/* Convenience function to catch expected signals during an operation.

   Copyright (C) 1996-2018 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 Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <hurd/signal.h>

#include <hurd/sigpreempt.h>

#include <string.h>

#include <assert.h>

error_t

__hurd_catch_signal (sigset_t sigset,

		     unsigned long int first, unsigned long int last,

		     error_t (*operate) (struct hurd_signal_preemptor *),

		     sighandler_t handler)

{

  /* We need to restore the signal mask, because otherwise the

     signal-handling code will have blocked the caught signal and for

     instance calling hurd_catch_signal again would then dump core.  */

  sigjmp_buf buf;

  void throw (int signo, long int sigcode, struct sigcontext *scp)

    { siglongjmp (buf, scp->sc_error ?: EGRATUITOUS); }

  struct hurd_signal_preemptor preemptor =

    {

      sigset, first, last,

      NULL, handler == SIG_ERR ? (sighandler_t) &throw : handler,

    };

  struct hurd_sigstate *const ss = _hurd_self_sigstate ();

  error_t error;

  if (handler != SIG_ERR)

    /* Not our handler; don't bother saving state.  */

    error = 0;

  else

    /* This returns again with nonzero value when we preempt a signal.  */

    error = sigsetjmp (buf, 1);

  if (error == 0)

    {

      /* Install a signal preemptor for the thread.  */

      __spin_lock (&ss->lock);

      preemptor.next = ss->preemptors;

      ss->preemptors = &preemptor;

      __spin_unlock (&ss->lock);

      /* Try the operation that might crash.  */

      (*operate) (&preemptor);

    }

  /* Either FUNCTION completed happily and ERROR is still zero, or it hit

     an expected signal and `throw' made setjmp return the signal error

     code in ERROR.  Now we can remove the preemptor and return.  */

  __spin_lock (&ss->lock);

  assert (ss->preemptors == &preemptor);

  ss->preemptors = preemptor.next;

  __spin_unlock (&ss->lock);

  return error;

}

strong_alias (__hurd_catch_signal, hurd_catch_signal)

error_t

hurd_safe_memset (void *dest, int byte, size_t nbytes)

{

  error_t operate (struct hurd_signal_preemptor *preemptor)

    {

      memset (dest, byte, nbytes);

      return 0;

    }

  return __hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),

			      (vm_address_t) dest, (vm_address_t) dest + nbytes,

			      &operate, SIG_ERR);

}

error_t

hurd_safe_copyout (void *dest, const void *src, size_t nbytes)

{

  error_t operate (struct hurd_signal_preemptor *preemptor)

    {

      memcpy (dest, src, nbytes);

      return 0;

    }

  return __hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),

			      (vm_address_t) dest, (vm_address_t) dest + nbytes,

			      &operate, SIG_ERR);

}

error_t

hurd_safe_copyin (void *dest, const void *src, size_t nbytes)

{

  error_t operate (struct hurd_signal_preemptor *preemptor)

    {

      memcpy (dest, src, nbytes);

      return 0;

    }

  return __hurd_catch_signal (sigmask (SIGBUS) | sigmask (SIGSEGV),

			      (vm_address_t) src, (vm_address_t) src + nbytes,

			      &operate, SIG_ERR);

}

error_t

hurd_safe_memmove (void *dest, const void *src, size_t nbytes)

{

  jmp_buf buf;

  void throw (int signo, long int sigcode, struct sigcontext *scp)

    { longjmp (buf, scp->sc_error ?: EGRATUITOUS); }

  struct hurd_signal_preemptor src_preemptor =

    {

      sigmask (SIGBUS) | sigmask (SIGSEGV),

      (vm_address_t) src, (vm_address_t) src + nbytes,

      NULL, (sighandler_t) &throw,

    };

  struct hurd_signal_preemptor dest_preemptor =

    {

      sigmask (SIGBUS) | sigmask (SIGSEGV),

      (vm_address_t) dest, (vm_address_t) dest + nbytes,

      NULL, (sighandler_t) &throw,

      &src_preemptor

    };

  struct hurd_sigstate *const ss = _hurd_self_sigstate ();

  error_t error;

  /* This returns again with nonzero value when we preempt a signal.  */

  error = setjmp (buf);

  if (error == 0)

    {

      /* Install a signal preemptor for the thread.  */

      __spin_lock (&ss->lock);

      src_preemptor.next = ss->preemptors;

      ss->preemptors = &dest_preemptor;

      __spin_unlock (&ss->lock);

      /* Do the copy; it might fault.  */

      memmove (dest, src, nbytes);

    }

  /* Either memmove completed happily and ERROR is still zero, or it hit

     an expected signal and `throw' made setjmp return the signal error

     code in ERROR.  Now we can remove the preemptor and return.  */

  __spin_lock (&ss->lock);

  assert (ss->preemptors == &dest_preemptor);

  ss->preemptors = src_preemptor.next;

  __spin_unlock (&ss->lock);

  return error;

}