libtiff/tif_lzw.c

   1 /* $Id: tif_lzw.c,v 1.57 2017-07-11 10:54:29 erouault Exp $ */
   2
   3 /*
   4  * Copyright (c) 1988-1997 Sam Leffler
   5  * Copyright (c) 1991-1997 Silicon Graphics, Inc.
   6  *
   7  * Permission to use, copy, modify, distribute, and sell this software and
   8  * its documentation for any purpose is hereby granted without fee, provided
   9  * that (i) the above copyright notices and this permission notice appear in
  10  * all copies of the software and related documentation, and (ii) the names of
  11  * Sam Leffler and Silicon Graphics may not be used in any advertising or
  12  * publicity relating to the software without the specific, prior written
  13  * permission of Sam Leffler and Silicon Graphics.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  17  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  18  *
  19  * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
  20  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  21  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  22  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  24  * OF THIS SOFTWARE.
  25  */
  26
  27 #include "tiffiop.h"
  28 #ifdef LZW_SUPPORT
  29 /*
  30  * TIFF Library.
  31  * Rev 5.0 Lempel-Ziv & Welch Compression Support
  32  *
  33  * This code is derived from the compress program whose code is
  34  * derived from software contributed to Berkeley by James A. Woods,
  35  * derived from original work by Spencer Thomas and Joseph Orost.
  36  *
  37  * The original Berkeley copyright notice appears below in its entirety.
  38  */
  39 #include "tif_predict.h"
  40
  41 #include <stdio.h>
  42
  43 /*
  44  * NB: The 5.0 spec describes a different algorithm than Aldus
  45  *     implements.  Specifically, Aldus does code length transitions
  46  *     one code earlier than should be done (for real LZW).
  47  *     Earlier versions of this library implemented the correct
  48  *     LZW algorithm, but emitted codes in a bit order opposite
  49  *     to the TIFF spec.  Thus, to maintain compatibility w/ Aldus
  50  *     we interpret MSB-LSB ordered codes to be images written w/
  51  *     old versions of this library, but otherwise adhere to the
  52  *     Aldus "off by one" algorithm.
  53  *
  54  * Future revisions to the TIFF spec are expected to "clarify this issue".
  55  */
  56 #define LZW_COMPAT              /* include backwards compatibility code */
  57 /*
  58  * Each strip of data is supposed to be terminated by a CODE_EOI.
  59  * If the following #define is included, the decoder will also
  60  * check for end-of-strip w/o seeing this code.  This makes the
  61  * library more robust, but also slower.
  62  */
  63 #define LZW_CHECKEOS            /* include checks for strips w/o EOI code */
  64
  65 #define MAXCODE(n)      ((1L<<(n))-1)
  66 /*
  67  * The TIFF spec specifies that encoded bit
  68  * strings range from 9 to 12 bits.
  69  */
  70 #define BITS_MIN        9               /* start with 9 bits */
  71 #define BITS_MAX        12              /* max of 12 bit strings */
  72 /* predefined codes */
  73 #define CODE_CLEAR      256             /* code to clear string table */
  74 #define CODE_EOI        257             /* end-of-information code */
  75 #define CODE_FIRST      258             /* first free code entry */
  76 #define CODE_MAX        MAXCODE(BITS_MAX)
  77 #define HSIZE           9001L           /* 91% occupancy */
  78 #define HSHIFT          (13-8)
  79 #ifdef LZW_COMPAT
  80 /* NB: +1024 is for compatibility with old files */
  81 #define CSIZE           (MAXCODE(BITS_MAX)+1024L)
  82 #else
  83 #define CSIZE           (MAXCODE(BITS_MAX)+1L)
  84 #endif
  85
  86 /*
  87  * State block for each open TIFF file using LZW
  88  * compression/decompression.  Note that the predictor
  89  * state block must be first in this data structure.
  90  */
  91 typedef struct {
  92         TIFFPredictorState predict;     /* predictor super class */
  93
  94         unsigned short  nbits;          /* # of bits/code */
  95         unsigned short  maxcode;        /* maximum code for lzw_nbits */
  96         unsigned short  free_ent;       /* next free entry in hash table */
  97         unsigned long   nextdata;       /* next bits of i/o */
  98         long            nextbits;       /* # of valid bits in lzw_nextdata */
  99
 100         int             rw_mode;        /* preserve rw_mode from init */
 101 } LZWBaseState;
 102
 103 #define lzw_nbits       base.nbits
 104 #define lzw_maxcode     base.maxcode
 105 #define lzw_free_ent    base.free_ent
 106 #define lzw_nextdata    base.nextdata
 107 #define lzw_nextbits    base.nextbits
 108
 109 /*
 110  * Encoding-specific state.
 111  */
 112 typedef uint16 hcode_t;                 /* codes fit in 16 bits */
 113 typedef struct {
 114         long    hash;
 115         hcode_t code;
 116 } hash_t;
 117
 118 /*
 119  * Decoding-specific state.
 120  */
 121 typedef struct code_ent {
 122         struct code_ent *next;
 123         unsigned short  length;         /* string len, including this token */
 124         unsigned char   value;          /* data value */
 125         unsigned char   firstchar;      /* first token of string */
 126 } code_t;
 127
 128 typedef int (*decodeFunc)(TIFF*, uint8*, tmsize_t, uint16);
 129
 130 typedef struct {
 131         LZWBaseState base;
 132
 133         /* Decoding specific data */
 134         long    dec_nbitsmask;          /* lzw_nbits 1 bits, right adjusted */
 135         long    dec_restart;            /* restart count */
 136 #ifdef LZW_CHECKEOS
 137         uint64  dec_bitsleft;           /* available bits in raw data */
 138 #endif
 139         decodeFunc dec_decode;          /* regular or backwards compatible */
 140         code_t* dec_codep;              /* current recognized code */
 141         code_t* dec_oldcodep;           /* previously recognized code */
 142         code_t* dec_free_entp;          /* next free entry */
 143         code_t* dec_maxcodep;           /* max available entry */
 144         code_t* dec_codetab;            /* kept separate for small machines */
 145
 146         /* Encoding specific data */
 147         int     enc_oldcode;            /* last code encountered */
 148         long    enc_checkpoint;         /* point at which to clear table */
 149 #define CHECK_GAP       10000           /* enc_ratio check interval */
 150         long    enc_ratio;              /* current compression ratio */
 151         long    enc_incount;            /* (input) data bytes encoded */
 152         long    enc_outcount;           /* encoded (output) bytes */
 153         uint8*  enc_rawlimit;           /* bound on tif_rawdata buffer */
 154         hash_t* enc_hashtab;            /* kept separate for small machines */
 155 } LZWCodecState;
 156
 157 #define LZWState(tif)           ((LZWBaseState*) (tif)->tif_data)
 158 #define DecoderState(tif)       ((LZWCodecState*) LZWState(tif))
 159 #define EncoderState(tif)       ((LZWCodecState*) LZWState(tif))
 160
 161 static int LZWDecode(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
 162 #ifdef LZW_COMPAT
 163 static int LZWDecodeCompat(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
 164 #endif
 165 static void cl_hash(LZWCodecState*);
 166
 167 /*
 168  * LZW Decoder.
 169  */
 170
 171 #ifdef LZW_CHECKEOS
 172 /*
 173  * This check shouldn't be necessary because each
 174  * strip is suppose to be terminated with CODE_EOI.
 175  */
 176 #define NextCode(_tif, _sp, _bp, _code, _get) {                         \
 177         if ((_sp)->dec_bitsleft < (uint64)nbits) {                      \
 178                 TIFFWarningExt(_tif->tif_clientdata, module,            \
 179                     "LZWDecode: Strip %d not terminated with EOI code", \
 180                     _tif->tif_curstrip);                                \
 181                 _code = CODE_EOI;                                       \
 182         } else {                                                        \
 183                 _get(_sp,_bp,_code);                                    \
 184                 (_sp)->dec_bitsleft -= nbits;                           \
 185         }                                                               \
 186 }
 187 #else
 188 #define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
 189 #endif
 190
 191 static int
 192 LZWFixupTags(TIFF* tif)
 193 {
 194         (void) tif;
 195         return (1);
 196 }
 197
 198 static int
 199 LZWSetupDecode(TIFF* tif)
 200 {
 201         static const char module[] = "LZWSetupDecode";
 202         LZWCodecState* sp = DecoderState(tif);
 203         int code;
 204
 205         if( sp == NULL )
 206         {
 207                 /*
 208                  * Allocate state block so tag methods have storage to record
 209                  * values.
 210                 */
 211                 tif->tif_data = (uint8*) _TIFFmalloc(sizeof(LZWCodecState));
 212                 if (tif->tif_data == NULL)
 213                 {
 214                         TIFFErrorExt(tif->tif_clientdata, module, "No space for LZW state block");
 215                         return (0);
 216                 }
 217
 218                 DecoderState(tif)->dec_codetab = NULL;
 219                 DecoderState(tif)->dec_decode = NULL;
 220
 221                 /*
 222                  * Setup predictor setup.
 223                  */
 224                 (void) TIFFPredictorInit(tif);
 225
 226                 sp = DecoderState(tif);
 227         }
 228
 229         assert(sp != NULL);
 230
 231         if (sp->dec_codetab == NULL) {
 232                 sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
 233                 if (sp->dec_codetab == NULL) {
 234                         TIFFErrorExt(tif->tif_clientdata, module,
 235                                      "No space for LZW code table");
 236                         return (0);
 237                 }
 238                 /*
 239                  * Pre-load the table.
 240                  */
 241                 code = 255;
 242                 do {
 243                         sp->dec_codetab[code].value = (unsigned char)code;
 244                         sp->dec_codetab[code].firstchar = (unsigned char)code;
 245                         sp->dec_codetab[code].length = 1;
 246                         sp->dec_codetab[code].next = NULL;
 247                 } while (code--);
 248                 /*
 249                  * Zero-out the unused entries
 250                  */
 251                  _TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
 252                              (CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
 253         }
 254         return (1);
 255 }
 256
 257 /*
 258  * Setup state for decoding a strip.
 259  */
 260 static int
 261 LZWPreDecode(TIFF* tif, uint16 s)
 262 {
 263         static const char module[] = "LZWPreDecode";
 264         LZWCodecState *sp = DecoderState(tif);
 265
 266         (void) s;
 267         assert(sp != NULL);
 268         if( sp->dec_codetab == NULL )
 269         {
 270             tif->tif_setupdecode( tif );
 271             if( sp->dec_codetab == NULL )
 272                 return (0);
 273         }
 274
 275         /*
 276          * Check for old bit-reversed codes.
 277          */
 278         if (tif->tif_rawcc >= 2 &&
 279             tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
 280 #ifdef LZW_COMPAT
 281                 if (!sp->dec_decode) {
 282                         TIFFWarningExt(tif->tif_clientdata, module,
 283                             "Old-style LZW codes, convert file");
 284                         /*
 285                          * Override default decoding methods with
 286                          * ones that deal with the old coding.
 287                          * Otherwise the predictor versions set
 288                          * above will call the compatibility routines
 289                          * through the dec_decode method.
 290                          */
 291                         tif->tif_decoderow = LZWDecodeCompat;
 292                         tif->tif_decodestrip = LZWDecodeCompat;
 293                         tif->tif_decodetile = LZWDecodeCompat;
 294                         /*
 295                          * If doing horizontal differencing, must
 296                          * re-setup the predictor logic since we
 297                          * switched the basic decoder methods...
 298                          */
 299                         (*tif->tif_setupdecode)(tif);
 300                         sp->dec_decode = LZWDecodeCompat;
 301                 }
 302                 sp->lzw_maxcode = MAXCODE(BITS_MIN);
 303 #else /* !LZW_COMPAT */
 304                 if (!sp->dec_decode) {
 305                         TIFFErrorExt(tif->tif_clientdata, module,
 306                             "Old-style LZW codes not supported");
 307                         sp->dec_decode = LZWDecode;
 308                 }
 309                 return (0);
 310 #endif/* !LZW_COMPAT */
 311         } else {
 312                 sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
 313                 sp->dec_decode = LZWDecode;
 314         }
 315         sp->lzw_nbits = BITS_MIN;
 316         sp->lzw_nextbits = 0;
 317         sp->lzw_nextdata = 0;
 318
 319         sp->dec_restart = 0;
 320         sp->dec_nbitsmask = MAXCODE(BITS_MIN);
 321 #ifdef LZW_CHECKEOS
 322         sp->dec_bitsleft = 0;
 323 #endif
 324         sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
 325         /*
 326          * Zero entries that are not yet filled in.  We do
 327          * this to guard against bogus input data that causes
 328          * us to index into undefined entries.  If you can
 329          * come up with a way to safely bounds-check input codes
 330          * while decoding then you can remove this operation.
 331          */
 332         _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
 333         sp->dec_oldcodep = &sp->dec_codetab[-1];
 334         sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
 335         return (1);
 336 }
 337
 338 /*
 339  * Decode a "hunk of data".
 340  */
 341 #define GetNextCode(sp, bp, code) {                             \
 342         nextdata = (nextdata<<8) | *(bp)++;                     \
 343         nextbits += 8;                                          \
 344         if (nextbits < nbits) {                                 \
 345                 nextdata = (nextdata<<8) | *(bp)++;             \
 346                 nextbits += 8;                                  \
 347         }                                                       \
 348         code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask);   \
 349         nextbits -= nbits;                                      \
 350 }
 351
 352 static void
 353 codeLoop(TIFF* tif, const char* module)
 354 {
 355         TIFFErrorExt(tif->tif_clientdata, module,
 356             "Bogus encoding, loop in the code table; scanline %d",
 357             tif->tif_row);
 358 }
 359
 360 static int
 361 LZWDecode(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
 362 {
 363         static const char module[] = "LZWDecode";
 364         LZWCodecState *sp = DecoderState(tif);
 365         char *op = (char*) op0;
 366         long occ = (long) occ0;
 367         char *tp;
 368         unsigned char *bp;
 369         hcode_t code;
 370         int len;
 371         long nbits, nextbits, nbitsmask;
 372         unsigned long nextdata;
 373         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 374
 375         (void) s;
 376         assert(sp != NULL);
 377         assert(sp->dec_codetab != NULL);
 378
 379         /*
 380           Fail if value does not fit in long.
 381         */
 382         if ((tmsize_t) occ != occ0)
 383                 return (0);
 384         /*
 385          * Restart interrupted output operation.
 386          */
 387         if (sp->dec_restart) {
 388                 long residue;
 389
 390                 codep = sp->dec_codep;
 391                 residue = codep->length - sp->dec_restart;
 392                 if (residue > occ) {
 393                         /*
 394                          * Residue from previous decode is sufficient
 395                          * to satisfy decode request.  Skip to the
 396                          * start of the decoded string, place decoded
 397                          * values in the output buffer, and return.
 398                          */
 399                         sp->dec_restart += occ;
 400                         do {
 401                                 codep = codep->next;
 402                         } while (--residue > occ && codep);
 403                         if (codep) {
 404                                 tp = op + occ;
 405                                 do {
 406                                         *--tp = codep->value;
 407                                         codep = codep->next;
 408                                 } while (--occ && codep);
 409                         }
 410                         return (1);
 411                 }
 412                 /*
 413                  * Residue satisfies only part of the decode request.
 414                  */
 415                 op += residue;
 416                 occ -= residue;
 417                 tp = op;
 418                 do {
 419                         int t;
 420                         --tp;
 421                         t = codep->value;
 422                         codep = codep->next;
 423                         *tp = (char)t;
 424                 } while (--residue && codep);
 425                 sp->dec_restart = 0;
 426         }
 427
 428         bp = (unsigned char *)tif->tif_rawcp;
 429 #ifdef LZW_CHECKEOS
 430         sp->dec_bitsleft = (((uint64)tif->tif_rawcc) << 3);
 431 #endif
 432         nbits = sp->lzw_nbits;
 433         nextdata = sp->lzw_nextdata;
 434         nextbits = sp->lzw_nextbits;
 435         nbitsmask = sp->dec_nbitsmask;
 436         oldcodep = sp->dec_oldcodep;
 437         free_entp = sp->dec_free_entp;
 438         maxcodep = sp->dec_maxcodep;
 439
 440         while (occ > 0) {
 441                 NextCode(tif, sp, bp, code, GetNextCode);
 442                 if (code == CODE_EOI)
 443                         break;
 444                 if (code == CODE_CLEAR) {
 445                         do {
 446                                 free_entp = sp->dec_codetab + CODE_FIRST;
 447                                 _TIFFmemset(free_entp, 0,
 448                                             (CSIZE - CODE_FIRST) * sizeof (code_t));
 449                                 nbits = BITS_MIN;
 450                                 nbitsmask = MAXCODE(BITS_MIN);
 451                                 maxcodep = sp->dec_codetab + nbitsmask-1;
 452                                 NextCode(tif, sp, bp, code, GetNextCode);
 453                         } while (code == CODE_CLEAR);   /* consecutive CODE_CLEAR codes */
 454                         if (code == CODE_EOI)
 455                                 break;
 456                         if (code > CODE_CLEAR) {
 457                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 458                                 "LZWDecode: Corrupted LZW table at scanline %d",
 459                                              tif->tif_row);
 460                                 return (0);
 461                         }
 462                         *op++ = (char)code;
 463                         occ--;
 464                         oldcodep = sp->dec_codetab + code;
 465                         continue;
 466                 }
 467                 codep = sp->dec_codetab + code;
 468
 469                 /*
 470                  * Add the new entry to the code table.
 471                  */
 472                 if (free_entp < &sp->dec_codetab[0] ||
 473                     free_entp >= &sp->dec_codetab[CSIZE]) {
 474                         TIFFErrorExt(tif->tif_clientdata, module,
 475                             "Corrupted LZW table at scanline %d",
 476                             tif->tif_row);
 477                         return (0);
 478                 }
 479
 480                 free_entp->next = oldcodep;
 481                 if (free_entp->next < &sp->dec_codetab[0] ||
 482                     free_entp->next >= &sp->dec_codetab[CSIZE]) {
 483                         TIFFErrorExt(tif->tif_clientdata, module,
 484                             "Corrupted LZW table at scanline %d",
 485                             tif->tif_row);
 486                         return (0);
 487                 }
 488                 free_entp->firstchar = free_entp->next->firstchar;
 489                 free_entp->length = free_entp->next->length+1;
 490                 free_entp->value = (codep < free_entp) ?
 491                     codep->firstchar : free_entp->firstchar;
 492                 if (++free_entp > maxcodep) {
 493                         if (++nbits > BITS_MAX)         /* should not happen */
 494                                 nbits = BITS_MAX;
 495                         nbitsmask = MAXCODE(nbits);
 496                         maxcodep = sp->dec_codetab + nbitsmask-1;
 497                 }
 498                 oldcodep = codep;
 499                 if (code >= 256) {
 500                         /*
 501                          * Code maps to a string, copy string
 502                          * value to output (written in reverse).
 503                          */
 504                         if(codep->length == 0) {
 505                                 TIFFErrorExt(tif->tif_clientdata, module,
 506                                     "Wrong length of decoded string: "
 507                                     "data probably corrupted at scanline %d",
 508                                     tif->tif_row);
 509                                 return (0);
 510                         }
 511                         if (codep->length > occ) {
 512                                 /*
 513                                  * String is too long for decode buffer,
 514                                  * locate portion that will fit, copy to
 515                                  * the decode buffer, and setup restart
 516                                  * logic for the next decoding call.
 517                                  */
 518                                 sp->dec_codep = codep;
 519                                 do {
 520                                         codep = codep->next;
 521                                 } while (codep && codep->length > occ);
 522                                 if (codep) {
 523                                         sp->dec_restart = (long)occ;
 524                                         tp = op + occ;
 525                                         do  {
 526                                                 *--tp = codep->value;
 527                                                 codep = codep->next;
 528                                         }  while (--occ && codep);
 529                                         if (codep)
 530                                                 codeLoop(tif, module);
 531                                 }
 532                                 break;
 533                         }
 534                         len = codep->length;
 535                         tp = op + len;
 536                         do {
 537                                 int t;
 538                                 --tp;
 539                                 t = codep->value;
 540                                 codep = codep->next;
 541                                 *tp = (char)t;
 542                         } while (codep && tp > op);
 543                         if (codep) {
 544                             codeLoop(tif, module);
 545                             break;
 546                         }
 547                         assert(occ >= len);
 548                         op += len;
 549                         occ -= len;
 550                 } else {
 551                         *op++ = (char)code;
 552                         occ--;
 553                 }
 554         }
 555
 556         tif->tif_rawcc -= (tmsize_t)( (uint8*) bp - tif->tif_rawcp );
 557         tif->tif_rawcp = (uint8*) bp;
 558         sp->lzw_nbits = (unsigned short) nbits;
 559         sp->lzw_nextdata = nextdata;
 560         sp->lzw_nextbits = nextbits;
 561         sp->dec_nbitsmask = nbitsmask;
 562         sp->dec_oldcodep = oldcodep;
 563         sp->dec_free_entp = free_entp;
 564         sp->dec_maxcodep = maxcodep;
 565
 566         if (occ > 0) {
 567 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 568                 TIFFErrorExt(tif->tif_clientdata, module,
 569                         "Not enough data at scanline %d (short %I64d bytes)",
 570                              tif->tif_row, (unsigned __int64) occ);
 571 #else
 572                 TIFFErrorExt(tif->tif_clientdata, module,
 573                         "Not enough data at scanline %d (short %llu bytes)",
 574                              tif->tif_row, (unsigned long long) occ);
 575 #endif
 576                 return (0);
 577         }
 578         return (1);
 579 }
 580
 581 #ifdef LZW_COMPAT
 582 /*
 583  * Decode a "hunk of data" for old images.
 584  */
 585 #define GetNextCodeCompat(sp, bp, code) {                       \
 586         nextdata |= (unsigned long) *(bp)++ << nextbits;        \
 587         nextbits += 8;                                          \
 588         if (nextbits < nbits) {                                 \
 589                 nextdata |= (unsigned long) *(bp)++ << nextbits;\
 590                 nextbits += 8;                                  \
 591         }                                                       \
 592         code = (hcode_t)(nextdata & nbitsmask);                 \
 593         nextdata >>= nbits;                                     \
 594         nextbits -= nbits;                                      \
 595 }
 596
 597 static int
 598 LZWDecodeCompat(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
 599 {
 600         static const char module[] = "LZWDecodeCompat";
 601         LZWCodecState *sp = DecoderState(tif);
 602         char *op = (char*) op0;
 603         long occ = (long) occ0;
 604         char *tp;
 605         unsigned char *bp;
 606         int code, nbits;
 607         long nextbits, nextdata, nbitsmask;
 608         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 609
 610         (void) s;
 611         assert(sp != NULL);
 612
 613         /*
 614           Fail if value does not fit in long.
 615         */
 616         if ((tmsize_t) occ != occ0)
 617                 return (0);
 618
 619         /*
 620          * Restart interrupted output operation.
 621          */
 622         if (sp->dec_restart) {
 623                 long residue;
 624
 625                 codep = sp->dec_codep;
 626                 residue = codep->length - sp->dec_restart;
 627                 if (residue > occ) {
 628                         /*
 629                          * Residue from previous decode is sufficient
 630                          * to satisfy decode request.  Skip to the
 631                          * start of the decoded string, place decoded
 632                          * values in the output buffer, and return.
 633                          */
 634                         sp->dec_restart += occ;
 635                         do {
 636                                 codep = codep->next;
 637                         } while (--residue > occ);
 638                         tp = op + occ;
 639                         do {
 640                                 *--tp = codep->value;
 641                                 codep = codep->next;
 642                         } while (--occ);
 643                         return (1);
 644                 }
 645                 /*
 646                  * Residue satisfies only part of the decode request.
 647                  */
 648                 op += residue;
 649                 occ -= residue;
 650                 tp = op;
 651                 do {
 652                         *--tp = codep->value;
 653                         codep = codep->next;
 654                 } while (--residue);
 655                 sp->dec_restart = 0;
 656         }
 657
 658         bp = (unsigned char *)tif->tif_rawcp;
 659 #ifdef LZW_CHECKEOS
 660         sp->dec_bitsleft = (((uint64)tif->tif_rawcc) << 3);
 661 #endif
 662         nbits = sp->lzw_nbits;
 663         nextdata = sp->lzw_nextdata;
 664         nextbits = sp->lzw_nextbits;
 665         nbitsmask = sp->dec_nbitsmask;
 666         oldcodep = sp->dec_oldcodep;
 667         free_entp = sp->dec_free_entp;
 668         maxcodep = sp->dec_maxcodep;
 669
 670         while (occ > 0) {
 671                 NextCode(tif, sp, bp, code, GetNextCodeCompat);
 672                 if (code == CODE_EOI)
 673                         break;
 674                 if (code == CODE_CLEAR) {
 675                         do {
 676                                 free_entp = sp->dec_codetab + CODE_FIRST;
 677                                 _TIFFmemset(free_entp, 0,
 678                                             (CSIZE - CODE_FIRST) * sizeof (code_t));
 679                                 nbits = BITS_MIN;
 680                                 nbitsmask = MAXCODE(BITS_MIN);
 681                                 maxcodep = sp->dec_codetab + nbitsmask;
 682                                 NextCode(tif, sp, bp, code, GetNextCodeCompat);
 683                         } while (code == CODE_CLEAR);   /* consecutive CODE_CLEAR codes */
 684                         if (code == CODE_EOI)
 685                                 break;
 686                         if (code > CODE_CLEAR) {
 687                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 688                                 "LZWDecode: Corrupted LZW table at scanline %d",
 689                                              tif->tif_row);
 690                                 return (0);
 691                         }
 692                         *op++ = (char)code;
 693                         occ--;
 694                         oldcodep = sp->dec_codetab + code;
 695                         continue;
 696                 }
 697                 codep = sp->dec_codetab + code;
 698
 699                 /*
 700                  * Add the new entry to the code table.
 701                  */
 702                 if (free_entp < &sp->dec_codetab[0] ||
 703                     free_entp >= &sp->dec_codetab[CSIZE]) {
 704                         TIFFErrorExt(tif->tif_clientdata, module,
 705                             "Corrupted LZW table at scanline %d", tif->tif_row);
 706                         return (0);
 707                 }
 708
 709                 free_entp->next = oldcodep;
 710                 if (free_entp->next < &sp->dec_codetab[0] ||
 711                     free_entp->next >= &sp->dec_codetab[CSIZE]) {
 712                         TIFFErrorExt(tif->tif_clientdata, module,
 713                             "Corrupted LZW table at scanline %d", tif->tif_row);
 714                         return (0);
 715                 }
 716                 free_entp->firstchar = free_entp->next->firstchar;
 717                 free_entp->length = free_entp->next->length+1;
 718                 free_entp->value = (codep < free_entp) ?
 719                     codep->firstchar : free_entp->firstchar;
 720                 if (++free_entp > maxcodep) {
 721                         if (++nbits > BITS_MAX)         /* should not happen */
 722                                 nbits = BITS_MAX;
 723                         nbitsmask = MAXCODE(nbits);
 724                         maxcodep = sp->dec_codetab + nbitsmask;
 725                 }
 726                 oldcodep = codep;
 727                 if (code >= 256) {
 728                         /*
 729                          * Code maps to a string, copy string
 730                          * value to output (written in reverse).
 731                          */
 732                         if(codep->length == 0) {
 733                                 TIFFErrorExt(tif->tif_clientdata, module,
 734                                     "Wrong length of decoded "
 735                                     "string: data probably corrupted at scanline %d",
 736                                     tif->tif_row);
 737                                 return (0);
 738                         }
 739                         if (codep->length > occ) {
 740                                 /*
 741                                  * String is too long for decode buffer,
 742                                  * locate portion that will fit, copy to
 743                                  * the decode buffer, and setup restart
 744                                  * logic for the next decoding call.
 745                                  */
 746                                 sp->dec_codep = codep;
 747                                 do {
 748                                         codep = codep->next;
 749                                 } while (codep->length > occ);
 750                                 sp->dec_restart = occ;
 751                                 tp = op + occ;
 752                                 do  {
 753                                         *--tp = codep->value;
 754                                         codep = codep->next;
 755                                 }  while (--occ);
 756                                 break;
 757                         }
 758                         assert(occ >= codep->length);
 759                         op += codep->length;
 760                         occ -= codep->length;
 761                         tp = op;
 762                         do {
 763                                 *--tp = codep->value;
 764                         } while( (codep = codep->next) != NULL );
 765                 } else {
 766                         *op++ = (char)code;
 767                         occ--;
 768                 }
 769         }
 770
 771         tif->tif_rawcc -= (tmsize_t)( (uint8*) bp - tif->tif_rawcp );
 772         tif->tif_rawcp = (uint8*) bp;
 773         sp->lzw_nbits = (unsigned short)nbits;
 774         sp->lzw_nextdata = nextdata;
 775         sp->lzw_nextbits = nextbits;
 776         sp->dec_nbitsmask = nbitsmask;
 777         sp->dec_oldcodep = oldcodep;
 778         sp->dec_free_entp = free_entp;
 779         sp->dec_maxcodep = maxcodep;
 780
 781         if (occ > 0) {
 782 #if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
 783                 TIFFErrorExt(tif->tif_clientdata, module,
 784                         "Not enough data at scanline %d (short %I64d bytes)",
 785                              tif->tif_row, (unsigned __int64) occ);
 786 #else
 787                 TIFFErrorExt(tif->tif_clientdata, module,
 788                         "Not enough data at scanline %d (short %llu bytes)",
 789                              tif->tif_row, (unsigned long long) occ);
 790 #endif
 791                 return (0);
 792         }
 793         return (1);
 794 }
 795 #endif /* LZW_COMPAT */
 796
 797 /*
 798  * LZW Encoding.
 799  */
 800
 801 static int
 802 LZWSetupEncode(TIFF* tif)
 803 {
 804         static const char module[] = "LZWSetupEncode";
 805         LZWCodecState* sp = EncoderState(tif);
 806
 807         assert(sp != NULL);
 808         sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
 809         if (sp->enc_hashtab == NULL) {
 810                 TIFFErrorExt(tif->tif_clientdata, module,
 811                              "No space for LZW hash table");
 812                 return (0);
 813         }
 814         return (1);
 815 }
 816
 817 /*
 818  * Reset encoding state at the start of a strip.
 819  */
 820 static int
 821 LZWPreEncode(TIFF* tif, uint16 s)
 822 {
 823         LZWCodecState *sp = EncoderState(tif);
 824
 825         (void) s;
 826         assert(sp != NULL);
 827
 828         if( sp->enc_hashtab == NULL )
 829         {
 830             tif->tif_setupencode( tif );
 831         }
 832
 833         sp->lzw_nbits = BITS_MIN;
 834         sp->lzw_maxcode = MAXCODE(BITS_MIN);
 835         sp->lzw_free_ent = CODE_FIRST;
 836         sp->lzw_nextbits = 0;
 837         sp->lzw_nextdata = 0;
 838         sp->enc_checkpoint = CHECK_GAP;
 839         sp->enc_ratio = 0;
 840         sp->enc_incount = 0;
 841         sp->enc_outcount = 0;
 842         /*
 843          * The 4 here insures there is space for 2 max-sized
 844          * codes in LZWEncode and LZWPostDecode.
 845          */
 846         sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
 847         cl_hash(sp);            /* clear hash table */
 848         sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
 849         return (1);
 850 }
 851
 852 #define CALCRATIO(sp, rat) {                                    \
 853         if (incount > 0x007fffff) { /* NB: shift will overflow */\
 854                 rat = outcount >> 8;                            \
 855                 rat = (rat == 0 ? 0x7fffffff : incount/rat);    \
 856         } else                                                  \
 857                 rat = (incount<<8) / outcount;                  \
 858 }
 859
 860 /* Explicit 0xff masking to make icc -check=conversions happy */
 861 #define PutNextCode(op, c) {                                    \
 862         nextdata = (nextdata << nbits) | c;                     \
 863         nextbits += nbits;                                      \
 864         *op++ = (unsigned char)((nextdata >> (nextbits-8))&0xff);               \
 865         nextbits -= 8;                                          \
 866         if (nextbits >= 8) {                                    \
 867                 *op++ = (unsigned char)((nextdata >> (nextbits-8))&0xff);       \
 868                 nextbits -= 8;                                  \
 869         }                                                       \
 870         outcount += nbits;                                      \
 871 }
 872
 873 /*
 874  * Encode a chunk of pixels.
 875  *
 876  * Uses an open addressing double hashing (no chaining) on the
 877  * prefix code/next character combination.  We do a variant of
 878  * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
 879  * relatively-prime secondary probe.  Here, the modular division
 880  * first probe is gives way to a faster exclusive-or manipulation.
 881  * Also do block compression with an adaptive reset, whereby the
 882  * code table is cleared when the compression ratio decreases,
 883  * but after the table fills.  The variable-length output codes
 884  * are re-sized at this point, and a CODE_CLEAR is generated
 885  * for the decoder.
 886  */
 887 static int
 888 LZWEncode(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
 889 {
 890         register LZWCodecState *sp = EncoderState(tif);
 891         register long fcode;
 892         register hash_t *hp;
 893         register int h, c;
 894         hcode_t ent;
 895         long disp;
 896         long incount, outcount, checkpoint;
 897         unsigned long nextdata;
 898         long nextbits;
 899         int free_ent, maxcode, nbits;
 900         uint8* op;
 901         uint8* limit;
 902
 903         (void) s;
 904         if (sp == NULL)
 905                 return (0);
 906
 907         assert(sp->enc_hashtab != NULL);
 908
 909         /*
 910          * Load local state.
 911          */
 912         incount = sp->enc_incount;
 913         outcount = sp->enc_outcount;
 914         checkpoint = sp->enc_checkpoint;
 915         nextdata = sp->lzw_nextdata;
 916         nextbits = sp->lzw_nextbits;
 917         free_ent = sp->lzw_free_ent;
 918         maxcode = sp->lzw_maxcode;
 919         nbits = sp->lzw_nbits;
 920         op = tif->tif_rawcp;
 921         limit = sp->enc_rawlimit;
 922         ent = (hcode_t)sp->enc_oldcode;
 923
 924         if (ent == (hcode_t) -1 && cc > 0) {
 925                 /*
 926                  * NB: This is safe because it can only happen
 927                  *     at the start of a strip where we know there
 928                  *     is space in the data buffer.
 929                  */
 930                 PutNextCode(op, CODE_CLEAR);
 931                 ent = *bp++; cc--; incount++;
 932         }
 933         while (cc > 0) {
 934                 c = *bp++; cc--; incount++;
 935                 fcode = ((long)c << BITS_MAX) + ent;
 936                 h = (c << HSHIFT) ^ ent;        /* xor hashing */
 937 #ifdef _WINDOWS
 938                 /*
 939                  * Check hash index for an overflow.
 940                  */
 941                 if (h >= HSIZE)
 942                         h -= HSIZE;
 943 #endif
 944                 hp = &sp->enc_hashtab[h];
 945                 if (hp->hash == fcode) {
 946                         ent = hp->code;
 947                         continue;
 948                 }
 949                 if (hp->hash >= 0) {
 950                         /*
 951                          * Primary hash failed, check secondary hash.
 952                          */
 953                         disp = HSIZE - h;
 954                         if (h == 0)
 955                                 disp = 1;
 956                         do {
 957                                 /*
 958                                  * Avoid pointer arithmetic because of
 959                                  * wraparound problems with segments.
 960                                  */
 961                                 if ((h -= disp) < 0)
 962                                         h += HSIZE;
 963                                 hp = &sp->enc_hashtab[h];
 964                                 if (hp->hash == fcode) {
 965                                         ent = hp->code;
 966                                         goto hit;
 967                                 }
 968                         } while (hp->hash >= 0);
 969                 }
 970                 /*
 971                  * New entry, emit code and add to table.
 972                  */
 973                 /*
 974                  * Verify there is space in the buffer for the code
 975                  * and any potential Clear code that might be emitted
 976                  * below.  The value of limit is setup so that there
 977                  * are at least 4 bytes free--room for 2 codes.
 978                  */
 979                 if (op > limit) {
 980                         tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
 981                         if( !TIFFFlushData1(tif) )
 982                             return 0;
 983                         op = tif->tif_rawdata;
 984                 }
 985                 PutNextCode(op, ent);
 986                 ent = (hcode_t)c;
 987                 hp->code = (hcode_t)(free_ent++);
 988                 hp->hash = fcode;
 989                 if (free_ent == CODE_MAX-1) {
 990                         /* table is full, emit clear code and reset */
 991                         cl_hash(sp);
 992                         sp->enc_ratio = 0;
 993                         incount = 0;
 994                         outcount = 0;
 995                         free_ent = CODE_FIRST;
 996                         PutNextCode(op, CODE_CLEAR);
 997                         nbits = BITS_MIN;
 998                         maxcode = MAXCODE(BITS_MIN);
 999                 } else {
1000                         /*
1001                          * If the next entry is going to be too big for
1002                          * the code size, then increase it, if possible.
1003                          */
1004                         if (free_ent > maxcode) {
1005                                 nbits++;
1006                                 assert(nbits <= BITS_MAX);
1007                                 maxcode = (int) MAXCODE(nbits);
1008                         } else if (incount >= checkpoint) {
1009                                 long rat;
1010                                 /*
1011                                  * Check compression ratio and, if things seem
1012                                  * to be slipping, clear the hash table and
1013                                  * reset state.  The compression ratio is a
1014                                  * 24+8-bit fractional number.
1015                                  */
1016                                 checkpoint = incount+CHECK_GAP;
1017                                 CALCRATIO(sp, rat);
1018                                 if (rat <= sp->enc_ratio) {
1019                                         cl_hash(sp);
1020                                         sp->enc_ratio = 0;
1021                                         incount = 0;
1022                                         outcount = 0;
1023                                         free_ent = CODE_FIRST;
1024                                         PutNextCode(op, CODE_CLEAR);
1025                                         nbits = BITS_MIN;
1026                                         maxcode = MAXCODE(BITS_MIN);
1027                                 } else
1028                                         sp->enc_ratio = rat;
1029                         }
1030                 }
1031         hit:
1032                 ;
1033         }
1034
1035         /*
1036          * Restore global state.
1037          */
1038         sp->enc_incount = incount;
1039         sp->enc_outcount = outcount;
1040         sp->enc_checkpoint = checkpoint;
1041         sp->enc_oldcode = ent;
1042         sp->lzw_nextdata = nextdata;
1043         sp->lzw_nextbits = nextbits;
1044         sp->lzw_free_ent = (unsigned short)free_ent;
1045         sp->lzw_maxcode = (unsigned short)maxcode;
1046         sp->lzw_nbits = (unsigned short)nbits;
1047         tif->tif_rawcp = op;
1048         return (1);
1049 }
1050
1051 /*
1052  * Finish off an encoded strip by flushing the last
1053  * string and tacking on an End Of Information code.
1054  */
1055 static int
1056 LZWPostEncode(TIFF* tif)
1057 {
1058         register LZWCodecState *sp = EncoderState(tif);
1059         uint8* op = tif->tif_rawcp;
1060         long nextbits = sp->lzw_nextbits;
1061         unsigned long nextdata = sp->lzw_nextdata;
1062         long outcount = sp->enc_outcount;
1063         int nbits = sp->lzw_nbits;
1064
1065         if (op > sp->enc_rawlimit) {
1066                 tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
1067                 if( !TIFFFlushData1(tif) )
1068                     return 0;
1069                 op = tif->tif_rawdata;
1070         }
1071         if (sp->enc_oldcode != (hcode_t) -1) {
1072                 int free_ent = sp->lzw_free_ent;
1073
1074                 PutNextCode(op, sp->enc_oldcode);
1075                 sp->enc_oldcode = (hcode_t) -1;
1076                 free_ent ++;
1077
1078                 if (free_ent == CODE_MAX-1) {
1079                         /* table is full, emit clear code and reset */
1080                         outcount = 0;
1081                         PutNextCode(op, CODE_CLEAR);
1082                         nbits = BITS_MIN;
1083                 } else {
1084                         /*
1085                         * If the next entry is going to be too big for
1086                         * the code size, then increase it, if possible.
1087                         */
1088                         if (free_ent > sp->lzw_maxcode) {
1089                                 nbits++;
1090                                 assert(nbits <= BITS_MAX);
1091                         }
1092                 }
1093         }
1094         PutNextCode(op, CODE_EOI);
1095         /* Explicit 0xff masking to make icc -check=conversions happy */
1096         if (nextbits > 0)
1097                 *op++ = (unsigned char)((nextdata << (8-nextbits))&0xff);
1098         tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
1099         return (1);
1100 }
1101
1102 /*
1103  * Reset encoding hash table.
1104  */
1105 static void
1106 cl_hash(LZWCodecState* sp)
1107 {
1108         register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
1109         register long i = HSIZE-8;
1110
1111         do {
1112                 i -= 8;
1113                 hp[-7].hash = -1;
1114                 hp[-6].hash = -1;
1115                 hp[-5].hash = -1;
1116                 hp[-4].hash = -1;
1117                 hp[-3].hash = -1;
1118                 hp[-2].hash = -1;
1119                 hp[-1].hash = -1;
1120                 hp[ 0].hash = -1;
1121                 hp -= 8;
1122         } while (i >= 0);
1123         for (i += 8; i > 0; i--, hp--)
1124                 hp->hash = -1;
1125 }
1126
1127 static void
1128 LZWCleanup(TIFF* tif)
1129 {
1130         (void)TIFFPredictorCleanup(tif);
1131
1132         assert(tif->tif_data != 0);
1133
1134         if (DecoderState(tif)->dec_codetab)
1135                 _TIFFfree(DecoderState(tif)->dec_codetab);
1136
1137         if (EncoderState(tif)->enc_hashtab)
1138                 _TIFFfree(EncoderState(tif)->enc_hashtab);
1139
1140         _TIFFfree(tif->tif_data);
1141         tif->tif_data = NULL;
1142
1143         _TIFFSetDefaultCompressionState(tif);
1144 }
1145
1146 int
1147 TIFFInitLZW(TIFF* tif, int scheme)
1148 {
1149         static const char module[] = "TIFFInitLZW";
1150         assert(scheme == COMPRESSION_LZW);
1151         /*
1152          * Allocate state block so tag methods have storage to record values.
1153          */
1154         tif->tif_data = (uint8*) _TIFFmalloc(sizeof (LZWCodecState));
1155         if (tif->tif_data == NULL)
1156                 goto bad;
1157         DecoderState(tif)->dec_codetab = NULL;
1158         DecoderState(tif)->dec_decode = NULL;
1159         EncoderState(tif)->enc_hashtab = NULL;
1160         LZWState(tif)->rw_mode = tif->tif_mode;
1161
1162         /*
1163          * Install codec methods.
1164          */
1165         tif->tif_fixuptags = LZWFixupTags;
1166         tif->tif_setupdecode = LZWSetupDecode;
1167         tif->tif_predecode = LZWPreDecode;
1168         tif->tif_decoderow = LZWDecode;
1169         tif->tif_decodestrip = LZWDecode;
1170         tif->tif_decodetile = LZWDecode;
1171         tif->tif_setupencode = LZWSetupEncode;
1172         tif->tif_preencode = LZWPreEncode;
1173         tif->tif_postencode = LZWPostEncode;
1174         tif->tif_encoderow = LZWEncode;
1175         tif->tif_encodestrip = LZWEncode;
1176         tif->tif_encodetile = LZWEncode;
1177         tif->tif_cleanup = LZWCleanup;
1178         /*
1179          * Setup predictor setup.
1180          */
1181         (void) TIFFPredictorInit(tif);
1182         return (1);
1183 bad:
1184         TIFFErrorExt(tif->tif_clientdata, module,
1185                      "No space for LZW state block");
1186         return (0);
1187 }
1188
1189 /*
1190  * Copyright (c) 1985, 1986 The Regents of the University of California.
1191  * All rights reserved.
1192  *
1193  * This code is derived from software contributed to Berkeley by
1194  * James A. Woods, derived from original work by Spencer Thomas
1195  * and Joseph Orost.
1196  *
1197  * Redistribution and use in source and binary forms are permitted
1198  * provided that the above copyright notice and this paragraph are
1199  * duplicated in all such forms and that any documentation,
1200  * advertising materials, and other materials related to such
1201  * distribution and use acknowledge that the software was developed
1202  * by the University of California, Berkeley.  The name of the
1203  * University may not be used to endorse or promote products derived
1204  * from this software without specific prior written permission.
1205  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1206  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1207  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1208  */
1209 #endif /* LZW_SUPPORT */
1210
1211 /* vim: set ts=8 sts=8 sw=8 noet: */
1212 /*
1213  * Local Variables:
1214  * mode: c
1215  * c-basic-offset: 8
1216  * fill-column: 78
1217  * End:
1218  */