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

   1 /* Special use of signals internally.  Linux version.
   2    Copyright (C) 2014-2022 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 <internal-sigset.h>
  23 #include <limits.h>
  24 #include <signal.h>
  25 #include <sigsetops.h>
  26 #include <stdbool.h>
  27 #include <stddef.h>
  28 #include <sysdep.h>
  29
  30 /* The signal used for asynchronous cancelation.  */
  31 #define SIGCANCEL       __SIGRTMIN
  32
  33
  34 /* Signal needed for the kernel-supported POSIX timer implementation.
  35    We can reuse the cancellation signal since we can distinguish
  36    cancellation from timer expirations.  */
  37 #define SIGTIMER        SIGCANCEL
  38
  39
  40 /* Signal used to implement the setuid et.al. functions.  */
  41 #define SIGSETXID       (__SIGRTMIN + 1)
  42
  43
  44 /* How many signal numbers need to be reserved for libpthread's private uses
  45    (SIGCANCEL and SIGSETXID).  */
  46 #define RESERVED_SIGRT  2
  47
  48
  49 /* Return is sig is used internally.  */
  50 static inline bool
  51 is_internal_signal (int sig)
  52 {
  53   return (sig == SIGCANCEL) || (sig == SIGSETXID);
  54 }
  55
  56 /* Remove internal glibc signal from the mask.  */
  57 static inline void
  58 clear_internal_signals (sigset_t *set)
  59 {
  60   __sigdelset (set, SIGCANCEL);
  61   __sigdelset (set, SIGSETXID);
  62 }
  63
  64 static const internal_sigset_t sigall_set = {
  65    .__val = {[0 ...  __NSIG_WORDS-1 ] =  -1 }
  66 };
  67
  68 /* Obtain and change blocked signals, including internal glibc ones.  */
  69 static inline int
  70 internal_sigprocmask (int how, const internal_sigset_t *set,
  71                       internal_sigset_t *oldset)
  72 {
  73   return INTERNAL_SYSCALL_CALL (rt_sigprocmask, how, set, oldset,
  74                                 __NSIG_BYTES);
  75 }
  76
  77 /* Block all signals, including internal glibc ones.  */
  78 static inline void
  79 internal_signal_block_all (internal_sigset_t *oset)
  80 {
  81   INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_BLOCK, &sigall_set, oset,
  82                          __NSIG_BYTES);
  83 }
  84
  85 /* Restore current process signal mask.  */
  86 static inline void
  87 internal_signal_restore_set (const internal_sigset_t *set)
  88 {
  89   INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_SETMASK, set, NULL,
  90                          __NSIG_BYTES);
  91 }
  92
  93
  94 /* It is used on timer_create code directly on sigwaitinfo call, so it can not
  95    use the internal_sigset_t definitions.  */
  96 static const sigset_t sigtimer_set = {
  97   .__val = { [0]                      = __sigmask (SIGTIMER),
  98              [1 ... _SIGSET_NWORDS-1] = 0
  99   }
 100 };
 101
 102 /* Unblock only SIGTIMER.  */
 103 static inline void
 104 signal_unblock_sigtimer (void)
 105 {
 106   INTERNAL_SYSCALL_CALL (rt_sigprocmask, SIG_UNBLOCK, &sigtimer_set, NULL,
 107                          __NSIG_BYTES);
 108 }
 109
 110 #endif