1/* $OpenLDAP$ */
2/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
3 *
4 * Copyright 1998-2011 The OpenLDAP Foundation.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted only as authorized by the OpenLDAP
9 * Public License.
10 *
11 * A copy of this license is available in the file LICENSE in the
12 * top-level directory of the distribution or, alternatively, at
13 * <http://www.OpenLDAP.org/license.html>.
14 */
15
16/*
17 * File Locking Routines
18 *
19 * Implementations (in order of preference)
20 *	- lockf
21 *	- fcntl
22 *  - flock
23 *
24 * Other implementations will be added as needed.
25 *
26 * NOTE: lutil_lockf() MUST block until an exclusive lock is acquired.
27 */
28
29#include "portable.h"
30
31#include <stdio.h>
32#include <ac/unistd.h>
33
34#undef LOCK_API
35
36#if defined(HAVE_LOCKF) && defined(F_LOCK)
37#	define USE_LOCKF 1
38#	define LOCK_API	"lockf"
39#endif
40
41#if !defined(LOCK_API) && defined(HAVE_FCNTL)
42#	ifdef HAVE_FCNTL_H
43#		include <fcntl.h>
44#	endif
45#	ifdef F_WRLCK
46#		define USE_FCNTL 1
47#		define LOCK_API	"fcntl"
48#	endif
49#endif
50
51#if !defined(LOCK_API) && defined(HAVE_FLOCK)
52#	ifdef HAVE_SYS_FILE_H
53#		include <sys/file.h>
54#	endif
55#	define USE_FLOCK 1
56#	define LOCK_API	"flock"
57#endif
58
59#if !defined(USE_LOCKF) && !defined(USE_FCNTL) && !defined(USE_FLOCK)
60int lutil_lockf ( int fd ) {
61    fd = fd;
62    return 0;
63}
64
65int lutil_unlockf ( int fd ) {
66    fd = fd;
67    return 0;
68}
69#endif
70
71#ifdef USE_LOCKF
72int lutil_lockf ( int fd ) {
73	/* use F_LOCK instead of F_TLOCK, ie: block */
74	return lockf( fd, F_LOCK, 0 );
75}
76
77int lutil_unlockf ( int fd ) {
78	return lockf( fd, F_ULOCK, 0 );
79}
80#endif
81
82#ifdef USE_FCNTL
83int lutil_lockf ( int fd ) {
84	struct flock file_lock;
85
86	memset( &file_lock, '\0', sizeof( file_lock ) );
87	file_lock.l_type = F_WRLCK;
88	file_lock.l_whence = SEEK_SET;
89	file_lock.l_start = 0;
90	file_lock.l_len = 0;
91
92	/* use F_SETLKW instead of F_SETLK, ie: block */
93	return( fcntl( fd, F_SETLKW, &file_lock ) );
94}
95
96int lutil_unlockf ( int fd ) {
97	struct flock file_lock;
98
99	memset( &file_lock, '\0', sizeof( file_lock ) );
100	file_lock.l_type = F_UNLCK;
101	file_lock.l_whence = SEEK_SET;
102	file_lock.l_start = 0;
103	file_lock.l_len = 0;
104
105	return( fcntl ( fd, F_SETLKW, &file_lock ) );
106}
107#endif
108
109#ifdef USE_FLOCK
110int lutil_lockf ( int fd ) {
111	/* use LOCK_EX instead of LOCK_EX|LOCK_NB, ie: block */
112	return flock( fd, LOCK_EX );
113}
114
115int lutil_unlockf ( int fd ) {
116	return flock( fd, LOCK_UN );
117}
118#endif
119