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-rw-r--r--e2fslib/unix_io.c556
1 files changed, 556 insertions, 0 deletions
diff --git a/e2fslib/unix_io.c b/e2fslib/unix_io.c
new file mode 100644
index 0000000..40bb6c2
--- /dev/null
+++ b/e2fslib/unix_io.c
@@ -0,0 +1,556 @@
+/*
+ * 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%
+ */
+
+#define _LARGEFILE_SOURCE
+#define _LARGEFILE64_SOURCE
+
+#include <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <fcntl.h>
+#include <time.h>
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#include "ext2_fs.h"
+#include "ext2fs.h"
+
+/*
+ * For checking structure magic numbers...
+ */
+
+#define EXT2_CHECK_MAGIC(struct, code) \
+ if ((struct)->magic != (code)) return (code)
+
+struct unix_cache {
+ char *buf;
+ unsigned long block;
+ int access_time;
+ int dirty:1;
+ int in_use:1;
+};
+
+#define CACHE_SIZE 8
+#define WRITE_VIA_CACHE_SIZE 4 /* Must be smaller than CACHE_SIZE */
+
+struct unix_private_data {
+ int magic;
+ int dev;
+ int flags;
+ int access_time;
+ struct unix_cache cache[CACHE_SIZE];
+};
+
+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 errcode_t unix_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *data);
+
+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,
+ unix_write_byte
+};
+
+io_manager unix_io_manager = &struct_unix_manager;
+
+/*
+ * Here are the raw I/O functions
+ */
+static errcode_t raw_read_blk(io_channel channel,
+ struct unix_private_data *data,
+ unsigned long block,
+ int count, void *buf)
+{
+ errcode_t retval;
+ size_t size;
+ ext2_loff_t location;
+ int actual = 0;
+
+ 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_ET_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;
+ }
+ 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 raw_write_blk(io_channel channel,
+ struct unix_private_data *data,
+ unsigned long block,
+ int count, const void *buf)
+{
+ size_t size;
+ ext2_loff_t location;
+ int actual = 0;
+ errcode_t retval;
+
+ if (count == 1)
+ size = channel->block_size;
+ else {
+ 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_ET_LLSEEK_FAILED;
+ goto error_out;
+ }
+
+ actual = write(data->dev, buf, size);
+ if (actual != size) {
+ retval = EXT2_ET_SHORT_WRITE;
+ goto error_out;
+ }
+ return 0;
+
+error_out:
+ if (channel->write_error)
+ retval = (channel->write_error)(channel, block, count, buf,
+ size, actual, retval);
+ return retval;
+}
+
+
+/*
+ * Here we implement the cache functions
+ */
+
+/* Allocate the cache buffers */
+static errcode_t alloc_cache(io_channel channel,
+ struct unix_private_data *data)
+{
+ errcode_t retval;
+ struct unix_cache *cache;
+ int i;
+
+ data->access_time = 0;
+ for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ cache->block = 0;
+ cache->access_time = 0;
+ cache->dirty = 0;
+ cache->in_use = 0;
+ if ((retval = ext2fs_get_mem(channel->block_size,
+ (void **) &cache->buf)))
+ return retval;
+ }
+ return 0;
+}
+
+/* Free the cache buffers */
+static void free_cache(io_channel channel,
+ struct unix_private_data *data)
+{
+ struct unix_cache *cache;
+ int i;
+
+ data->access_time = 0;
+ for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ cache->block = 0;
+ cache->access_time = 0;
+ cache->dirty = 0;
+ cache->in_use = 0;
+ if (cache->buf)
+ ext2fs_free_mem((void **) &cache->buf);
+ cache->buf = 0;
+ }
+}
+
+/*
+ * Try to find a block in the cache. If get_cache is non-zero, then
+ * if the block isn't in the cache, evict the oldest block in the
+ * cache and create a new cache entry for the requested block.
+ */
+static struct unix_cache *find_cached_block(io_channel channel,
+ struct unix_private_data *data,
+ unsigned long block,
+ int get_cache)
+{
+ struct unix_cache *cache, *unused_cache, *oldest_cache;
+ int i;
+
+ unused_cache = oldest_cache = 0;
+ for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ if (!cache->in_use) {
+ unused_cache = cache;
+ continue;
+ }
+ if (cache->block == block) {
+ cache->access_time = ++data->access_time;
+ return cache;
+ }
+ if (!oldest_cache ||
+ (cache->access_time < oldest_cache->access_time))
+ oldest_cache = cache;
+ }
+ if (!get_cache)
+ return 0;
+
+ /*
+ * Try to allocate cache slot.
+ */
+ if (unused_cache)
+ cache = unused_cache;
+ else {
+ cache = oldest_cache;
+ if (cache->dirty)
+ raw_write_blk(channel, data,
+ cache->block, 1, cache->buf);
+ }
+ cache->in_use = 1;
+ cache->block = block;
+ cache->access_time = ++data->access_time;
+ return cache;
+}
+
+/*
+ * Flush all of the blocks in the cache
+ */
+static errcode_t flush_cached_blocks(io_channel channel,
+ struct unix_private_data *data,
+ int invalidate)
+
+{
+ struct unix_cache *cache;
+ errcode_t retval, retval2;
+ int i;
+
+ retval2 = 0;
+ for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
+ if (!cache->in_use)
+ continue;
+
+ if (invalidate)
+ cache->in_use = 0;
+
+ if (!cache->dirty)
+ continue;
+
+ retval = raw_write_blk(channel, data,
+ cache->block, 1, cache->buf);
+ if (retval)
+ retval2 = retval;
+ else
+ cache->dirty = 0;
+ }
+ return retval2;
+}
+
+
+
+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;
+ int open_flags;
+
+ if (name == 0)
+ return EXT2_ET_BAD_DEVICE_NAME;
+ retval = ext2fs_get_mem(sizeof(struct struct_io_channel),
+ (void **) &io);
+ if (retval)
+ return retval;
+ memset(io, 0, sizeof(struct struct_io_channel));
+ io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
+ retval = ext2fs_get_mem(sizeof(struct unix_private_data),
+ (void **) &data);
+ if (retval)
+ goto cleanup;
+
+ io->manager = unix_io_manager;
+ retval = ext2fs_get_mem(strlen(name)+1, (void **) &io->name);
+ if (retval)
+ 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;
+
+ if ((retval = alloc_cache(io, data)))
+ goto cleanup;
+
+ open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
+#ifdef HAVE_OPEN64
+ data->dev = open64(name, open_flags);
+#else
+ data->dev = open(name, open_flags);
+#endif
+ if (data->dev < 0) {
+ retval = errno;
+ goto cleanup;
+ }
+ *channel = io;
+ return 0;
+
+cleanup:
+ if (data) {
+ free_cache(io, data);
+ ext2fs_free_mem((void **) &data);
+ }
+ if (io)
+ ext2fs_free_mem((void **) &io);
+ 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;
+
+ retval = flush_cached_blocks(channel, data, 0);
+
+ if (close(data->dev) < 0)
+ retval = errno;
+ free_cache(channel, data);
+ if (channel->private_data)
+ ext2fs_free_mem((void **) &channel->private_data);
+ if (channel->name)
+ ext2fs_free_mem((void **) &channel->name);
+ ext2fs_free_mem((void **) &channel);
+ return retval;
+}
+
+static errcode_t unix_set_blksize(io_channel channel, int blksize)
+{
+ struct unix_private_data *data;
+ 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 (channel->block_size != blksize) {
+ if ((retval = flush_cached_blocks(channel, data, 0)))
+ return retval;
+
+ channel->block_size = blksize;
+ free_cache(channel, data);
+ if ((retval = alloc_cache(channel, data)))
+ return retval;
+ }
+ return 0;
+}
+
+
+static errcode_t unix_read_blk(io_channel channel, unsigned long block,
+ int count, void *buf)
+{
+ struct unix_private_data *data;
+ struct unix_cache *cache;
+ errcode_t retval;
+ char *cp;
+ int i, j;
+
+ 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 we're doing an odd-sized read, flush out the cache and
+ * then do a direct read.
+ */
+ if (count < 0) {
+ if ((retval = flush_cached_blocks(channel, data, 0)))
+ return retval;
+ return raw_read_blk(channel, data, block, count, buf);
+ }
+
+ cp = buf;
+ while (count > 0) {
+ /* If it's in the cache, use it! */
+ if ((cache = find_cached_block(channel, data, block, 0))) {
+#ifdef DEBUG
+ printf("Using cached block %d\n", block);
+#endif
+ memcpy(cp, cache->buf, channel->block_size);
+ count--;
+ block++;
+ cp += channel->block_size;
+ continue;
+ }
+ /*
+ * Find the number of uncached blocks so we can do a
+ * single read request
+ */
+ for (i=1; i < count; i++)
+ if (find_cached_block(channel, data, block+i, 0))
+ break;
+#ifdef DEBUG
+ printf("Reading %d blocks starting at %d\n", i, block);
+#endif
+ if ((retval = raw_read_blk(channel, data, block, i, cp)))
+ return retval;
+
+ /* Save the results in the cache */
+ for (j=0; j < i; j++) {
+ count--;
+ cache = find_cached_block(channel, data, block++, 1);
+ if (cache)
+ memcpy(cache->buf, cp, channel->block_size);
+ cp += channel->block_size;
+ }
+ }
+ return 0;
+}
+
+static errcode_t unix_write_blk(io_channel channel, unsigned long block,
+ int count, const void *buf)
+{
+ struct unix_private_data *data;
+ struct unix_cache *cache;
+ errcode_t retval = 0, retval2;
+ const char *cp;
+ int writethrough;
+
+ 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 we're doing an odd-sized write or a very large write,
+ * flush out the cache completely and then do a direct write.
+ */
+ if (count < 0 || count > WRITE_VIA_CACHE_SIZE) {
+ if ((retval = flush_cached_blocks(channel, data, 1)))
+ return retval;
+ return raw_write_blk(channel, data, block, count, buf);
+ }
+
+ /*
+ * For a moderate-sized multi-block write, first force a write
+ * if we're in write-through cache mode, and then fill the
+ * cache with the blocks.
+ */
+ writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
+ if (writethrough)
+ retval = raw_write_blk(channel, data, block, count, buf);
+
+ cp = buf;
+ while (count > 0) {
+ cache = find_cached_block(channel, data, block, 1);
+ if (!cache) {
+ /*
+ * Oh shit, we couldn't get cache descriptor.
+ * Force the write directly.
+ */
+ if ((retval2 = raw_write_blk(channel, data, block,
+ 1, cp)))
+ retval = retval2;
+ } else {
+ memcpy(cache->buf, cp, channel->block_size);
+ cache->dirty = !writethrough;
+ }
+ count--;
+ block++;
+ cp += channel->block_size;
+ }
+ return retval;
+}
+
+static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
+ int size, const void *buf)
+{
+ struct unix_private_data *data;
+ errcode_t retval = 0;
+ size_t actual;
+
+ 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);
+
+ /*
+ * Flush out the cache completely
+ */
+ if ((retval = flush_cached_blocks(channel, data, 1)))
+ return retval;
+
+ if (lseek(data->dev, offset, SEEK_SET) < 0)
+ return errno;
+
+ actual = write(data->dev, buf, size);
+ if (actual != size)
+ return EXT2_ET_SHORT_WRITE;
+
+ return 0;
+}
+
+/*
+ * Flush data buffers to disk.
+ */
+static errcode_t unix_flush(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);
+
+ retval = flush_cached_blocks(channel, data, 0);
+ fsync(data->dev);
+ return retval;
+}
+