Use rdaemon() in dhclient too.

dhclient already has code to pre-open /dev/null, in order to properly go
to the background after chroot(2).  Use rdaemon() like in tftpd,
ftp-proxy, dhcrelay and rtadvd.

No objection krw@, ok dlg@

1 files changed, 29 insertions, 12 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index 281ce9a123b..9642e4e2e95 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.387 2016/09/04 11:21:24 jca Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.388 2016/09/15 16:19:04 jca Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -167,6 +167,7 @@ char *lease_as_string(struct interface_info *, char *, struct client_lease *);
 struct client_lease *packet_to_lease(struct interface_info *, struct in_addr,
     struct option_data *);
 void go_daemon(void);
+int rdaemon(int);
 
 #define	ROUNDUP(a) \
 	    ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
@@ -2057,17 +2058,8 @@ go_daemon(void)
 	/* Stop logging to stderr. */
 	log_perror = 0;
 
-	if (daemon(1, 0) == -1)
-		error("daemon");
-
-	/* we are chrooted, daemon(3) fails to open /dev/null */
-	if (nullfd != -1) {
-		dup2(nullfd, STDIN_FILENO);
-		dup2(nullfd, STDOUT_FILENO);
-		dup2(nullfd, STDERR_FILENO);
-		close(nullfd);
-		nullfd = -1;
-	}
+	if (rdaemon(nullfd) == -1)
+		error("rdaemon");
 
 	/* Catch stuff that might be trying to terminate the program. */
 	signal(SIGHUP, sighdlr);
@@ -2080,6 +2072,31 @@ go_daemon(void)
 }
 
 int
+rdaemon(int devnull)
+{
+
+	switch (fork()) {
+	case -1:
+		return (-1);
+	case 0:
+		break;
+	default:
+		_exit(0);
+	}
+
+	if (setsid() == -1)
+		return (-1);
+
+	(void)dup2(devnull, STDIN_FILENO);
+	(void)dup2(devnull, STDOUT_FILENO);
+	(void)dup2(devnull, STDERR_FILENO);
+	if (devnull > 2)
+		(void)close(devnull);
+
+	return (0);
+}
+
+int
 res_hnok(const char *name)
 {
 	const char *dn = name;