Don't use imsg_flush(), roll a local flush_unpriv_ibuf() that loops

on EAGAIN, sets quit to INTERNALSIG on errors (unless quit is already
set to something else), and prints a consistant error message when
errors other than EPIPE and end of file are encountered.

Fixes failure to write resolv.conf when -L is used, and makes
add_address() and add_route() also wait until imsg is in pipe.

4 files changed, 32 insertions, 26 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index e8eb8a93f1f..74205ff3fb0 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.292 2014/02/08 18:12:17 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.293 2014/02/09 20:45:56 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -2419,10 +2419,7 @@ write_file(char *path, int flags, mode_t mode, uid_t uid, gid_t gid,
 	if (rslt == -1)
 		warning("write_file: imsg_composev: %s", strerror(errno));
 
-	/* Do flush to maximize chances of keeping file current. */
-	rslt = imsg_flush(unpriv_ibuf);
-	if (rslt == -1)
-		warning("write_file: imsg_flush: %s", strerror(errno));
+	flush_unpriv_ibuf("write_file");
 }
 
 void
diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index 08ef9b279da..10efd27559d 100644
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcpd.h,v 1.135 2014/01/21 05:17:45 krw Exp $	*/
+/*	$OpenBSD: dhcpd.h,v 1.136 2014/02/09 20:45:56 krw Exp $	*/
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -312,3 +312,5 @@ void add_route(int, struct in_addr, struct in_addr, struct in_addr, int, int);
 void sendhup(struct client_lease *);
 
 int resolv_conf_priority(int);
+
+void flush_unpriv_ibuf(const char *);
diff --git a/sbin/dhclient/dispatch.c b/sbin/dhclient/dispatch.c
index e445f83ef84..da9916451be 100644
--- a/sbin/dhclient/dispatch.c
+++ b/sbin/dhclient/dispatch.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dispatch.c,v 1.87 2013/12/08 22:49:02 krw Exp $	*/
+/*	$OpenBSD: dispatch.c,v 1.88 2014/02/09 20:45:56 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -209,12 +209,7 @@ another:
 				routehandler();
 		}
 		if (fds[2].revents & POLLOUT) {
-			if (msgbuf_write(&unpriv_ibuf->w) <= 0 &&
-			    errno != EAGAIN) {
-				warning("pipe write error to [priv]");
-				quit = INTERNALSIG;
-				continue;
-			}
+			flush_unpriv_ibuf("dispatch");
 		}
 		if ((fds[2].revents & (POLLIN | POLLHUP))) {
 			/* Pipe to [priv] closed. Assume it emitted error. */
diff --git a/sbin/dhclient/kroute.c b/sbin/dhclient/kroute.c
index 2cd86e41df3..4b3930de435 100644
--- a/sbin/dhclient/kroute.c
+++ b/sbin/dhclient/kroute.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kroute.c,v 1.62 2014/02/09 20:23:22 krw Exp $	*/
+/*	$OpenBSD: kroute.c,v 1.63 2014/02/09 20:45:56 krw Exp $	*/
 
 /*
  * Copyright 2012 Kenneth R Westerback <krw@openbsd.org>
@@ -65,10 +65,7 @@ flush_routes(char *ifname, int rdomain)
 	if (rslt == -1)
 		warning("flush_routes: imsg_compose: %s", strerror(errno));
 
-	/* Do flush to maximize chances of cleaning up routes on exit. */
-	rslt = imsg_flush(unpriv_ibuf);
-	if (rslt == -1)
-		warning("flush_routes: imsg_flush: %s", strerror(errno));
+	flush_unpriv_ibuf("flush_routes");
 }
 
 void
@@ -190,6 +187,8 @@ add_route(int rdomain, struct in_addr dest, struct in_addr netmask,
 	    &imsg, sizeof(imsg));
 	if (rslt == -1)
 		warning("add_route: imsg_compose: %s", strerror(errno));
+
+ 	flush_unpriv_ibuf("add_route");
 }
 
 void
@@ -333,10 +332,7 @@ delete_address(char *ifname, int rdomain, struct in_addr addr)
 	if (rslt == -1)
 		warning("delete_address: imsg_compose: %s", strerror(errno));
 
-	/* Do flush to quickly kill previous dhclient, if any. */
-	rslt = imsg_flush(unpriv_ibuf);
-	if (rslt == -1 && errno != EPIPE)
-		warning("delete_address: imsg_flush: %s", strerror(errno));
+	flush_unpriv_ibuf("delete_address");
 }
 
 void
@@ -400,6 +396,8 @@ add_address(char *ifname, int rdomain, struct in_addr addr,
 	    sizeof(imsg));
 	if (rslt == -1)
 		warning("add_address: imsg_compose: %s", strerror(errno));
+
+	flush_unpriv_ibuf("add_address");
 }
 
 void
@@ -471,10 +469,7 @@ sendhup(struct client_lease *active)
 	if (rslt == -1)
 		warning("sendhup: imsg_compose: %s", strerror(errno));
 
-	/* Do flush so cleanup message gets through immediately. */
-	rslt = imsg_flush(unpriv_ibuf);
-	if (rslt == -1 && errno != EPIPE)
-		warning("sendhup: imsg_flush: %s", strerror(errno));
+	flush_unpriv_ibuf("sendhup");
 }
 
 /*
@@ -690,3 +685,20 @@ delete_route(int s, int rdomain, struct rt_msghdr *rtm)
 	} else if (rlen < (int)rtm->rtm_msglen)
 		error("short RTM_DELETE write (%zd)\n", rlen);
 }
+
+void
+flush_unpriv_ibuf(const char *who)
+{
+	while (unpriv_ibuf->w.queued) {
+		if (msgbuf_write(&unpriv_ibuf->w) <= 0) {
+			if (errno == EAGAIN)
+				continue;
+			if (quit == 0)
+				quit = INTERNALSIG;
+			if (errno != EPIPE && errno != 0)
+				warning("%s: msgbuf_write: %s", who,
+				    strerror(errno));
+			break;
+		}
+	}
+}