee2a5c6c5e 100755
--- a/channel.c
+++ b/channel.c
@@ -1996,26 +1996,32 @@ int ast_channel_make_compatible(struct ast_channel *chan, struct ast_channel *pe
 int ast_channel_masquerade(struct ast_channel *original, struct ast_channel *clone)
 {
 	struct ast_frame null = { AST_FRAME_NULL, };
+	int res = -1;
+	ast_mutex_lock(&original->lock);
+	while(ast_mutex_trylock(&clone->lock)) {
+		ast_mutex_unlock(&original->lock);
+		usleep(1);
+		ast_mutex_lock(&original->lock);
+	}
 	ast_log(LOG_DEBUG, "Planning to masquerade %s into the structure of %s\n",
 		clone->name, original->name);
 	if (original->masq) {
 		ast_log(LOG_WARNING, "%s is already going to masquerade as %s\n", 
 			original->masq->name, original->name);
-		return -1;
-	}
-	if (clone->masqr) {
+	} else if (clone->masqr) {
 		ast_log(LOG_WARNING, "%s is already going to masquerade as %s\n", 
 			clone->name, clone->masqr->name);
-		return -1;
-	}
-	original->masq = clone;
-	clone->masqr = original;
-	/* XXX can't really hold the lock here, but at the same time, it' s
-	   not really safe not to XXX */
-	ast_queue_frame(original, &null);
-	ast_queue_frame(clone, &null);
-	ast_log(LOG_DEBUG, "Done planning to masquerade %s into the structure of %s\n", original->name, clone->name);
-	return 0;
+	} else {
+		original->masq = clone;
+		clone->masqr = original;
+		ast_queue_frame(original, &null);
+		ast_queue_frame(clone, &null);
+		ast_log(LOG_DEBUG, "Done planning to masquerade %s into the structure of %s\n", original->name, clone->name);
+		res = 0;
+	}
+	ast_mutex_unlock(&clone->lock);
+	ast_mutex_unlock(&original->lock);
+	return res;
 }
 
 void ast_change_name(struct ast_channel *chan, char *newname)