1/* System-specific extensions of <unistd.h>, Linux version.
2 Copyright (C) 2019-2020 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#endif
37