Clarify some documentation of queues.conf.sample

It had always been possible to explicitly specify a "blank"
value for a sound file in queues.conf and have no sound played
back. The problem with this is that it would result in some ugly
CLI warnings from file.c.

This commit introduces a check when playing a file in app_queue
to see if the name of the file is zero-length and return early if
that is the case. Also, the ability to specify the blank sound
files in queues.conf is now mentioned more clearly in queues.conf.sample

(closes issue #14227)
Reported by: caspy




git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@180006 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_queue.c

@@ -1486,6 +1486,10 @@ static int play_file(struct ast_channel *chan, char *filename)
 {
 	int res;
 
+	if (ast_strlen_zero(filename)) {
+		return 0;
+	}
+
 	ast_stopstream(chan);
 
 	res = ast_streamfile(chan, filename, chan->language);

configs/queues.conf.sample

@@ -155,6 +155,13 @@ monitor-type = MixMonitor
 ;
 ; Use these sound files in making position/holdtime announcements.  The
 ; defaults are as listed below -- change only if you need to.
+;
+; Keep in mind that you may also prevent a sound from being played if you
+; explicitly set a sound to be an empty string. For example, if you want to
+; prevent the queue from playing queue-thankyou, you may set the sound using
+; the following line:
+;
+; queue-thankyou=
 ;
 			;	("You are now first in line.")
 ;queue-youarenext = queue-youarenext