syslogd has always bugged me with it's async startup at boot time.

For me, more often than not, the backgrounded syslogd daemon is not
yet ready to process log messages before other things (such as named)
want to log a heap of them.  It seems that it's the O_SYNC writes of
the stuff coming in from /dev/klog that's the slowdown.

Anyway, instead of using the libc daemon, roll a modified version.  This
one has a timeout.  The child will wait for either the timeout to expire
or the child process to signal it to let it know that it's "ready" and
the /dev/log socket is set up and active, so it's safe to continue the
boot.  It adds a small fraction of a second pause to the boot time, but on
the other hand the overall boot time is *quicker* since the disk is not
being thrashed while the log messages are getting written out synchronously
one by one while other daemons are loading in parallel.

The timeout is in case the child segfaults or something before becoming
fully operational.

1 files changed, 71 insertions, 6 deletions

diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index 5979a925fdc7..8bff619a0059 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -39,7 +39,7 @@ static const char copyright[] =
 static char sccsid[] = "@(#)syslogd.c	8.3 (Berkeley) 4/4/94";
 */
 static const char rcsid[] =
-	"$Id: syslogd.c,v 1.8 1995/11/14 23:39:39 peter Exp $";
+	"$Id: syslogd.c,v 1.9 1996/07/22 16:35:50 pst Exp $";
 #endif /* not lint */
 
 /*
@@ -212,6 +212,7 @@ void	reapchild __P((int));
 char   *ttymsg __P((struct iovec *, int, char *, int));
 void	usage __P((void));
 void	wallmsg __P((struct filed *, struct iovec *));
+int	waitdaemon __P((int, int, int));
 
 int
 main(argc, argv)
@@ -223,6 +224,8 @@ main(argc, argv)
 	struct sockaddr_in sin, frominet;
 	FILE *fp;
 	char *p, line[MSG_BSIZE + 1];
+	struct timeval tv, *tvp;
+	pid_t ppid;
 
 	while ((ch = getopt(argc, argv, "dsf:Im:p:")) != EOF)
 		switch(ch) {
@@ -249,9 +252,11 @@ main(argc, argv)
 	if ((argc -= optind) != 0)
 		usage();
 
-	if (!Debug)
-		(void)daemon(0, 0);
-	else
+	if (!Debug) {
+		ppid = waitdaemon(0, 0, 30);
+		if (ppid < 0)
+			err(1, "could not become daemon");
+	} else
 		setlinebuf(stdout);
 
 	consfile.f_type = F_CONSOLE;
@@ -333,14 +338,23 @@ main(argc, argv)
 	init(0);
 	(void)signal(SIGHUP, init);
 
+	tvp = &tv;
+	tv.tv_sec = tv.tv_usec = 0;
+
 	for (;;) {
 		int nfds, readfds = FDMASK(funix) | inetm | klogm;
 
 		dprintf("readfds = %#x\n", readfds);
 		nfds = select(20, (fd_set *)&readfds, (fd_set *)NULL,
-		    (fd_set *)NULL, (struct timeval *)NULL);
-		if (nfds == 0)
+		    (fd_set *)NULL, tvp);
+		if (nfds == 0) {
+			if (tvp) {
+				tvp = NULL;
+				if (ppid != 1)
+					kill(ppid, SIGALRM);
+			}
 			continue;
+		}
 		if (nfds < 0) {
 			if (errno != EINTR)
 				logerror("select");
@@ -1212,3 +1226,54 @@ decode(name, codetab)
 
 	return (-1);
 }
+
+static char *exitmsg;
+
+void
+timeout(sig)
+	int sig __unused;
+{
+	int left;
+	left = alarm(0);
+	signal(SIGALRM, SIG_DFL);
+	if (left == 0)
+		exitmsg = "timed out waiting for child";
+	return;
+}
+
+int
+waitdaemon(nochdir, noclose, maxwait)
+	int nochdir, noclose, maxwait;
+{
+	int fd;
+
+	switch (fork()) {
+	case -1:
+		return (-1);
+	case 0:
+		break;
+	default:
+		signal(SIGALRM, timeout);
+		alarm(maxwait);
+		pause();
+		if (exitmsg)
+			err(1, exitmsg);
+		else
+			exit(0);
+	}
+
+	if (setsid() == -1)
+		return (-1);
+
+	if (!nochdir)
+		(void)chdir("/");
+
+	if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
+		(void)dup2(fd, STDIN_FILENO);
+		(void)dup2(fd, STDOUT_FILENO);
+		(void)dup2(fd, STDERR_FILENO);
+		if (fd > 2)
+			(void)close (fd);
+	}
+	return (getppid());
+}