/* _longjmp_unwind -- Clean up stack frames unwound by longjmp.  Hurd version.

   Copyright (C) 1995-2018 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 <jmpbuf-unwind.h>

#include <hurd/userlink.h>

#include <hurd/signal.h>

#include <hurd/sigpreempt.h>

#include <assert.h>

#include <stdint.h>

#ifndef _JMPBUF_UNWINDS

#error "<jmpbuf-unwind.h> fails to define _JMPBUF_UNWINDS"

#endif

static inline uintptr_t

demangle_ptr (uintptr_t x)

{

# ifdef PTR_DEMANGLE

  PTR_DEMANGLE (x);

# endif

  return x;

}

/* This function is called by `longjmp' (with its arguments) to restore

   active resources to a sane state before the frames code using them are

   jumped out of.  */

void

_longjmp_unwind (jmp_buf env, int val)

{

  struct hurd_sigstate *ss = _hurd_self_sigstate ();

  struct hurd_userlink *link;

  /* All access to SS->active_resources must take place inside a critical

     section where signal handlers cannot run.  */

  __spin_lock (&ss->lock);

  assert (! __spin_lock_locked (&ss->critical_section_lock));

  __spin_lock (&ss->critical_section_lock);

  /* Remove local signal preemptors being unwound past.  */

  while (ss->preemptors &&

	 _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors, demangle_ptr))

    ss->preemptors = ss->preemptors->next;

  __spin_unlock (&ss->lock);

  /* Iterate over the current thread's list of active resources.

     Process the head portion of the list whose links reside

     in stack frames being unwound by this jump.  */

  for (link = ss->active_resources;

       link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link, demangle_ptr);

       link = link->thread.next)

    /* Remove this link from the resource's users list,

       since the frame using the resource is being unwound.

       This call returns nonzero if that was the last user.  */

    if (_hurd_userlink_unlink (link))

      /* One of the frames being unwound by the longjmp was the last user

	 of its resource.  Call the cleanup function to deallocate it.  */

      (*link->cleanup) (link->cleanup_data, env, val);

  _hurd_critical_section_unlock (ss);

}