Make it easier to detect an improper call to ast_read().

When you call ast_waitfor() on a channel, the index into the channel fds array
that holds the file descriptor that poll() determines has input available is
stored in fdno.  This patch clears out this value after a call to ast_read()
and also reports errors if ast_read() is called without an fdno set.

From a discussion on the asterisk-dev list.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@179608 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/channel.c

@@ -2039,6 +2039,12 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 		usleep(1);
 	}
 
+	if (chan->fdno == -1) {
+		ast_log(LOG_ERROR, "ast_read() called with no recorded file descriptor.\n");
+		f = &ast_null_frame;
+		goto done;
+	}
+
 	if (chan->masq) {
 		if (ast_do_masquerade(chan))
 			ast_log(LOG_WARNING, "Failed to perform masquerade\n");
@@ -2055,6 +2061,12 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 	}
 	prestate = chan->_state;
 
+	/* 
+	 * Reset the recorded file descriptor that triggered this read so that we can
+	 * easily detect when ast_read() is called without properly using ast_waitfor().
+	 */
+	chan->fdno = -1;
+
 	/* Read and ignore anything on the alertpipe, but read only
 	   one sizeof(blah) per frame that we send from it */
 	if (chan->alertpipe[0] > -1) {