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[EDIT] FILE: file.h

/* Copyright (C) 1991-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef	_SYS_FILE_H
#define	_SYS_FILE_H	1

#include <features.h>

#ifndef	_FCNTL_H
# include <fcntl.h>
#endif

__BEGIN_DECLS

/* Alternate names for values for the WHENCE argument to `lseek'.
   These are the same as SEEK_SET, SEEK_CUR, and SEEK_END, respectively.  */
#ifndef L_SET
# define L_SET	0	/* Seek from beginning of file.  */
# define L_INCR	1	/* Seek from current position.  */
# define L_XTND	2	/* Seek from end of file.  */
#endif

/* Operations for the `flock' call.  */
#define	LOCK_SH	1	/* Shared lock.  */
#define	LOCK_EX	2 	/* Exclusive lock.  */
#define	LOCK_UN	8	/* Unlock.  */

/* Can be OR'd in to one of the above.  */
#define	LOCK_NB	4	/* Don't block when locking.  */

/* Apply or remove an advisory lock, according to OPERATION,
   on the file FD refers to.  */
extern int flock (int __fd, int __operation) __THROW;

__END_DECLS

#endif /* sys/file.h  */

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