1/* Special use of signals internally. Linux version.
2 Copyright (C) 2014-2020 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 <sysdep.h>
27
28/* The signal used for asynchronous cancelation. */
29#define SIGCANCEL __SIGRTMIN
30
31
32/* Signal needed for the kernel-supported POSIX timer implementation.
33 We can reuse the cancellation signal since we can distinguish
34 cancellation from timer expirations. */
35#define SIGTIMER SIGCANCEL
36
37
38/* Signal used to implement the setuid et.al. functions. */
39#define SIGSETXID (__SIGRTMIN + 1)
40
41
42/* Return is sig is used internally. */
43static inline bool
44__is_internal_signal (int sig)
45{
46 return (sig == SIGCANCEL) || (sig == SIGSETXID);
47}
48
49/* Remove internal glibc signal from the mask. */
50static inline void
51__clear_internal_signals (sigset_t *set)
52{
53 __sigdelset (set, SIGCANCEL);
54 __sigdelset (set, SIGSETXID);
55}
56
57static const sigset_t sigall_set = {
58 .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
59};
60
61static const sigset_t sigtimer_set = {
62 .__val = { [0] = __sigmask (SIGTIMER),
63 [1 ... _SIGSET_NWORDS-1] = 0 }
64};
65
66/* Block all signals, including internal glibc ones. */
67static inline void
68__libc_signal_block_all (sigset_t *set)
69{
70 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, set,
71 __NSIG_BYTES);
72}
73
74/* Block all application signals (excluding internal glibc ones). */
75static inline void
76__libc_signal_block_app (sigset_t *set)
77{
78 sigset_t allset = sigall_set;
79 __clear_internal_signals (&allset);
80 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &allset, set,
81 __NSIG_BYTES);
82}
83
84/* Block only SIGTIMER and return the previous set on SET. */
85static inline void
86__libc_signal_block_sigtimer (sigset_t *set)
87{
88 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigtimer_set, set,
89 __NSIG_BYTES);
90}
91
92/* Unblock only SIGTIMER and return the previous set on SET. */
93static inline void
94__libc_signal_unblock_sigtimer (sigset_t *set)
95{
96 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, set,
97 __NSIG_BYTES);
98}
99
100/* Restore current process signal mask. */
101static inline void
102__libc_signal_restore_set (const sigset_t *set)
103{
104 INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
105 __NSIG_BYTES);
106}
107
108/* Used to communicate with signal handler. */
109extern struct xid_command *__xidcmd attribute_hidden;
110
111#endif
112