Check to make sure a value has been given to the VMCOUNT dialplan function.

(closes issue #10996)
Reported by: marsosa


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@85850 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_hasnewvoicemail.c

@@ -161,6 +161,9 @@ static int acf_vmcount_exec(struct ast_channel *chan, char *cmd, char *argsstr,
 		AST_APP_ARG(folder);
 	);
 
+	if (ast_strlen_zero(argsstr))
+		return -1;
+
 	u = ast_module_user_add(chan);
 
 	buf[0] = '\0';