sysdeps/unix/sysv/linux/internal-signals.h

   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 <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.  */
  44 static 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.  */
  51 static inline void
  52 __clear_internal_signals (sigset_t *set)
  53 {
  54   __sigdelset (set, SIGCANCEL);
  55   __sigdelset (set, SIGSETXID);
  56 }
  57
  58 static const sigset_t sigall_set = {
  59    .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 }
  60 };
  61
  62 static 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.  */
  68 static 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).  */
  76 static 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.  */
  86 static 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.  */
  94 static 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.  */
 102 static 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.  */
 110 extern struct xid_command *__xidcmd attribute_hidden;
 111
 112 #endif