1/* Setup of nscd worker threads. Linux verison.
2 Copyright (C) 2004-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <https://www.gnu.org/licenses/>. */
18
19#include <string.h>
20#include <unistd.h>
21#include <nscd.h>
22#include <sysdep.h>
23
24
25int
26setup_thread (struct database_dyn *db)
27{
28 /* Only supported when NPTL is used. */
29 char buf[100];
30 if (confstr (_CS_GNU_LIBPTHREAD_VERSION, buf, sizeof (buf)) >= sizeof (buf)
31 || strncmp (buf, "NPTL", 4) != 0)
32 return 0;
33
34 /* Do not try this at home, kids. We play with the SETTID address
35 even thought the process is multi-threaded. This can only work
36 since none of the threads ever terminates. */
37 int r = INTERNAL_SYSCALL_CALL (set_tid_address,
38 &db->head->nscd_certainly_running);
39 if (!INTERNAL_SYSCALL_ERROR_P (r))
40 /* We know the kernel can reset this field when nscd terminates.
41 So, set the field to a nonzero value which indicates that nscd
42 is certainly running and clients can skip the test. */
43 return db->head->nscd_certainly_running = 1;
44
45 return 0;
46}
47