glibc/sysdeps/mach/hurd/sigaction.c

/* Copyright (C) 1991, 92, 93, 94, 95, 96 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 <ansidecl.h>
#include <errno.h>
#include <signal.h>
#include <hurd.h>
#include <hurd/signal.h>

/* If ACT is not NULL, change the action for SIG to *ACT.
   If OACT is not NULL, put the old action for SIG in *OACT.  */
int
DEFUN(__sigaction, (sig, act, oact),
      int sig AND CONST struct sigaction *act AND struct sigaction *oact)
{
  struct hurd_sigstate *ss;
  struct sigaction a, old;
  sigset_t pending;

  if (sig <= 0 || sig >= NSIG ||
      (act != NULL && act->sa_handler != SIG_DFL &&
       ((__sigmask (sig) & _SIG_CANT_MASK) ||
	act->sa_handler == SIG_ERR)))
    {
      errno = EINVAL;
      return -1;
    }

  /* Copy so we fault before taking locks.  */
  if (act != NULL)
    a = *act;

  ss = _hurd_self_sigstate ();

  __spin_lock (&ss->critical_section_lock);
  __spin_lock (&ss->lock);
  old = ss->actions[sig];
  if (act != NULL)
    ss->actions[sig] = a;

  if (act != NULL && sig == SIGCHLD &&
      (a.sa_flags & SA_NOCLDSTOP) != (old.sa_flags & SA_NOCLDSTOP))
    {
      __spin_unlock (&ss->lock);

      /* Inform the proc server whether or not it should send us SIGCHLD for
	 stopped children.  We do this in a critical section so that no
	 SIGCHLD can arrive in the middle and be of indeterminate status.  */
      __USEPORT (PROC,
		 __proc_mod_stopchild (port, !(a.sa_flags & SA_NOCLDSTOP)));

      __spin_lock (&ss->lock);
      pending = ss->pending & ~ss->blocked;
    }
  else if (a.sa_handler == SIG_IGN || a.sa_handler == SIG_DFL)
    /* We are changing to an action that might be to ignore SIG signals.
       If SIG is blocked and pending and the new action is to ignore it, we
       must remove it from the pending set now; if the action is changed
       back and then SIG is unblocked, the signal pending now should not
       arrive.  So wake up the signal thread to check the new state and do
       the right thing.  */
    pending = ss->pending & __sigmask (sig);
  else
    pending = 0;

  __spin_unlock (&ss->lock);
  __spin_unlock (&ss->critical_section_lock);

  if (pending)
    __msg_sig_post (_hurd_msgport, 0, 0, __mach_task_self ());

  if (oact != NULL)
    *oact = old;

  return 0;
}

weak_alias (__sigaction, sigaction)