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/* Zero store backend
Copyright (C) 1995,96,97,99,2000,01, 02 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.org>
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., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <sys/mman.h>
#include "store.h"
static error_t
zero_read (struct store *store,
store_offset_t addr, size_t index, size_t amount, void **buf,
size_t *len)
{
if (*len < amount)
{
*buf = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0);
if (*buf == MAP_FAILED)
return errno;
*len = amount;
return 0;
}
else
memset (*buf, 0, amount);
*len = amount;
return 0;
}
static error_t
zero_write (struct store *store,
store_offset_t addr, size_t index, const void *buf, size_t len,
size_t *amount)
{
return 0;
}
static error_t
zero_set_size (struct store *store, size_t newsize)
{
return EOPNOTSUPP;
}
/* Modify SOURCE to reflect those runs in RUNS, and return it in STORE. */
error_t
zero_remap (struct store *source,
const struct store_run *runs, size_t num_runs,
struct store **store)
{
/* Because all blocks are the same, a zero store always contains just one
run; here we simply count up the number of blocks specified by RUNS, and
modify SOURCE's one run to reflect that. */
int i;
store_offset_t length = 0, old_length = source->runs[0].length;
for (i = 0; i < num_runs; i++)
if (runs[i].start < 0 || runs[i].start + runs[i].length >= old_length)
return EINVAL;
else
length += runs[i].length;
source->runs[0].length = length;
*store = source;
return 0;
}
error_t
zero_allocate_encoding (const struct store *store, struct store_enc *enc)
{
enc->num_ints += 2;
enc->num_offsets += 1;
return 0;
}
error_t
zero_encode (const struct store *store, struct store_enc *enc)
{
enc->ints[enc->cur_int++] = store->class->id;
enc->ints[enc->cur_int++] = store->flags;
enc->offsets[enc->cur_offset++] = store->size;
return 0;
}
error_t
zero_decode (struct store_enc *enc, const struct store_class *const *classes,
struct store **store)
{
store_offset_t size;
int flags;
if (enc->cur_int + 2 > enc->num_ints
|| enc->cur_offset + 1 > enc->num_offsets)
return EINVAL;
/* Ignore type. */
enc->cur_int++;
flags = enc->ints[enc->cur_int++];
size = enc->offsets[enc->cur_offset++];
return store_zero_create (size, flags, store);
}
static error_t
zero_open (const char *name, int flags,
const struct store_class *const *classes,
struct store **store)
{
if (name)
{
char *end;
store_offset_t size = strtoull (name, &end, 0);
if (end == name || end == NULL)
return EINVAL;
switch (*end)
{
case 'b':
size *= 512;
break;
case 'k':
case 'K':
size *= 1024;
break;
case 'm':
case 'M':
size *= 1024 * 1024;
break;
case 'g':
case 'G':
size *= 1024 * 1024 * 1024;
break;
}
return store_zero_create (size, flags, store);
}
else
{
store_offset_t max_offs = ~((store_offset_t)1
<< (CHAR_BIT * sizeof (store_offset_t) - 1));
return store_zero_create (max_offs, flags, store);
}
}
static error_t
zero_validate_name (const char *name, const struct store_class *const *classes)
{
if (name)
{
char *end;
strtoul (name, &end, 0);
return end == name ? EINVAL : 0;
}
else
return 0; /* `maximum size' */
}
static error_t
zero_map (const struct store *store, vm_prot_t prot, mach_port_t *memobj)
{
*memobj = MACH_PORT_NULL;
return 0;
}
const struct store_class
store_zero_class =
{
STORAGE_ZERO, "zero", zero_read, zero_write, zero_set_size,
zero_allocate_encoding, zero_encode, zero_decode,
0, 0, 0, 0, zero_remap, zero_open, zero_validate_name,
zero_map
};
STORE_STD_CLASS (zero);
/* Return a new zero store SIZE bytes long in STORE. */
error_t
store_zero_create (store_offset_t size, int flags, struct store **store)
{
struct store_run run = { 0, size };
return
_store_create (&store_zero_class, MACH_PORT_NULL,
flags | STORE_INNOCUOUS, 1, &run, 1, 0, store);
}
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