glibc (2.38)

(root)/
include/
bits/
unistd_ext.h
       1  /* System-specific extensions of <unistd.h>, Linux version.
       2     Copyright (C) 2019-2023 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.  */
      34  extern __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  */