--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/vdb-posix.c	Fri Nov 25 01:42:08 2005 +0000
@@ -0,0 +1,153 @@
+/* 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 \
+     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 \
+     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 
+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)
+	signal_name = "SIGBUS";
+      else 
+	ABORT (); /* something weird happened: wrong signal caught */
+      fprintf (stderr, "\n\nFatal Error: Received %s (%d) for address 0x%x\n",
+	       signal_name, signum, (int) 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, sizeof(struct sigaction), 0);
+  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 ();
+    }
+}