summaryrefslogtreecommitdiffstats
path: root/lib/lzo/lzo1x_decompress.c
blob: 35f3793f31c61e045df3c634b5299d7c735fc623 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
/*
 *  LZO1X Decompressor from MiniLZO
 *
 *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <markus@oberhumer.com>
 *
 *  The full LZO package can be found at:
 *  http://www.oberhumer.com/opensource/lzo/
 *
 *  Changed for kernel use by:
 *  Nitin Gupta <nitingupta910@gmail.com>
 *  Richard Purdie <rpurdie@openedhand.com>
 */

#include <common.h>
#include <linux/lzo.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include "lzodefs.h"

#define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x))
#define HAVE_OP(x, op_end, op) ((size_t)(op_end - op) < (x))
#define HAVE_LB(m_pos, out, op) (m_pos < out || m_pos >= op)

#define COPY4(dst, src)	\
		put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))

static const unsigned char lzop_magic[] = {
	0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a
};

#define HEADER_HAS_FILTER	0x00000800L

static inline const unsigned char *parse_header(const unsigned char *src)
{
	u16 version;
	int i;

	/* read magic: 9 first bytes */
	for (i = 0; i < ARRAY_SIZE(lzop_magic); i++) {
		if (*src++ != lzop_magic[i])
			return NULL;
	}
	/* get version (2bytes), skip library version (2),
	 * 'need to be extracted' version (2) and
	 * method (1) */
	version = get_unaligned_be16(src);
	src += 7;
	if (version >= 0x0940)
		src++;
	if (get_unaligned_be32(src) & HEADER_HAS_FILTER)
		src += 4; /* filter info */

	/* skip flags, mode and mtime_low */
	src += 12;
	if (version >= 0x0940)
		src += 4;	/* skip mtime_high */

	i = *src++;
	/* don't care about the file name, and skip checksum */
	src += i + 4;

	return src;
}

int lzop_decompress(const unsigned char *src, size_t src_len,
		    unsigned char *dst, size_t *dst_len)
{
	unsigned char *start = dst;
	const unsigned char *send = src + src_len;
	u32 slen, dlen;
	size_t tmp, remaining;
	int r;

	src = parse_header(src);
	if (!src)
		return LZO_E_ERROR;

	remaining = *dst_len;
	while (src < send) {
		/* read uncompressed block size */
		dlen = get_unaligned_be32(src);
		src += 4;

		/* exit if last block */
		if (dlen == 0) {
			*dst_len = dst - start;
			return LZO_E_OK;
		}

		/* read compressed block size, and skip block checksum info */
		slen = get_unaligned_be32(src);
		src += 8;

		if (slen <= 0 || slen > dlen)
			return LZO_E_ERROR;

		/* abort if buffer ran out of room */
		if (dlen > remaining)
			return LZO_E_OUTPUT_OVERRUN;

		/* decompress */
		tmp = dlen;
		r = lzo1x_decompress_safe((u8 *) src, slen, dst, &tmp);

		if (r != LZO_E_OK)
			return r;

		if (dlen != tmp)
			return LZO_E_ERROR;

		src += slen;
		dst += dlen;
		remaining -= dlen;
	}

	return LZO_E_INPUT_OVERRUN;
}

int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
			unsigned char *out, size_t *out_len)
{
	const unsigned char * const ip_end = in + in_len;
	unsigned char * const op_end = out + *out_len;
	const unsigned char *ip = in, *m_pos;
	unsigned char *op = out;
	size_t t;

	*out_len = 0;

	if (*ip > 17) {
		t = *ip++ - 17;
		if (t < 4)
			goto match_next;
		if (HAVE_OP(t, op_end, op))
			goto output_overrun;
		if (HAVE_IP(t + 1, ip_end, ip))
			goto input_overrun;
		do {
			*op++ = *ip++;
		} while (--t > 0);
		goto first_literal_run;
	}

	while ((ip < ip_end)) {
		t = *ip++;
		if (t >= 16)
			goto match;
		if (t == 0) {
			if (HAVE_IP(1, ip_end, ip))
				goto input_overrun;
			while (*ip == 0) {
				t += 255;
				ip++;
				if (HAVE_IP(1, ip_end, ip))
					goto input_overrun;
			}
			t += 15 + *ip++;
		}
		if (HAVE_OP(t + 3, op_end, op))
			goto output_overrun;
		if (HAVE_IP(t + 4, ip_end, ip))
			goto input_overrun;

		COPY4(op, ip);
		op += 4;
		ip += 4;
		if (--t > 0) {
			if (t >= 4) {
				do {
					COPY4(op, ip);
					op += 4;
					ip += 4;
					t -= 4;
				} while (t >= 4);
				if (t > 0) {
					do {
						*op++ = *ip++;
					} while (--t > 0);
				}
			} else {
				do {
					*op++ = *ip++;
				} while (--t > 0);
			}
		}

first_literal_run:
		t = *ip++;
		if (t >= 16)
			goto match;
		m_pos = op - (1 + M2_MAX_OFFSET);
		m_pos -= t >> 2;
		m_pos -= *ip++ << 2;

		if (HAVE_LB(m_pos, out, op))
			goto lookbehind_overrun;

		if (HAVE_OP(3, op_end, op))
			goto output_overrun;
		*op++ = *m_pos++;
		*op++ = *m_pos++;
		*op++ = *m_pos;

		goto match_done;

		do {
match:
			if (t >= 64) {
				m_pos = op - 1;
				m_pos -= (t >> 2) & 7;
				m_pos -= *ip++ << 3;
				t = (t >> 5) - 1;
				if (HAVE_LB(m_pos, out, op))
					goto lookbehind_overrun;
				if (HAVE_OP(t + 3 - 1, op_end, op))
					goto output_overrun;
				goto copy_match;
			} else if (t >= 32) {
				t &= 31;
				if (t == 0) {
					if (HAVE_IP(1, ip_end, ip))
						goto input_overrun;
					while (*ip == 0) {
						t += 255;
						ip++;
						if (HAVE_IP(1, ip_end, ip))
							goto input_overrun;
					}
					t += 31 + *ip++;
				}
				m_pos = op - 1;
				m_pos -= get_unaligned_le16(ip) >> 2;
				ip += 2;
			} else if (t >= 16) {
				m_pos = op;
				m_pos -= (t & 8) << 11;

				t &= 7;
				if (t == 0) {
					if (HAVE_IP(1, ip_end, ip))
						goto input_overrun;
					while (*ip == 0) {
						t += 255;
						ip++;
						if (HAVE_IP(1, ip_end, ip))
							goto input_overrun;
					}
					t += 7 + *ip++;
				}
				m_pos -= get_unaligned_le16(ip) >> 2;
				ip += 2;
				if (m_pos == op)
					goto eof_found;
				m_pos -= 0x4000;
			} else {
				m_pos = op - 1;
				m_pos -= t >> 2;
				m_pos -= *ip++ << 2;

				if (HAVE_LB(m_pos, out, op))
					goto lookbehind_overrun;
				if (HAVE_OP(2, op_end, op))
					goto output_overrun;

				*op++ = *m_pos++;
				*op++ = *m_pos;
				goto match_done;
			}

			if (HAVE_LB(m_pos, out, op))
				goto lookbehind_overrun;
			if (HAVE_OP(t + 3 - 1, op_end, op))
				goto output_overrun;

			if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
				COPY4(op, m_pos);
				op += 4;
				m_pos += 4;
				t -= 4 - (3 - 1);
				do {
					COPY4(op, m_pos);
					op += 4;
					m_pos += 4;
					t -= 4;
				} while (t >= 4);
				if (t > 0)
					do {
						*op++ = *m_pos++;
					} while (--t > 0);
			} else {
copy_match:
				*op++ = *m_pos++;
				*op++ = *m_pos++;
				do {
					*op++ = *m_pos++;
				} while (--t > 0);
			}
match_done:
			t = ip[-2] & 3;
			if (t == 0)
				break;
match_next:
			if (HAVE_OP(t, op_end, op))
				goto output_overrun;
			if (HAVE_IP(t + 1, ip_end, ip))
				goto input_overrun;

			*op++ = *ip++;
			if (t > 1) {
				*op++ = *ip++;
				if (t > 2)
					*op++ = *ip++;
			}

			t = *ip++;
		} while (ip < ip_end);
	}

	*out_len = op - out;
	return LZO_E_EOF_NOT_FOUND;

eof_found:
	*out_len = op - out;
	return (ip == ip_end ? LZO_E_OK :
		(ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
input_overrun:
	*out_len = op - out;
	return LZO_E_INPUT_OVERRUN;

output_overrun:
	*out_len = op - out;
	return LZO_E_OUTPUT_OVERRUN;

lookbehind_overrun:
	*out_len = op - out;
	return LZO_E_LOOKBEHIND_OVERRUN;
}
OpenPOWER on IntegriCloud