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/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
* Copyright 1998-2021 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*/
/*
* File Locking Routines
*
* Implementations (in order of preference)
* - lockf
* - fcntl
* - flock
*
* Other implementations will be added as needed.
*
* NOTE: lutil_lockf() MUST block until an exclusive lock is acquired.
*/
#include "portable.h"
#include <stdio.h>
#include <ac/unistd.h>
#undef LOCK_API
#if defined(HAVE_LOCKF) && defined(F_LOCK)
# define USE_LOCKF 1
# define LOCK_API "lockf"
#endif
#if !defined(LOCK_API) && defined(HAVE_FCNTL)
# ifdef HAVE_FCNTL_H
# include <fcntl.h>
# endif
# ifdef F_WRLCK
# define USE_FCNTL 1
# define LOCK_API "fcntl"
# endif
#endif
#if !defined(LOCK_API) && defined(HAVE_FLOCK)
# ifdef HAVE_SYS_FILE_H
# include <sys/file.h>
# endif
# define USE_FLOCK 1
# define LOCK_API "flock"
#endif
#if !defined(USE_LOCKF) && !defined(USE_FCNTL) && !defined(USE_FLOCK)
int lutil_lockf ( int fd ) {
fd = fd;
return 0;
}
int lutil_unlockf ( int fd ) {
fd = fd;
return 0;
}
#endif
#ifdef USE_LOCKF
int lutil_lockf ( int fd ) {
/* use F_LOCK instead of F_TLOCK, ie: block */
return lockf( fd, F_LOCK, 0 );
}
int lutil_unlockf ( int fd ) {
return lockf( fd, F_ULOCK, 0 );
}
#endif
#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_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 );
}
int lutil_unlockf ( int fd ) {
return flock( fd, LOCK_UN );
}
#endif
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