9c06a46f15
Add support for reading file systems compressed with the LZ4 compression algorithm. This patch adds the LZ4 decompressor wrapper code. Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
142 lines
3 KiB
C
142 lines
3 KiB
C
/*
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* Copyright (c) 2013, 2014
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/buffer_head.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/lz4.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs.h"
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#include "decompressor.h"
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#include "page_actor.h"
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#define LZ4_LEGACY 1
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struct lz4_comp_opts {
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__le32 version;
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__le32 flags;
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};
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struct squashfs_lz4 {
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void *input;
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void *output;
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};
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static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
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void *buff, int len)
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{
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struct lz4_comp_opts *comp_opts = buff;
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/* LZ4 compressed filesystems always have compression options */
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if (comp_opts == NULL || len < sizeof(*comp_opts))
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return ERR_PTR(-EIO);
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if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
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/* LZ4 format currently used by the kernel is the 'legacy'
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* format */
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ERROR("Unknown LZ4 version\n");
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return ERR_PTR(-EINVAL);
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}
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return NULL;
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}
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static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
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{
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int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
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struct squashfs_lz4 *stream;
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stream = kzalloc(sizeof(*stream), GFP_KERNEL);
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if (stream == NULL)
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goto failed;
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stream->input = vmalloc(block_size);
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if (stream->input == NULL)
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goto failed2;
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stream->output = vmalloc(block_size);
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if (stream->output == NULL)
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goto failed3;
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return stream;
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failed3:
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vfree(stream->input);
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failed2:
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kfree(stream);
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failed:
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ERROR("Failed to initialise LZ4 decompressor\n");
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return ERR_PTR(-ENOMEM);
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}
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static void lz4_free(void *strm)
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{
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struct squashfs_lz4 *stream = strm;
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if (stream) {
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vfree(stream->input);
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vfree(stream->output);
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}
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kfree(stream);
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}
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static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
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struct buffer_head **bh, int b, int offset, int length,
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struct squashfs_page_actor *output)
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{
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struct squashfs_lz4 *stream = strm;
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void *buff = stream->input, *data;
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int avail, i, bytes = length, res;
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size_t dest_len = output->length;
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for (i = 0; i < b; i++) {
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avail = min(bytes, msblk->devblksize - offset);
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memcpy(buff, bh[i]->b_data + offset, avail);
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buff += avail;
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bytes -= avail;
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offset = 0;
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put_bh(bh[i]);
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}
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res = lz4_decompress_unknownoutputsize(stream->input, length,
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stream->output, &dest_len);
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if (res)
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return -EIO;
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bytes = dest_len;
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data = squashfs_first_page(output);
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buff = stream->output;
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while (data) {
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if (bytes <= PAGE_CACHE_SIZE) {
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memcpy(data, buff, bytes);
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break;
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}
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memcpy(data, buff, PAGE_CACHE_SIZE);
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buff += PAGE_CACHE_SIZE;
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bytes -= PAGE_CACHE_SIZE;
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data = squashfs_next_page(output);
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}
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squashfs_finish_page(output);
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return dest_len;
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}
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const struct squashfs_decompressor squashfs_lz4_comp_ops = {
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.init = lz4_init,
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.comp_opts = lz4_comp_opts,
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.free = lz4_free,
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.decompress = lz4_uncompress,
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.id = LZ4_COMPRESSION,
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.name = "lz4",
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.supported = 1
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};
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