1/* Setup of nscd worker threads. Linux verison.
2 Copyright (C) 2004-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; version 2 of the License, or
8 (at your option) any later version.
9
10 This program 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
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <https://www.gnu.org/licenses/>. */
17
18#include <string.h>
19#include <unistd.h>
20#include <nscd.h>
21#include <sysdep.h>
22
23
24int
25setup_thread (struct database_dyn *db)
26{
27 /* Only supported when NPTL is used. */
28 char buf[100];
29 if (confstr (_CS_GNU_LIBPTHREAD_VERSION, buf, sizeof (buf)) >= sizeof (buf)
30 || strncmp (buf, "NPTL", 4) != 0)
31 return 0;
32
33 /* Do not try this at home, kids. We play with the SETTID address
34 even thought the process is multi-threaded. This can only work
35 since none of the threads ever terminates. */
36 int r = INTERNAL_SYSCALL_CALL (set_tid_address,
37 &db->head->nscd_certainly_running);
38 if (!INTERNAL_SYSCALL_ERROR_P (r))
39 /* We know the kernel can reset this field when nscd terminates.
40 So, set the field to a nonzero value which indicates that nscd
41 is certainly running and clients can skip the test. */
42 return db->head->nscd_certainly_running = 1;
43
44 return 0;
45}
46