lib/lz4/lz4_decompress.c

   1 /*
   2  * LZ4 Decompressor for Linux kernel
   3  *
   4  * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
   5  *
   6  * Based on LZ4 implementation by Yann Collet.
   7  *
   8  * LZ4 - Fast LZ compression algorithm
   9  * Copyright (C) 2011-2012, Yann Collet.
  10  * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions are
  14  * met:
  15  *
  16  *     * Redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer.
  18  *     * Redistributions in binary form must reproduce the above
  19  * copyright notice, this list of conditions and the following disclaimer
  20  * in the documentation and/or other materials provided with the
  21  * distribution.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  27  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  29  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  33  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  *
  35  *  You can contact the author at :
  36  *  - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
  37  *  - LZ4 source repository : http://code.google.com/p/lz4/
  38  */
  39
  40 #ifndef STATIC
  41 #include <linux/module.h>
  42 #include <linux/kernel.h>
  43 #endif
  44 #include <linux/lz4.h>
  45
  46 #include <asm/unaligned.h>
  47
  48 #include "lz4defs.h"
  49
  50 static int lz4_uncompress(const char *source, char *dest, int osize)
  51 {
  52         const BYTE *ip = (const BYTE *) source;
  53         const BYTE *ref;
  54         BYTE *op = (BYTE *) dest;
  55         BYTE * const oend = op + osize;
  56         BYTE *cpy;
  57         unsigned token;
  58         size_t length;
  59         size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
  60 #if LZ4_ARCH64
  61         size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
  62 #endif
  63
  64         while (1) {
  65
  66                 /* get runlength */
  67                 token = *ip++;
  68                 length = (token >> ML_BITS);
  69                 if (length == RUN_MASK) {
  70                         size_t len;
  71
  72                         len = *ip++;
  73                         for (; len == 255; length += 255)
  74                                 len = *ip++;
  75                         if (unlikely(length > (size_t)(length + len)))
  76                                 goto _output_error;
  77                         length += len;
  78                 }
  79
  80                 /* copy literals */
  81                 cpy = op + length;
  82                 if (unlikely(cpy > oend - COPYLENGTH)) {
  83                         /*
  84                          * Error: not enough place for another match
  85                          * (min 4) + 5 literals
  86                          */
  87                         if (cpy != oend)
  88                                 goto _output_error;
  89
  90                         memcpy(op, ip, length);
  91                         ip += length;
  92                         break; /* EOF */
  93                 }
  94                 LZ4_WILDCOPY(ip, op, cpy);
  95                 ip -= (op - cpy);
  96                 op = cpy;
  97
  98                 /* get offset */
  99                 LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
 100                 ip += 2;
 101
 102                 /* Error: offset create reference outside destination buffer */
 103                 if (unlikely(ref < (BYTE *const) dest))
 104                         goto _output_error;
 105
 106                 /* get matchlength */
 107                 length = token & ML_MASK;
 108                 if (length == ML_MASK) {
 109                         for (; *ip == 255; length += 255)
 110                                 ip++;
 111                         if (unlikely(length > (size_t)(length + *ip)))
 112                                 goto _output_error;
 113                         length += *ip++;
 114                 }
 115
 116                 /* copy repeated sequence */
 117                 if (unlikely((op - ref) < STEPSIZE)) {
 118 #if LZ4_ARCH64
 119                         size_t dec64 = dec64table[op - ref];
 120 #else
 121                         const int dec64 = 0;
 122 #endif
 123                         op[0] = ref[0];
 124                         op[1] = ref[1];
 125                         op[2] = ref[2];
 126                         op[3] = ref[3];
 127                         op += 4;
 128                         ref += 4;
 129                         ref -= dec32table[op-ref];
 130                         PUT4(ref, op);
 131                         op += STEPSIZE - 4;
 132                         ref -= dec64;
 133                 } else {
 134                         LZ4_COPYSTEP(ref, op);
 135                 }
 136                 cpy = op + length - (STEPSIZE - 4);
 137                 if (cpy > (oend - COPYLENGTH)) {
 138
 139                         /* Error: request to write beyond destination buffer */
 140                         if (cpy > oend)
 141                                 goto _output_error;
 142                         LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
 143                         while (op < cpy)
 144                                 *op++ = *ref++;
 145                         op = cpy;
 146                         /*
 147                          * Check EOF (should never happen, since last 5 bytes
 148                          * are supposed to be literals)
 149                          */
 150                         if (op == oend)
 151                                 goto _output_error;
 152                         continue;
 153                 }
 154                 LZ4_SECURECOPY(ref, op, cpy);
 155                 op = cpy; /* correction */
 156         }
 157         /* end of decoding */
 158         return (int) (((char *)ip) - source);
 159
 160         /* write overflow error detected */
 161 _output_error:
 162         return -1;
 163 }
 164
 165 static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
 166                                 int isize, size_t maxoutputsize)
 167 {
 168         const BYTE *ip = (const BYTE *) source;
 169         const BYTE *const iend = ip + isize;
 170         const BYTE *ref;
 171
 172
 173         BYTE *op = (BYTE *) dest;
 174         BYTE * const oend = op + maxoutputsize;
 175         BYTE *cpy;
 176
 177         size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
 178 #if LZ4_ARCH64
 179         size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
 180 #endif
 181
 182         /* Main Loop */
 183         while (ip < iend) {
 184
 185                 unsigned token;
 186                 size_t length;
 187
 188                 /* get runlength */
 189                 token = *ip++;
 190                 length = (token >> ML_BITS);
 191                 if (length == RUN_MASK) {
 192                         int s = 255;
 193                         while ((ip < iend) && (s == 255)) {
 194                                 s = *ip++;
 195                                 if (unlikely(length > (size_t)(length + s)))
 196                                         goto _output_error;
 197                                 length += s;
 198                         }
 199                 }
 200                 /* copy literals */
 201                 cpy = op + length;
 202                 if ((cpy > oend - COPYLENGTH) ||
 203                         (ip + length > iend - COPYLENGTH)) {
 204
 205                         if (cpy > oend)
 206                                 goto _output_error;/* writes beyond buffer */
 207
 208                         if (ip + length != iend)
 209                                 goto _output_error;/*
 210                                                     * Error: LZ4 format requires
 211                                                     * to consume all input
 212                                                     * at this stage
 213                                                     */
 214                         memcpy(op, ip, length);
 215                         op += length;
 216                         break;/* Necessarily EOF, due to parsing restrictions */
 217                 }
 218                 LZ4_WILDCOPY(ip, op, cpy);
 219                 ip -= (op - cpy);
 220                 op = cpy;
 221
 222                 /* get offset */
 223                 LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
 224                 ip += 2;
 225                 if (ref < (BYTE * const) dest)
 226                         goto _output_error;
 227                         /*
 228                          * Error : offset creates reference
 229                          * outside of destination buffer
 230                          */
 231
 232                 /* get matchlength */
 233                 length = (token & ML_MASK);
 234                 if (length == ML_MASK) {
 235                         while (ip < iend) {
 236                                 int s = *ip++;
 237                                 if (unlikely(length > (size_t)(length + s)))
 238                                         goto _output_error;
 239                                 length += s;
 240                                 if (s == 255)
 241                                         continue;
 242                                 break;
 243                         }
 244                 }
 245
 246                 /* copy repeated sequence */
 247                 if (unlikely((op - ref) < STEPSIZE)) {
 248 #if LZ4_ARCH64
 249                         size_t dec64 = dec64table[op - ref];
 250 #else
 251                         const int dec64 = 0;
 252 #endif
 253                                 op[0] = ref[0];
 254                                 op[1] = ref[1];
 255                                 op[2] = ref[2];
 256                                 op[3] = ref[3];
 257                                 op += 4;
 258                                 ref += 4;
 259                                 ref -= dec32table[op - ref];
 260                                 PUT4(ref, op);
 261                                 op += STEPSIZE - 4;
 262                                 ref -= dec64;
 263                 } else {
 264                         LZ4_COPYSTEP(ref, op);
 265                 }
 266                 cpy = op + length - (STEPSIZE-4);
 267                 if (cpy > oend - COPYLENGTH) {
 268                         if (cpy > oend)
 269                                 goto _output_error; /* write outside of buf */
 270
 271                         LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
 272                         while (op < cpy)
 273                                 *op++ = *ref++;
 274                         op = cpy;
 275                         /*
 276                          * Check EOF (should never happen, since last 5 bytes
 277                          * are supposed to be literals)
 278                          */
 279                         if (op == oend)
 280                                 goto _output_error;
 281                         continue;
 282                 }
 283                 LZ4_SECURECOPY(ref, op, cpy);
 284                 op = cpy; /* correction */
 285         }
 286         /* end of decoding */
 287         return (int) (((char *) op) - dest);
 288
 289         /* write overflow error detected */
 290 _output_error:
 291         return -1;
 292 }
 293
 294 int lz4_decompress(const unsigned char *src, size_t *src_len,
 295                 unsigned char *dest, size_t actual_dest_len)
 296 {
 297         int ret = -1;
 298         int input_len = 0;
 299
 300         input_len = lz4_uncompress(src, dest, actual_dest_len);
 301         if (input_len < 0)
 302                 goto exit_0;
 303         *src_len = input_len;
 304
 305         return 0;
 306 exit_0:
 307         return ret;
 308 }
 309 #ifndef STATIC
 310 EXPORT_SYMBOL(lz4_decompress);
 311 #endif
 312
 313 int lz4_decompress_unknownoutputsize(const unsigned char *src, size_t src_len,
 314                 unsigned char *dest, size_t *dest_len)
 315 {
 316         int ret = -1;
 317         int out_len = 0;
 318
 319         out_len = lz4_uncompress_unknownoutputsize(src, dest, src_len,
 320                                         *dest_len);
 321         if (out_len < 0)
 322                 goto exit_0;
 323         *dest_len = out_len;
 324
 325         return 0;
 326 exit_0:
 327         return ret;
 328 }
 329 #ifndef STATIC
 330 EXPORT_SYMBOL(lz4_decompress_unknownoutputsize);
 331
 332 MODULE_LICENSE("Dual BSD/GPL");
 333 MODULE_DESCRIPTION("LZ4 Decompressor");
 334 #endif