1/* System-specific extensions of <unistd.h>, Linux version.
 2   Copyright (C) 2019-2025 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 _UNISTD_H
20# error "Never include <bits/unistd_ext.h> directly; use <unistd.h> instead."
21#endif
22
23#ifdef __USE_GNU
24
25/* Return the kernel thread ID (TID) of the current thread.  The
26   returned value is not subject to caching.  Most Linux system calls
27   accept a TID in place of a PID.  Using the TID to change properties
28   of a thread that has been created using pthread_create can lead to
29   undefined behavior (comparable to manipulating file descriptors
30   directly that have not been created explicitly).  Note that a TID
31   uniquely identifies a thread only while this thread is running; a
32   TID can be reused once a thread has exited, even if the thread is
33   not detached and has not been joined.  */
34extern __pid_t gettid (void) __THROW;
35
36#ifdef __has_include
37# if __has_include ("linux/close_range.h")
38#  include "linux/close_range.h"
39# endif
40#endif
41/* Unshare the file descriptor table before closing file descriptors.  */
42#ifndef CLOSE_RANGE_UNSHARE
43# define CLOSE_RANGE_UNSHARE (1U << 1)
44#endif
45/* Set the FD_CLOEXEC bit instead of closing the file descriptor.  */
46#ifndef CLOSE_RANGE_CLOEXEC
47# define CLOSE_RANGE_CLOEXEC (1U << 2)
48#endif
49
50#endif /* __USE_GNU  */