1/*
2 * Copyright (c) 2013, 2014
3 * Phillip Lougher <phillip@squashfs.org.uk>
4 *
5 * This work is licensed under the terms of the GNU GPL, version 2. See
6 * the COPYING file in the top-level directory.
7 */
8
9#include <linux/buffer_head.h>
10#include <linux/mutex.h>
11#include <linux/slab.h>
12#include <linux/vmalloc.h>
13#include <linux/lz4.h>
14
15#include "squashfs_fs.h"
16#include "squashfs_fs_sb.h"
17#include "squashfs.h"
18#include "decompressor.h"
19#include "page_actor.h"
20
21#define LZ4_LEGACY	1
22
23struct lz4_comp_opts {
24	__le32 version;
25	__le32 flags;
26};
27
28struct squashfs_lz4 {
29	void *input;
30	void *output;
31};
32
33
34static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
35	void *buff, int len)
36{
37	struct lz4_comp_opts *comp_opts = buff;
38
39	/* LZ4 compressed filesystems always have compression options */
40	if (comp_opts == NULL || len < sizeof(*comp_opts))
41		return ERR_PTR(-EIO);
42
43	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
44		/* LZ4 format currently used by the kernel is the 'legacy'
45		 * format */
46		ERROR("Unknown LZ4 version\n");
47		return ERR_PTR(-EINVAL);
48	}
49
50	return NULL;
51}
52
53
54static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
55{
56	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
57	struct squashfs_lz4 *stream;
58
59	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
60	if (stream == NULL)
61		goto failed;
62	stream->input = vmalloc(block_size);
63	if (stream->input == NULL)
64		goto failed2;
65	stream->output = vmalloc(block_size);
66	if (stream->output == NULL)
67		goto failed3;
68
69	return stream;
70
71failed3:
72	vfree(stream->input);
73failed2:
74	kfree(stream);
75failed:
76	ERROR("Failed to initialise LZ4 decompressor\n");
77	return ERR_PTR(-ENOMEM);
78}
79
80
81static void lz4_free(void *strm)
82{
83	struct squashfs_lz4 *stream = strm;
84
85	if (stream) {
86		vfree(stream->input);
87		vfree(stream->output);
88	}
89	kfree(stream);
90}
91
92
93static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
94	struct buffer_head **bh, int b, int offset, int length,
95	struct squashfs_page_actor *output)
96{
97	struct squashfs_lz4 *stream = strm;
98	void *buff = stream->input, *data;
99	int avail, i, bytes = length, res;
100	size_t dest_len = output->length;
101
102	for (i = 0; i < b; i++) {
103		avail = min(bytes, msblk->devblksize - offset);
104		memcpy(buff, bh[i]->b_data + offset, avail);
105		buff += avail;
106		bytes -= avail;
107		offset = 0;
108		put_bh(bh[i]);
109	}
110
111	res = lz4_decompress_unknownoutputsize(stream->input, length,
112					stream->output, &dest_len);
113	if (res)
114		return -EIO;
115
116	bytes = dest_len;
117	data = squashfs_first_page(output);
118	buff = stream->output;
119	while (data) {
120		if (bytes <= PAGE_CACHE_SIZE) {
121			memcpy(data, buff, bytes);
122			break;
123		}
124		memcpy(data, buff, PAGE_CACHE_SIZE);
125		buff += PAGE_CACHE_SIZE;
126		bytes -= PAGE_CACHE_SIZE;
127		data = squashfs_next_page(output);
128	}
129	squashfs_finish_page(output);
130
131	return dest_len;
132}
133
134const struct squashfs_decompressor squashfs_lz4_comp_ops = {
135	.init = lz4_init,
136	.comp_opts = lz4_comp_opts,
137	.free = lz4_free,
138	.decompress = lz4_uncompress,
139	.id = LZ4_COMPRESSION,
140	.name = "lz4",
141	.supported = 1
142};
143