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/* Store I/O
Copyright (C) 1995 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.,
675 Mass Ave, Cambridge, MA 02139, USA. */
/* Write LEN bytes from BUF to STORE at ADDR. Returns the amount written in
AMOUNT. ADDR is in BLOCKS (as defined by store->block_size). */
error_t
store_write (struct store *store,
off_t addr, char *buf, size_t len, size_t *amount);
{
error_t err = 0;
size_t request_len = len;
off_t *runs = store->runs;
unsigned runs_len = store->runs_len;
store_write_meth_t write = store->meths->write;
int block_shift = store->log2_block_size;
/* XXX: this isn't going to be very efficient if RUNS is very complex...
But it should do dandy if it's short. For long run lists, we could do a
binary search or something to find the starting run. */
while (runs_len)
{
off_t run_offs = runs[0];
off_t run_len = runs[1];
if (run_len <= addr)
/* Not to the right place yet, move on... */
addr -= run_len;
else if (run_offs < 0)
/* A hole! Can't write here. Must stop. */
break;
else
/* Ok, we can write in this run, at least a bit. */
{
size_t written, blocks_written;
off_t end = addr + len;
off_t seg_len = end > run_len ? run_len - addr : len;
/* Write to the actual object at the correct address. */
err = (*write)(store, run_offs + addr, buf, seg_len, &written);
if (err)
/* Ack */
break;
buf += written;
len -= written;
blocks_written = written >> block_shift;
if ((blocks_written << block_shift) != seg_amount)
/* A non-block multiple amount was written!? What do we do? */
break;
addr += blocks_written;
}
runs += 2;
runs_len -= 2;
}
if (!err)
*amount = request_len - len;
return err;
}
error_t
store_read (struct store *store,
off_t addr, size_t amount, char **buf, size_t *len)
{
}
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