1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2013, 2014
  4 * Phillip Lougher <phillip@squashfs.org.uk>
  5 */
  6
  7#include <linux/buffer_head.h>
  8#include <linux/mutex.h>
  9#include <linux/slab.h>
 10#include <linux/vmalloc.h>
 11#include <linux/lz4.h>
 12
 13#include "squashfs_fs.h"
 14#include "squashfs_fs_sb.h"
 15#include "squashfs.h"
 16#include "decompressor.h"
 17#include "page_actor.h"
 18
 19#define LZ4_LEGACY	1
 20
 21struct lz4_comp_opts {
 22	__le32 version;
 23	__le32 flags;
 24};
 25
 26struct squashfs_lz4 {
 27	void *input;
 28	void *output;
 29};
 30
 31
 32static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
 33	void *buff, int len)
 34{
 35	struct lz4_comp_opts *comp_opts = buff;
 36
 37	/* LZ4 compressed filesystems always have compression options */
 38	if (comp_opts == NULL || len < sizeof(*comp_opts))
 39		return ERR_PTR(-EIO);
 40
 41	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
 42		/* LZ4 format currently used by the kernel is the 'legacy'
 43		 * format */
 44		ERROR("Unknown LZ4 version\n");
 45		return ERR_PTR(-EINVAL);
 46	}
 47
 48	return NULL;
 49}
 50
 51
 52static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
 53{
 54	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
 55	struct squashfs_lz4 *stream;
 56
 57	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
 58	if (stream == NULL)
 59		goto failed;
 60	stream->input = vmalloc(block_size);
 61	if (stream->input == NULL)
 62		goto failed2;
 63	stream->output = vmalloc(block_size);
 64	if (stream->output == NULL)
 65		goto failed3;
 66
 67	return stream;
 68
 69failed3:
 70	vfree(stream->input);
 71failed2:
 72	kfree(stream);
 73failed:
 74	ERROR("Failed to initialise LZ4 decompressor\n");
 75	return ERR_PTR(-ENOMEM);
 76}
 77
 78
 79static void lz4_free(void *strm)
 80{
 81	struct squashfs_lz4 *stream = strm;
 82
 83	if (stream) {
 84		vfree(stream->input);
 85		vfree(stream->output);
 86	}
 87	kfree(stream);
 88}
 89
 90
 91static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
 92	struct buffer_head **bh, int b, int offset, int length,
 93	struct squashfs_page_actor *output)
 94{
 95	struct squashfs_lz4 *stream = strm;
 96	void *buff = stream->input, *data;
 97	int avail, i, bytes = length, res;
 98
 99	for (i = 0; i < b; i++) {
100		avail = min(bytes, msblk->devblksize - offset);
101		memcpy(buff, bh[i]->b_data + offset, avail);
102		buff += avail;
103		bytes -= avail;
104		offset = 0;
105		put_bh(bh[i]);
106	}
107
108	res = LZ4_decompress_safe(stream->input, stream->output,
109		length, output->length);
110
111	if (res < 0)
112		return -EIO;
113
114	bytes = res;
115	data = squashfs_first_page(output);
116	buff = stream->output;
117	while (data) {
118		if (bytes <= PAGE_SIZE) {
119			memcpy(data, buff, bytes);
120			break;
121		}
122		memcpy(data, buff, PAGE_SIZE);
123		buff += PAGE_SIZE;
124		bytes -= PAGE_SIZE;
125		data = squashfs_next_page(output);
126	}
127	squashfs_finish_page(output);
128
129	return res;
130}
131
132const struct squashfs_decompressor squashfs_lz4_comp_ops = {
133	.init = lz4_init,
134	.comp_opts = lz4_comp_opts,
135	.free = lz4_free,
136	.decompress = lz4_uncompress,
137	.id = LZ4_COMPRESSION,
138	.name = "lz4",
139	.supported = 1
140};