1/* Special use of signals internally. Linux version.
2 Copyright (C) 2014-2023 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 __INTERNAL_SIGNALS_H
20# define __INTERNAL_SIGNALS_H
21
22#include <internal-sigset.h>
23#include <limits.h>
24#include <signal.h>
25#include <sigsetops.h>
26#include <stdbool.h>
27#include <stddef.h>
28#include <sysdep.h>
29
30/* The signal used for asynchronous cancelation. */
31#define SIGCANCEL __SIGRTMIN
32
33
34/* Signal needed for the kernel-supported POSIX timer implementation.
35 We can reuse the cancellation signal since we can distinguish
36 cancellation from timer expirations. */
37#define SIGTIMER SIGCANCEL
38
39
40/* Signal used to implement the setuid et.al. functions. */
41#define SIGSETXID (__SIGRTMIN + 1)
42
43
44/* How many signal numbers need to be reserved for libpthread's private uses
45 (SIGCANCEL and SIGSETXID). */
46#define RESERVED_SIGRT 2
47
48
49/* Return is sig is used internally. */
50static inline bool
51is_internal_signal (int sig)
52{
53 return (sig == SIGCANCEL) || (sig == SIGSETXID);
54}
55
56/* Remove internal glibc signal from the mask. */
57static inline void
58clear_internal_signals (sigset_t *set)
59{
60 __sigdelset (set, SIGCANCEL);
61 __sigdelset (set, SIGSETXID);
62}
63
64static const internal_sigset_t sigall_set = {
65 .__val = {[0 ... __NSIG_WORDS-1 ] = -1 }
66};
67
68/* Obtain and change blocked signals, including internal glibc ones. */
69static inline int
70internal_sigprocmask (int how, const internal_sigset_t *set,
71 internal_sigset_t *oldset)
72{
73 return INTERNAL_SYSCALL_CALL (rt_sigprocmask, how, set, oldset,
74 __NSIG_BYTES);
75}
76
77/* Block all signals, including internal glibc ones. */
78static inline void
79internal_signal_block_all (internal_sigset_t *oset)
80{
81 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, oset,
82 __NSIG_BYTES);
83}
84
85/* Restore current process signal mask. */
86static inline void
87internal_signal_restore_set (const internal_sigset_t *set)
88{
89 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
90 __NSIG_BYTES);
91}
92
93
94/* It is used on timer_create code directly on sigwaitinfo call, so it can not
95 use the internal_sigset_t definitions. */
96static const sigset_t sigtimer_set = {
97 .__val = { [0] = __sigmask (SIGTIMER),
98 [1 ... _SIGSET_NWORDS-1] = 0
99 }
100};
101
102/* Unblock only SIGTIMER. */
103static inline void
104signal_unblock_sigtimer (void)
105{
106 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, NULL,
107 __NSIG_BYTES);
108}
109
110#endif
111