1 /*
2 * Squashfs - a compressed read only filesystem for Linux
3 *
4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
5 * Phillip Lougher <phillip@squashfs.org.uk>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2,
10 * or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 * xz_wrapper.c
22 */
23
24
25 #include <linux/mutex.h>
26 #include <linux/buffer_head.h>
27 #include <linux/slab.h>
28 #include <linux/xz.h>
29 #include <linux/bitops.h>
30
31 #include "squashfs_fs.h"
32 #include "squashfs_fs_sb.h"
33 #include "squashfs.h"
34 #include "decompressor.h"
35 #include "page_actor.h"
36
37 struct squashfs_xz {
38 struct xz_dec *state;
39 struct xz_buf buf;
40 };
41
42 struct disk_comp_opts {
43 __le32 dictionary_size;
44 __le32 flags;
45 };
46
47 struct comp_opts {
48 int dict_size;
49 };
50
squashfs_xz_comp_opts(struct squashfs_sb_info * msblk,void * buff,int len)51 static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
52 void *buff, int len)
53 {
54 struct disk_comp_opts *comp_opts = buff;
55 struct comp_opts *opts;
56 int err = 0, n;
57
58 opts = kmalloc(sizeof(*opts), GFP_ATOMIC);
59 if (opts == NULL) {
60 err = -ENOMEM;
61 goto out2;
62 }
63
64 if (comp_opts) {
65 /* check compressor options are the expected length */
66 if (len < sizeof(*comp_opts)) {
67 err = -EIO;
68 goto out;
69 }
70
71 opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
72
73 /* the dictionary size should be 2^n or 2^n+2^(n+1) */
74 n = ffs(opts->dict_size) - 1;
75 if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
76 (1 << (n + 1))) {
77 err = -EIO;
78 goto out;
79 }
80 } else
81 /* use defaults */
82 opts->dict_size = max_t(int, msblk->block_size,
83 SQUASHFS_METADATA_SIZE);
84
85 return opts;
86
87 out:
88 kfree(opts);
89 out2:
90 return ERR_PTR(err);
91 }
92
93
squashfs_xz_init(struct squashfs_sb_info * msblk,void * buff)94 static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
95 {
96 struct comp_opts *comp_opts = buff;
97 struct squashfs_xz *stream;
98 int err;
99
100 stream = kmalloc(sizeof(*stream), GFP_KERNEL);
101 if (stream == NULL) {
102 err = -ENOMEM;
103 goto failed;
104 }
105
106 stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
107 if (stream->state == NULL) {
108 kfree(stream);
109 err = -ENOMEM;
110 goto failed;
111 }
112
113 return stream;
114
115 failed:
116 ERROR("Failed to initialise xz decompressor\n");
117 return ERR_PTR(err);
118 }
119
120
squashfs_xz_free(void * strm)121 static void squashfs_xz_free(void *strm)
122 {
123 struct squashfs_xz *stream = strm;
124
125 if (stream) {
126 xz_dec_end(stream->state);
127 kfree(stream);
128 }
129 }
130
131
squashfs_xz_uncompress(struct squashfs_sb_info * msblk,void * strm,struct buffer_head ** bh,int b,int offset,int length,struct squashfs_page_actor * output)132 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
133 struct buffer_head **bh, int b, int offset, int length,
134 struct squashfs_page_actor *output)
135 {
136 enum xz_ret xz_err;
137 int avail, total = 0, k = 0;
138 struct squashfs_xz *stream = strm;
139 void *buf = NULL;
140
141 xz_dec_reset(stream->state);
142 stream->buf.in_pos = 0;
143 stream->buf.in_size = 0;
144 stream->buf.out_pos = 0;
145 stream->buf.out_size = PAGE_SIZE;
146 stream->buf.out = squashfs_first_page(output);
147
148 do {
149 if (stream->buf.in_pos == stream->buf.in_size && k < b) {
150 avail = min(length, msblk->devblksize - offset);
151 length -= avail;
152 stream->buf.in = bh[k]->b_data + offset;
153 stream->buf.in_size = avail;
154 stream->buf.in_pos = 0;
155 offset = 0;
156 }
157
158 if (stream->buf.out_pos == stream->buf.out_size) {
159 stream->buf.out = squashfs_next_page(output);
160 if (!IS_ERR(stream->buf.out)) {
161 stream->buf.out_pos = 0;
162 total += PAGE_SIZE;
163 }
164 }
165
166 if (!stream->buf.out) {
167 if (!buf) {
168 buf = kmalloc(PAGE_SIZE, GFP_ATOMIC);
169 if (!buf)
170 goto out;
171 }
172 stream->buf.out = buf;
173 }
174 xz_err = xz_dec_run(stream->state, &stream->buf);
175
176 if (stream->buf.in_pos == stream->buf.in_size && k < b)
177 put_bh(bh[k++]);
178 } while (xz_err == XZ_OK);
179
180 squashfs_finish_page(output);
181
182 if (xz_err != XZ_STREAM_END || k < b)
183 goto out;
184
185 kfree(buf);
186 return total + stream->buf.out_pos;
187
188 out:
189 for (; k < b; k++)
190 put_bh(bh[k]);
191 kfree(buf);
192
193 return -EIO;
194 }
195
196 const struct squashfs_decompressor squashfs_xz_comp_ops = {
197 .init = squashfs_xz_init,
198 .comp_opts = squashfs_xz_comp_opts,
199 .free = squashfs_xz_free,
200 .decompress = squashfs_xz_uncompress,
201 .id = XZ_COMPRESSION,
202 .name = "xz",
203 .supported = 1
204 };
205