1 /* $NetBSD: lockf.c,v 1.3 2021/08/14 16:14:58 christos Exp $ */
2
3 /* $OpenLDAP$ */
4 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
5 *
6 * Copyright 1998-2021 The OpenLDAP Foundation.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted only as authorized by the OpenLDAP
11 * Public License.
12 *
13 * A copy of this license is available in the file LICENSE in the
14 * top-level directory of the distribution or, alternatively, at
15 * <http://www.OpenLDAP.org/license.html>.
16 */
17
18 /*
19 * File Locking Routines
20 *
21 * Implementations (in order of preference)
22 * - lockf
23 * - fcntl
24 * - flock
25 *
26 * Other implementations will be added as needed.
27 *
28 * NOTE: lutil_lockf() MUST block until an exclusive lock is acquired.
29 */
30
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: lockf.c,v 1.3 2021/08/14 16:14:58 christos Exp $");
33
34 #include "portable.h"
35
36 #include <stdio.h>
37 #include <ac/unistd.h>
38
39 #undef LOCK_API
40
41 #if defined(HAVE_LOCKF) && defined(F_LOCK)
42 # define USE_LOCKF 1
43 # define LOCK_API "lockf"
44 #endif
45
46 #if !defined(LOCK_API) && defined(HAVE_FCNTL)
47 # ifdef HAVE_FCNTL_H
48 # include <fcntl.h>
49 # endif
50 # ifdef F_WRLCK
51 # define USE_FCNTL 1
52 # define LOCK_API "fcntl"
53 # endif
54 #endif
55
56 #if !defined(LOCK_API) && defined(HAVE_FLOCK)
57 # ifdef HAVE_SYS_FILE_H
58 # include <sys/file.h>
59 # endif
60 # define USE_FLOCK 1
61 # define LOCK_API "flock"
62 #endif
63
64 #if !defined(USE_LOCKF) && !defined(USE_FCNTL) && !defined(USE_FLOCK)
lutil_lockf(int fd)65 int lutil_lockf ( int fd ) {
66 fd = fd;
67 return 0;
68 }
69
lutil_unlockf(int fd)70 int lutil_unlockf ( int fd ) {
71 fd = fd;
72 return 0;
73 }
74 #endif
75
76 #ifdef USE_LOCKF
lutil_lockf(int fd)77 int lutil_lockf ( int fd ) {
78 /* use F_LOCK instead of F_TLOCK, ie: block */
79 return lockf( fd, F_LOCK, 0 );
80 }
81
lutil_unlockf(int fd)82 int lutil_unlockf ( int fd ) {
83 return lockf( fd, F_ULOCK, 0 );
84 }
85 #endif
86
87 #ifdef USE_FCNTL
lutil_lockf(int fd)88 int lutil_lockf ( int fd ) {
89 struct flock file_lock;
90
91 memset( &file_lock, '\0', sizeof( file_lock ) );
92 file_lock.l_type = F_WRLCK;
93 file_lock.l_whence = SEEK_SET;
94 file_lock.l_start = 0;
95 file_lock.l_len = 0;
96
97 /* use F_SETLKW instead of F_SETLK, ie: block */
98 return( fcntl( fd, F_SETLKW, &file_lock ) );
99 }
100
lutil_unlockf(int fd)101 int lutil_unlockf ( int fd ) {
102 struct flock file_lock;
103
104 memset( &file_lock, '\0', sizeof( file_lock ) );
105 file_lock.l_type = F_UNLCK;
106 file_lock.l_whence = SEEK_SET;
107 file_lock.l_start = 0;
108 file_lock.l_len = 0;
109
110 return( fcntl ( fd, F_SETLKW, &file_lock ) );
111 }
112 #endif
113
114 #ifdef USE_FLOCK
lutil_lockf(int fd)115 int lutil_lockf ( int fd ) {
116 /* use LOCK_EX instead of LOCK_EX|LOCK_NB, ie: block */
117 return flock( fd, LOCK_EX );
118 }
119
lutil_unlockf(int fd)120 int lutil_unlockf ( int fd ) {
121 return flock( fd, LOCK_UN );
122 }
123 #endif
124