text: Respawn input method process if it exits

Just the same as it is done in shell.c, if the input method process exits
for any reason, we relaunch it automatically, as it is not possible to
launch a standalone application outside of the weston process.

In v2:
 - Proper error message when giving up.

Signed-off-by: Eduardo Lima (Etrunko) <eduardo.lima@intel.com>

src/text-backend.c

@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <time.h>
 
 #include "compositor.h"
 #include "text-server-protocol.h"
@@ -92,6 +93,9 @@ struct text_backend {
 		struct wl_resource *binding;
 		struct weston_process process;
 		struct wl_client *client;
+
+		unsigned deathcount;
+		uint32_t deathstamp;
 	} input_method;
 
 	struct wl_listener seat_created_listener;
@@ -820,14 +824,33 @@ input_method_init_seat(struct weston_seat *seat)
 	seat->input_method->focus_listener_initialized = 1;
 }
 
+static void launch_input_method(struct text_backend *text_backend);
+
 static void
 handle_input_method_sigchld(struct weston_process *process, int status)
 {
+	uint32_t time;
 	struct text_backend *text_backend =
 		container_of(process, struct text_backend, input_method.process);
 
 	text_backend->input_method.process.pid = 0;
 	text_backend->input_method.client = NULL;
+
+	/* if input_method dies more than 5 times in 10 seconds, give up */
+	time = weston_compositor_get_time();
+	if (time - text_backend->input_method.deathstamp > 10000) {
+		text_backend->input_method.deathstamp = time;
+		text_backend->input_method.deathcount = 0;
+	}
+
+	text_backend->input_method.deathcount++;
+	if (text_backend->input_method.deathcount > 5) {
+		weston_log("input_method died, giving up.\n");
+		return;
+	}
+
+	weston_log("input_method died, respawning...\n");
+	launch_input_method(text_backend);
 }
 
 static void