| /* |
| * 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, 1994, 1995 Theodore Ts'o. |
| * |
| * %Begin-Header% |
| * This file may be redistributed under the terms of the GNU Public |
| * License. |
| * %End-Header% |
| */ |
| |
| #include <stdio.h> |
| #include <string.h> |
| #if HAVE_UNISTD_H |
| #include <unistd.h> |
| #endif |
| #include <stdlib.h> |
| #include <fcntl.h> |
| #include <time.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #if HAVE_ERRNO_H |
| #include <errno.h> |
| #endif |
| |
| #include "et/com_err.h" |
| #include "ext2fs/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; |
| |
| if (name == 0) |
| return EXT2_ET_BAD_DEVICE_NAME; |
| 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; |
| io->refcount = 1; |
| |
| 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 (--channel->refcount > 0) |
| return 0; |
| |
| 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 (ext2fs_llseek(data->dev, location, SEEK_SET) != location) { |
| retval = errno ? errno : EXT2_IO_LLSEEK_FAILED; |
| 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 (ext2fs_llseek(data->dev, location, SEEK_SET) != location) { |
| retval = errno ? errno : EXT2_IO_LLSEEK_FAILED; |
| 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. |
| */ |
| 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); |
| |
| fsync(data->dev); |
| return 0; |
| } |
| |