1 /* $NetBSD: lockf.c,v 1.1.1.2 2010/03/08 02:14:20 lukem Exp $ */ 2 3 /* OpenLDAP: pkg/ldap/libraries/liblutil/lockf.c,v 1.15.2.4 2009/01/22 00:00:58 kurt Exp */ 4 /* This work is part of OpenLDAP Software <http://www.openldap.org/>. 5 * 6 * Copyright 1998-2009 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 "portable.h" 32 33 #include <stdio.h> 34 #include <ac/unistd.h> 35 36 #undef LOCK_API 37 38 #if defined(HAVE_LOCKF) && defined(F_LOCK) 39 # define USE_LOCKF 1 40 # define LOCK_API "lockf" 41 #endif 42 43 #if !defined(LOCK_API) && defined(HAVE_FCNTL) 44 # ifdef HAVE_FCNTL_H 45 # include <fcntl.h> 46 # endif 47 # ifdef F_WRLCK 48 # define USE_FCNTL 1 49 # define LOCK_API "fcntl" 50 # endif 51 #endif 52 53 #if !defined(LOCK_API) && defined(HAVE_FLOCK) 54 # ifdef HAVE_SYS_FILE_H 55 # include <sys/file.h> 56 # endif 57 # define USE_FLOCK 1 58 # define LOCK_API "flock" 59 #endif 60 61 #if !defined(USE_LOCKF) && !defined(USE_FCNTL) && !defined(USE_FLOCK) 62 int lutil_lockf ( int fd ) { 63 fd = fd; 64 return 0; 65 } 66 67 int lutil_unlockf ( int fd ) { 68 fd = fd; 69 return 0; 70 } 71 #endif 72 73 #ifdef USE_LOCKF 74 int lutil_lockf ( int fd ) { 75 /* use F_LOCK instead of F_TLOCK, ie: block */ 76 return lockf( fd, F_LOCK, 0 ); 77 } 78 79 int lutil_unlockf ( int fd ) { 80 return lockf( fd, F_ULOCK, 0 ); 81 } 82 #endif 83 84 #ifdef USE_FCNTL 85 int lutil_lockf ( int fd ) { 86 struct flock file_lock; 87 88 memset( &file_lock, '\0', sizeof( file_lock ) ); 89 file_lock.l_type = F_WRLCK; 90 file_lock.l_whence = SEEK_SET; 91 file_lock.l_start = 0; 92 file_lock.l_len = 0; 93 94 /* use F_SETLKW instead of F_SETLK, ie: block */ 95 return( fcntl( fd, F_SETLKW, &file_lock ) ); 96 } 97 98 int lutil_unlockf ( int fd ) { 99 struct flock file_lock; 100 101 memset( &file_lock, '\0', sizeof( file_lock ) ); 102 file_lock.l_type = F_UNLCK; 103 file_lock.l_whence = SEEK_SET; 104 file_lock.l_start = 0; 105 file_lock.l_len = 0; 106 107 return( fcntl ( fd, F_SETLKW, &file_lock ) ); 108 } 109 #endif 110 111 #ifdef USE_FLOCK 112 int lutil_lockf ( int fd ) { 113 /* use LOCK_EX instead of LOCK_EX|LOCK_NB, ie: block */ 114 return flock( fd, LOCK_EX ); 115 } 116 117 int lutil_unlockf ( int fd ) { 118 return flock( fd, LOCK_UN ); 119 } 120 #endif 121