1/*
2 * LZO decompressor for the Linux kernel. Code borrowed from the lzo
3 * implementation by Markus Franz Xaver Johannes Oberhumer.
4 *
5 * Linux kernel adaptation:
6 * Copyright (C) 2009
7 * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
8 *
9 * Original code:
10 * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
11 * All Rights Reserved.
12 *
13 * lzop and the LZO library are free software; you can redistribute them
14 * and/or modify them under the terms of the GNU General Public License as
15 * published by the Free Software Foundation; either version 2 of
16 * the License, or (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; see the file COPYING.
25 * If not, write to the Free Software Foundation, Inc.,
26 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27 *
28 * Markus F.X.J. Oberhumer
29 * <markus@oberhumer.com>
30 * http://www.oberhumer.com/opensource/lzop/
31 */
32
33#ifdef STATIC
34#include "lzo/lzo1x_decompress.c"
35#else
36#include <linux/slab.h>
37#include <linux/decompress/unlzo.h>
38#endif
39
40#include <linux/types.h>
41#include <linux/lzo.h>
42#include <linux/decompress/mm.h>
43
44#include <linux/compiler.h>
45#include <asm/unaligned.h>
46
47static const unsigned char lzop_magic[] = {
48	0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
49
50#define LZO_BLOCK_SIZE        (256*1024l)
51#define HEADER_HAS_FILTER      0x00000800L
52
53STATIC inline int INIT parse_header(u8 *input, u8 *skip)
54{
55	int l;
56	u8 *parse = input;
57	u8 level = 0;
58	u16 version;
59
60	/* read magic: 9 first bits */
61	for (l = 0; l < 9; l++) {
62		if (*parse++ != lzop_magic[l])
63			return 0;
64	}
65	/* get version (2bytes), skip library version (2),
66	 * 'need to be extracted' version (2) and
67	 * method (1) */
68	version = get_unaligned_be16(parse);
69	parse += 7;
70	if (version >= 0x0940)
71		level = *parse++;
72	if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
73		parse += 8; /* flags + filter info */
74	else
75		parse += 4; /* flags */
76
77	/* skip mode and mtime_low */
78	parse += 8;
79	if (version >= 0x0940)
80		parse += 4;	/* skip mtime_high */
81
82	l = *parse++;
83	/* don't care about the file name, and skip checksum */
84	parse += l + 4;
85
86	*skip = parse - input;
87	return 1;
88}
89
90STATIC inline int INIT unlzo(u8 *input, int in_len,
91				int (*fill) (void *, unsigned int),
92				int (*flush) (void *, unsigned int),
93				u8 *output, int *posp,
94				void (*error_fn) (char *x))
95{
96	u8 skip = 0, r = 0;
97	u32 src_len, dst_len;
98	size_t tmp;
99	u8 *in_buf, *in_buf_save, *out_buf;
100	int ret = -1;
101
102	set_error_fn(error_fn);
103
104	if (output) {
105		out_buf = output;
106	} else if (!flush) {
107		error("NULL output pointer and no flush function provided");
108		goto exit;
109	} else {
110		out_buf = malloc(LZO_BLOCK_SIZE);
111		if (!out_buf) {
112			error("Could not allocate output buffer");
113			goto exit;
114		}
115	}
116
117	if (input && fill) {
118		error("Both input pointer and fill function provided, don't know what to do");
119		goto exit_1;
120	} else if (input) {
121		in_buf = input;
122	} else if (!fill || !posp) {
123		error("NULL input pointer and missing position pointer or fill function");
124		goto exit_1;
125	} else {
126		in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
127		if (!in_buf) {
128			error("Could not allocate input buffer");
129			goto exit_1;
130		}
131	}
132	in_buf_save = in_buf;
133
134	if (posp)
135		*posp = 0;
136
137	if (fill)
138		fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
139
140	if (!parse_header(input, &skip)) {
141		error("invalid header");
142		goto exit_2;
143	}
144	in_buf += skip;
145
146	if (posp)
147		*posp = skip;
148
149	for (;;) {
150		/* read uncompressed block size */
151		dst_len = get_unaligned_be32(in_buf);
152		in_buf += 4;
153
154		/* exit if last block */
155		if (dst_len == 0) {
156			if (posp)
157				*posp += 4;
158			break;
159		}
160
161		if (dst_len > LZO_BLOCK_SIZE) {
162			error("dest len longer than block size");
163			goto exit_2;
164		}
165
166		/* read compressed block size, and skip block checksum info */
167		src_len = get_unaligned_be32(in_buf);
168		in_buf += 8;
169
170		if (src_len <= 0 || src_len > dst_len) {
171			error("file corrupted");
172			goto exit_2;
173		}
174
175		/* decompress */
176		tmp = dst_len;
177
178		/* When the input data is not compressed at all,
179		 * lzo1x_decompress_safe will fail, so call memcpy()
180		 * instead */
181		if (unlikely(dst_len == src_len))
182			memcpy(out_buf, in_buf, src_len);
183		else {
184			r = lzo1x_decompress_safe((u8 *) in_buf, src_len,
185						out_buf, &tmp);
186
187			if (r != LZO_E_OK || dst_len != tmp) {
188				error("Compressed data violation");
189				goto exit_2;
190			}
191		}
192
193		if (flush)
194			flush(out_buf, dst_len);
195		if (output)
196			out_buf += dst_len;
197		if (posp)
198			*posp += src_len + 12;
199		if (fill) {
200			in_buf = in_buf_save;
201			fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
202		} else
203			in_buf += src_len;
204	}
205
206	ret = 0;
207exit_2:
208	if (!input)
209		free(in_buf);
210exit_1:
211	if (!output)
212		free(out_buf);
213exit:
214	return ret;
215}
216
217#define decompress unlzo
218