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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 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 "<bits/setjmp.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 (! __spin_lock_locked (&ss->critical_section_lock));
  45   __spin_lock (&ss->critical_section_lock);
  46
  47   /* Remove local signal preemptors being unwound past.  */
  48   while (ss->preemptors &&
  49          _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors))
  50     ss->preemptors = ss->preemptors->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 }