Bug 6091 - Fix race condition around uniqueid

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@7677 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channel.c

@@ -94,6 +94,7 @@ struct ast_channel_spy_list {
  */
 static int shutting_down = 0;
 
+AST_MUTEX_DEFINE_STATIC(uniquelock);
 static int uniqueint = 0;
 
 unsigned long global_fin = 0, global_fout = 0;
@@ -583,7 +584,9 @@ struct ast_channel *ast_channel_alloc(int needqueue)
 	tmp->data = NULL;
 	tmp->fin = global_fin;
 	tmp->fout = global_fout;
+	ast_mutex_lock(&uniquelock);
 	snprintf(tmp->uniqueid, sizeof(tmp->uniqueid), "%li.%d", (long) time(NULL), uniqueint++);
+	ast_mutex_unlock(&uniquelock);
 	headp = &tmp->varshead;
 	ast_mutex_init(&tmp->lock);
 	AST_LIST_HEAD_INIT_NOLOCK(headp);