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The C and C++ Include Header Files

cat -n /usr/include/x86_64-linux-gnu/bits/openat2.h

     1	/* openat2 definition.  Linux specific.
     2	   Copyright (C) 2025-2026 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 _FCNTL_H
    20	# error "Never use <bits/openat2.h> directly; include <fcntl.h> instead."
    21	#endif
    22	
    23	#ifndef __glibc_has_open_how
    24	/* Arguments for how openat2 should open the target path.  */
    25	struct open_how
    26	{
    27	  __uint64_t flags;
    28	  __uint64_t mode;
    29	  __uint64_t resolve;
    30	};
    31	#endif
    32	
    33	/* how->resolve flags for openat2. */
    34	#ifndef RESOLVE_NO_XDEV
    35	# define RESOLVE_NO_XDEV	0x01 /* Block mount-point crossings
    36						(includes bind-mounts).  */
    37	#endif
    38	#ifndef RESOLVE_NO_MAGICLINKS
    39	# define RESOLVE_NO_MAGICLINKS	0x02 /* Block traversal through procfs-style
    40						"magic-links".  */
    41	#endif
    42	#ifndef RESOLVE_NO_SYMLINKS
    43	# define RESOLVE_NO_SYMLINKS	0x04 /* Block traversal through all symlinks.  */
    44	#endif
    45	#ifndef RESOLVE_BENEATH
    46	# define RESOLVE_BENEATH	0x08 /* Block "lexical" trickery like
    47						"..", symlinks, and absolute
    48						paths which escape the dirfd.  */
    49	#endif
    50	#ifndef RESOLVE_IN_ROOT
    51	# define RESOLVE_IN_ROOT	0x10 /* Make all jumps to "/" and ".."
    52						be scoped inside the dirfd
    53						(similar to chroot).  */
    54	#endif
    55	#ifndef RESOLVE_CACHED
    56	# define RESOLVE_CACHED		0x20 /* Only complete if resolution can be
    57						completed through cached lookup. May
    58						return -EAGAIN if that's not
    59						possible.  */
    60	#endif