sysdeps/mach/hurd/jmp-unwind.c

   1 /* _longjmp_unwind -- Clean up stack frames unwound by longjmp.  Hurd version.
   2 Copyright (C) 1995 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/signal.h>
  22 #include <hurd/userlink.h>
  23 #include <assert.h>
  24
  25 /* This function is called by `longjmp' (with its arguments) to restore
  26    active resources to a sane state before the frames code using them are
  27    jumped out of.  */
  28
  29 void
  30 _longjmp_unwind (jmp_buf env, int val)
  31 {
  32   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  33   struct hurd_userlink *link;
  34
  35   /* All access to SS->active_resources must take place inside a critical
  36      section where signal handlers cannot run.  */
  37   __spin_lock (&ss->lock);
  38   assert (! ss->critical_section);
  39   ss->critical_section = 1;
  40   __spin_unlock (&ss->lock);
  41
  42 #ifndef _JMPBUF_UNWINDS
  43  #error "sysdeps/MACHINE/jmp_buf.h fails to define _JMPBUF_UNWINDS"
  44 #endif
  45
  46   /* Iterate over the current thread's list of active resources.
  47      Process the head portion of the list whose links reside
  48      in stack frames being unwound by this jump.  */
  49
  50   for (link = ss->active_resources;
  51        link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link);
  52        link = link->thread.next)
  53     /* Remove this link from the resource's users list,
  54        since the frame using the resource is being unwound.
  55        This call returns nonzero if that was the last user.  */
  56     if (_hurd_userlink_unlink (link))
  57       /* One of the frames being unwound by the longjmp was the last user
  58          of its resource.  Call the cleanup function to deallocate it.  */
  59       (*link->cleanup) (link->cleanup_data, env, val);
  60
  61   _hurd_critical_section_unlock (ss);
  62 }