From 598b7473fea63177f65d94a354a9336c6d136097 Mon Sep 17 00:00:00 2001
From: Kurt Zeilenga <kurt@openldap.org>
Date: Sun, 28 Mar 1999 22:43:43 +0000
Subject: [PATCH] All implementations of lutil_lockf (aka ldap_lockf) block
 until the lock is acquired.  Add comments to that effect.  Remove unnecessary
 busy loops from slapd/lock.c and slurpd/lock.c.

---
 include/lutil_lockf.h      |  6 ++++--
 libraries/liblutil/lockf.c | 11 ++++++++++-
 servers/slapd/lock.c       |  4 +---
 servers/slurpd/lock.c      |  5 +----
 4 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/include/lutil_lockf.h b/include/lutil_lockf.h
index 49d2c01e05..2ff75b9bb0 100644
--- a/include/lutil_lockf.h
+++ b/include/lutil_lockf.h
@@ -8,8 +8,10 @@
  * in file LICENSE in the top-level directory of the distribution.
  */
 
-/* File locking methods */
-/* only available if fcntl() locking is required */
+/* File locking methods
+ *
+ * lutil_lockf() will block until an exclusive lock is acquired.
+ */
 
 #ifndef _LUTIL_LOCKF_H_
 #define _LUTIL_LOCKF_H_
diff --git a/libraries/liblutil/lockf.c b/libraries/liblutil/lockf.c
index c21d2a8dfc..3daf88c695 100644
--- a/libraries/liblutil/lockf.c
+++ b/libraries/liblutil/lockf.c
@@ -17,6 +17,8 @@
  *  - flock
  *
  * Other implementations will be added as needed.
+ *
+ * NOTE: lutil_lockf() MUST block until an exclusive lock is acquired.
  */
 
 #include "portable.h"
@@ -51,6 +53,7 @@
 
 #ifdef USE_LOCKF
 int lutil_lockf ( int fd ) {
+	/* use F_LOCK instead of F_TLOCK, ie: block */
 	return lockf( fd, F_LOCK, 0 );
 }
 
@@ -62,27 +65,33 @@ int lutil_unlockf ( int fd ) {
 #ifdef USE_FCNTL
 int lutil_lockf ( int fd ) {
 	struct flock file_lock;
+
 	memset( &file_lock, 0, sizeof( file_lock ) );
 	file_lock.l_type = F_WRLCK;
 	file_lock.l_whence = SEEK_SET;
 	file_lock.l_start = 0;
 	file_lock.l_len = 0;
+
+	/* use F_SETLKW instead of F_SETLK, ie: block */
 	return( fcntl( fd, F_SETLKW, &file_lock ) );
 }
 
 int lutil_unlockf ( int fd ) {
 	struct flock file_lock;
+
 	memset( &file_lock, 0, sizeof( file_lock ) );
 	file_lock.l_type = F_UNLCK;
 	file_lock.l_whence = SEEK_SET;
 	file_lock.l_start = 0;
 	file_lock.l_len = 0;
-	return( fcntl ( fd, F_SETLK, &file_lock ) );
+
+	return( fcntl ( fd, F_SETLKW, &file_lock ) );
 }
 #endif
 
 #ifdef USE_FLOCK
 int lutil_lockf ( int fd ) {
+	/* use LOCK_EX instead of LOCK_EX|LOCK_NB, ie: block */
 	return flock( fd, LOCK_EX );
 }
 
diff --git a/servers/slapd/lock.c b/servers/slapd/lock.c
index b23aa9028c..9325389d12 100644
--- a/servers/slapd/lock.c
+++ b/servers/slapd/lock.c
@@ -30,9 +30,7 @@ lock_fopen( char *fname, char *type, FILE **lfp )
 	}
 
 	/* acquire the lock */
-	while ( ldap_lockf( fileno(*lfp) ) != 0 ) {
-		;	/* NULL */
-	}
+	ldap_lockf( fileno(*lfp) );
 
 	/* open the log file */
 	if ( (fp = fopen( fname, type )) == NULL ) {
diff --git a/servers/slurpd/lock.c b/servers/slurpd/lock.c
index cca1bed3f8..40c61a2517 100644
--- a/servers/slurpd/lock.c
+++ b/servers/slurpd/lock.c
@@ -53,10 +53,7 @@ lock_fopen(
 	}
 
 	/* acquire the lock */
-	while ( ldap_lockf( fileno(*lfp) ) != 0 )
-	{
-		;	/* NULL */
-	}
+	ldap_lockf( fileno(*lfp) );
 
 	/* open the log file */
 	if ( (fp = fopen( fname, type )) == NULL ) {
-- 
2.39.5