Root/lib/decompress_unlzo.c

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

Archive Download this file



interactive