sysdeps/mach/hurd/jmp-unwind.c

   1 /* _longjmp_unwind -- Clean up stack frames unwound by longjmp.  Hurd version.
   2 Copyright (C) 1995, 1996 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <setjmp.h>
  21 #include <hurd/userlink.h>
  22 #include <hurd/signal.h>
  23 #include <hurd/sigpreempt.h>
  24 #include <assert.h>
  25
  26
  27 #ifndef _JMPBUF_UNWINDS
  28  #error "sysdeps/MACHINE/jmp_buf.h fails to define _JMPBUF_UNWINDS"
  29 #endif
  30
  31 /* This function is called by `longjmp' (with its arguments) to restore
  32    active resources to a sane state before the frames code using them are
  33    jumped out of.  */
  34
  35 void
  36 _longjmp_unwind (jmp_buf env, int val)
  37 {
  38   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  39   struct hurd_userlink *link;
  40
  41   /* All access to SS->active_resources must take place inside a critical
  42      section where signal handlers cannot run.  */
  43   __spin_lock (&ss->lock);
  44   assert (! ss->critical_section);
  45   ss->critical_section = 1;
  46
  47   /* Remove local signal preempters being unwound past.  */
  48   while (ss->preempters &&
  49          _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preempters))
  50     ss->preempters = ss->preempters->next;
  51
  52   __spin_unlock (&ss->lock);
  53
  54   /* Iterate over the current thread's list of active resources.
  55      Process the head portion of the list whose links reside
  56      in stack frames being unwound by this jump.  */
  57
  58   for (link = ss->active_resources;
  59        link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link);
  60        link = link->thread.next)
  61     /* Remove this link from the resource's users list,
  62        since the frame using the resource is being unwound.
  63        This call returns nonzero if that was the last user.  */
  64     if (_hurd_userlink_unlink (link))
  65       /* One of the frames being unwound by the longjmp was the last user
  66          of its resource.  Call the cleanup function to deallocate it.  */
  67       (*link->cleanup) (link->cleanup_data, env, val);
  68
  69   _hurd_critical_section_unlock (ss);
  70 }