1/* Special use of signals internally. Linux version.
2 Copyright (C) 2014-2022 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 <signal.h>
23#include <sigsetops.h>
24#include <stdbool.h>
25#include <limits.h>
26#include <stddef.h>
27#include <sysdep.h>
28
29/* The signal used for asynchronous cancelation. */
30#define SIGCANCEL __SIGRTMIN
31
32
33/* Signal needed for the kernel-supported POSIX timer implementation.
34 We can reuse the cancellation signal since we can distinguish
35 cancellation from timer expirations. */
36#define SIGTIMER SIGCANCEL
37
38
39/* Signal used to implement the setuid et.al. functions. */
40#define SIGSETXID (__SIGRTMIN + 1)
41
42
43/* How many signal numbers need to be reserved for libpthread's private uses
44 (SIGCANCEL and SIGSETXID). */
45#define RESERVED_SIGRT 2
46
47
48/* Return is sig is used internally. */
49static inline bool
50__is_internal_signal (int sig)
51{
52 return (sig == SIGCANCEL) || (sig == SIGSETXID);
53}
54
55/* Remove internal glibc signal from the mask. */
56static inline void
57__clear_internal_signals (sigset_t *set)
58{
59 __sigdelset (set, SIGCANCEL);
60 __sigdelset (set, SIGSETXID);
61}
62
63static const sigset_t sigall_set = {
64 .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
65};
66
67static const sigset_t sigtimer_set = {
68 .__val = { [0] = __sigmask (SIGTIMER),
69 [1 ... _SIGSET_NWORDS-1] = 0 }
70};
71
72/* Block all signals, including internal glibc ones. */
73static inline void
74__libc_signal_block_all (sigset_t *set)
75{
76 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, set,
77 __NSIG_BYTES);
78}
79
80/* Block all application signals (excluding internal glibc ones). */
81static inline void
82__libc_signal_block_app (sigset_t *set)
83{
84 sigset_t allset = sigall_set;
85 __clear_internal_signals (&allset);
86 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &allset, set,
87 __NSIG_BYTES);
88}
89
90/* Block only SIGTIMER and return the previous set on SET. */
91static inline void
92__libc_signal_block_sigtimer (sigset_t *set)
93{
94 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigtimer_set, set,
95 __NSIG_BYTES);
96}
97
98/* Unblock only SIGTIMER and return the previous set on SET. */
99static inline void
100__libc_signal_unblock_sigtimer (sigset_t *set)
101{
102 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, set,
103 __NSIG_BYTES);
104}
105
106/* Restore current process signal mask. */
107static inline void
108__libc_signal_restore_set (const sigset_t *set)
109{
110 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
111 __NSIG_BYTES);
112}
113#endif
114