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/*
* unix_io.c --- This is the Unix I/O interface to the I/O manager.
*
* Implements a one-block write-through cache.
*
* Copyright (C) 1993 Theodore Ts'o. This file may be redistributed
* under the terms of the GNU Public License.
*/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "et/com_err.h"
#include "ext2_err.h"
#include "io.h"
/*
* For checking structure magic numbers...
*/
#define EXT2_CHECK_MAGIC(struct, code) \
if ((struct)->magic != (code)) return (code)
struct unix_private_data {
int magic;
int dev;
int flags;
char *buf;
int buf_block_nr;
};
static errcode_t unix_open(const char *name, int flags, io_channel *channel);
static errcode_t unix_close(io_channel channel);
static errcode_t unix_set_blksize(io_channel channel, int blksize);
static errcode_t unix_read_blk(io_channel channel, unsigned long block,
int count, void *data);
static errcode_t unix_write_blk(io_channel channel, unsigned long block,
int count, const void *data);
static errcode_t unix_flush(io_channel channel);
static struct struct_io_manager struct_unix_manager = {
EXT2_ET_MAGIC_IO_MANAGER,
"Unix I/O Manager",
unix_open,
unix_close,
unix_set_blksize,
unix_read_blk,
unix_write_blk,
unix_flush
};
io_manager unix_io_manager = &struct_unix_manager;
static errcode_t unix_open(const char *name, int flags, io_channel *channel)
{
io_channel io = NULL;
struct unix_private_data *data = NULL;
errcode_t retval;
io = (io_channel) malloc(sizeof(struct struct_io_channel));
if (!io)
return ENOMEM;
memset(io, 0, sizeof(struct struct_io_channel));
io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
data = (struct unix_private_data *)
malloc(sizeof(struct unix_private_data));
if (!data) {
retval = ENOMEM;
goto cleanup;
}
io->manager = unix_io_manager;
io->name = malloc(strlen(name)+1);
if (!io->name) {
retval = ENOMEM;
goto cleanup;
}
strcpy(io->name, name);
io->private_data = data;
io->block_size = 1024;
io->read_error = 0;
io->write_error = 0;
memset(data, 0, sizeof(struct unix_private_data));
data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
data->buf = malloc(io->block_size);
data->buf_block_nr = -1;
if (!data->buf) {
retval = ENOMEM;
goto cleanup;
}
data->dev = open(name, (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY);
if (data->dev < 0) {
retval = errno;
goto cleanup;
}
*channel = io;
return 0;
cleanup:
if (io)
free(io);
if (data) {
if (data->buf)
free(data->buf);
free(data);
}
return retval;
}
static errcode_t unix_close(io_channel channel)
{
struct unix_private_data *data;
errcode_t retval = 0;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (close(data->dev) < 0)
retval = errno;
if (data->buf)
free(data->buf);
if (channel->private_data)
free(channel->private_data);
if (channel->name)
free(channel->name);
free(channel);
return retval;
}
static errcode_t unix_set_blksize(io_channel channel, int blksize)
{
struct unix_private_data *data;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (channel->block_size != blksize) {
channel->block_size = blksize;
free(data->buf);
data->buf = malloc(blksize);
if (!data->buf)
return ENOMEM;
data->buf_block_nr = -1;
}
return 0;
}
static errcode_t unix_read_blk(io_channel channel, unsigned long block,
int count, void *buf)
{
struct unix_private_data *data;
errcode_t retval;
size_t size;
ext2_loff_t location;
int actual = 0;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
/*
* If it's in the cache, use it!
*/
if ((count == 1) && (block == data->buf_block_nr)) {
memcpy(buf, data->buf, channel->block_size);
return 0;
}
#if 0
printf("read_block %lu (%d)\n", block, count);
#endif
size = (count < 0) ? -count : count * channel->block_size;
location = (ext2_loff_t) block * channel->block_size;
if (ext2_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno;
goto error_out;
}
actual = read(data->dev, buf, size);
if (actual != size) {
if (actual < 0)
actual = 0;
retval = EXT2_ET_SHORT_READ;
goto error_out;
}
if (count == 1) {
data->buf_block_nr = block;
memcpy(data->buf, buf, size); /* Update the cache */
}
return 0;
error_out:
memset((char *) buf+actual, 0, size-actual);
if (channel->read_error)
retval = (channel->read_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
static errcode_t unix_write_blk(io_channel channel, unsigned long block,
int count, const void *buf)
{
struct unix_private_data *data;
size_t size;
ext2_loff_t location;
int actual = 0;
errcode_t retval;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (count == 1)
size = channel->block_size;
else {
data->buf_block_nr = -1; /* Invalidate the cache */
if (count < 0)
size = -count;
else
size = count * channel->block_size;
}
location = (ext2_loff_t) block * channel->block_size;
if (ext2_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno;
goto error_out;
}
actual = write(data->dev, buf, size);
if (actual != size) {
retval = EXT2_ET_SHORT_WRITE;
goto error_out;
}
if ((count == 1) && (block == data->buf_block_nr))
memcpy(data->buf, buf, size); /* Update the cache */
return 0;
error_out:
if (channel->write_error)
retval = (channel->write_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
/*
* Flush data buffers to disk. Since we are currently using a
* write-through cache, this is a no-op.
*/
static errcode_t unix_flush(io_channel channel)
{
struct unix_private_data *data;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
return 0;
}
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