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+ − 1 /* Virtual diry bit implementation for XEmacs.
+ − 2 Copyright (C) 2005 Marcus Crestani.
+ − 3
+ − 4 This file is part of XEmacs.
+ − 5
+ − 6 XEmacs is free software; you can redistribute it and/or modify it
+ − 7 under the terms of the GNU General Public License as published by the
+ − 8 Free Software Foundation; either version 2, or (at your option) any
+ − 9 later version.
+ − 10
+ − 11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ − 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ − 13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ − 14 for more details.
+ − 15
+ − 16 You should have received a copy of the GNU General Public License
+ − 17 along with XEmacs; see the file COPYING. If not, write to
+ − 18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ − 19 Boston, MA 02111-1307, USA. */
+ − 20
+ − 21 /* Synched up with: Not in FSF. */
+ − 22
+ − 23 #include <config.h>
+ − 24 #include "lisp.h"
+ − 25 #include "gc.h"
+ − 26 #include "mc-alloc.h"
+ − 27 #include "vdb.h"
+ − 28
+ − 29 #include <errno.h>
+ − 30 #include <signal.h>
+ − 31 #include <sys/mman.h>
+ − 32
+ − 33 #if defined (HAVE_SIGACTION)
+ − 34 # if defined (HAVE_STRUCT_SIGINFO_SI_ADDR)
+ − 35 # define FAULT_HANDLER_ARGUMENTS \
+ − 36 int signum, struct siginfo *siginfo, void *UNUSED (ctx)
+ − 37 # define GET_FAULT_ADDRESS siginfo->si_addr
+ − 38 # elif defined (HAVE_SIGINFO_T_SI_ADDR)
+ − 39 # define FAULT_HANDLER_ARGUMENTS \
+ − 40 int signum, siginfo_t *siginfo, void *UNUSED (ctx)
+ − 41 # define GET_FAULT_ADDRESS siginfo->si_addr
+ − 42 # endif
+ − 43 # define USE_SIGACTION
+ − 44 # define FAULT_HANDLER_REMOVE_HANDLER
+ − 45 #elif defined (HAVE_SIGNAL)
+ − 46 # define FAULT_HANDLER_ARGUMENTS int signum, struct sigcontext sc
+ − 47 # define GET_FAULT_ADDRESS (void *) sc.cr2
+ − 48 # define USE_SIGNAL
+ − 49 #endif
+ − 50
+ − 51
+ − 52 #ifdef USE_SIGACTION
+ − 53 struct sigaction act, segv_oact, bus_oact;
+ − 54 #endif /* USE_SIGACTION */
+ − 55
+ − 56 #ifdef USE_SIGNAL
+ − 57 sighandler_t segv_oact, bus_oact;
+ − 58 #endif /* USE_SIGNAL */
+ − 59
+ − 60 void vdb_remove_signal_handler (void);
+ − 61
+ − 62 void
+ − 63 vdb_fault_handler (FAULT_HANDLER_ARGUMENTS)
+ − 64 {
+ − 65 if (write_barrier_enabled
+ − 66 && (fault_on_protected_page (GET_FAULT_ADDRESS)))
+ − 67 {
+ − 68 vdb_designate_modified (GET_FAULT_ADDRESS);
+ − 69 unprotect_page_and_mark_dirty (GET_FAULT_ADDRESS);
+ − 70 #ifdef FAULT_HANDLER_REINSTALL_HANDLER
+ − 71 vdb_install_signal_handler ();
+ − 72 #endif /* FAULT_HANDLER_REINSTALL_HANDLER */
+ − 73 }
+ − 74 else /* default sigsegv handler */
+ − 75 {
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+ − 76 char *signal_name = "";
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+ − 77 if (signum == SIGSEGV)
+ − 78 signal_name = "SIGSEGV";
+ − 79 else if (signum == SIGBUS)
+ − 80 signal_name = "SIGBUS";
+ − 81 else
+ − 82 ABORT (); /* something weird happened: wrong signal caught */
3519
+ − 83 fprintf (stderr, "\n\nFatal Error: Received %s (%d) for address %p\n",
+ − 84 signal_name, signum, (void *) GET_FAULT_ADDRESS);
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+ − 85 #ifdef FAULT_HANDLER_CALL_PREVIOUS_HANDLER
+ − 86 if (signum == SIGSEGV)
+ − 87 segv_oact (signum);
+ − 88 else if (signum == SIGBUS)
+ − 89 bus_oact (signum);
+ − 90 #endif /* FAULT_HANDLER_CALL_PREVIOUS_HANDLER */
+ − 91 #ifdef FAULT_HANDLER_REMOVE_HANDLER
+ − 92 vdb_remove_signal_handler ();
+ − 93 #endif /* FAULT_HANDLER_REMOVE_HANDLER */
+ − 94 }
+ − 95 }
+ − 96
+ − 97 void
+ − 98 vdb_remove_signal_handler (void)
+ − 99 {
+ − 100 #ifdef USE_SIGACTION
+ − 101 sigaction(SIGSEGV, &segv_oact, 0);
+ − 102 sigaction(SIGBUS, &bus_oact, 0);
+ − 103 #endif /* USE_SIGACTION */
+ − 104 #ifdef USE_SIGNAL
+ − 105 signal (SIGSEGV, segv_oact);
+ − 106 signal (SIGBUS, bus_oact);
+ − 107 #endif
+ − 108 }
+ − 109
+ − 110 void
+ − 111 vdb_install_signal_handler (void)
+ − 112 {
+ − 113 /* See init_signals_very_early () in signal.c. */
+ − 114 if (noninteractive && !initialized)
+ − 115 {
+ − 116 allow_incremental_gc = 0;
+ − 117 return;
+ − 118 }
+ − 119
+ − 120 #ifdef USE_SIGACTION
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+ − 121 memset(&act, 0, sizeof(struct sigaction));
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+ − 122 act.sa_sigaction = vdb_fault_handler;
+ − 123 sigemptyset (&act.sa_mask);
+ − 124 act.sa_flags = SA_SIGINFO;
+ − 125 sigaction (SIGSEGV, &act, &segv_oact);
+ − 126 sigaction (SIGBUS, &act, &bus_oact);
+ − 127 allow_incremental_gc = 1;
+ − 128 #endif /* USE_SIGACTION */
+ − 129 #ifdef USE_SIGNAL
+ − 130 segv_oact = signal (SIGSEGV, (void (*)(int)) vdb_fault_handler);
+ − 131 bus_oact = signal (SIGBUS, (void (*)(int)) vdb_fault_handler);
+ − 132 #endif /* USE_SIGNAL */
+ − 133 }
+ − 134
+ − 135 void
+ − 136 vdb_protect (void *ptr, EMACS_INT len)
+ − 137 {
+ − 138 if (mprotect (ptr, len, PROT_READ))
+ − 139 {
+ − 140 perror ("Couldn't mprotect");
+ − 141 ABORT ();
+ − 142 }
+ − 143 }
+ − 144
+ − 145 void
+ − 146 vdb_unprotect (void *ptr, EMACS_INT len)
+ − 147 {
+ − 148 if (mprotect (ptr, len, PROT_READ | PROT_WRITE))
+ − 149 {
+ − 150 perror ("Couldn't mprotect");
+ − 151 ABORT ();
+ − 152 }
+ − 153 }
