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/* State for an I/O stream.
Copyright (C) 1995 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
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 <hurd.h>
#include "iostate.h"
#include "dev.h"
/* ---------------------------------------------------------------- */
/* Initialize the io_state structure IOS to be used with the device DEV. If
a memory allocation error occurs, ENOMEM is returned, otherwise 0. */
error_t
io_state_init(struct io_state *ios, struct dev *dev)
{
error_t err =
vm_allocate(mach_task_self(),
(vm_address_t *)&ios->buffer, dev->block_size, 1);
ios->location = 0;
ios->buffer_size = dev->block_size;
ios->buffer_use = 0;
mutex_init(&ios->lock);
return err;
}
/* Frees all resources used by IOS. */
void
io_state_finalize(struct io_state *ios)
{
vm_deallocate(mach_task_self(), (vm_address_t)ios->buffer, ios->buffer_size);
}
/* If IOS's location isn't block aligned because writes have been buffered
there, then sync the whole buffer out to the device. Any error that
occurs while writing is returned, otherwise 0. */
error_t
io_state_sync(struct io_state *ios, struct dev *dev)
{
error_t err = 0;
if (ios->buffer_use == IO_STATE_BUFFERED_WRITE)
{
vm_offset_t pos = ios->location;
int block_offs = pos % dev->block_size;
if (block_offs > 0)
{
bzero((char *)ios->buffer + block_offs,
dev->block_size - block_offs);
ios->location -= block_offs;
err =
dev_write(dev, ios->buffer, dev->block_size, &ios->location);
}
/* Remember that there's nothing left in the buffer. */
ios->buffer_use = 0;
}
return err;
}
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