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/*
* Copyright © 2013 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif
#include <X11/Xos.h>
#include <X11/Xdefs.h>
#include "misc.h"
#include <busfault.h>
#include <list.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/mman.h>
#include <signal.h>
struct busfault {
struct xorg_list list;
void *addr;
size_t size;
Bool valid;
busfault_notify_ptr notify;
void *context;
};
static Bool busfaulted;
static struct xorg_list busfaults;
struct busfault *
busfault_register_mmap(void *addr, size_t size, busfault_notify_ptr notify, void *context)
{
struct busfault *busfault;
busfault = calloc(1, sizeof (struct busfault));
if (!busfault)
return NULL;
busfault->addr = addr;
busfault->size = size;
busfault->notify = notify;
busfault->context = context;
busfault->valid = TRUE;
xorg_list_add(&busfault->list, &busfaults);
return busfault;
}
void
busfault_unregister(struct busfault *busfault)
{
xorg_list_del(&busfault->list);
free(busfault);
}
void
busfault_check(void)
{
struct busfault *busfault, *tmp;
if (!busfaulted)
return;
busfaulted = FALSE;
xorg_list_for_each_entry_safe(busfault, tmp, &busfaults, list) {
if (!busfault->valid)
(*busfault->notify)(busfault->context);
}
}
static void (*previous_busfault_sigaction)(int sig, siginfo_t *info, void *param);
static void
busfault_sigaction(int sig, siginfo_t *info, void *param)
{
void *fault = info->si_addr;
struct busfault *iter, *busfault = NULL;
void *new_addr;
/* Locate the faulting address in our list of shared segments
*/
xorg_list_for_each_entry(iter, &busfaults, list) {
if ((char *) iter->addr <= (char *) fault && (char *) fault < (char *) iter->addr + iter->size) {
busfault = iter;
break;
}
}
if (!busfault)
goto panic;
if (!busfault->valid)
goto panic;
busfault->valid = FALSE;
busfaulted = TRUE;
/* The client truncated the file; unmap the shared file, map
* /dev/zero over that area and keep going
*/
new_addr = mmap(busfault->addr, busfault->size, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
if (new_addr == MAP_FAILED)
goto panic;
return;
panic:
if (previous_busfault_sigaction)
(*previous_busfault_sigaction)(sig, info, param);
else
FatalError("bus error\n");
}
Bool
busfault_init(void)
{
struct sigaction act, old_act;
act.sa_sigaction = busfault_sigaction;
act.sa_flags = SA_SIGINFO;
sigemptyset(&act.sa_mask);
if (sigaction(SIGBUS, &act, &old_act) < 0)
return FALSE;
previous_busfault_sigaction = old_act.sa_sigaction;
xorg_list_init(&busfaults);
return TRUE;
}
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