res_alarmsystem: Add ALARMSYSTEM_STATE function.

Add a function that can be used to retrieve the current state
of the alarm system as a whole, rather than an individual
sensor. This allows us to determine from the dialplan if the
system is actively "in alarm" - just because a sensor is triggered
doesn't mean the system is, as the system may be in the temporarily
disarmed mode (e.g. to allow egress). This allows dialplan logic
to do certain things when an alarm is actively going off.

Author: InterLinked1

res/res_alarmsystem.c

@@ -597,6 +597,16 @@ struct alarm_client {
 
 static AST_RWLIST_HEAD_STATIC(clients, alarm_client);
 
+static const char *state2str(enum alarm_state state)
+{
+	switch (state) {
+	case ALARM_STATE_OK: return "OK";
+	case ALARM_STATE_TRIGGERED: return "TRIGGERED";
+	case ALARM_STATE_BREACH: return "BREACH";
+	}
+	__builtin_unreachable();
+}
+
 static const char *state2text(int state)
 {
 	switch (state) {
@@ -2614,6 +2624,32 @@ static struct ast_custom_function acf_sensortriggered = {
 	.read = sensor_triggered_read,
 };
 
+static int alarm_state_read(struct ast_channel *chan, const char *cmd, char *parse, char *buffer, size_t buflen)
+{
+	struct alarm_client *c;
+
+	if (ast_strlen_zero(parse)) {
+		ast_log(LOG_ERROR, "Must specify client-name\n");
+		return -1;
+	}
+
+	AST_RWLIST_RDLOCK(&clients);
+	c = find_client_locked(parse);
+	if (!c) {
+		ast_log(LOG_ERROR, "Client '%s' not found in configuration\n", parse);
+		AST_RWLIST_UNLOCK(&clients);
+		return -1;
+	}
+	ast_copy_string(buffer, state2str(c->state), buflen);
+	AST_RWLIST_UNLOCK(&clients);
+	return 0;
+}
+
+static struct ast_custom_function acf_state = {
+	.name = "ALARMSYSTEM_STATE",
+	.read = alarm_state_read,
+};
+
 static char *handle_show_sensors(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
 {
 #define FORMAT  "%-12s %-20s %s\n"
@@ -2771,6 +2807,7 @@ static int unload_module(void)
 
 	ast_cli_unregister_multiple(alarmsystem_cli, ARRAY_LEN(alarmsystem_cli));
 	ast_custom_function_unregister(&acf_sensortriggered);
+	ast_custom_function_unregister(&acf_state);
 	ast_unregister_application("AlarmSensor");
 	ast_unregister_application("AlarmEventReceiver");
 	ast_unregister_application("AlarmKeypad");
@@ -2825,6 +2862,7 @@ static int load_module(void)
 	}
 
 	ast_custom_function_register(&acf_sensortriggered);
+	ast_custom_function_register(&acf_state);
 	ast_cli_register_multiple(alarmsystem_cli, ARRAY_LEN(alarmsystem_cli));
 	return 0;
 }