Issue #223: add type:forking service option, with updated docs

- Add `type:forking` service option to trigger guessing pidfile to
   watch for, instead of `pid:!foo` option, which is not intuitive.
   This option may likely also survive into the new file format :)
 - Update docs and add examples
 - Update start-stop-serv.sh test case with this new variant

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

src/pid.c

@@ -158,6 +158,11 @@ int pid_file_set(svc_t *svc, char *file, int not)
 		file++;
 	}
 
+	if (svc_is_forking(svc) && !not) {
+		logit(LOG_WARNING, "Service %s is forking, adjusting to pid:!%s", svc->name, file);
+		not = 1;
+	}
+
 	pid_runpath(file, &svc->pidfile[not], sizeof(svc->pidfile) - not);
 	if (not)
 		svc->pidfile[0] = '!';

src/service.c

@@ -1154,7 +1154,7 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 	char *dev = NULL;
 	int respawn = 0;
 	int levels = 0;
-	int manual = 0;
+	int forking = 0, manual = 0;
 	int restart_max = SVC_RESPAWN_MAX;
 	int restart_tmo = 0;
 	unsigned oncrash_action = SVC_ONCRASH_IGNORE;
@@ -1213,6 +1213,8 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 			pid = cmd;
 		else if (!strncasecmp(cmd, "name:", 5))
 			name = cmd;
+		else if (!strncasecmp(cmd, "type:forking", 10))
+			forking = 1;
 		else if (!strncasecmp(cmd, "manual:yes", 10))
 			manual = 1;
 		else if (!strncasecmp(cmd, "restart:", 8))
@@ -1324,10 +1326,6 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 			svc_unblock(svc);
 	}
 
-	/* Decode any optional pid:/optional/path/to/file.pid */
-	if (pid && (svc_is_daemon(svc) || svc_is_sysv(svc)) && pid_file_parse(svc, pid))
-		_e("Invalid 'pid' argument to service: %s", pid);
-
 	if (username) {
 		char *ptr = strchr(username, ':');
 
@@ -1406,6 +1404,25 @@ int service_register(int type, char *cfg, struct rlimit rlimit[], char *file)
 	if (file)
 		strlcpy(svc->file, file, sizeof(svc->file));
 	svc->respawn = respawn;
+	svc->forking = forking;
+
+	/* Decode any (optional) pid:/optional/path/to/file.pid */
+	if (svc_is_daemon(svc) || svc_is_sysv(svc)) {
+		char tmp[sizeof(svc->name) + 6]; /* pid:! + svc->name */
+
+		/* no pid: set, figure out a default to track this svc */
+		if (!pid && forking) {
+			snprintf(tmp, sizeof(tmp), "pid:!%s", svc->name);
+			pid = tmp;
+			logit(LOG_INFO, "%s: forking but no pid:!file set, guessing -> %s", svc->name, tmp);
+		}
+
+		if (pid && pid_file_parse(svc, pid))
+			logit(LOG_WARNING, "%s: service has invalid 'pid:' config: %s", svc->name, pid);
+
+		if (svc->pidfile[0] == '!')
+			svc->forking = 1;
+	}
 
 	/* Set configured limits */
 	memcpy(svc->rlimit, rlimit, sizeof(svc->rlimit));

src/svc.h

@@ -127,6 +127,7 @@ typedef struct svc {
 	int            starting;       /* ... waiting for pidfile to be re-asserted */
 	int	       runlevels;
 	int            sighup;	       /* This service supports SIGHUP :) */
+	int	       forking;	       /* This is a service/sysv daemon that forks, wait for it ... */
 	svc_block_t    block;	       /* Reason that this service is currently stopped */
 	char           cond[MAX_COND_LEN];
 
@@ -228,7 +229,7 @@ static inline int svc_is_daemon    (svc_t *svc) { return svc && SVC_TYPE_SERVICE
 static inline int svc_is_sysv      (svc_t *svc) { return svc && SVC_TYPE_SYSV    == svc->type; }
 static inline int svc_is_tty       (svc_t *svc) { return svc && SVC_TYPE_TTY     == svc->type; }
 static inline int svc_is_runtask   (svc_t *svc) { return svc && (SVC_TYPE_RUNTASK & svc->type);}
-static inline int svc_is_forking   (svc_t *svc) { return (svc_is_daemon(svc) || svc_is_sysv(svc)) && svc->pidfile[0] == '!'; }
+static inline int svc_is_forking   (svc_t *svc) { return svc && svc->forking; }
 
 static inline int svc_in_runlevel  (svc_t *svc, int runlevel) { return svc && ISSET(svc->runlevels, runlevel); }
 static inline int svc_nohup        (svc_t *svc) { return svc &&  (0 == svc->sighup || 0 != svc->args_dirty); }