sysdeps/mach/hurd/jmp-unwind.c

   1 /* _longjmp_unwind -- Clean up stack frames unwound by longjmp.  Hurd version.
   2    Copyright (C) 1995,1996,2005,2006 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 <jmpbuf-unwind.h>
  21 #include <hurd/userlink.h>
  22 #include <hurd/signal.h>
  23 #include <hurd/sigpreempt.h>
  24 #include <assert.h>
  25 #include <stdint.h>
  26
  27
  28 #ifndef _JMPBUF_UNWINDS
  29 #error "<jmpbuf-unwind.h> fails to define _JMPBUF_UNWINDS"
  30 #endif
  31
  32 static inline uintptr_t
  33 demangle_ptr (uintptr_t x)
  34 {
  35 # ifdef PTR_DEMANGLE
  36   PTR_DEMANGLE (x);
  37 # endif
  38   return x;
  39 }
  40
  41 /* This function is called by `longjmp' (with its arguments) to restore
  42    active resources to a sane state before the frames code using them are
  43    jumped out of.  */
  44
  45 void
  46 _longjmp_unwind (jmp_buf env, int val)
  47 {
  48   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  49   struct hurd_userlink *link;
  50
  51   /* All access to SS->active_resources must take place inside a critical
  52      section where signal handlers cannot run.  */
  53   __spin_lock (&ss->lock);
  54   assert (! __spin_lock_locked (&ss->critical_section_lock));
  55   __spin_lock (&ss->critical_section_lock);
  56
  57   /* Remove local signal preemptors being unwound past.  */
  58   while (ss->preemptors &&
  59          _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors, demangle_ptr))
  60     ss->preemptors = ss->preemptors->next;
  61
  62   __spin_unlock (&ss->lock);
  63
  64   /* Iterate over the current thread's list of active resources.
  65      Process the head portion of the list whose links reside
  66      in stack frames being unwound by this jump.  */
  67
  68   for (link = ss->active_resources;
  69        link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link, demangle_ptr);
  70        link = link->thread.next)
  71     /* Remove this link from the resource's users list,
  72        since the frame using the resource is being unwound.
  73        This call returns nonzero if that was the last user.  */
  74     if (_hurd_userlink_unlink (link))
  75       /* One of the frames being unwound by the longjmp was the last user
  76          of its resource.  Call the cleanup function to deallocate it.  */
  77       (*link->cleanup) (link->cleanup_data, env, val);
  78
  79   _hurd_critical_section_unlock (ss);
  80 }