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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417
|
/*
Copyright 2011, Google Inc.
All rights reserved.
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.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
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.
File modified for the Linux Kernel by
Zeev Tarantov <zeev.tarantov@gmail.com>
File modified for Sereal by
Steffen Mueller <smueller@cpan.org>
*/
#include "csnappy_internal.h"
#ifdef __KERNEL__
#include <linux/kernel.h>
#include <linux/module.h>
#endif
#include "csnappy.h"
int
csnappy_get_uncompressed_length(
const char *src,
uint32_t src_len,
uint32_t *result)
{
const char *src_base = src;
uint32_t shift = 0;
uint8_t c;
/* Length is encoded in 1..5 bytes */
*result = 0;
for (;;) {
if (shift >= 32)
goto err_out;
if (src_len == 0)
goto err_out;
c = *(const uint8_t *)src++;
src_len -= 1;
*result |= (uint32_t)(c & 0x7f) << shift;
if (c < 128)
break;
shift += 7;
}
return src - src_base;
err_out:
return CSNAPPY_E_HEADER_BAD;
}
#if defined(__KERNEL__) && !defined(STATIC)
EXPORT_SYMBOL(csnappy_get_uncompressed_length);
#endif
#if defined(__arm__) && !defined(ARCH_ARM_HAVE_UNALIGNED)
int csnappy_decompress_noheader(
const char *src_,
uint32_t src_remaining,
char *dst,
uint32_t *dst_len)
{
const uint8_t * src = (const uint8_t *)src_;
const uint8_t * const src_end = src + src_remaining;
char * const dst_base = dst;
char * const dst_end = dst + *dst_len;
while (src < src_end) {
uint32_t opcode = *src++;
uint32_t length = (opcode >> 2) + 1;
const uint8_t *copy_src;
if (likely((opcode & 3) == 0)) {
if (unlikely(length > 60)) {
uint32_t extra_bytes = length - 60;
int shift, max_shift;
if (unlikely(src + extra_bytes > src_end))
return CSNAPPY_E_DATA_MALFORMED;
length = 0;
for (shift = 0, max_shift = extra_bytes*8;
shift < max_shift;
shift += 8)
length |= *src++ << shift;
++length;
}
if (unlikely(src + length > src_end))
return CSNAPPY_E_DATA_MALFORMED;
copy_src = src;
src += length;
} else {
uint32_t offset;
if (likely((opcode & 3) == 1)) {
if (unlikely(src + 1 > src_end))
return CSNAPPY_E_DATA_MALFORMED;
length = ((length - 1) & 7) + 4;
offset = ((opcode >> 5) << 8) + *src++;
} else if (likely((opcode & 3) == 2)) {
if (unlikely(src + 2 > src_end))
return CSNAPPY_E_DATA_MALFORMED;
offset = src[0] | (src[1] << 8);
src += 2;
} else {
if (unlikely(src + 4 > src_end))
return CSNAPPY_E_DATA_MALFORMED;
offset = src[0] | (src[1] << 8) |
(src[2] << 16) | (src[3] << 24);
src += 4;
}
if (unlikely(!offset || (offset > dst - dst_base)))
return CSNAPPY_E_DATA_MALFORMED;
copy_src = (const uint8_t *)dst - offset;
}
if (unlikely(dst + length > dst_end))
return CSNAPPY_E_OUTPUT_OVERRUN;
do *dst++ = *copy_src++; while (--length);
}
*dst_len = dst - dst_base;
return CSNAPPY_E_OK;
}
#else /* !(arm with no unaligned access) */
/*
* Data stored per entry in lookup table:
* Range Bits-used Description
* ------------------------------------
* 1..64 0..7 Literal/copy length encoded in opcode byte
* 0..7 8..10 Copy offset encoded in opcode byte / 256
* 0..4 11..13 Extra bytes after opcode
*
* We use eight bits for the length even though 7 would have sufficed
* because of efficiency reasons:
* (1) Extracting a byte is faster than a bit-field
* (2) It properly aligns copy offset so we do not need a <<8
*/
static const uint16_t char_table[256] = {
0x0001, 0x0804, 0x1001, 0x2001, 0x0002, 0x0805, 0x1002, 0x2002,
0x0003, 0x0806, 0x1003, 0x2003, 0x0004, 0x0807, 0x1004, 0x2004,
0x0005, 0x0808, 0x1005, 0x2005, 0x0006, 0x0809, 0x1006, 0x2006,
0x0007, 0x080a, 0x1007, 0x2007, 0x0008, 0x080b, 0x1008, 0x2008,
0x0009, 0x0904, 0x1009, 0x2009, 0x000a, 0x0905, 0x100a, 0x200a,
0x000b, 0x0906, 0x100b, 0x200b, 0x000c, 0x0907, 0x100c, 0x200c,
0x000d, 0x0908, 0x100d, 0x200d, 0x000e, 0x0909, 0x100e, 0x200e,
0x000f, 0x090a, 0x100f, 0x200f, 0x0010, 0x090b, 0x1010, 0x2010,
0x0011, 0x0a04, 0x1011, 0x2011, 0x0012, 0x0a05, 0x1012, 0x2012,
0x0013, 0x0a06, 0x1013, 0x2013, 0x0014, 0x0a07, 0x1014, 0x2014,
0x0015, 0x0a08, 0x1015, 0x2015, 0x0016, 0x0a09, 0x1016, 0x2016,
0x0017, 0x0a0a, 0x1017, 0x2017, 0x0018, 0x0a0b, 0x1018, 0x2018,
0x0019, 0x0b04, 0x1019, 0x2019, 0x001a, 0x0b05, 0x101a, 0x201a,
0x001b, 0x0b06, 0x101b, 0x201b, 0x001c, 0x0b07, 0x101c, 0x201c,
0x001d, 0x0b08, 0x101d, 0x201d, 0x001e, 0x0b09, 0x101e, 0x201e,
0x001f, 0x0b0a, 0x101f, 0x201f, 0x0020, 0x0b0b, 0x1020, 0x2020,
0x0021, 0x0c04, 0x1021, 0x2021, 0x0022, 0x0c05, 0x1022, 0x2022,
0x0023, 0x0c06, 0x1023, 0x2023, 0x0024, 0x0c07, 0x1024, 0x2024,
0x0025, 0x0c08, 0x1025, 0x2025, 0x0026, 0x0c09, 0x1026, 0x2026,
0x0027, 0x0c0a, 0x1027, 0x2027, 0x0028, 0x0c0b, 0x1028, 0x2028,
0x0029, 0x0d04, 0x1029, 0x2029, 0x002a, 0x0d05, 0x102a, 0x202a,
0x002b, 0x0d06, 0x102b, 0x202b, 0x002c, 0x0d07, 0x102c, 0x202c,
0x002d, 0x0d08, 0x102d, 0x202d, 0x002e, 0x0d09, 0x102e, 0x202e,
0x002f, 0x0d0a, 0x102f, 0x202f, 0x0030, 0x0d0b, 0x1030, 0x2030,
0x0031, 0x0e04, 0x1031, 0x2031, 0x0032, 0x0e05, 0x1032, 0x2032,
0x0033, 0x0e06, 0x1033, 0x2033, 0x0034, 0x0e07, 0x1034, 0x2034,
0x0035, 0x0e08, 0x1035, 0x2035, 0x0036, 0x0e09, 0x1036, 0x2036,
0x0037, 0x0e0a, 0x1037, 0x2037, 0x0038, 0x0e0b, 0x1038, 0x2038,
0x0039, 0x0f04, 0x1039, 0x2039, 0x003a, 0x0f05, 0x103a, 0x203a,
0x003b, 0x0f06, 0x103b, 0x203b, 0x003c, 0x0f07, 0x103c, 0x203c,
0x0801, 0x0f08, 0x103d, 0x203d, 0x1001, 0x0f09, 0x103e, 0x203e,
0x1801, 0x0f0a, 0x103f, 0x203f, 0x2001, 0x0f0b, 0x1040, 0x2040
};
/*
* Copy "len" bytes from "src" to "op", one byte at a time. Used for
* handling COPY operations where the input and output regions may
* overlap. For example, suppose:
* src == "ab"
* op == src + 2
* len == 20
* After IncrementalCopy(src, op, len), the result will have
* eleven copies of "ab"
* ababababababababababab
* Note that this does not match the semantics of either memcpy()
* or memmove().
*/
static INLINE void IncrementalCopy(const char *src, char *op, int len)
{
DCHECK_GT(len, 0);
do {
*op++ = *src++;
} while (--len > 0);
}
/*
* Equivalent to IncrementalCopy except that it can write up to ten extra
* bytes after the end of the copy, and that it is faster.
*
* The main part of this loop is a simple copy of eight bytes at a time until
* we've copied (at least) the requested amount of bytes. However, if op and
* src are less than eight bytes apart (indicating a repeating pattern of
* length < 8), we first need to expand the pattern in order to get the correct
* results. For instance, if the buffer looks like this, with the eight-byte
* <src> and <op> patterns marked as intervals:
*
* abxxxxxxxxxxxx
* [------] src
* [------] op
*
* a single eight-byte copy from <src> to <op> will repeat the pattern once,
* after which we can move <op> two bytes without moving <src>:
*
* ababxxxxxxxxxx
* [------] src
* [------] op
*
* and repeat the exercise until the two no longer overlap.
*
* This allows us to do very well in the special case of one single byte
* repeated many times, without taking a big hit for more general cases.
*
* The worst case of extra writing past the end of the match occurs when
* op - src == 1 and len == 1; the last copy will read from byte positions
* [0..7] and write to [4..11], whereas it was only supposed to write to
* position 1. Thus, ten excess bytes.
*/
static const int kMaxIncrementCopyOverflow = 10;
static INLINE void IncrementalCopyFastPath(const char *src, char *op, int len)
{
while (op - src < 8) {
UnalignedCopy64(src, op);
len -= op - src;
op += op - src;
}
while (len > 0) {
UnalignedCopy64(src, op);
src += 8;
op += 8;
len -= 8;
}
}
/* A type that writes to a flat array. */
struct SnappyArrayWriter {
char *base;
char *op;
char *op_limit;
};
static INLINE int
SAW__AppendFastPath(struct SnappyArrayWriter *this,
const char *ip, uint32_t len)
{
char *op = this->op;
const uint32_t space_left = this->op_limit - op;
if (likely(space_left >= 16)) {
UnalignedCopy64(ip, op);
UnalignedCopy64(ip + 8, op + 8);
} else {
if (unlikely(space_left < len))
return CSNAPPY_E_OUTPUT_OVERRUN;
memcpy(op, ip, len);
}
this->op = op + len;
return CSNAPPY_E_OK;
}
static INLINE int
SAW__Append(struct SnappyArrayWriter *this,
const char *ip, uint32_t len)
{
char *op = this->op;
const uint32_t space_left = this->op_limit - op;
if (unlikely(space_left < len))
return CSNAPPY_E_OUTPUT_OVERRUN;
memcpy(op, ip, len);
this->op = op + len;
return CSNAPPY_E_OK;
}
static INLINE int
SAW__AppendFromSelf(struct SnappyArrayWriter *this,
uint32_t offset, uint32_t len)
{
char *op = this->op;
const uint32_t space_left = this->op_limit - op;
/* -1u catches offset==0 */
if (op - this->base <= offset - 1u)
return CSNAPPY_E_DATA_MALFORMED;
/* Fast path, used for the majority (70-80%) of dynamic invocations. */
if (len <= 16 && offset >= 8 && space_left >= 16) {
UnalignedCopy64(op - offset, op);
UnalignedCopy64(op - offset + 8, op + 8);
} else if (space_left >= (len + kMaxIncrementCopyOverflow)) {
IncrementalCopyFastPath(op - offset, op, len);
} else {
if (space_left < len)
return CSNAPPY_E_OUTPUT_OVERRUN;
IncrementalCopy(op - offset, op, len);
}
this->op = op + len;
return CSNAPPY_E_OK;
}
int
csnappy_decompress_noheader(
const char *src,
uint32_t src_remaining,
char *dst,
uint32_t *dst_len)
{
struct SnappyArrayWriter writer;
const char *end_minus5 = src + src_remaining - 5;
uint32_t length, trailer, opword, extra_bytes;
int ret, available;
uint8_t opcode;
char scratch[5];
writer.op = writer.base = dst;
writer.op_limit = writer.op + *dst_len;
#define LOOP_COND() \
if (unlikely(src >= end_minus5)) { \
available = end_minus5 + 5 - src; \
if (unlikely(available <= 0)) \
goto out; \
memmove(scratch, src, available); \
src = scratch; \
end_minus5 = scratch + available - 5; \
}
LOOP_COND();
for (;;) {
opcode = *(const uint8_t *)src++;
if (opcode & 0x3) {
opword = char_table[opcode];
extra_bytes = opword >> 11;
trailer = get_unaligned_le(src, extra_bytes);
length = opword & 0xff;
src += extra_bytes;
trailer += opword & 0x700;
ret = SAW__AppendFromSelf(&writer, trailer, length);
if (ret < 0)
return ret;
LOOP_COND();
} else {
length = (opcode >> 2) + 1;
available = end_minus5 + 5 - src;
if (length <= 16 && available >= 16) {
if ((ret = SAW__AppendFastPath(&writer, src, length)) < 0)
return ret;
src += length;
LOOP_COND();
continue;
}
if (unlikely(length > 60)) {
extra_bytes = length - 60;
length = get_unaligned_le(src, extra_bytes) + 1;
src += extra_bytes;
available = end_minus5 + 5 - src;
}
if (unlikely(available < (int32_t)length))
return CSNAPPY_E_DATA_MALFORMED;
ret = SAW__Append(&writer, src, length);
if (ret < 0)
return ret;
src += length;
LOOP_COND();
}
}
#undef LOOP_COND
out:
*dst_len = writer.op - writer.base;
return CSNAPPY_E_OK;
}
#endif /* optimized for unaligned arch */
#if defined(__KERNEL__) && !defined(STATIC)
EXPORT_SYMBOL(csnappy_decompress_noheader);
#endif
int
csnappy_decompress(
const char *src,
uint32_t src_len,
char *dst,
uint32_t dst_len)
{
int n;
uint32_t olen = 0;
/* Read uncompressed length from the front of the compressed input */
n = csnappy_get_uncompressed_length(src, src_len, &olen);
if (unlikely(n < CSNAPPY_E_OK))
return n;
/* Protect against possible DoS attack */
if (unlikely(olen > dst_len))
return CSNAPPY_E_OUTPUT_INSUF;
return csnappy_decompress_noheader(src + n, src_len - n, dst, &olen);
}
#if defined(__KERNEL__) && !defined(STATIC)
EXPORT_SYMBOL(csnappy_decompress);
MODULE_LICENSE("BSD");
MODULE_DESCRIPTION("Snappy Decompressor");
#endif
|