/* Map the disk image and handle faults accessing it.
   Copyright (C) 1996 Free Software Foundation, Inc.
   Written by Roland McGrath.

   This program 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.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include "priv.h"
#include "diskfs-pager.h"
#include <hurd/sigpreempt.h>
#include <error.h>

struct pager *disk_pager;
void *disk_image;
extern struct port_bucket *pager_bucket;

static void fault_handler (int sig, long int sigcode, struct sigcontext *scp);
static struct hurd_signal_preempter preempter =
  {
  signals: sigmask (SIGSEGV) | sigmask (SIGBUS),
  preempter: NULL,
  handler: (sighandler_t) &fault_handler,
  };


/* A top-level function for the paging thread that just services paging
   requests.  */
static void
service_paging_requests (any_t foo __attribute__ ((unused)))
{
  for (;;)
    ports_manage_port_operations_multithread (pager_bucket, pager_demuxer,
					      1000 * 60 * 2, 1000 * 60 * 10,
					      1, MACH_PORT_NULL);
}

void
disk_pager_setup (struct user_pager_info *upi, int may_cache)
{
  error_t err;
  mach_port_t disk_pager_port;

  if (! pager_bucket)
    pager_bucket = ports_create_bucket ();

  /* Make a thread to service paging requests.  */
  cthread_detach (cthread_fork ((cthread_fn_t) service_paging_requests,
				(any_t) 0));

  /* Create the pager.  */
  disk_pager = pager_create (upi, pager_bucket,
			     may_cache, MEMORY_OBJECT_COPY_NONE);
  assert (disk_pager);

  /* Get a port to the disk pager.  */
  disk_pager_port = pager_get_port (disk_pager);
  mach_port_insert_right (mach_task_self (), disk_pager_port, disk_pager_port,
			  MACH_MSG_TYPE_MAKE_SEND);

  /* Now map the disk image.  */
  err = vm_map (mach_task_self (), (vm_address_t *)&disk_image,
		diskfs_device_size << diskfs_log2_device_block_size,
		0, 1, disk_pager_port, 0, 0,
		VM_PROT_READ | (diskfs_readonly ? 0 : VM_PROT_WRITE),
		VM_PROT_READ | VM_PROT_WRITE,
		VM_INHERIT_NONE);
  if (err)
    error (2, err, "cannot vm_map whole disk");

  /* Set up the signal preempter to catch faults on the disk image.  */
  preempter.first = (vm_address_t) disk_image;
  preempter.last = ((vm_address_t) disk_image +
		    (diskfs_device_size << diskfs_log2_device_block_size));
  hurd_preempt_signals (&preempter);

  /* We have the mapping; we no longer need the send right.  */
  mach_port_deallocate (mach_task_self (), disk_pager_port);
}

static void
fault_handler (int sig, long int sigcode, struct sigcontext *scp)
{
  jmp_buf *env = cthread_data (cthread_self ());
  error_t err;

  assert (env && "unexpected fault on disk image");

  /* Clear the record, since the faulting thread will not.  */
  cthread_set_data (cthread_self (), 0);

  /* Fetch the error code from the pager.  */
  assert (scp->sc_error == EKERN_MEMORY_ERROR);
  err = pager_get_error (disk_pager, sigcode);
  assert (err);

  /* Make `diskfault_catch' return the error code.  */
  longjmp (*env, err);
}