OS-1822 svc.startd dies in getutxent_frec()

Reviewed by: Keith Wesolowski <keith.wesolowski@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>

3 files changed, 34 insertions, 2 deletions

diff --git a/usr/src/cmd/svc/startd/fork.c b/usr/src/cmd/svc/startd/fork.c
index 4717d491b3..7bce347854 100644
--- a/usr/src/cmd/svc/startd/fork.c
+++ b/usr/src/cmd/svc/startd/fork.c
@@ -25,6 +25,10 @@
  */
 
 /*
+ * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+ */
+
+/*
  * fork.c - safe forking for svc.startd
  *
  * fork_configd() and fork_sulogin() are related, special cases that handle the
@@ -72,6 +76,7 @@ startd_fork1(int *forkerr)
 	 * prefork stack
 	 */
 	wait_prefork();
+	utmpx_prefork();
 
 	p = fork1();
 
@@ -81,6 +86,7 @@ startd_fork1(int *forkerr)
 	/*
 	 * postfork stack
 	 */
+	utmpx_postfork();
 	wait_postfork(p);
 
 	return (p);
@@ -169,6 +175,8 @@ fork_common(const char *name, const char *svc_fmri, int retries, ctid_t *ctidp,
 		/* NOTREACHED */
 	}
 
+	utmpx_prefork();
+
 	/*
 	 * Attempt to fork "retries" times.
 	 */
@@ -181,6 +189,7 @@ fork_common(const char *name, const char *svc_fmri, int retries, ctid_t *ctidp,
 			err = errno;
 			(void) ct_tmpl_clear(ctfd);
 			(void) close(ctfd);
+			utmpx_postfork();
 			fork_sulogin(B_TRUE, "Could not fork to start %s: %s\n",
 			    name, strerror(err));
 			/* NOTREACHED */
@@ -188,6 +197,8 @@ fork_common(const char *name, const char *svc_fmri, int retries, ctid_t *ctidp,
 		(void) sleep(tries);
 	}
 
+	utmpx_postfork();
+
 	/*
 	 * Clean up, return pid and ctid.
 	 */
diff --git a/usr/src/cmd/svc/startd/startd.h b/usr/src/cmd/svc/startd/startd.h
index 61f710c31e..e4f37a4213 100644
--- a/usr/src/cmd/svc/startd/startd.h
+++ b/usr/src/cmd/svc/startd/startd.h
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  */
 
 #ifndef	_STARTD_H
@@ -775,6 +775,8 @@ void utmpx_mark_dead(pid_t, int, boolean_t);
 char utmpx_get_runlevel(void);
 void utmpx_set_runlevel(char, char, boolean_t);
 void utmpx_write_boottime(void);
+void utmpx_prefork(void);
+void utmpx_postfork(void);
 
 /* wait.c */
 void wait_init(void);
diff --git a/usr/src/cmd/svc/startd/utmpx.c b/usr/src/cmd/svc/startd/utmpx.c
index 83b9380271..1b3ca95010 100644
--- a/usr/src/cmd/svc/startd/utmpx.c
+++ b/usr/src/cmd/svc/startd/utmpx.c
@@ -24,7 +24,9 @@
  * Use is subject to license terms.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
+/*
+ * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+ */
 
 /*
  * utmpx.c - utmpx utility routines
@@ -418,3 +420,20 @@ utmpx_init()
 {
 	(void) pthread_mutex_init(&utmpx_lock, &mutex_attrs);
 }
+
+void
+utmpx_prefork()
+{
+	/*
+	 * The libc utmpx routines are entirely MT-unsafe; we must assure
+	 * that no other thread is in these routines when we fork lest we
+	 * leave the child with inconsistent library state.
+	 */
+	MUTEX_LOCK(&utmpx_lock);
+}
+
+void
+utmpx_postfork()
+{
+	MUTEX_UNLOCK(&utmpx_lock);
+}