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/bio.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 bio *bio, int offset, int length,
93	struct squashfs_page_actor *output)
94{
95	struct bvec_iter_all iter_all = {};
96	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
97	struct squashfs_lz4 *stream = strm;
98	void *buff = stream->input, *data;
99	int bytes = length, res;
100
101	while (bio_next_segment(bio, &iter_all)) {
102		int avail = min(bytes, ((int)bvec->bv_len) - offset);
103
104		data = bvec_virt(bvec);
105		memcpy(buff, data + offset, avail);
106		buff += avail;
107		bytes -= avail;
108		offset = 0;
109	}
110
111	res = LZ4_decompress_safe(stream->input, stream->output,
112		length, output->length);
113
114	if (res < 0)
115		return -EIO;
116
117	bytes = res;
118	data = squashfs_first_page(output);
119	buff = stream->output;
120	while (data) {
121		if (bytes <= PAGE_SIZE) {
122			if (!IS_ERR(data))
123				memcpy(data, buff, bytes);
124			break;
125		}
126		if (!IS_ERR(data))
127			memcpy(data, buff, PAGE_SIZE);
128		buff += PAGE_SIZE;
129		bytes -= PAGE_SIZE;
130		data = squashfs_next_page(output);
131	}
132	squashfs_finish_page(output);
133
134	return res;
135}
136
137const struct squashfs_decompressor squashfs_lz4_comp_ops = {
138	.init = lz4_init,
139	.comp_opts = lz4_comp_opts,
140	.free = lz4_free,
141	.decompress = lz4_uncompress,
142	.id = LZ4_COMPRESSION,
143	.name = "lz4",
144	.alloc_buffer = 0,
145	.supported = 1
146};
147