sysdeps/unix/sysv/linux/sigsuspend.c

   1 /* Copyright (C) 1996,1997,1998,1999,2000,2002,2003,2006
   2         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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <signal.h>
  21 #include <unistd.h>
  22
  23 #include <sysdep-cancel.h>
  24 #include <sys/syscall.h>
  25 #include <bp-checks.h>
  26
  27 #include <kernel-features.h>
  28
  29
  30 #if !__ASSUME_REALTIME_SIGNALS
  31 /* The variable is shared between all wrappers around signal handling
  32    functions which have RT equivalents.  The definition is in sigaction.c.  */
  33 extern int __libc_missing_rt_sigs;
  34
  35
  36 static int
  37 do_sigsuspend (const sigset_t *set)
  38 {
  39 # ifdef __NR_rt_sigsuspend
  40   /* First try the RT signals.  */
  41   if (!__libc_missing_rt_sigs)
  42     {
  43       /* XXX The size argument hopefully will have to be changed to the
  44          real size of the user-level sigset_t.  */
  45       int saved_errno = errno;
  46       int result = INLINE_SYSCALL (rt_sigsuspend, 2,
  47                                    CHECK_SIGSET (set), _NSIG / 8);
  48       if (result >= 0 || errno != ENOSYS)
  49         return result;
  50
  51       __set_errno (saved_errno);
  52       __libc_missing_rt_sigs = 1;
  53     }
  54 # endif
  55
  56   return INLINE_SYSCALL (sigsuspend, 3, 0, 0, set->__val[0]);
  57 }
  58 #else
  59 static inline int __attribute__ ((always_inline))
  60 do_sigsuspend (const sigset_t *set)
  61 {
  62   return INLINE_SYSCALL (rt_sigsuspend, 2, CHECK_SIGSET (set), _NSIG / 8);
  63 }
  64 #endif
  65
  66 /* Change the set of blocked signals to SET,
  67    wait until a signal arrives, and restore the set of blocked signals.  */
  68 int
  69 __sigsuspend (set)
  70      const sigset_t *set;
  71 {
  72   if (SINGLE_THREAD_P)
  73     return do_sigsuspend (set);
  74
  75   int oldtype = LIBC_CANCEL_ASYNC ();
  76
  77   int result = do_sigsuspend (set);
  78
  79   LIBC_CANCEL_RESET (oldtype);
  80
  81   return result;
  82 }
  83 libc_hidden_def (__sigsuspend)
  84 weak_alias (__sigsuspend, sigsuspend)
  85 strong_alias (__sigsuspend, __libc_sigsuspend)
  86
  87 #ifndef NO_CANCELLATION
  88 int
  89 __sigsuspend_nocancel (set)
  90      const sigset_t *set;
  91 {
  92   return do_sigsuspend (set);
  93 }
  94 #endif