Fix #300: add ready:script for services, called when daemon is ready

In Finit a daemon can signal its readiness by creating/touching its PID
file.  An ancient UNIX concept -- a daemon creates its PID file when it
has set up signal handlers and is ready to receive IPC (signals), right
before entering its while(1) loop.

Finit took the concept a bit further, adding readiness signalling also
to daemon's by touching their PID file after having processed a SIGHUP.

For both these conditions Finit now supports a ready:script, called when
readiness is detected.  In later commits support for s6 and systemd
style readiness notification will be added that will hook the mechanism
implemented in this commit as well.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/cond-w.c

@@ -297,10 +297,17 @@ int cond_set_noupdate(const char *name)
 
 void cond_set(const char *name)
 {
+	svc_t *svc;
+
 	_d("%s", name);
 	if (cond_set_noupdate(name))
 		return;
 
+	/* XXX: refactor when new notify framework is in place */
+	svc = svc_find_by_cond(name);
+	if (svc && svc_has_ready(svc))
+		service_ready_script(svc);
+
 	cond_update(name);
 }
 

src/service.c

@@ -1266,6 +1266,7 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 	char *name = NULL, *halt = NULL, *delay = NULL;
 	char *id = NULL, *env = NULL, *cgroup = NULL;
 	char *pre_script = NULL, *post_script = NULL;
+	char *ready_script = NULL;
 	struct tty tty = { 0 };
 	char *dev = NULL;
 	int respawn = 0;
@@ -1361,6 +1362,8 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 			pre_script = arg;
 		else if (MATCH_CMD(cmd, "post:", arg))
 			post_script = arg;
+		else if (MATCH_CMD(cmd, "ready:", arg))
+			ready_script = arg;
 		else if (MATCH_CMD(cmd, "env:", arg))
 			env = arg;
 		else if (MATCH_CMD(cmd, "cgroup:", arg))
@@ -1516,6 +1519,8 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 		parse_script("pre", pre_script, svc->pre_script, sizeof(svc->pre_script));
 	if (post_script)
 		parse_script("post", post_script, svc->post_script, sizeof(svc->post_script));
+	if (ready_script)
+		parse_script("ready", ready_script, svc->ready_script, sizeof(svc->ready_script));
 	if (log)
 		parse_log(svc, log);
 	if (desc)
@@ -1607,7 +1612,8 @@ void service_monitor(pid_t lost, int status)
 
 	svc = svc_find_by_pid(lost);
 	if (!svc) {
-		_d("collected unknown PID %d", lost);
+		if (service_script_del(lost))
+			_d("collected unknown PID %d", lost);
 		return;
 	}
 
@@ -1805,6 +1811,43 @@ static void service_post_script(svc_t *svc)
 	service_timeout_after(svc, svc->killdelay, service_kill_script);
 }
 
+void service_ready_script(svc_t *svc)
+{
+	pid_t pid;
+
+	if (access(svc->ready_script, X_OK))
+		return;
+
+	pid = service_fork(svc);
+	if (pid < 0) {
+		_pe("Failed forking off %s ready-script %s", svc_ident(svc, NULL, 0), svc->ready_script);
+		return;
+	}
+
+	if (pid == 0) {
+		char buf[CMD_SIZE];
+		char *argv[4] = {
+			"sh",
+			"-ac",
+			buf,
+			NULL
+		};
+		char *env_file;
+
+		env_file = svc_getenv(svc);
+		if (env_file)
+			snprintf(buf, sizeof(buf), ". %s; exec %s", env_file, svc->ready_script);
+		else
+			strlcpy(buf, svc->ready_script, sizeof(buf));
+
+		set_pre_post_envs(svc, "ready");
+		execvp(_PATH_BSHELL, argv);
+		_exit(EX_OSERR);
+	}
+
+	service_script_add(svc, pid);
+}
+
 static void service_retry(svc_t *svc)
 {
 	char *restart_cnt = (char *)&svc->restart_cnt;

src/service.h

@@ -35,6 +35,8 @@ void      service_runtask_clean  (void);
 void      service_reload_dynamic (void);
 void      service_update_rdeps   (void);
 
+void      service_ready_script   (svc_t *svc); /* XXX: only for pidfile plugin before notify framework */
+
 int       service_timeout_after  (svc_t *svc, int timeout, void (*cb)(svc_t *svc));
 int       service_timeout_cancel (svc_t *svc);
 

src/svc.h

@@ -183,6 +183,7 @@ typedef struct svc {
 	char	       env[MAX_ARG_LEN];
 	char	       pre_script[MAX_ARG_LEN];
 	char	       post_script[MAX_ARG_LEN];
+	char	       ready_script[MAX_ARG_LEN];
 
 	/*
 	 * Used to forcefully kill services that won't shutdown on
@@ -239,6 +240,7 @@ static inline int svc_nohup        (svc_t *svc) { return svc &&  (0 == svc->sigh
 static inline int svc_has_pidfile  (svc_t *svc) { return svc_is_daemon(svc) && svc->pidfile[0] != 0 && svc->pidfile[0] != '!'; }
 static inline int svc_has_pre      (svc_t *svc) { return svc->pre_script[0];  }
 static inline int svc_has_post     (svc_t *svc) { return svc->post_script[0]; }
+static inline int svc_has_ready    (svc_t *svc) { return svc->ready_script[0];}
 
 static inline void svc_starting    (svc_t *svc) { if (svc) svc->starting = 1;       }
 static inline void svc_started     (svc_t *svc) { if (svc) svc->starting = 0;       }