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/* Default pager for GNU Hurd.
Copyright (C) 1996 Free Software Foundation, Inc.
Written by Thomas Bushnell, n/BSG.
This file is part of the GNU Hurd.
The GNU Hurd 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.
The GNU Hurd 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 <hurd/pager.h>
#include <hurd/store.h>
struct user_pager_info
{
/* Size of the object */
vm_size_t size;
/* One entry for each page of the object. */
off_t *map;
};
/* Expand the P->map as necessary to handle an incoming request of the
page at ADDR. */
static inline void
expand_map (struct user_pager_info *p, vm_offset_t addr)
{
/* See if this is beyond the current extent */
if (page >= pager->size)
{
off_t *newmap;
vm_size_t newsize;
newsize = page + vm_page_size;
newmap = realloc (pager->map, size / vm_page_size * sizeof (off_t));
memset (pager->map + pager->size / vm_page_size * sizeof(off_t), 0, (newsize - pager->size) / vm_page_size * sizeof(off_t));
pager->size = newsize;
pager->map = newmap;
}
}
error_t
pager_read_page (struct user_pager_info *pager,
vm_offset_t page,
vm_address_t *buf,
int *write_lock)
{
int pfn = page / vm_page_size;
size_t nread;
/* We never request write locks. */
*write_lock = 0;
expand_map (pager, page);
if (!pager->map[pfn])
vm_allocate (mach_task_self (), buf, vm_page_size, 1);
else
{
store_read (backing_store, pager->map[pfn], vm_page_size,
(void **)buf, &nread);
if (nread != vm_page_size)
{
munmap ((caddr_t) *buf, nread);
return EIO;
}
}
return 0;
}
error_t
pager_write_page (struct user_pager_info *pager,
vm_offset_t page,
vm_address_t buf)
{
int pfn = page / vm_page_size;
size_t nwritten;
expand_map (pager, page);
if (!pager->map[pfn])
pager->map[pfn] = allocate_backing_page ();
/* No more backing store. Oh dear. */
if (!pager->map[pfn])
return EIO;
err = store_write (backing_store, pager->map[pfn], (void *) buf,
vm_page_size, &nwritten);
if (!err && nwritten != vm_page_size)
err = EIO;
return err;
}
error_t
pager_unlock_page (struct user_pager_info *pager,
vm_offset_t address)
{
return 0;
}
error_t
pager_report_extent (struct user_pager_info *pager,
vm_address_t *offset,
vm_size_t *size)
{
*offset = 0;
*size = pager->size;
return 0;
}
void
pager_clear_user_data (struct user_pager_info *pager)
{
return_backing_pages (pager->map, pager->size / vm_page_size);
free (pager->map);
}
void
pager_dropweak (struct user_pager_info *pager)
{
}
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