The C and C++ Include Header Files

/usr/include/x86_64-linux-gnu/bits/semaphore.h


$ cat -n /usr/include/x86_64-linux-gnu/bits/semaphore.h

     1	/* Generic POSIX semaphore type layout
     2	   Copyright (C) 1995-2024 Free Software Foundation, Inc.
     3	   This file is part of the GNU C Library.
     4	
     5	   The GNU C Library is free software; you can redistribute it and/or
     6	   modify it under the terms of the GNU Lesser General Public
     7	   License as published by the Free Software Foundation; either
     8	   version 2.1 of the License, or (at your option) any later version.
     9	
    10	   The GNU C Library is distributed in the hope that it will be useful,
    11	   but WITHOUT ANY WARRANTY; without even the implied warranty of
    12	   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13	   Lesser General Public License for more details.
    14	
    15	   You should have received a copy of the GNU Lesser General Public
    16	   License along with the GNU C Library; if not, see
    17	   <https://www.gnu.org/licenses/>.  */
    18	
    19	#ifndef _SEMAPHORE_H
    20	# error "Never use <bits/semaphore.h> directly; include <semaphore.h> instead."
    21	#endif
    22	
    23	#include <bits/wordsize.h>
    24	
    25	#if __WORDSIZE == 64
    26	# define __SIZEOF_SEM_T	32
    27	#else
    28	# define __SIZEOF_SEM_T	16
    29	#endif
    30	
    31	/* Value returned if `sem_open' failed.  */
    32	#define SEM_FAILED      ((sem_t *) 0)
    33	
    34	
    35	typedef union
    36	{
    37	  char __size[__SIZEOF_SEM_T];
    38	  long int __align;
    39	} sem_t;