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_KERNEL);
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 
140 	xz_dec_reset(stream->state);
141 	stream->buf.in_pos = 0;
142 	stream->buf.in_size = 0;
143 	stream->buf.out_pos = 0;
144 	stream->buf.out_size = PAGE_SIZE;
145 	stream->buf.out = squashfs_first_page(output);
146 
147 	do {
148 		if (stream->buf.in_pos == stream->buf.in_size && k < b) {
149 			avail = min(length, msblk->devblksize - offset);
150 			length -= avail;
151 			stream->buf.in = bh[k]->b_data + offset;
152 			stream->buf.in_size = avail;
153 			stream->buf.in_pos = 0;
154 			offset = 0;
155 		}
156 
157 		if (stream->buf.out_pos == stream->buf.out_size) {
158 			stream->buf.out = squashfs_next_page(output);
159 			if (stream->buf.out != NULL) {
160 				stream->buf.out_pos = 0;
161 				total += PAGE_SIZE;
162 			}
163 		}
164 
165 		xz_err = xz_dec_run(stream->state, &stream->buf);
166 
167 		if (stream->buf.in_pos == stream->buf.in_size && k < b)
168 			put_bh(bh[k++]);
169 	} while (xz_err == XZ_OK);
170 
171 	squashfs_finish_page(output);
172 
173 	if (xz_err != XZ_STREAM_END || k < b)
174 		goto out;
175 
176 	return total + stream->buf.out_pos;
177 
178 out:
179 	for (; k < b; k++)
180 		put_bh(bh[k]);
181 
182 	return -EIO;
183 }
184 
185 const struct squashfs_decompressor squashfs_xz_comp_ops = {
186 	.init = squashfs_xz_init,
187 	.comp_opts = squashfs_xz_comp_opts,
188 	.free = squashfs_xz_free,
189 	.decompress = squashfs_xz_uncompress,
190 	.id = XZ_COMPRESSION,
191 	.name = "xz",
192 	.supported = 1
193 };
194