1/* Special use of signals internally. Linux version.
2 Copyright (C) 2014-2021 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/* Return is sig is used internally. */
44static inline bool
45__is_internal_signal (int sig)
46{
47 return (sig == SIGCANCEL) || (sig == SIGSETXID);
48}
49
50/* Remove internal glibc signal from the mask. */
51static inline void
52__clear_internal_signals (sigset_t *set)
53{
54 __sigdelset (set, SIGCANCEL);
55 __sigdelset (set, SIGSETXID);
56}
57
58static const sigset_t sigall_set = {
59 .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
60};
61
62static const sigset_t sigtimer_set = {
63 .__val = { [0] = __sigmask (SIGTIMER),
64 [1 ... _SIGSET_NWORDS-1] = 0 }
65};
66
67/* Block all signals, including internal glibc ones. */
68static inline void
69__libc_signal_block_all (sigset_t *set)
70{
71 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, set,
72 __NSIG_BYTES);
73}
74
75/* Block all application signals (excluding internal glibc ones). */
76static inline void
77__libc_signal_block_app (sigset_t *set)
78{
79 sigset_t allset = sigall_set;
80 __clear_internal_signals (&allset);
81 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &allset, set,
82 __NSIG_BYTES);
83}
84
85/* Block only SIGTIMER and return the previous set on SET. */
86static inline void
87__libc_signal_block_sigtimer (sigset_t *set)
88{
89 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigtimer_set, set,
90 __NSIG_BYTES);
91}
92
93/* Unblock only SIGTIMER and return the previous set on SET. */
94static inline void
95__libc_signal_unblock_sigtimer (sigset_t *set)
96{
97 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, set,
98 __NSIG_BYTES);
99}
100
101/* Restore current process signal mask. */
102static inline void
103__libc_signal_restore_set (const sigset_t *set)
104{
105 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
106 __NSIG_BYTES);
107}
108
109/* Used to communicate with signal handler. */
110extern struct xid_command *__xidcmd attribute_hidden;
111
112#endif
113