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 <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.  */
  43 static 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.  */
  50 static inline void
  51 __clear_internal_signals (sigset_t *set)
  52 {
  53   __sigdelset (set, SIGCANCEL);
  54   __sigdelset (set, SIGSETXID);
  55 }
  56
  57 static const sigset_t sigall_set = {
  58    .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 }
  59 };
  60
  61 /* Block all signals, including internal glibc ones.  */
  62 static inline void
  63 __libc_signal_block_all (sigset_t *set)
  64 {
  65   INTERNAL_SYSCALL_DECL (err);
  66   INTERNAL_SYSCALL_CALL (rt_sigprocmask, err, SIG_BLOCK, &sigall_set, set,
  67                          _NSIG / 8);
  68 }
  69
  70 /* Block all application signals (excluding internal glibc ones).  */
  71 static inline void
  72 __libc_signal_block_app (sigset_t *set)
  73 {
  74   sigset_t allset = sigall_set;
  75   __clear_internal_signals (&allset);
  76   INTERNAL_SYSCALL_DECL (err);
  77   INTERNAL_SYSCALL_CALL (rt_sigprocmask, err, SIG_BLOCK, &allset, set,
  78                          _NSIG / 8);
  79 }
  80
  81 /* Restore current process signal mask.  */
  82 static inline void
  83 __libc_signal_restore_set (const sigset_t *set)
  84 {
  85   INTERNAL_SYSCALL_DECL (err);
  86   INTERNAL_SYSCALL_CALL (rt_sigprocmask, err, SIG_SETMASK, set, NULL,
  87                          _NSIG / 8);
  88 }
  89
  90 /* Used to communicate with signal handler.  */
  91 extern struct xid_command *__xidcmd attribute_hidden;
  92
  93 #endif