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/* Setup of nscd worker threads. Linux verison.
Copyright (C) 2004-2019 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 <https://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;
}
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