mirror of https://github.com/vitalif/e2fsprogs
299 lines
6.9 KiB
C
299 lines
6.9 KiB
C
/*
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* unix_io.c --- This is the Unix I/O interface to the I/O manager.
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*
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* Implements a one-block write-through cache.
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*
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* Copyright (C) 1993, 1994, 1995 Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#define _LARGEFILE_SOURCE
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#define _LARGEFILE64_SOURCE
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#if HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#include <fcntl.h>
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#include <time.h>
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#if EXT2_FLAT_INCLUDES
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#include "ext2_fs.h"
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#else
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#include <linux/ext2_fs.h>
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#endif
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#include "ext2fs.h"
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/*
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* For checking structure magic numbers...
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*/
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#define EXT2_CHECK_MAGIC(struct, code) \
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if ((struct)->magic != (code)) return (code)
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struct unix_private_data {
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int magic;
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int dev;
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int flags;
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char *buf;
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int buf_block_nr;
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};
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static errcode_t unix_open(const char *name, int flags, io_channel *channel);
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static errcode_t unix_close(io_channel channel);
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static errcode_t unix_set_blksize(io_channel channel, int blksize);
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static errcode_t unix_read_blk(io_channel channel, unsigned long block,
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int count, void *data);
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static errcode_t unix_write_blk(io_channel channel, unsigned long block,
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int count, const void *data);
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static errcode_t unix_flush(io_channel channel);
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static struct struct_io_manager struct_unix_manager = {
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EXT2_ET_MAGIC_IO_MANAGER,
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"Unix I/O Manager",
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unix_open,
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unix_close,
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unix_set_blksize,
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unix_read_blk,
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unix_write_blk,
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unix_flush
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};
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io_manager unix_io_manager = &struct_unix_manager;
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static errcode_t unix_open(const char *name, int flags, io_channel *channel)
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{
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io_channel io = NULL;
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struct unix_private_data *data = NULL;
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errcode_t retval;
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int open_flags;
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if (name == 0)
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return EXT2_ET_BAD_DEVICE_NAME;
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retval = ext2fs_get_mem(sizeof(struct struct_io_channel),
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(void **) &io);
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if (retval)
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return retval;
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memset(io, 0, sizeof(struct struct_io_channel));
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io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
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retval = ext2fs_get_mem(sizeof(struct unix_private_data),
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(void **) &data);
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if (retval)
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goto cleanup;
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io->manager = unix_io_manager;
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retval = ext2fs_get_mem(strlen(name)+1, (void **) &io->name);
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if (retval)
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goto cleanup;
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strcpy(io->name, name);
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io->private_data = data;
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io->block_size = 1024;
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io->read_error = 0;
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io->write_error = 0;
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io->refcount = 1;
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memset(data, 0, sizeof(struct unix_private_data));
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data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
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retval = ext2fs_get_mem(io->block_size, (void **) &data->buf);
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data->buf_block_nr = -1;
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if (retval)
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goto cleanup;
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open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
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#ifdef HAVE_OPEN64
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data->dev = open64(name, open_flags);
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#else
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data->dev = open(name, open_flags);
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#endif
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if (data->dev < 0) {
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retval = errno;
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goto cleanup;
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}
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*channel = io;
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return 0;
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cleanup:
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if (io)
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ext2fs_free_mem((void **) &io);
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if (data) {
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if (data->buf)
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ext2fs_free_mem((void **) &data->buf);
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ext2fs_free_mem((void **) &data);
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}
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return retval;
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}
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static errcode_t unix_close(io_channel channel)
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{
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struct unix_private_data *data;
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errcode_t retval = 0;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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data = (struct unix_private_data *) channel->private_data;
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EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
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if (--channel->refcount > 0)
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return 0;
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if (close(data->dev) < 0)
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retval = errno;
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if (data->buf)
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ext2fs_free_mem((void **) &data->buf);
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if (channel->private_data)
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ext2fs_free_mem((void **) &channel->private_data);
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if (channel->name)
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ext2fs_free_mem((void **) &channel->name);
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ext2fs_free_mem((void **) &channel);
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return retval;
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}
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static errcode_t unix_set_blksize(io_channel channel, int blksize)
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{
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struct unix_private_data *data;
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errcode_t retval;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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data = (struct unix_private_data *) channel->private_data;
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EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
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if (channel->block_size != blksize) {
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channel->block_size = blksize;
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ext2fs_free_mem((void **) &data->buf);
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retval = ext2fs_get_mem(blksize, (void **) &data->buf);
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if (retval)
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return retval;
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data->buf_block_nr = -1;
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}
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return 0;
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}
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static errcode_t unix_read_blk(io_channel channel, unsigned long block,
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int count, void *buf)
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{
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struct unix_private_data *data;
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errcode_t retval;
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size_t size;
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ext2_loff_t location;
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int actual = 0;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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data = (struct unix_private_data *) channel->private_data;
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EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
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/*
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* If it's in the cache, use it!
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*/
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if ((count == 1) && (block == data->buf_block_nr)) {
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memcpy(buf, data->buf, channel->block_size);
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return 0;
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}
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#if 0
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printf("read_block %lu (%d)\n", block, count);
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#endif
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size = (count < 0) ? -count : count * channel->block_size;
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location = (ext2_loff_t) block * channel->block_size;
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if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
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retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
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goto error_out;
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}
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actual = read(data->dev, buf, size);
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if (actual != size) {
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if (actual < 0)
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actual = 0;
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retval = EXT2_ET_SHORT_READ;
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goto error_out;
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}
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if (count == 1) {
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data->buf_block_nr = block;
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memcpy(data->buf, buf, size); /* Update the cache */
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}
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return 0;
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error_out:
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memset((char *) buf+actual, 0, size-actual);
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if (channel->read_error)
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retval = (channel->read_error)(channel, block, count, buf,
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size, actual, retval);
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return retval;
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}
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static errcode_t unix_write_blk(io_channel channel, unsigned long block,
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int count, const void *buf)
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{
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struct unix_private_data *data;
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size_t size;
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ext2_loff_t location;
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int actual = 0;
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errcode_t retval;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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data = (struct unix_private_data *) channel->private_data;
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EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
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if (count == 1)
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size = channel->block_size;
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else {
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data->buf_block_nr = -1; /* Invalidate the cache */
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if (count < 0)
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size = -count;
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else
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size = count * channel->block_size;
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}
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location = (ext2_loff_t) block * channel->block_size;
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if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
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retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
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goto error_out;
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}
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actual = write(data->dev, buf, size);
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if (actual != size) {
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retval = EXT2_ET_SHORT_WRITE;
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goto error_out;
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}
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if ((count == 1) && (block == data->buf_block_nr))
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memcpy(data->buf, buf, size); /* Update the cache */
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return 0;
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error_out:
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if (channel->write_error)
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retval = (channel->write_error)(channel, block, count, buf,
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size, actual, retval);
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return retval;
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}
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/*
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* Flush data buffers to disk.
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*/
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static errcode_t unix_flush(io_channel channel)
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{
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struct unix_private_data *data;
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EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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data = (struct unix_private_data *) channel->private_data;
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EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
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fsync(data->dev);
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return 0;
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}
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