1  /* Copyright (C) 1991-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #ifndef	_SYS_FILE_H
      19  #define	_SYS_FILE_H	1
      20  
      21  #include <features.h>
      22  
      23  #ifndef	_FCNTL_H
      24  # include <fcntl.h>
      25  #endif
      26  
      27  __BEGIN_DECLS
      28  
      29  
      30  /* Alternate names for values for the WHENCE argument to `lseek'.
      31     These are the same as SEEK_SET, SEEK_CUR, and SEEK_END, respectively.  */
      32  #ifndef L_SET
      33  # define L_SET	0	/* Seek from beginning of file.  */
      34  # define L_INCR	1	/* Seek from current position.  */
      35  # define L_XTND	2	/* Seek from end of file.  */
      36  #endif
      37  
      38  
      39  /* Operations for the `flock' call.  */
      40  #define	LOCK_SH	1	/* Shared lock.  */
      41  #define	LOCK_EX	2 	/* Exclusive lock.  */
      42  #define	LOCK_UN	8	/* Unlock.  */
      43  
      44  /* Can be OR'd in to one of the above.  */
      45  #define	LOCK_NB	4	/* Don't block when locking.  */
      46  
      47  
      48  /* Apply or remove an advisory lock, according to OPERATION,
      49     on the file FD refers to.  */
      50  extern int flock (int __fd, int __operation) __THROW;
      51  
      52  
      53  __END_DECLS
      54  
      55  #endif /* sys/file.h  */