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/* Multiple-volume store backend
Copyright (C) 1996, 1997 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
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 <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "store.h"
struct mvol_state
{
/* The current `volume'. */
ssize_t cur_vol;
/* A function to change volumes, making NEW_VOL readable on the store
instead of OLD_VOL. OLD_VOL is initially -1, */
error_t (*swap_vols) (struct store *store, size_t new_vol, ssize_t old_vol);
};
static error_t
ensure_vol (struct store *store, size_t vol)
{
error_t err = 0;
struct mvol_state *mv = store->hook;
if (vol != mv->cur_vol)
{
err = (*mv->swap_vols) (store, vol, mv->cur_vol);
if (! err)
mv->cur_vol = vol;
}
return err;
}
static error_t
mvol_read (struct store *store,
store_offset_t addr, size_t index, size_t amount,
void **buf, size_t *len)
{
error_t err = ensure_vol (store, index);
if (! err)
err = store_read (store->children[0], addr, amount, buf, len);
return err;
}
static error_t
mvol_write (struct store *store,
store_offset_t addr, size_t index, void *buf, size_t len,
size_t *amount)
{
error_t err = ensure_vol (store, index);
if (! err)
err = store_write (store->children[0], addr, buf, len, amount);
return err;
}
error_t
mvol_remap (struct store *source,
const struct store_run *runs, size_t num_runs,
struct store **store)
{
return store_remap_create (source, runs, num_runs, 0, store);
}
struct store_class
store_mvol_class =
{
-1, "mvol", mvol_read, mvol_write,
0, 0, 0,
store_set_child_flags, store_clear_child_flags, 0, 0, mvol_remap
};
/* Return a new store in STORE that multiplexes multiple physical volumes
from PHYS as one larger virtual volume. SWAP_VOLS is a function that will
be called whenever the volume currently active isn't correct. PHYS is
consumed. */
error_t
store_mvol_create (struct store *phys,
error_t (*swap_vols) (struct store *store, size_t new_vol,
ssize_t old_vol),
int flags,
struct store **store)
{
error_t err;
struct store_run run;
run.start = 0;
run.length = phys->end;
err = _store_create (&store_mvol_class, MACH_PORT_NULL,
flags | phys->flags, phys->block_size,
&run, 1, 0, store);
if (! err)
{
struct mvol_state *mv = malloc (sizeof (struct mvol_state));
if (mv)
{
mv->swap_vols = swap_vols;
mv->cur_vol = -1;
(*store)->hook = mv;
}
else
err = ENOMEM;
if (! err)
err = store_set_children (*store, &phys, 1);
if (! err)
{
if (phys->name)
{
size_t nlen =
strlen (phys->class->name) + 1 + strlen (phys->name) + 1;
char *name = malloc (nlen);
if (name)
{
snprintf (name, nlen, "%s:%s", phys->class->name, phys->name);
(*store)->name = name;
}
else
err = ENOMEM;
}
}
if (err)
{
if (mv)
free (mv);
store_free (*store);
}
}
return err;
}
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