1/*
2 * LZ4 - Fast LZ compression algorithm
3 * Header File
4 * Copyright (C) 2011-2013, Yann Collet.
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
9 * met:
10 *
11 *     * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 *     * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * You can contact the author at :
31 * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
32 * - LZ4 source repository : http://code.google.com/p/lz4/
33 *
34 * $FreeBSD$
35 */
36
37#include <arpa/inet.h>
38
39static int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
40					    int isize, int maxOutputSize);
41
42/* ARGSUSED */
43static int
44lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int dummy __unused)
45{
46	const uint8_t *src = s_start;
47	uint32_t bufsiz = htonl(*(uint32_t *)src);
48
49	/* invalid compressed buffer size encoded at start */
50	if (bufsiz + 4 > s_len)
51		return (1);
52
53	/*
54	 * Returns 0 on success (decompression function returned non-negative)
55	 * and non-zero on failure (decompression function returned negative).
56	 */
57	return (LZ4_uncompress_unknownOutputSize((const char *)s_start + 4, d_start, bufsiz,
58	    d_len) < 0);
59}
60
61/*
62 * CPU Feature Detection
63 */
64
65/* 32 or 64 bits ? */
66#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || \
67	defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
68	defined(__LP64__) || defined(_LP64))
69#define	LZ4_ARCH64	1
70#else
71#define	LZ4_ARCH64	0
72#endif
73
74/*
75 * Little Endian or Big Endian?
76 * Note: overwrite the below #define if you know your architecture endianess.
77 */
78#if BYTE_ORDER == BIG_ENDIAN
79#define	LZ4_BIG_ENDIAN	1
80#else
81	/*
82	 * Little Endian assumed. PDP Endian and other very rare endian format
83	 * are unsupported.
84	 */
85#endif
86
87/*
88 * Unaligned memory access is automatically enabled for "common" CPU,
89 * such as x86. For others CPU, the compiler will be more cautious, and
90 * insert extra code to ensure aligned access is respected. If you know
91 * your target CPU supports unaligned memory access, you may want to
92 * force this option manually to improve performance
93 */
94#if defined(__ARM_FEATURE_UNALIGNED)
95#define	LZ4_FORCE_UNALIGNED_ACCESS 1
96#endif
97
98/*
99 * Compiler Options
100 */
101#if __STDC_VERSION__ >= 199901L	/* C99 */
102/* "restrict" is a known keyword */
103#else
104/* Disable restrict */
105#define	restrict
106#endif
107
108#define	GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
109
110#define	lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) \
111	| (((x) & 0xffu) << 8)))
112
113#if (GCC_VERSION >= 302) || (__INTEL_COMPILER >= 800) || defined(__clang__)
114#define	expect(expr, value)    (__builtin_expect((expr), (value)))
115#else
116#define	expect(expr, value)    (expr)
117#endif
118
119#define	likely(expr)	expect((expr) != 0, 1)
120#define	unlikely(expr)	expect((expr) != 0, 0)
121
122/* Basic types */
123#define	BYTE	uint8_t
124#define	U16	uint16_t
125#define	U32	uint32_t
126#define	S32	int32_t
127#define	U64	uint64_t
128
129#ifndef LZ4_FORCE_UNALIGNED_ACCESS
130#pragma pack(1)
131#endif
132
133typedef struct _U16_S {
134	U16 v;
135} U16_S;
136typedef struct _U32_S {
137	U32 v;
138} U32_S;
139typedef struct _U64_S {
140	U64 v;
141} U64_S;
142
143#ifndef LZ4_FORCE_UNALIGNED_ACCESS
144#pragma pack()
145#endif
146
147#define	A64(x)	(((U64_S *)(x))->v)
148#define	A32(x)	(((U32_S *)(x))->v)
149#define	A16(x)	(((U16_S *)(x))->v)
150
151/*
152 * Constants
153 */
154#define	MINMATCH 4
155
156#define	COPYLENGTH 8
157#define	LASTLITERALS 5
158
159#define	ML_BITS 4
160#define	ML_MASK ((1U<<ML_BITS)-1)
161#define	RUN_BITS (8-ML_BITS)
162#define	RUN_MASK ((1U<<RUN_BITS)-1)
163
164/*
165 * Architecture-specific macros
166 */
167#if LZ4_ARCH64
168#define	STEPSIZE 8
169#define	UARCH U64
170#define	AARCH A64
171#define	LZ4_COPYSTEP(s, d)	A64(d) = A64(s); d += 8; s += 8;
172#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d)
173#define	LZ4_SECURECOPY(s, d, e)	if (d < e) LZ4_WILDCOPY(s, d, e)
174#define	HTYPE U32
175#define	INITBASE(base)		const BYTE* const base = ip
176#else
177#define	STEPSIZE 4
178#define	UARCH U32
179#define	AARCH A32
180#define	LZ4_COPYSTEP(s, d)	A32(d) = A32(s); d += 4; s += 4;
181#define	LZ4_COPYPACKET(s, d)	LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
182#define	LZ4_SECURECOPY		LZ4_WILDCOPY
183#define	HTYPE const BYTE*
184#define	INITBASE(base)		const int base = 0
185#endif
186
187#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
188#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) \
189	{ U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
190#define	LZ4_WRITE_LITTLEENDIAN_16(p, i) \
191	{ U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
192#else
193#define	LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
194#define	LZ4_WRITE_LITTLEENDIAN_16(p, v)  { A16(p) = v; p += 2; }
195#endif
196
197/* Macros */
198#define	LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
199
200/* Decompression functions */
201
202static int
203LZ4_uncompress_unknownOutputSize(const char *source,
204    char *dest, int isize, int maxOutputSize)
205{
206	/* Local Variables */
207	const BYTE *restrict ip = (const BYTE *) source;
208	const BYTE *const iend = ip + isize;
209	const BYTE *restrict ref;
210
211	BYTE *restrict op = (BYTE *) dest;
212	BYTE *const oend = op + maxOutputSize;
213	BYTE *cpy;
214
215	size_t dec[] = { 0, 3, 2, 3, 0, 0, 0, 0 };
216
217	/* Main Loop */
218	while (ip < iend) {
219		BYTE token;
220		int length;
221
222		/* get runlength */
223		token = *ip++;
224		if ((length = (token >> ML_BITS)) == RUN_MASK) {
225			int s = 255;
226			while ((ip < iend) && (s == 255)) {
227				s = *ip++;
228				length += s;
229			}
230		}
231		/* copy literals */
232		cpy = op + length;
233		if ((cpy > oend - COPYLENGTH) ||
234		    (ip + length > iend - COPYLENGTH)) {
235			if (cpy > oend)
236				/*
237				 * Error: request to write beyond destination
238				 * buffer.
239				 */
240				goto _output_error;
241			if (ip + length > iend)
242				/*
243				 * Error : request to read beyond source
244				 * buffer.
245				 */
246				goto _output_error;
247			memcpy(op, ip, length);
248			op += length;
249			ip += length;
250			if (ip < iend)
251				/* Error : LZ4 format violation */
252				goto _output_error;
253			/* Necessarily EOF, due to parsing restrictions. */
254			break;
255		}
256		LZ4_WILDCOPY(ip, op, cpy);
257		ip -= (op - cpy);
258		op = cpy;
259
260		/* get offset */
261		LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
262		ip += 2;
263		if (ref < (BYTE * const) dest)
264			/*
265			 * Error: offset creates reference outside of
266			 * destination buffer.
267			 */
268			goto _output_error;
269
270		/* get matchlength */
271		if ((length = (token & ML_MASK)) == ML_MASK) {
272			while (ip < iend) {
273				int s = *ip++;
274				length += s;
275				if (s == 255)
276					continue;
277				break;
278			}
279		}
280		/* copy repeated sequence */
281		if unlikely(op - ref < STEPSIZE) {
282#if LZ4_ARCH64
283			size_t dec2table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
284			size_t dec2 = dec2table[op - ref];
285#else
286			const int dec2 = 0;
287#endif
288			*op++ = *ref++;
289			*op++ = *ref++;
290			*op++ = *ref++;
291			*op++ = *ref++;
292			ref -= dec[op - ref];
293			A32(op) = A32(ref);
294			op += STEPSIZE - 4;
295			ref -= dec2;
296		} else {
297			LZ4_COPYSTEP(ref, op);
298		}
299		cpy = op + length - (STEPSIZE - 4);
300		if (cpy > oend - COPYLENGTH) {
301			if (cpy > oend)
302				/*
303				 * Error: request to write outside of
304				 * destination buffer.
305				 */
306				goto _output_error;
307			LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
308			while (op < cpy)
309				*op++ = *ref++;
310			op = cpy;
311			if (op == oend)
312				/*
313				 * Check EOF (should never happen, since last
314				 * 5 bytes are supposed to be literals).
315				 */
316				break;
317			continue;
318		}
319		LZ4_SECURECOPY(ref, op, cpy);
320		op = cpy;	/* correction */
321	}
322
323	/* end of decoding */
324	return (int)(((char *)op) - dest);
325
326	/* write overflow error detected */
327	_output_error:
328	return (int)(-(((char *)ip) - source));
329}
330