1  /* Special use of signals internally.  Linux version.
       2     Copyright (C) 2014-2023 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