discover: Add safe mode

Safe mode configures the discover server to not start any device
parsing; this can be used to diagnose any problems with early device
handing.

In safe mode, we don't initialise any of the device sources - udev,
network and user events are disabled.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

2 files changed, 13 insertions, 0 deletions

diff --git a/discover/device-handler.c b/discover/device-handler.c
index b93cdfa..e4978fa 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -285,6 +285,9 @@ struct device_handler *device_handler_init(struct discover_server *server,
 
 	parser_init();
 
+	if (config_get()->safe_mode)
+		return handler;
+
 	rc = device_handler_init_sources(handler);
 	if (rc) {
 		talloc_free(handler);
@@ -842,6 +845,13 @@ static int device_handler_init_sources(struct device_handler *handler)
 
 static void device_handler_reinit_sources(struct device_handler *handler)
 {
+	/* if we haven't initialised sources previously (becuase we started in
+	 * safe mode), then init once here. */
+	if (!(handler->udev || handler->network || handler->user_event)) {
+		device_handler_init_sources(handler);
+		return;
+	}
+
 	udev_reinit(handler->udev);
 
 	network_shutdown(handler->network);
diff --git a/discover/platform.c b/discover/platform.c
index 3ab6b7b..be60f00 100644
--- a/discover/platform.c
+++ b/discover/platform.c
@@ -43,6 +43,9 @@ static void dump_config(struct config *config)
 	if (config->network.n_interfaces || config->network.n_dns_servers)
 		pb_log(" network configuration:\n");
 
+	if (config->safe_mode)
+		pb_log(" safe mode: active\n");
+
 	for (i = 0; i < config->network.n_interfaces; i++) {
 		struct interface_config *ifconf =
 			config->network.interfaces[i];