+
−/* Virtual diry bit implementation for XEmacs.
+
−   Copyright (C) 2005 Marcus Crestani.
+
−
+
−This file is part of XEmacs.
+
−
+
−XEmacs is free software; you can redistribute it and/or modify it
+
−under the terms of the GNU General Public License as published by the
+
−Free Software Foundation; either version 2, or (at your option) any
+
−later version.
+
−
+
−XEmacs 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 General Public License
+
−for more details.
+
−
+
−You should have received a copy of the GNU General Public License
+
−along with XEmacs; see the file COPYING.  If not, write to
+
−the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+
−Boston, MA 02111-1307, USA.  */
+
−
+
−/* Synched up with: Not in FSF. */
+
−
+
−#include <config.h>
+
−#include "lisp.h"
+
−#include "gc.h"
+
−#include "mc-alloc.h"
+
−#include "vdb.h"
+
−
+
−#include <errno.h>
+
−#include <signal.h>
+
−#include <sys/mman.h>
+
−
+
−#if defined (HAVE_SIGACTION)
+
−# if defined (HAVE_STRUCT_SIGINFO_SI_ADDR)
+
−#  define FAULT_HANDLER_ARGUMENTS \
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−     int signum, struct siginfo *siginfo, void *UNUSED (ctx)
+
−#  define GET_FAULT_ADDRESS siginfo->si_addr
+
−# elif defined (HAVE_SIGINFO_T_SI_ADDR)
+
−#  define FAULT_HANDLER_ARGUMENTS \
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−     int signum, siginfo_t *siginfo, void *UNUSED (ctx)
+
−#  define GET_FAULT_ADDRESS siginfo->si_addr
+
−# endif
+
−# define USE_SIGACTION
+
−# define FAULT_HANDLER_REMOVE_HANDLER
+
−#elif defined (HAVE_SIGNAL)
+
−# define FAULT_HANDLER_ARGUMENTS int signum, struct sigcontext sc
+
−# define GET_FAULT_ADDRESS (void *) sc.cr2
+
−# define USE_SIGNAL
+
−#endif
+
−
+
−
+
−#ifdef USE_SIGACTION
+
−struct sigaction act, segv_oact, bus_oact;
+
−#endif /* USE_SIGACTION */
+
−
+
−#ifdef USE_SIGNAL
+
−sighandler_t segv_oact, bus_oact;
+
−#endif /* USE_SIGNAL */
+
−
+
−void vdb_remove_signal_handler (void);
+
−
+
−void 
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−vdb_fault_handler (FAULT_HANDLER_ARGUMENTS)
+
−{
+
−  if (write_barrier_enabled
+
−      && (fault_on_protected_page (GET_FAULT_ADDRESS)))
+
−    {
+
−      vdb_designate_modified (GET_FAULT_ADDRESS);
+
−      unprotect_page_and_mark_dirty (GET_FAULT_ADDRESS);
+
−#ifdef FAULT_HANDLER_REINSTALL_HANDLER
+
−      vdb_install_signal_handler ();
+
−#endif /* FAULT_HANDLER_REINSTALL_HANDLER */
+
−    }
+
−  else  /* default sigsegv handler */
+
−    {
+
−      char *signal_name = "";
+
−      if (signum == SIGSEGV)
+
−	signal_name = "SIGSEGV";
+
−      else if (signum == SIGBUS)
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−	signal_name = "SIGBUS";
+
−      else 
+
−	ABORT (); /* something weird happened: wrong signal caught */
+
−      fprintf (stderr, "\n\nFatal Error: Received %s (%d) for address %p\n",
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−	       signal_name, signum, (void *) GET_FAULT_ADDRESS);
+
−#ifdef FAULT_HANDLER_CALL_PREVIOUS_HANDLER
+
−      if (signum == SIGSEGV)
+
−	segv_oact (signum);
+
−      else if (signum == SIGBUS)
+
−	bus_oact (signum);
+
−#endif /* FAULT_HANDLER_CALL_PREVIOUS_HANDLER */
+
−#ifdef FAULT_HANDLER_REMOVE_HANDLER
+
−      vdb_remove_signal_handler ();
+
−#endif /* FAULT_HANDLER_REMOVE_HANDLER */
+
−    }
+
−}
+
−
+
−void 
+
−vdb_remove_signal_handler (void)
+
−{
+
−#ifdef USE_SIGACTION
+
−  sigaction(SIGSEGV, &segv_oact, 0);
+
−  sigaction(SIGBUS, &bus_oact, 0);
+
−#endif /* USE_SIGACTION */
+
−#ifdef USE_SIGNAL
+
−  signal (SIGSEGV, segv_oact);
+
−  signal (SIGBUS, bus_oact);
+
−#endif
+
−}
+
−
+
−void
+
−vdb_install_signal_handler (void)
+
−{
+
−  /* See init_signals_very_early () in signal.c. */
+
−  if (noninteractive && !initialized)
+
−    {
+
−      allow_incremental_gc = 0;
+
−      return;
+
−    }
+
−
+
−#ifdef USE_SIGACTION
+
−  memset(&act, 0, sizeof(struct sigaction));
+
−  act.sa_sigaction = vdb_fault_handler;
+
−  sigemptyset (&act.sa_mask);
+
−  act.sa_flags = SA_SIGINFO;
+
−  sigaction (SIGSEGV, &act, &segv_oact);
+
−  sigaction (SIGBUS, &act, &bus_oact);
+
−  allow_incremental_gc = 1;
+
−#endif /* USE_SIGACTION */
+
−#ifdef USE_SIGNAL
+
−  segv_oact = signal (SIGSEGV, (void (*)(int)) vdb_fault_handler);
+
−  bus_oact = signal (SIGBUS, (void (*)(int)) vdb_fault_handler);
+
−#endif /* USE_SIGNAL */
+
−}
+
−
+
−void
+
−vdb_protect (void *ptr, EMACS_INT len)
+
−{
+
−  if (mprotect (ptr, len, PROT_READ))
+
−    {
+
−      perror ("Couldn't mprotect");
+
−      ABORT ();
+
−    }
+
−}
+
−
+
−void
+
−vdb_unprotect (void *ptr, EMACS_INT len)
+
−{
+
−  if (mprotect (ptr, len, PROT_READ | PROT_WRITE))
+
−    {
+
−      perror ("Couldn't mprotect");
+
−      ABORT ();
+
−    }
+
−}