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

   1 /* Special use of signals internally.  Linux version.
   2    Copyright (C) 2014-2019 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 <sysdep.h>
  26
  27 /* The signal used for asynchronous cancelation.  */
  28 #define SIGCANCEL       __SIGRTMIN
  29
  30
  31 /* Signal needed for the kernel-supported POSIX timer implementation.
  32    We can reuse the cancellation signal since we can distinguish
  33    cancellation from timer expirations.  */
  34 #define SIGTIMER        SIGCANCEL
  35
  36
  37 /* Signal used to implement the setuid et.al. functions.  */
  38 #define SIGSETXID       (__SIGRTMIN + 1)
  39
  40
  41 /* Return is sig is used internally.  */
  42 static inline bool
  43 __is_internal_signal (int sig)
  44 {
  45   return (sig == SIGCANCEL) || (sig == SIGSETXID);
  46 }
  47
  48 /* Remove internal glibc signal from the mask.  */
  49 static inline void
  50 __clear_internal_signals (sigset_t *set)
  51 {
  52   __sigdelset (set, SIGCANCEL);
  53   __sigdelset (set, SIGSETXID);
  54 }
  55
  56 #define SIGALL_SET \
  57   ((__sigset_t) { .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 } })
  58
  59 /* Block all signals, including internal glibc ones.  */
  60 static inline int
  61 __libc_signal_block_all (sigset_t *set)
  62 {
  63   INTERNAL_SYSCALL_DECL (err);
  64   return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
  65                            set, _NSIG / 8);
  66 }
  67
  68 /* Block all application signals (excluding internal glibc ones).  */
  69 static inline int
  70 __libc_signal_block_app (sigset_t *set)
  71 {
  72   sigset_t allset = SIGALL_SET;
  73   __clear_internal_signals (&allset);
  74   INTERNAL_SYSCALL_DECL (err);
  75   return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
  76                            _NSIG / 8);
  77 }
  78
  79 /* Restore current process signal mask.  */
  80 static inline int
  81 __libc_signal_restore_set (const sigset_t *set)
  82 {
  83   INTERNAL_SYSCALL_DECL (err);
  84   return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, set, NULL,
  85                            _NSIG / 8);
  86 }
  87
  88 /* Used to communicate with signal handler.  */
  89 extern struct xid_command *__xidcmd attribute_hidden;
  90
  91 #endif