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 /* 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. */
49 static inline bool
__is_internal_signal(int sig)50 __is_internal_signal (int sig)
51 {
52 return (sig == SIGCANCEL) || (sig == SIGSETXID);
53 }
54
55 /* Remove internal glibc signal from the mask. */
56 static inline void
__clear_internal_signals(sigset_t * set)57 __clear_internal_signals (sigset_t *set)
58 {
59 __sigdelset (set, SIGCANCEL);
60 __sigdelset (set, SIGSETXID);
61 }
62
63 static const sigset_t sigall_set = {
64 .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 }
65 };
66
67 static 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. */
73 static inline void
__libc_signal_block_all(sigset_t * set)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). */
81 static inline void
__libc_signal_block_app(sigset_t * set)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. */
91 static inline void
__libc_signal_block_sigtimer(sigset_t * set)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. */
99 static inline void
__libc_signal_unblock_sigtimer(sigset_t * set)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. */
107 static inline void
__libc_signal_restore_set(const sigset_t * set)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