glibc/sysdeps/mach/hurd/sigwait.c

/* Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <errno.h>
#include <hurd.h>
#include <hurd/signal.h>
#include <hurd/msg.h>
#include <hurd/sigpreempt.h>
#include <assert.h>

/* Select any of pending signals from SET or wait for any to arrive.  */
int
__sigwait (const sigset_t *set, int *sig)
{
  struct hurd_sigstate *ss;
  sigset_t mask;
  int signo = 0;
  struct hurd_signal_preempter preempter;
  jmp_buf buf;
  mach_port_t wait;
  mach_msg_header_t msg;
  
  sighandler_t
    preempt_fun (struct hurd_signal_preempter *pe,
		 struct hurd_sigstate *ss,
		 int *sigp,
		 struct hurd_signal_detail *detail)
    {
      if (signo)
	/* We've already been run; don't interfere. */
	return SIG_ERR;
      
      signo = *sigp;

      /* Make sure this is all kosher */
      assert (__sigismember (&mask, signo));

      /* Make sure this signal is unblocked */
      __sigdelset (&ss->blocked, signo);

      return pe->handler;
    }
  
  void
    handler (int sig)
    {
      assert (sig == signo);
      longjmp (buf, 1);
    }

  wait = __mach_reply_port ();

  if (set != NULL)
    /* Crash before locking */
    mask = *set;
  
  ss = _hurd_self_sigstate ();
  __spin_lock (&ss->lock);
  
  /* See if one of these signals is currently pending */
  if (ss->pending & mask)
    {
      for (signo = 1; signo < NSIG; signo++)
	if (__sigismember (&ss->pending, signo))
	  {
	    __sigdelset (&ss->pending, signo);
	    goto all_done;
	  }
      /* Huh?  Where'd it go? */
      abort ();
    }

  /* Wait for one of them to show up */
      
  if (!setjmp (buf))
    {
      /* Make the preempter */
      preempter.signals = mask;
      preempter.first = 0;
      preempter.last = -1;
      preempter.preempter = preempt_fun;
      preempter.handler = handler;
  
      /* Install this preempter */
      preempter.next = ss->preempters;
      ss->preempters = &preempter;
  
      __spin_unlock (&ss->lock);
  
      /* Wait. */
      __mach_msg (&msg, MACH_RCV_MSG, 0, sizeof (msg), wait,
		  MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
      abort ();
    }
  else
    {
      assert (signo);

      __spin_lock (&ss->lock);

      /* Delete our preempter. */
      assert (ss->preempters == &preempter);
      ss->preempters = preempter.next;
    }
  

all_done:
  /* Cause the pointless side-effect. */
  __sigfillset (&ss->blocked);
  for (signo = 1; signo < NSIG; signo++)
    if (__sigismember (&mask, signo))
      __sigdelset (&ss->blocked, signo);

  spin_unlock (&ss->lock);

  __mach_port_destroy (__mach_task_self (), wait);
  *sig = signo;
  return 0;
}

weak_alias (__sigwait, sigwait)