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                         length += *ip++;
 112                 }
 113
 114                 /* copy repeated sequence */
 115                 if (unlikely((op - ref) < STEPSIZE)) {
 116 #if LZ4_ARCH64
 117                         size_t dec64 = dec64table[op - ref];
 118 #else
 119                         const int dec64 = 0;
 120 #endif
 121                         op[0] = ref[0];
 122                         op[1] = ref[1];
 123                         op[2] = ref[2];
 124                         op[3] = ref[3];
 125                         op += 4;
 126                         ref += 4;
 127                         ref -= dec32table[op-ref];
 128                         PUT4(ref, op);
 129                         op += STEPSIZE - 4;
 130                         ref -= dec64;
 131                 } else {
 132                         LZ4_COPYSTEP(ref, op);
 133                 }
 134                 cpy = op + length - (STEPSIZE - 4);
 135                 if (cpy > (oend - COPYLENGTH)) {
 136
 137                         /* Error: request to write beyond destination buffer */
 138                         if (cpy > oend)
 139                                 goto _output_error;
 140                         LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
 141                         while (op < cpy)
 142                                 *op++ = *ref++;
 143                         op = cpy;
 144                         /*
 145                          * Check EOF (should never happen, since last 5 bytes
 146                          * are supposed to be literals)
 147                          */
 148                         if (op == oend)
 149                                 goto _output_error;
 150                         continue;
 151                 }
 152                 LZ4_SECURECOPY(ref, op, cpy);
 153                 op = cpy; /* correction */
 154         }
 155         /* end of decoding */
 156         return (int) (((char *)ip) - source);
 157
 158         /* write overflow error detected */
 159 _output_error:
 160         return (int) (-(((char *)ip) - source));
 161 }
 162
 163 static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
 164                                 int isize, size_t maxoutputsize)
 165 {
 166         const BYTE *ip = (const BYTE *) source;
 167         const BYTE *const iend = ip + isize;
 168         const BYTE *ref;
 169
 170
 171         BYTE *op = (BYTE *) dest;
 172         BYTE * const oend = op + maxoutputsize;
 173         BYTE *cpy;
 174
 175         size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
 176 #if LZ4_ARCH64
 177         size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
 178 #endif
 179
 180         /* Main Loop */
 181         while (ip < iend) {
 182
 183                 unsigned token;
 184                 size_t length;
 185
 186                 /* get runlength */
 187                 token = *ip++;
 188                 length = (token >> ML_BITS);
 189                 if (length == RUN_MASK) {
 190                         int s = 255;
 191                         while ((ip < iend) && (s == 255)) {
 192                                 s = *ip++;
 193                                 length += s;
 194                         }
 195                 }
 196                 /* copy literals */
 197                 cpy = op + length;
 198                 if ((cpy > oend - COPYLENGTH) ||
 199                         (ip + length > iend - COPYLENGTH)) {
 200
 201                         if (cpy > oend)
 202                                 goto _output_error;/* writes beyond buffer */
 203
 204                         if (ip + length != iend)
 205                                 goto _output_error;/*
 206                                                     * Error: LZ4 format requires
 207                                                     * to consume all input
 208                                                     * at this stage
 209                                                     */
 210                         memcpy(op, ip, length);
 211                         op += length;
 212                         break;/* Necessarily EOF, due to parsing restrictions */
 213                 }
 214                 LZ4_WILDCOPY(ip, op, cpy);
 215                 ip -= (op - cpy);
 216                 op = cpy;
 217
 218                 /* get offset */
 219                 LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
 220                 ip += 2;
 221                 if (ref < (BYTE * const) dest)
 222                         goto _output_error;
 223                         /*
 224                          * Error : offset creates reference
 225                          * outside of destination buffer
 226                          */
 227
 228                 /* get matchlength */
 229                 length = (token & ML_MASK);
 230                 if (length == ML_MASK) {
 231                         while (ip < iend) {
 232                                 int s = *ip++;
 233                                 length += s;
 234                                 if (s == 255)
 235                                         continue;
 236                                 break;
 237                         }
 238                 }
 239
 240                 /* copy repeated sequence */
 241                 if (unlikely((op - ref) < STEPSIZE)) {
 242 #if LZ4_ARCH64
 243                         size_t dec64 = dec64table[op - ref];
 244 #else
 245                         const int dec64 = 0;
 246 #endif
 247                                 op[0] = ref[0];
 248                                 op[1] = ref[1];
 249                                 op[2] = ref[2];
 250                                 op[3] = ref[3];
 251                                 op += 4;
 252                                 ref += 4;
 253                                 ref -= dec32table[op - ref];
 254                                 PUT4(ref, op);
 255                                 op += STEPSIZE - 4;
 256                                 ref -= dec64;
 257                 } else {
 258                         LZ4_COPYSTEP(ref, op);
 259                 }
 260                 cpy = op + length - (STEPSIZE-4);
 261                 if (cpy > oend - COPYLENGTH) {
 262                         if (cpy > oend)
 263                                 goto _output_error; /* write outside of buf */
 264
 265                         LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
 266                         while (op < cpy)
 267                                 *op++ = *ref++;
 268                         op = cpy;
 269                         /*
 270                          * Check EOF (should never happen, since last 5 bytes
 271                          * are supposed to be literals)
 272                          */
 273                         if (op == oend)
 274                                 goto _output_error;
 275                         continue;
 276                 }
 277                 LZ4_SECURECOPY(ref, op, cpy);
 278                 op = cpy; /* correction */
 279         }
 280         /* end of decoding */
 281         return (int) (((char *) op) - dest);
 282
 283         /* write overflow error detected */
 284 _output_error:
 285         return (int) (-(((char *) ip) - source));
 286 }
 287
 288 int lz4_decompress(const unsigned char *src, size_t *src_len,
 289                 unsigned char *dest, size_t actual_dest_len)
 290 {
 291         int ret = -1;
 292         int input_len = 0;
 293
 294         input_len = lz4_uncompress(src, dest, actual_dest_len);
 295         if (input_len < 0)
 296                 goto exit_0;
 297         *src_len = input_len;
 298
 299         return 0;
 300 exit_0:
 301         return ret;
 302 }
 303 #ifndef STATIC
 304 EXPORT_SYMBOL(lz4_decompress);
 305 #endif
 306
 307 int lz4_decompress_unknownoutputsize(const unsigned char *src, size_t src_len,
 308                 unsigned char *dest, size_t *dest_len)
 309 {
 310         int ret = -1;
 311         int out_len = 0;
 312
 313         out_len = lz4_uncompress_unknownoutputsize(src, dest, src_len,
 314                                         *dest_len);
 315         if (out_len < 0)
 316                 goto exit_0;
 317         *dest_len = out_len;
 318
 319         return 0;
 320 exit_0:
 321         return ret;
 322 }
 323 #ifndef STATIC
 324 EXPORT_SYMBOL(lz4_decompress_unknownoutputsize);
 325
 326 MODULE_LICENSE("Dual BSD/GPL");
 327 MODULE_DESCRIPTION("LZ4 Decompressor");
 328 #endif