/src/ghostpdl/tiff/libtiff/tif_lzw.c

Source (jump to first uncovered line)
/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

#include "tiffiop.h"
#ifdef LZW_SUPPORT
/*
 * TIFF Library.  
 * Rev 5.0 Lempel-Ziv & Welch Compression Support
 *
 * This code is derived from the compress program whose code is
 * derived from software contributed to Berkeley by James A. Woods,
 * derived from original work by Spencer Thomas and Joseph Orost.
 *
 * The original Berkeley copyright notice appears below in its entirety.
 */
#include "tif_predict.h"

#include <stdio.h>

/*
 * NB: The 5.0 spec describes a different algorithm than Aldus
 *     implements.  Specifically, Aldus does code length transitions
 *     one code earlier than should be done (for real LZW).
 *     Earlier versions of this library implemented the correct
 *     LZW algorithm, but emitted codes in a bit order opposite
 *     to the TIFF spec.  Thus, to maintain compatibility w/ Aldus
 *     we interpret MSB-LSB ordered codes to be images written w/
 *     old versions of this library, but otherwise adhere to the
 *     Aldus "off by one" algorithm.
 *
 * Future revisions to the TIFF spec are expected to "clarify this issue".
 */
#define LZW_COMPAT              /* include backwards compatibility code */
/*
 * Each strip of data is supposed to be terminated by a CODE_EOI.
 * If the following #define is included, the decoder will also
 * check for end-of-strip w/o seeing this code.  This makes the
 * library more robust, but also slower.
 */
#define LZW_CHECKEOS            /* include checks for strips w/o EOI code */

#define MAXCODE(n)  ((1L<<(n))-1)
/*
 * The TIFF spec specifies that encoded bit
 * strings range from 9 to 12 bits.
 */
#define BITS_MIN        9               /* start with 9 bits */
#define BITS_MAX        12              /* max of 12 bit strings */
/* predefined codes */
#define CODE_CLEAR      256             /* code to clear string table */
#define CODE_EOI        257             /* end-of-information code */
#define CODE_FIRST      258             /* first free code entry */
#define CODE_MAX        MAXCODE(BITS_MAX)
#define HSIZE           9001L           /* 91% occupancy */
#define HSHIFT          (13-8)
#ifdef LZW_COMPAT
/* NB: +1024 is for compatibility with old files */
#define CSIZE           (MAXCODE(BITS_MAX)+1024L)
#else
#define CSIZE           (MAXCODE(BITS_MAX)+1L)
#endif

/*
 * State block for each open TIFF file using LZW
 * compression/decompression.  Note that the predictor
 * state block must be first in this data structure.
 */
typedef struct {
  TIFFPredictorState predict;     /* predictor super class */

  unsigned short  nbits;          /* # of bits/code */
  unsigned short  maxcode;        /* maximum code for lzw_nbits */
  unsigned short  free_ent;       /* next free entry in hash table */
  unsigned long   nextdata;       /* next bits of i/o */
  long            nextbits;       /* # of valid bits in lzw_nextdata */

  int             rw_mode;        /* preserve rw_mode from init */
} LZWBaseState;

#define lzw_nbits       base.nbits
#define lzw_maxcode     base.maxcode
#define lzw_free_ent    base.free_ent
#define lzw_nextdata    base.nextdata
#define lzw_nextbits    base.nextbits

/*
 * Encoding-specific state.
 */
typedef uint16_t hcode_t;     /* codes fit in 16 bits */
typedef struct {
  long  hash;
  hcode_t code;
} hash_t;

/*
 * Decoding-specific state.
 */
typedef struct code_ent {
  struct code_ent *next;
  unsigned short  length;   /* string len, including this token */
  unsigned char value;    /* data value */
  unsigned char firstchar;  /* first token of string */
} code_t;

typedef int (*decodeFunc)(TIFF*, uint8_t*, tmsize_t, uint16_t);

typedef struct {
  LZWBaseState base;

  /* Decoding specific data */
  long    dec_nbitsmask;    /* lzw_nbits 1 bits, right adjusted */
  long    dec_restart;    /* restart count */
#ifdef LZW_CHECKEOS
  uint64_t  dec_bitsleft;   /* available bits in raw data */
  tmsize_t old_tif_rawcc;         /* value of tif_rawcc at the end of the previous TIFLZWDecode() call */
#endif
  decodeFunc dec_decode;    /* regular or backwards compatible */
  code_t* dec_codep;    /* current recognized code */
  code_t* dec_oldcodep;   /* previously recognized code */
  code_t* dec_free_entp;    /* next free entry */
  code_t* dec_maxcodep;   /* max available entry */
  code_t* dec_codetab;    /* kept separate for small machines */

  /* Encoding specific data */
  int     enc_oldcode;    /* last code encountered */
  long    enc_checkpoint;   /* point at which to clear table */
#define CHECK_GAP 10000    /* enc_ratio check interval */
  long    enc_ratio;    /* current compression ratio */
  long    enc_incount;    /* (input) data bytes encoded */
  long    enc_outcount;   /* encoded (output) bytes */
  uint8_t*  enc_rawlimit;   /* bound on tif_rawdata buffer */
  hash_t* enc_hashtab;    /* kept separate for small machines */
} LZWCodecState;

#define LZWState(tif)   ((LZWBaseState*) (tif)->tif_data)
#define DecoderState(tif) ((LZWCodecState*) LZWState(tif))
#define EncoderState(tif) ((LZWCodecState*) LZWState(tif))

static int LZWDecode(TIFF* tif, uint8_t* op0, tmsize_t occ0, uint16_t s);
#ifdef LZW_COMPAT
static int LZWDecodeCompat(TIFF* tif, uint8_t* op0, tmsize_t occ0, uint16_t s);
#endif
static void cl_hash(LZWCodecState*);

/*
 * LZW Decoder.
 */

#ifdef LZW_CHECKEOS
/*
 * This check shouldn't be necessary because each
 * strip is suppose to be terminated with CODE_EOI.
 */
#define NextCode(_tif, _sp, _bp, _code, _get) {       \
  if ((_sp)->dec_bitsleft < (uint64_t)nbits) {     \
    TIFFWarningExt(_tif->tif_clientdata, module,    \
        "LZWDecode: Strip %"PRIu32" not terminated with EOI code", \
        _tif->tif_curstrip);        \
    _code = CODE_EOI;         \
  } else {             \
    _get(_sp,_bp,_code);          \
    (_sp)->dec_bitsleft -= nbits;       \
  }               \
}
#else
#define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
#endif

static int
LZWFixupTags(TIFF* tif)
{
  (void) tif;
  return (1);
}

static int
LZWSetupDecode(TIFF* tif)
{
  static const char module[] = "LZWSetupDecode";
  LZWCodecState* sp = DecoderState(tif);
  int code;

  if( sp == NULL )
  {
    /*
     * Allocate state block so tag methods have storage to record
     * values.
    */
    tif->tif_data = (uint8_t*) _TIFFmalloc(sizeof(LZWCodecState));
    if (tif->tif_data == NULL)
    {
      TIFFErrorExt(tif->tif_clientdata, module, "No space for LZW state block");
      return (0);
    }

    sp = DecoderState(tif);
    sp->dec_codetab = NULL;
    sp->dec_decode = NULL;

    /*
     * Setup predictor setup.
     */
    (void) TIFFPredictorInit(tif);
  }

  if (sp->dec_codetab == NULL) {
    sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
    if (sp->dec_codetab == NULL) {
      TIFFErrorExt(tif->tif_clientdata, module,
             "No space for LZW code table");
      return (0);
    }
    /*
     * Pre-load the table.
     */
    code = 255;
    do {
      sp->dec_codetab[code].value = (unsigned char)code;
      sp->dec_codetab[code].firstchar = (unsigned char)code;
      sp->dec_codetab[code].length = 1;
      sp->dec_codetab[code].next = NULL;
    } while (code--);
    /*
     * Zero-out the unused entries
                 */
                /* Silence false positive */
                /* coverity[overrun-buffer-arg] */
                 _TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
           (CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
  }
  return (1);
}

/*
 * Setup state for decoding a strip.
 */
static int
LZWPreDecode(TIFF* tif, uint16_t s)
{
  static const char module[] = "LZWPreDecode";
  LZWCodecState *sp = DecoderState(tif);

  (void) s;
  assert(sp != NULL);
  if( sp->dec_codetab == NULL )
        {
            tif->tif_setupdecode( tif );
      if( sp->dec_codetab == NULL )
    return (0);
        }

  /*
   * Check for old bit-reversed codes.
   */
  if (tif->tif_rawcc >= 2 &&
      tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
#ifdef LZW_COMPAT
    if (!sp->dec_decode) {
      TIFFWarningExt(tif->tif_clientdata, module,
          "Old-style LZW codes, convert file");
      /*
       * Override default decoding methods with
       * ones that deal with the old coding.
       * Otherwise the predictor versions set
       * above will call the compatibility routines
       * through the dec_decode method.
       */
      tif->tif_decoderow = LZWDecodeCompat;
      tif->tif_decodestrip = LZWDecodeCompat;
      tif->tif_decodetile = LZWDecodeCompat;
      /*
       * If doing horizontal differencing, must
       * re-setup the predictor logic since we
       * switched the basic decoder methods...
       */
      (*tif->tif_setupdecode)(tif);
      sp->dec_decode = LZWDecodeCompat;
    }
    sp->lzw_maxcode = MAXCODE(BITS_MIN);
#else /* !LZW_COMPAT */
    if (!sp->dec_decode) {
      TIFFErrorExt(tif->tif_clientdata, module,
          "Old-style LZW codes not supported");
      sp->dec_decode = LZWDecode;
    }
    return (0);
#endif/* !LZW_COMPAT */
  } else {
    sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
    sp->dec_decode = LZWDecode;
  }
  sp->lzw_nbits = BITS_MIN;
  sp->lzw_nextbits = 0;
  sp->lzw_nextdata = 0;

  sp->dec_restart = 0;
  sp->dec_nbitsmask = MAXCODE(BITS_MIN);
#ifdef LZW_CHECKEOS
  sp->dec_bitsleft = 0;
        sp->old_tif_rawcc = 0;
#endif
  sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
  /*
   * Zero entries that are not yet filled in.  We do
   * this to guard against bogus input data that causes
   * us to index into undefined entries.  If you can
   * come up with a way to safely bounds-check input codes
   * while decoding then you can remove this operation.
   */
  _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
  sp->dec_oldcodep = &sp->dec_codetab[-1];
  sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
  return (1);
}

/*
 * Decode a "hunk of data".
 */
#define GetNextCode(sp, bp, code) {       \
  nextdata = (nextdata<<8) | *(bp)++;     \
  nextbits += 8;            \
  if (nextbits < nbits) {         \
    nextdata = (nextdata<<8) | *(bp)++;   \
    nextbits += 8;          \
  }              \
  code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \
  nextbits -= nbits;          \
}

static void
codeLoop(TIFF* tif, const char* module)
{
  TIFFErrorExt(tif->tif_clientdata, module,
      "Bogus encoding, loop in the code table; scanline %"PRIu32,
      tif->tif_row);
}

static int
LZWDecode(TIFF* tif, uint8_t* op0, tmsize_t occ0, uint16_t s)
{
  static const char module[] = "LZWDecode";
  LZWCodecState *sp = DecoderState(tif);
  char *op = (char*) op0;
  long occ = (long) occ0;
  char *tp;
  unsigned char *bp;
  hcode_t code;
  int len;
  long nbits, nextbits, nbitsmask;
        unsigned long nextdata;
  code_t *codep, *free_entp, *maxcodep, *oldcodep;

  (void) s;
  assert(sp != NULL);
        assert(sp->dec_codetab != NULL);

  /*
    Fail if value does not fit in long.
  */
  if ((tmsize_t) occ != occ0)
          return (0);
  /*
   * Restart interrupted output operation.
   */
  if (sp->dec_restart) {
    long residue;

    codep = sp->dec_codep;
    residue = codep->length - sp->dec_restart;
    if (residue > occ) {
      /*
       * Residue from previous decode is sufficient
       * to satisfy decode request.  Skip to the
       * start of the decoded string, place decoded
       * values in the output buffer, and return.
       */
      sp->dec_restart += occ;
      do {
        codep = codep->next;
      } while (--residue > occ && codep);
      if (codep) {
        tp = op + occ;
        do {
          *--tp = codep->value;
          codep = codep->next;
        } while (--occ && codep);
      }
      return (1);
    }
    /*
     * Residue satisfies only part of the decode request.
     */
    op += residue;
    occ -= residue;
    tp = op;
    do {
      int t;
      --tp;
      t = codep->value;
      codep = codep->next;
      *tp = (char)t;
    } while (--residue && codep);
    sp->dec_restart = 0;
  }

  bp = (unsigned char *)tif->tif_rawcp;
#ifdef LZW_CHECKEOS
  sp->dec_bitsleft += (((uint64_t)tif->tif_rawcc - sp->old_tif_rawcc) << 3);
#endif
  nbits = sp->lzw_nbits;
  nextdata = sp->lzw_nextdata;
  nextbits = sp->lzw_nextbits;
  nbitsmask = sp->dec_nbitsmask;
  oldcodep = sp->dec_oldcodep;
  free_entp = sp->dec_free_entp;
  maxcodep = sp->dec_maxcodep;

  while (occ > 0) {
    NextCode(tif, sp, bp, code, GetNextCode);
    if (code == CODE_EOI)
      break;
    if (code == CODE_CLEAR) {
      do {
        free_entp = sp->dec_codetab + CODE_FIRST;
        _TIFFmemset(free_entp, 0,
              (CSIZE - CODE_FIRST) * sizeof (code_t));
        nbits = BITS_MIN;
        nbitsmask = MAXCODE(BITS_MIN);
        maxcodep = sp->dec_codetab + nbitsmask-1;
        NextCode(tif, sp, bp, code, GetNextCode);
      } while (code == CODE_CLEAR);  /* consecutive CODE_CLEAR codes */
      if (code == CODE_EOI)
        break;
      if (code > CODE_CLEAR) {
        TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
        "LZWDecode: Corrupted LZW table at scanline %"PRIu32,
               tif->tif_row);
        return (0);
      }
      *op++ = (char)code;
      occ--;
      oldcodep = sp->dec_codetab + code;
      continue;
    }
    codep = sp->dec_codetab + code;

    /*
     * Add the new entry to the code table.
     */
    if (free_entp < &sp->dec_codetab[0] ||
        free_entp >= &sp->dec_codetab[CSIZE]) {
      TIFFErrorExt(tif->tif_clientdata, module,
          "Corrupted LZW table at scanline %"PRIu32,
          tif->tif_row);
      return (0);
    }

    free_entp->next = oldcodep;
    if (free_entp->next < &sp->dec_codetab[0] ||
        free_entp->next >= &sp->dec_codetab[CSIZE]) {
      TIFFErrorExt(tif->tif_clientdata, module,
          "Corrupted LZW table at scanline %"PRIu32,
          tif->tif_row);
      return (0);
    }
    free_entp->firstchar = free_entp->next->firstchar;
    free_entp->length = free_entp->next->length+1;
    free_entp->value = (codep < free_entp) ?
        codep->firstchar : free_entp->firstchar;
    if (++free_entp > maxcodep) {
      if (++nbits > BITS_MAX)   /* should not happen */
        nbits = BITS_MAX;
      nbitsmask = MAXCODE(nbits);
      maxcodep = sp->dec_codetab + nbitsmask-1;
    }
    oldcodep = codep;
    if (code >= 256) {
      /*
       * Code maps to a string, copy string
       * value to output (written in reverse).
       */
      if(codep->length == 0) {
        TIFFErrorExt(tif->tif_clientdata, module,
            "Wrong length of decoded string: "
            "data probably corrupted at scanline %"PRIu32,
            tif->tif_row);
        return (0);
      }
      if (codep->length > occ) {
        /*
         * String is too long for decode buffer,
         * locate portion that will fit, copy to
         * the decode buffer, and setup restart
         * logic for the next decoding call.
         */
        sp->dec_codep = codep;
        do {
          codep = codep->next;
        } while (codep && codep->length > occ);
        if (codep) {
          sp->dec_restart = (long)occ;
          tp = op + occ;
          do  {
            *--tp = codep->value;
            codep = codep->next;
          }  while (--occ && codep);
          if (codep)
            codeLoop(tif, module);
        }
        break;
      }
      len = codep->length;
      tp = op + len;
      do {
        int t;
        --tp;
        t = codep->value;
        codep = codep->next;
        *tp = (char)t;
      } while (codep && tp > op);
      if (codep) {
          codeLoop(tif, module);
          break;
      }
      assert(occ >= len);
      op += len;
      occ -= len;
    } else {
      *op++ = (char)code;
      occ--;
    }
  }

  tif->tif_rawcc -= (tmsize_t)((uint8_t*) bp - tif->tif_rawcp );
  tif->tif_rawcp = (uint8_t*) bp;
#ifdef LZW_CHECKEOS
  sp->old_tif_rawcc = tif->tif_rawcc;
#endif
  sp->lzw_nbits = (unsigned short) nbits;
  sp->lzw_nextdata = nextdata;
  sp->lzw_nextbits = nextbits;
  sp->dec_nbitsmask = nbitsmask;
  sp->dec_oldcodep = oldcodep;
  sp->dec_free_entp = free_entp;
  sp->dec_maxcodep = maxcodep;

  if (occ > 0) {
    TIFFErrorExt(tif->tif_clientdata, module,
      "Not enough data at scanline %"PRIu32" (short %ld bytes)",
           tif->tif_row, occ);
    return (0);
  }
  return (1);
}

#ifdef LZW_COMPAT
/*
 * Decode a "hunk of data" for old images.
 */
#define GetNextCodeCompat(sp, bp, code) {     \
  nextdata |= (unsigned long) *(bp)++ << nextbits;  \
  nextbits += 8;            \
  if (nextbits < nbits) {         \
    nextdata |= (unsigned long) *(bp)++ << nextbits;\
    nextbits += 8;          \
  }              \
  code = (hcode_t)(nextdata & nbitsmask);     \
  nextdata >>= nbits;         \
  nextbits -= nbits;          \
}

static int
LZWDecodeCompat(TIFF* tif, uint8_t* op0, tmsize_t occ0, uint16_t s)
{
  static const char module[] = "LZWDecodeCompat";
  LZWCodecState *sp = DecoderState(tif);
  char *op = (char*) op0;
  long occ = (long) occ0;
  char *tp;
  unsigned char *bp;
  int code, nbits;
  int len;
  long nextbits, nextdata, nbitsmask;
  code_t *codep, *free_entp, *maxcodep, *oldcodep;

  (void) s;
  assert(sp != NULL);

  /*
    Fail if value does not fit in long.
  */
  if ((tmsize_t) occ != occ0)
          return (0);

  /*
   * Restart interrupted output operation.
   */
  if (sp->dec_restart) {
    long residue;

    codep = sp->dec_codep;
    residue = codep->length - sp->dec_restart;
    if (residue > occ) {
      /*
       * Residue from previous decode is sufficient
       * to satisfy decode request.  Skip to the
       * start of the decoded string, place decoded
       * values in the output buffer, and return.
       */
      sp->dec_restart += occ;
      do {
        codep = codep->next;
      } while (--residue > occ);
      tp = op + occ;
      do {
        *--tp = codep->value;
        codep = codep->next;
      } while (--occ);
      return (1);
    }
    /*
     * Residue satisfies only part of the decode request.
     */
    op += residue;
    occ -= residue;
    tp = op;
    do {
      *--tp = codep->value;
      codep = codep->next;
    } while (--residue);
    sp->dec_restart = 0;
  }

  bp = (unsigned char *)tif->tif_rawcp;
#ifdef LZW_CHECKEOS
  sp->dec_bitsleft += (((uint64_t)tif->tif_rawcc - sp->old_tif_rawcc) << 3);
#endif
  nbits = sp->lzw_nbits;
  nextdata = sp->lzw_nextdata;
  nextbits = sp->lzw_nextbits;
  nbitsmask = sp->dec_nbitsmask;
  oldcodep = sp->dec_oldcodep;
  free_entp = sp->dec_free_entp;
  maxcodep = sp->dec_maxcodep;

  while (occ > 0) {
    NextCode(tif, sp, bp, code, GetNextCodeCompat);
    if (code == CODE_EOI)
      break;
    if (code == CODE_CLEAR) {
      do {
        free_entp = sp->dec_codetab + CODE_FIRST;
        _TIFFmemset(free_entp, 0,
              (CSIZE - CODE_FIRST) * sizeof (code_t));
        nbits = BITS_MIN;
        nbitsmask = MAXCODE(BITS_MIN);
        maxcodep = sp->dec_codetab + nbitsmask;
        NextCode(tif, sp, bp, code, GetNextCodeCompat);
      } while (code == CODE_CLEAR);  /* consecutive CODE_CLEAR codes */
      if (code == CODE_EOI)
        break;
      if (code > CODE_CLEAR) {
        TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
        "LZWDecode: Corrupted LZW table at scanline %"PRIu32,
               tif->tif_row);
        return (0);
      }
      *op++ = (char)code;
      occ--;
      oldcodep = sp->dec_codetab + code;
      continue;
    }
    codep = sp->dec_codetab + code;

    /*
     * Add the new entry to the code table.
     */
    if (free_entp < &sp->dec_codetab[0] ||
        free_entp >= &sp->dec_codetab[CSIZE]) {
      TIFFErrorExt(tif->tif_clientdata, module,
          "Corrupted LZW table at scanline %"PRIu32, tif->tif_row);
      return (0);
    }

    free_entp->next = oldcodep;
    if (free_entp->next < &sp->dec_codetab[0] ||
        free_entp->next >= &sp->dec_codetab[CSIZE]) {
      TIFFErrorExt(tif->tif_clientdata, module,
          "Corrupted LZW table at scanline %"PRIu32, tif->tif_row);
      return (0);
    }
    free_entp->firstchar = free_entp->next->firstchar;
    free_entp->length = free_entp->next->length+1;
    free_entp->value = (codep < free_entp) ?
        codep->firstchar : free_entp->firstchar;
    if (++free_entp > maxcodep) {
      if (++nbits > BITS_MAX)   /* should not happen */
        nbits = BITS_MAX;
      nbitsmask = MAXCODE(nbits);
      maxcodep = sp->dec_codetab + nbitsmask;
    }
    oldcodep = codep;
    if (code >= 256) {
      /*
       * Code maps to a string, copy string
       * value to output (written in reverse).
       */
      if(codep->length == 0) {
        TIFFErrorExt(tif->tif_clientdata, module,
            "Wrong length of decoded "
            "string: data probably corrupted at scanline %"PRIu32,
            tif->tif_row);
        return (0);
      }
      if (codep->length > occ) {
        /*
         * String is too long for decode buffer,
         * locate portion that will fit, copy to
         * the decode buffer, and setup restart
         * logic for the next decoding call.
         */
        sp->dec_codep = codep;
        do {
          codep = codep->next;
        } while (codep->length > occ);
        sp->dec_restart = occ;
        tp = op + occ;
        do  {
          *--tp = codep->value;
          codep = codep->next;
        }  while (--occ);
        break;
      }
      len = codep->length;
      tp = op + len;
      do {
        int t;
        --tp;
        t = codep->value;
        codep = codep->next;
        *tp = (char)t;
      } while (codep && tp > op);
      assert(occ >= len);
      op += len;
      occ -= len;
    } else {
      *op++ = (char)code;
      occ--;
    }
  }

  tif->tif_rawcc -= (tmsize_t)((uint8_t*) bp - tif->tif_rawcp );
  tif->tif_rawcp = (uint8_t*) bp;
#ifdef LZW_CHECKEOS
  sp->old_tif_rawcc = tif->tif_rawcc;
#endif
  sp->lzw_nbits = (unsigned short)nbits;
  sp->lzw_nextdata = nextdata;
  sp->lzw_nextbits = nextbits;
  sp->dec_nbitsmask = nbitsmask;
  sp->dec_oldcodep = oldcodep;
  sp->dec_free_entp = free_entp;
  sp->dec_maxcodep = maxcodep;

  if (occ > 0) {
    TIFFErrorExt(tif->tif_clientdata, module,
      "Not enough data at scanline %"PRIu32" (short %ld bytes)",
           tif->tif_row, occ);
    return (0);
  }
  return (1);
}
#endif /* LZW_COMPAT */

/*
 * LZW Encoding.
 */

static int
LZWSetupEncode(TIFF* tif)
{
  static const char module[] = "LZWSetupEncode";
  LZWCodecState* sp = EncoderState(tif);

  assert(sp != NULL);
  sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
  if (sp->enc_hashtab == NULL) {
    TIFFErrorExt(tif->tif_clientdata, module,
           "No space for LZW hash table");
    return (0);
  }
  return (1);
}

/*
 * Reset encoding state at the start of a strip.
 */
static int
LZWPreEncode(TIFF* tif, uint16_t s)
{
  LZWCodecState *sp = EncoderState(tif);

  (void) s;
  assert(sp != NULL);

  if( sp->enc_hashtab == NULL )
        {
            tif->tif_setupencode( tif );
        }

  sp->lzw_nbits = BITS_MIN;
  sp->lzw_maxcode = MAXCODE(BITS_MIN);
  sp->lzw_free_ent = CODE_FIRST;
  sp->lzw_nextbits = 0;
  sp->lzw_nextdata = 0;
  sp->enc_checkpoint = CHECK_GAP;
  sp->enc_ratio = 0;
  sp->enc_incount = 0;
  sp->enc_outcount = 0;
  /*
   * The 4 here insures there is space for 2 max-sized
   * codes in LZWEncode and LZWPostDecode.
   */
  sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
  cl_hash(sp);    /* clear hash table */
  sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
  return (1);
}

#define CALCRATIO(sp, rat) {         \
  if (incount > 0x007fffff) { /* NB: shift will overflow */\
    rat = outcount >> 8;        \
    rat = (rat == 0 ? 0x7fffffff : incount/rat);  \
  } else             \
    rat = (incount<<8) / outcount;     \
}

/* Explicit 0xff masking to make icc -check=conversions happy */
#define PutNextCode(op, c) {         \
  nextdata = (nextdata << nbits) | c;     \
  nextbits += nbits;          \
  *op++ = (unsigned char)((nextdata >> (nextbits-8))&0xff);   \
  nextbits -= 8;            \
  if (nextbits >= 8) {         \
    *op++ = (unsigned char)((nextdata >> (nextbits-8))&0xff); \
    nextbits -= 8;          \
  }              \
  outcount += nbits;          \
}

/*
 * Encode a chunk of pixels.
 *
 * Uses an open addressing double hashing (no chaining) on the 
 * prefix code/next character combination.  We do a variant of
 * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
 * relatively-prime secondary probe.  Here, the modular division
 * first probe is gives way to a faster exclusive-or manipulation. 
 * Also do block compression with an adaptive reset, whereby the
 * code table is cleared when the compression ratio decreases,
 * but after the table fills.  The variable-length output codes
 * are re-sized at this point, and a CODE_CLEAR is generated
 * for the decoder. 
 */
static int
LZWEncode(TIFF* tif, uint8_t* bp, tmsize_t cc, uint16_t s)
{
  register LZWCodecState *sp = EncoderState(tif);
  register long fcode;
  register hash_t *hp;
  register int h, c;
  hcode_t ent;
  long disp;
  long incount, outcount, checkpoint;
  unsigned long nextdata;
        long nextbits;
  int free_ent, maxcode, nbits;
  uint8_t* op;
  uint8_t* limit;

  (void) s;
  if (sp == NULL)
    return (0);

        assert(sp->enc_hashtab != NULL);

  /*
   * Load local state.
   */
  incount = sp->enc_incount;
  outcount = sp->enc_outcount;
  checkpoint = sp->enc_checkpoint;
  nextdata = sp->lzw_nextdata;
  nextbits = sp->lzw_nextbits;
  free_ent = sp->lzw_free_ent;
  maxcode = sp->lzw_maxcode;
  nbits = sp->lzw_nbits;
  op = tif->tif_rawcp;
  limit = sp->enc_rawlimit;
  ent = (hcode_t)sp->enc_oldcode;

  if (ent == (hcode_t) -1 && cc > 0) {
    /*
     * NB: This is safe because it can only happen
     *     at the start of a strip where we know there
     *     is space in the data buffer.
     */
    PutNextCode(op, CODE_CLEAR);
    ent = *bp++; cc--; incount++;
  }
  while (cc > 0) {
    c = *bp++; cc--; incount++;
    fcode = ((long)c << BITS_MAX) + ent;
    h = (c << HSHIFT) ^ ent;  /* xor hashing */
#ifdef _WINDOWS
    /*
     * Check hash index for an overflow.
     */
    if (h >= HSIZE)
      h -= HSIZE;
#endif
    hp = &sp->enc_hashtab[h];
    if (hp->hash == fcode) {
      ent = hp->code;
      continue;
    }
    if (hp->hash >= 0) {
      /*
       * Primary hash failed, check secondary hash.
       */
      disp = HSIZE - h;
      if (h == 0)
        disp = 1;
      do {
        /*
         * Avoid pointer arithmetic because of
         * wraparound problems with segments.
         */
        if ((h -= disp) < 0)
          h += HSIZE;
        hp = &sp->enc_hashtab[h];
        if (hp->hash == fcode) {
          ent = hp->code;
          goto hit;
        }
      } while (hp->hash >= 0);
    }
    /*
     * New entry, emit code and add to table.
     */
    /*
     * Verify there is space in the buffer for the code
     * and any potential Clear code that might be emitted
     * below.  The value of limit is setup so that there
     * are at least 4 bytes free--room for 2 codes.
     */
    if (op > limit) {
      tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
      if( !TIFFFlushData1(tif) )
                            return 0;
      op = tif->tif_rawdata;
    }
    PutNextCode(op, ent);
    ent = (hcode_t)c;
    hp->code = (hcode_t)(free_ent++);
    hp->hash = fcode;
    if (free_ent == CODE_MAX-1) {
      /* table is full, emit clear code and reset */
      cl_hash(sp);
      sp->enc_ratio = 0;
      incount = 0;
      outcount = 0;
      free_ent = CODE_FIRST;
      PutNextCode(op, CODE_CLEAR);
      nbits = BITS_MIN;
      maxcode = MAXCODE(BITS_MIN);
    } else {
      /*
       * If the next entry is going to be too big for
       * the code size, then increase it, if possible.
       */
      if (free_ent > maxcode) {
        nbits++;
        assert(nbits <= BITS_MAX);
        maxcode = (int) MAXCODE(nbits);
      } else if (incount >= checkpoint) {
        long rat;
        /*
         * Check compression ratio and, if things seem
         * to be slipping, clear the hash table and
         * reset state.  The compression ratio is a
         * 24+8-bit fractional number.
         */
        checkpoint = incount+CHECK_GAP;
        CALCRATIO(sp, rat);
        if (rat <= sp->enc_ratio) {
          cl_hash(sp);
          sp->enc_ratio = 0;
          incount = 0;
          outcount = 0;
          free_ent = CODE_FIRST;
          PutNextCode(op, CODE_CLEAR);
          nbits = BITS_MIN;
          maxcode = MAXCODE(BITS_MIN);
        } else
          sp->enc_ratio = rat;
      }
    }
  hit:
    ;
  }

  /*
   * Restore global state.
   */
  sp->enc_incount = incount;
  sp->enc_outcount = outcount;
  sp->enc_checkpoint = checkpoint;
  sp->enc_oldcode = ent;
  sp->lzw_nextdata = nextdata;
  sp->lzw_nextbits = nextbits;
  sp->lzw_free_ent = (unsigned short)free_ent;
  sp->lzw_maxcode = (unsigned short)maxcode;
  sp->lzw_nbits = (unsigned short)nbits;
  tif->tif_rawcp = op;
  return (1);
}

/*
 * Finish off an encoded strip by flushing the last
 * string and tacking on an End Of Information code.
 */
static int
LZWPostEncode(TIFF* tif)
{
  register LZWCodecState *sp = EncoderState(tif);
  uint8_t* op = tif->tif_rawcp;
  long nextbits = sp->lzw_nextbits;
  unsigned long nextdata = sp->lzw_nextdata;
  long outcount = sp->enc_outcount;
  int nbits = sp->lzw_nbits;

  if (op > sp->enc_rawlimit) {
    tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
    if( !TIFFFlushData1(tif) )
                    return 0;
    op = tif->tif_rawdata;
  }
  if (sp->enc_oldcode != (hcode_t) -1) {
                int free_ent = sp->lzw_free_ent;

    PutNextCode(op, sp->enc_oldcode);
    sp->enc_oldcode = (hcode_t) -1;
                free_ent ++;

                if (free_ent == CODE_MAX-1) {
                        /* table is full, emit clear code and reset */
                        outcount = 0;
                        PutNextCode(op, CODE_CLEAR);
                        nbits = BITS_MIN;
                } else {
                        /*
                        * If the next entry is going to be too big for
                        * the code size, then increase it, if possible.
                        */
                        if (free_ent > sp->lzw_maxcode) {
                                nbits++;
                                assert(nbits <= BITS_MAX);
                        }
                }
  }
  PutNextCode(op, CODE_EOI);
        /* Explicit 0xff masking to make icc -check=conversions happy */
  if (nextbits > 0) 
    *op++ = (unsigned char)((nextdata << (8-nextbits))&0xff);
  tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
  return (1);
}

/*
 * Reset encoding hash table.
 */
static void
cl_hash(LZWCodecState* sp)
{
  register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
  register long i = HSIZE-8;

  do {
    i -= 8;
    hp[-7].hash = -1;
    hp[-6].hash = -1;
    hp[-5].hash = -1;
    hp[-4].hash = -1;
    hp[-3].hash = -1;
    hp[-2].hash = -1;
    hp[-1].hash = -1;
    hp[ 0].hash = -1;
    hp -= 8;
  } while (i >= 0);
  for (i += 8; i > 0; i--, hp--)
    hp->hash = -1;
}

static void
LZWCleanup(TIFF* tif)
{
  (void)TIFFPredictorCleanup(tif);

  assert(tif->tif_data != 0);

  if (DecoderState(tif)->dec_codetab)
    _TIFFfree(DecoderState(tif)->dec_codetab);

  if (EncoderState(tif)->enc_hashtab)
    _TIFFfree(EncoderState(tif)->enc_hashtab);

  _TIFFfree(tif->tif_data);
  tif->tif_data = NULL;

  _TIFFSetDefaultCompressionState(tif);
}

int
TIFFInitLZW(TIFF* tif, int scheme)
{
  static const char module[] = "TIFFInitLZW";
        (void)scheme;
  assert(scheme == COMPRESSION_LZW);
  /*
   * Allocate state block so tag methods have storage to record values.
   */
  tif->tif_data = (uint8_t*) _TIFFmalloc(sizeof (LZWCodecState));
  if (tif->tif_data == NULL)
    goto bad;
  DecoderState(tif)->dec_codetab = NULL;
  DecoderState(tif)->dec_decode = NULL;
  EncoderState(tif)->enc_hashtab = NULL;
        LZWState(tif)->rw_mode = tif->tif_mode;

  /*
   * Install codec methods.
   */
  tif->tif_fixuptags = LZWFixupTags; 
  tif->tif_setupdecode = LZWSetupDecode;
  tif->tif_predecode = LZWPreDecode;
  tif->tif_decoderow = LZWDecode;
  tif->tif_decodestrip = LZWDecode;
  tif->tif_decodetile = LZWDecode;
  tif->tif_setupencode = LZWSetupEncode;
  tif->tif_preencode = LZWPreEncode;
  tif->tif_postencode = LZWPostEncode;
  tif->tif_encoderow = LZWEncode;
  tif->tif_encodestrip = LZWEncode;
  tif->tif_encodetile = LZWEncode;
  tif->tif_cleanup = LZWCleanup;
  /*
   * Setup predictor setup.
   */
  (void) TIFFPredictorInit(tif);
  return (1);
bad:
  TIFFErrorExt(tif->tif_clientdata, module, 
         "No space for LZW state block");
  return (0);
}

/*
 * Copyright (c) 1985, 1986 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * James A. Woods, derived from original work by Spencer Thomas
 * and Joseph Orost.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */
#endif /* LZW_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */
/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 8
 * fill-column: 78
 * End:
 */

Coverage Report

Created: 2022-10-31 07:00