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
24 struct squashfs_xz {
25 struct xz_dec *state;
26 struct xz_buf buf;
27 };
28
29 struct disk_comp_opts {
30 __le32 dictionary_size;
31 __le32 flags;
32 };
33
34 struct comp_opts {
35 int dict_size;
36 };
37
38 static 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
74 out:
75 kfree(opts);
76 out2:
77 return ERR_PTR(err);
78 }
79
80
81 static 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
102 failed:
103 ERROR("Failed to initialise xz decompressor\n");
104 return ERR_PTR(err);
105 }
106
107
108 static 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
119 static 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
181 finish:
182 squashfs_finish_page(output);
183
184 return error ? error : total + stream->buf.out_pos;
185 }
186
187 const 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
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