1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * xz_wrapper.c
9 */
10
11
12#include <linux/mutex.h>
13#include <linux/bio.h>
14#include <linux/slab.h>
15#include <linux/xz.h>
16#include <linux/bitops.h>
17
18#include "squashfs_fs.h"
19#include "squashfs_fs_sb.h"
20#include "squashfs.h"
21#include "decompressor.h"
22#include "page_actor.h"
23
24struct squashfs_xz {
25	struct xz_dec *state;
26	struct xz_buf buf;
27};
28
29struct disk_comp_opts {
30	__le32 dictionary_size;
31	__le32 flags;
32};
33
34struct comp_opts {
35	int dict_size;
36};
37
38static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
39	void *buff, int len)
40{
41	struct disk_comp_opts *comp_opts = buff;
42	struct comp_opts *opts;
43	int err = 0, n;
44
45	opts = kmalloc(sizeof(*opts), GFP_KERNEL);
46	if (opts == NULL) {
47		err = -ENOMEM;
48		goto out2;
49	}
50
51	if (comp_opts) {
52		/* check compressor options are the expected length */
53		if (len < sizeof(*comp_opts)) {
54			err = -EIO;
55			goto out;
56		}
57
58		opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
59
60		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
61		n = ffs(opts->dict_size) - 1;
62		if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
63						(1 << (n + 1))) {
64			err = -EIO;
65			goto out;
66		}
67	} else
68		/* use defaults */
69		opts->dict_size = max_t(int, msblk->block_size,
70							SQUASHFS_METADATA_SIZE);
71
72	return opts;
73
74out:
75	kfree(opts);
76out2:
77	return ERR_PTR(err);
78}
79
80
81static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
82{
83	struct comp_opts *comp_opts = buff;
84	struct squashfs_xz *stream;
85	int err;
86
87	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
88	if (stream == NULL) {
89		err = -ENOMEM;
90		goto failed;
91	}
92
93	stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
94	if (stream->state == NULL) {
95		kfree(stream);
96		err = -ENOMEM;
97		goto failed;
98	}
99
100	return stream;
101
102failed:
103	ERROR("Failed to initialise xz decompressor\n");
104	return ERR_PTR(err);
105}
106
107
108static void squashfs_xz_free(void *strm)
109{
110	struct squashfs_xz *stream = strm;
111
112	if (stream) {
113		xz_dec_end(stream->state);
114		kfree(stream);
115	}
116}
117
118
119static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
120	struct bio *bio, int offset, int length,
121	struct squashfs_page_actor *output)
122{
123	struct bvec_iter_all iter_all = {};
124	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
125	int total = 0, error = 0;
126	struct squashfs_xz *stream = strm;
127
128	xz_dec_reset(stream->state);
129	stream->buf.in_pos = 0;
130	stream->buf.in_size = 0;
131	stream->buf.out_pos = 0;
132	stream->buf.out_size = PAGE_SIZE;
133	stream->buf.out = squashfs_first_page(output);
134	if (IS_ERR(stream->buf.out)) {
135		error = PTR_ERR(stream->buf.out);
136		goto finish;
137	}
138
139	for (;;) {
140		enum xz_ret xz_err;
141
142		if (stream->buf.in_pos == stream->buf.in_size) {
143			const void *data;
144			int avail;
145
146			if (!bio_next_segment(bio, &iter_all)) {
147				/* XZ_STREAM_END must be reached. */
148				error = -EIO;
149				break;
150			}
151
152			avail = min(length, ((int)bvec->bv_len) - offset);
153			data = bvec_virt(bvec);
154			length -= avail;
155			stream->buf.in = data + offset;
156			stream->buf.in_size = avail;
157			stream->buf.in_pos = 0;
158			offset = 0;
159		}
160
161		if (stream->buf.out_pos == stream->buf.out_size) {
162			stream->buf.out = squashfs_next_page(output);
163			if (IS_ERR(stream->buf.out)) {
164				error = PTR_ERR(stream->buf.out);
165				break;
166			} else if (stream->buf.out != NULL) {
167				stream->buf.out_pos = 0;
168				total += PAGE_SIZE;
169			}
170		}
171
172		xz_err = xz_dec_run(stream->state, &stream->buf);
173		if (xz_err == XZ_STREAM_END)
174			break;
175		if (xz_err != XZ_OK) {
176			error = -EIO;
177			break;
178		}
179	}
180
181finish:
182	squashfs_finish_page(output);
183
184	return error ? error : total + stream->buf.out_pos;
185}
186
187const struct squashfs_decompressor squashfs_xz_comp_ops = {
188	.init = squashfs_xz_init,
189	.comp_opts = squashfs_xz_comp_opts,
190	.free = squashfs_xz_free,
191	.decompress = squashfs_xz_uncompress,
192	.id = XZ_COMPRESSION,
193	.name = "xz",
194	.alloc_buffer = 1,
195	.supported = 1
196};
197