/* Setup of nscd worker threads.  Linux verison.

   Copyright (C) 2004-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published

   by the Free Software Foundation; version 2 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, see <http://www.gnu.org/licenses/>.  */

#include <string.h>

#include <unistd.h>

#include <nscd.h>

#include <sysdep.h>

int

setup_thread (struct database_dyn *db)

{

#ifdef __NR_set_tid_address

  /* Only supported when NPTL is used.  */

  char buf[100];

  if (confstr (_CS_GNU_LIBPTHREAD_VERSION, buf, sizeof (buf)) >= sizeof (buf)

      || strncmp (buf, "NPTL", 4) != 0)

    return 0;

  /* Do not try this at home, kids.  We play with the SETTID address

     even thought the process is multi-threaded.  This can only work

     since none of the threads ever terminates.  */

  INTERNAL_SYSCALL_DECL (err);

  int r = INTERNAL_SYSCALL (set_tid_address, err, 1,

			    &db->head->nscd_certainly_running);

  if (!INTERNAL_SYSCALL_ERROR_P (r, err))

    /* We know the kernel can reset this field when nscd terminates.

       So, set the field to a nonzero value which indicates that nscd

       is certainly running and clients can skip the test.  */

    return db->head->nscd_certainly_running = 1;

#endif

  return 0;

}