freebsd-dev/sys/cddl/boot/zfs/lz4.c
Xin LI 43ac3722ac Diff reduction with kernel code: instruct the compiler that the data of
these types may be unaligned to their "normal" alignment and exercise
caution when accessing them.

PR:		194071
MFC after:	3 days
2014-10-02 00:13:08 +00:00

328 lines
8.4 KiB
C

/*
* LZ4 - Fast LZ compression algorithm
* Header File
* Copyright (C) 2011-2013, Yann Collet.
* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You can contact the author at :
* - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
* - LZ4 source repository : http://code.google.com/p/lz4/
*
* $FreeBSD$
*/
static int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
int isize, int maxOutputSize);
/* ARGSUSED */
static int
lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int dummy __unused)
{
const uint8_t *src = s_start;
uint32_t bufsiz = htonl(*(uint32_t *)src);
/* invalid compressed buffer size encoded at start */
if (bufsiz + 4 > s_len)
return (1);
/*
* Returns 0 on success (decompression function returned non-negative)
* and non-zero on failure (decompression function returned negative).
*/
return (LZ4_uncompress_unknownOutputSize(s_start + 4, d_start, bufsiz,
d_len) < 0);
}
/*
* CPU Feature Detection
*/
/* 32 or 64 bits ? */
#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || \
defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
defined(__LP64__) || defined(_LP64))
#define LZ4_ARCH64 1
#else
#define LZ4_ARCH64 0
#endif
/*
* Little Endian or Big Endian?
* Note: overwrite the below #define if you know your architecture endianess.
*/
#if BYTE_ORDER == BIG_ENDIAN
#define LZ4_BIG_ENDIAN 1
#else
/*
* Little Endian assumed. PDP Endian and other very rare endian format
* are unsupported.
*/
#endif
/*
* Unaligned memory access is automatically enabled for "common" CPU,
* such as x86. For others CPU, the compiler will be more cautious, and
* insert extra code to ensure aligned access is respected. If you know
* your target CPU supports unaligned memory access, you may want to
* force this option manually to improve performance
*/
#if defined(__ARM_FEATURE_UNALIGNED)
#define LZ4_FORCE_UNALIGNED_ACCESS 1
#endif
/*
* Compiler Options
*/
#if __STDC_VERSION__ >= 199901L /* C99 */
/* "restrict" is a known keyword */
#else
/* Disable restrict */
#define restrict
#endif
#define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
#define lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) \
| (((x) & 0xffu) << 8)))
#if (GCC_VERSION >= 302) || (__INTEL_COMPILER >= 800) || defined(__clang__)
#define expect(expr, value) (__builtin_expect((expr), (value)))
#else
#define expect(expr, value) (expr)
#endif
#define likely(expr) expect((expr) != 0, 1)
#define unlikely(expr) expect((expr) != 0, 0)
/* Basic types */
#define BYTE uint8_t
#define U16 uint16_t
#define U32 uint32_t
#define S32 int32_t
#define U64 uint64_t
#ifndef LZ4_FORCE_UNALIGNED_ACCESS
#pragma pack(1)
#endif
typedef struct _U16_S {
U16 v;
} U16_S;
typedef struct _U32_S {
U32 v;
} U32_S;
typedef struct _U64_S {
U64 v;
} U64_S;
#ifndef LZ4_FORCE_UNALIGNED_ACCESS
#pragma pack()
#endif
#define A64(x) (((U64_S *)(x))->v)
#define A32(x) (((U32_S *)(x))->v)
#define A16(x) (((U16_S *)(x))->v)
/*
* Constants
*/
#define MINMATCH 4
#define COPYLENGTH 8
#define LASTLITERALS 5
#define ML_BITS 4
#define ML_MASK ((1U<<ML_BITS)-1)
#define RUN_BITS (8-ML_BITS)
#define RUN_MASK ((1U<<RUN_BITS)-1)
/*
* Architecture-specific macros
*/
#if LZ4_ARCH64
#define STEPSIZE 8
#define UARCH U64
#define AARCH A64
#define LZ4_COPYSTEP(s, d) A64(d) = A64(s); d += 8; s += 8;
#define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d)
#define LZ4_SECURECOPY(s, d, e) if (d < e) LZ4_WILDCOPY(s, d, e)
#define HTYPE U32
#define INITBASE(base) const BYTE* const base = ip
#else
#define STEPSIZE 4
#define UARCH U32
#define AARCH A32
#define LZ4_COPYSTEP(s, d) A32(d) = A32(s); d += 4; s += 4;
#define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
#define LZ4_SECURECOPY LZ4_WILDCOPY
#define HTYPE const BYTE*
#define INITBASE(base) const int base = 0
#endif
#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
#define LZ4_READ_LITTLEENDIAN_16(d, s, p) \
{ U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
#define LZ4_WRITE_LITTLEENDIAN_16(p, i) \
{ U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
#else
#define LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
#define LZ4_WRITE_LITTLEENDIAN_16(p, v) { A16(p) = v; p += 2; }
#endif
/* Macros */
#define LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
/* Decompression functions */
static int
LZ4_uncompress_unknownOutputSize(const char *source,
char *dest, int isize, int maxOutputSize)
{
/* Local Variables */
const BYTE *restrict ip = (const BYTE *) source;
const BYTE *const iend = ip + isize;
const BYTE *restrict ref;
BYTE *restrict op = (BYTE *) dest;
BYTE *const oend = op + maxOutputSize;
BYTE *cpy;
size_t dec[] = { 0, 3, 2, 3, 0, 0, 0, 0 };
/* Main Loop */
while (ip < iend) {
BYTE token;
int length;
/* get runlength */
token = *ip++;
if ((length = (token >> ML_BITS)) == RUN_MASK) {
int s = 255;
while ((ip < iend) && (s == 255)) {
s = *ip++;
length += s;
}
}
/* copy literals */
cpy = op + length;
if ((cpy > oend - COPYLENGTH) ||
(ip + length > iend - COPYLENGTH)) {
if (cpy > oend)
/*
* Error: request to write beyond destination
* buffer.
*/
goto _output_error;
if (ip + length > iend)
/*
* Error : request to read beyond source
* buffer.
*/
goto _output_error;
memcpy(op, ip, length);
op += length;
ip += length;
if (ip < iend)
/* Error : LZ4 format violation */
goto _output_error;
/* Necessarily EOF, due to parsing restrictions. */
break;
}
LZ4_WILDCOPY(ip, op, cpy);
ip -= (op - cpy);
op = cpy;
/* get offset */
LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
ip += 2;
if (ref < (BYTE * const) dest)
/*
* Error: offset creates reference outside of
* destination buffer.
*/
goto _output_error;
/* get matchlength */
if ((length = (token & ML_MASK)) == ML_MASK) {
while (ip < iend) {
int s = *ip++;
length += s;
if (s == 255)
continue;
break;
}
}
/* copy repeated sequence */
if unlikely(op - ref < STEPSIZE) {
#if LZ4_ARCH64
size_t dec2table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
size_t dec2 = dec2table[op - ref];
#else
const int dec2 = 0;
#endif
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
ref -= dec[op - ref];
A32(op) = A32(ref);
op += STEPSIZE - 4;
ref -= dec2;
} else {
LZ4_COPYSTEP(ref, op);
}
cpy = op + length - (STEPSIZE - 4);
if (cpy > oend - COPYLENGTH) {
if (cpy > oend)
/*
* Error: request to write outside of
* destination buffer.
*/
goto _output_error;
LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
while (op < cpy)
*op++ = *ref++;
op = cpy;
if (op == oend)
/*
* Check EOF (should never happen, since last
* 5 bytes are supposed to be literals).
*/
break;
continue;
}
LZ4_SECURECOPY(ref, op, cpy);
op = cpy; /* correction */
}
/* end of decoding */
return (int)(((char *)op) - dest);
/* write overflow error detected */
_output_error:
return (int)(-(((char *)ip) - source));
}