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tif_lzw.c
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/*
* Copyright (c) 1988-1997 Sam Leffler
* Copyright (c) 1991-1997 Silicon Graphics, Inc.
* Copyright (c) 2022 Even Rouault
*
* 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 <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
/* Select the plausible largest natural integer type for the architecture */
#define SIZEOF_WORDTYPE SIZEOF_SIZE_T
typedef size_t WordType;
/*
* 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 */
#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 */
WordType 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 */
/* firstchar should be placed immediately before value in this structure */
unsigned char firstchar; /* first token of string */
unsigned char value; /* data value */
bool repeated;
} 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 */
tmsize_t dec_restart; /* restart count */
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 */
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 */
int read_error; /* whether a read error has occurred, and which should cause
further reads in the same strip/tile to be aborted */
/* Encoding specific data */
int enc_oldcode; /* last code encountered */
tmsize_t enc_checkpoint; /* point at which to clear table */
#define CHECK_GAP 10000 /* enc_ratio check interval */
tmsize_t enc_ratio; /* current compression ratio */
tmsize_t enc_incount; /* (input) data bytes encoded */
tmsize_t 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.
*/
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 *)_TIFFmallocExt(tif, sizeof(LZWCodecState));
if (tif->tif_data == NULL)
{
TIFFErrorExtR(tif, 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 *)_TIFFmallocExt(tif, CSIZE * sizeof(code_t));
if (sp->dec_codetab == NULL)
{
TIFFErrorExtR(tif, module, "No space for LZW code table");
return (0);
}
/*
* Pre-load the table.
*/
code = 255;
do
{
sp->dec_codetab[code].firstchar = (unsigned char)code;
sp->dec_codetab[code].value = (unsigned char)code;
sp->dec_codetab[code].repeated = true;
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] */
memset(&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)
{
TIFFWarningExtR(tif, 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)
{
TIFFErrorExtR(tif, 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);
sp->dec_bitsleft = 0;
sp->old_tif_rawcc = 0;
sp->dec_free_entp = sp->dec_codetab - 1; // + 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.
*/
sp->dec_oldcodep = &sp->dec_codetab[0];
sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask - 1];
sp->read_error = 0;
return (1);
}
/*
* Decode a "hunk of data".
*/
/* Get the next 32 or 64-bit from the input data */
#ifdef WORDS_BIGENDIAN
#define GetNextData(nextdata, bp) memcpy(&nextdata, bp, sizeof(nextdata))
#elif SIZEOF_WORDTYPE == 8
#if defined(__GNUC__) && defined(__x86_64__)
#define GetNextData(nextdata, bp) \
nextdata = __builtin_bswap64(*(uint64_t *)(bp))
#elif defined(_M_X64)
#define GetNextData(nextdata, bp) nextdata = _byteswap_uint64(*(uint64_t *)(bp))
#elif defined(__GNUC__)
#define GetNextData(nextdata, bp) \
memcpy(&nextdata, bp, sizeof(nextdata)); \
nextdata = __builtin_bswap64(nextdata)
#else
#define GetNextData(nextdata, bp) \
nextdata = (((uint64_t)bp[0]) << 56) | (((uint64_t)bp[1]) << 48) | \
(((uint64_t)bp[2]) << 40) | (((uint64_t)bp[3]) << 32) | \
(((uint64_t)bp[4]) << 24) | (((uint64_t)bp[5]) << 16) | \
(((uint64_t)bp[6]) << 8) | (((uint64_t)bp[7]))
#endif
#elif SIZEOF_WORDTYPE == 4
#if defined(__GNUC__) && defined(__i386__)
#define GetNextData(nextdata, bp) \
nextdata = __builtin_bswap32(*(uint32_t *)(bp))
#elif defined(_M_X86)
#define GetNextData(nextdata, bp) \
nextdata = _byteswap_ulong(*(unsigned long *)(bp))
#elif defined(__GNUC__)
#define GetNextData(nextdata, bp) \
memcpy(&nextdata, bp, sizeof(nextdata)); \
nextdata = __builtin_bswap32(nextdata)
#else
#define GetNextData(nextdata, bp) \
nextdata = (((uint32_t)bp[0]) << 24) | (((uint32_t)bp[1]) << 16) | \
(((uint32_t)bp[2]) << 8) | (((uint32_t)bp[3]))
#endif
#else
#error "Unhandled SIZEOF_WORDTYPE"
#endif
#define GetNextCodeLZW() \
do \
{ \
nextbits -= nbits; \
if (nextbits < 0) \
{ \
if (dec_bitsleft >= 8 * SIZEOF_WORDTYPE) \
{ \
unsigned codetmp = (unsigned)(nextdata << (-nextbits)); \
GetNextData(nextdata, bp); \
bp += SIZEOF_WORDTYPE; \
nextbits += 8 * SIZEOF_WORDTYPE; \
dec_bitsleft -= 8 * SIZEOF_WORDTYPE; \
code = (WordType)((codetmp | (nextdata >> nextbits)) & \
nbitsmask); \
break; \
} \
else \
{ \
if (dec_bitsleft < 8) \
{ \
goto no_eoi; \
} \
nextdata = (nextdata << 8) | *(bp)++; \
nextbits += 8; \
dec_bitsleft -= 8; \
if (nextbits < 0) \
{ \
if (dec_bitsleft < 8) \
{ \
goto no_eoi; \
} \
nextdata = (nextdata << 8) | *(bp)++; \
nextbits += 8; \
dec_bitsleft -= 8; \
} \
} \
} \
code = (WordType)((nextdata >> nextbits) & nbitsmask); \
} while (0)
static int LZWDecode(TIFF *tif, uint8_t *op0, tmsize_t occ0, uint16_t s)
{
static const char module[] = "LZWDecode";
LZWCodecState *sp = DecoderState(tif);
uint8_t *op = (uint8_t *)op0;
tmsize_t occ = occ0;
uint8_t *bp;
long nbits, nextbits, nbitsmask;
WordType nextdata;
code_t *free_entp, *maxcodep, *oldcodep;
(void)s;
assert(sp != NULL);
assert(sp->dec_codetab != NULL);
if (sp->read_error)
{
TIFFErrorExtR(tif, module,
"LZWDecode: Scanline %" PRIu32 " cannot be read due to "
"previous error",
tif->tif_row);
return 0;
}
/*
* Restart interrupted output operation.
*/
if (sp->dec_restart)
{
tmsize_t residue;
code_t *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)
{
uint8_t *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;
uint8_t *tp = op;
do
{
*--tp = codep->value;
codep = codep->next;
} while (--residue && codep);
sp->dec_restart = 0;
}
bp = (uint8_t *)tif->tif_rawcp;
sp->dec_bitsleft += (((uint64_t)tif->tif_rawcc - sp->old_tif_rawcc) << 3);
uint64_t dec_bitsleft = sp->dec_bitsleft;
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;
code_t *const dec_codetab = sp->dec_codetab;
code_t *codep;
if (occ == 0)
{
goto after_loop;
}
begin:
{
WordType code;
GetNextCodeLZW();
codep = dec_codetab + code;
if (code >= CODE_FIRST)
goto code_above_or_equal_to_258;
if (code < 256)
goto code_below_256;
if (code == CODE_EOI)
goto after_loop;
goto code_clear;
code_below_256:
{
if (codep > free_entp)
goto error_code;
free_entp->next = oldcodep;
free_entp->firstchar = oldcodep->firstchar;
free_entp->length = oldcodep->length + 1;
free_entp->value = (uint8_t)code;
free_entp->repeated =
(bool)(oldcodep->repeated & (oldcodep->value == code));
if (++free_entp > maxcodep)
{
if (++nbits > BITS_MAX) /* should not happen for a conformant encoder */
nbits = BITS_MAX;
nbitsmask = MAXCODE(nbits);
maxcodep = dec_codetab + nbitsmask - 1;
if (free_entp >= &dec_codetab[CSIZE])
{
/* At that point, the next valid states are either EOI or a */
/* CODE_CLEAR. If a regular code is read, at the next */
/* attempt at registering a new entry, we will error out */
/* due to setting free_entp before any valid code */
free_entp = dec_codetab - 1;
}
}
oldcodep = codep;
*op++ = (uint8_t)code;
occ--;
if (occ == 0)
goto after_loop;
goto begin;
}
code_above_or_equal_to_258:
{
/*
* Add the new entry to the code table.
*/
if (codep >= free_entp)
{
if (codep != free_entp)
goto error_code;
free_entp->value = oldcodep->firstchar;
}
else
{
free_entp->value = codep->firstchar;
}
free_entp->repeated =
(bool)(oldcodep->repeated & (oldcodep->value == free_entp->value));
free_entp->next = oldcodep;
free_entp->firstchar = oldcodep->firstchar;
free_entp->length = oldcodep->length + 1;
if (++free_entp > maxcodep)
{
if (++nbits > BITS_MAX) /* should not happen for a conformant encoder */
nbits = BITS_MAX;
nbitsmask = MAXCODE(nbits);
maxcodep = dec_codetab + nbitsmask - 1;
if (free_entp >= &dec_codetab[CSIZE])
{
/* At that point, the next valid states are either EOI or a */
/* CODE_CLEAR. If a regular code is read, at the next */
/* attempt at registering a new entry, we will error out */
/* due to setting free_entp before any valid code */
free_entp = dec_codetab - 1;
}
}
oldcodep = codep;
/*
* Code maps to a string, copy string
* value to output (written in reverse).
*/
/* tiny bit faster on x86_64 to store in unsigned short than int */
unsigned short len = codep->length;
if (len < 3) /* equivalent to len == 2 given all other conditions */
{
if (occ <= 2)
{
if (occ == 2)
{
memcpy(op, &(codep->firstchar), 2);
op += 2;
occ -= 2;
goto after_loop;
}
goto too_short_buffer;
}
memcpy(op, &(codep->firstchar), 2);
op += 2;
occ -= 2;
goto begin; /* we can save the comparison occ > 0 */
}
if (len == 3)
{
if (occ <= 3)
{
if (occ == 3)
{
op[0] = codep->firstchar;
op[1] = codep->next->value;
op[2] = codep->value;
op += 3;
occ -= 3;
goto after_loop;
}
goto too_short_buffer;
}
op[0] = codep->firstchar;
op[1] = codep->next->value;
op[2] = codep->value;
op += 3;
occ -= 3;
goto begin; /* we can save the comparison occ > 0 */
}
if (len > occ)
{
goto too_short_buffer;
}
if (codep->repeated)
{
memset(op, codep->value, len);
op += len;
occ -= len;
if (occ == 0)
goto after_loop;
goto begin;
}
uint8_t *tp = op + len;
assert(len >= 4);
*--tp = codep->value;
codep = codep->next;
*--tp = codep->value;
codep = codep->next;
*--tp = codep->value;
codep = codep->next;
*--tp = codep->value;
if (tp > op)
{
do
{
codep = codep->next;
*--tp = codep->value;
} while (tp > op);
}
assert(occ >= len);
op += len;
occ -= len;
if (occ == 0)
goto after_loop;
goto begin;
}
code_clear:
{
free_entp = dec_codetab + CODE_FIRST;
nbits = BITS_MIN;
nbitsmask = MAXCODE(BITS_MIN);
maxcodep = dec_codetab + nbitsmask - 1;
do
{
GetNextCodeLZW();
} while (code == CODE_CLEAR); /* consecutive CODE_CLEAR codes */
if (code == CODE_EOI)
goto after_loop;
if (code > CODE_EOI)
{
goto error_code;
}
*op++ = (uint8_t)code;
occ--;
oldcodep = dec_codetab + code;
if (occ == 0)
goto after_loop;
goto begin;
}
}
too_short_buffer:
{
/*
* 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;
uint8_t *tp = op + occ;
do
{
*--tp = codep->value;
codep = codep->next;
} while (--occ);
}
after_loop:
tif->tif_rawcc -= (tmsize_t)((uint8_t *)bp - tif->tif_rawcp);
tif->tif_rawcp = (uint8_t *)bp;
sp->old_tif_rawcc = tif->tif_rawcc;
sp->dec_bitsleft = dec_bitsleft;
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)
{
TIFFErrorExtR(tif, module,
"Not enough data at scanline %" PRIu32 " (short %" PRIu64
" bytes)",
tif->tif_row, (uint64_t)occ);
return (0);
}
return (1);
no_eoi:
sp->read_error = 1;
TIFFErrorExtR(tif, module,
"LZWDecode: Strip %" PRIu32 " not terminated with EOI code",
tif->tif_curstrip);
return 0;
error_code:
sp->read_error = 1;
TIFFErrorExtR(tif, tif->tif_name, "Using code not yet in table");
return 0;
}
#ifdef LZW_COMPAT
/*
* This check shouldn't be necessary because each
* strip is suppose to be terminated with CODE_EOI.
*/
#define NextCode(_tif, _sp, _bp, _code, _get, dec_bitsleft) \
{ \
if (dec_bitsleft < (uint64_t)nbits) \
{ \
TIFFWarningExtR(_tif, module, \
"LZWDecode: Strip %" PRIu32 \
" not terminated with EOI code", \
_tif->tif_curstrip); \
_code = CODE_EOI; \
} \
else \
{ \
_get(_sp, _bp, _code); \
dec_bitsleft -= nbits; \
} \
}
/*
* 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);
uint8_t *op = (uint8_t *)op0;
tmsize_t occ = occ0;
uint8_t *tp;
uint8_t *bp;
int code, nbits;
int len;
long nextbits, nbitsmask;
WordType nextdata;
code_t *codep, *free_entp, *maxcodep, *oldcodep;
(void)s;
assert(sp != NULL);
/*
* Restart interrupted output operation.
*/
if (sp->dec_restart)
{
tmsize_t 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 = (uint8_t *)tif->tif_rawcp;
sp->dec_bitsleft += (((uint64_t)tif->tif_rawcc - sp->old_tif_rawcc) << 3);
uint64_t dec_bitsleft = sp->dec_bitsleft;
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, dec_bitsleft);
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, dec_bitsleft);
} while (code == CODE_CLEAR); /* consecutive CODE_CLEAR codes */
if (code == CODE_EOI)
break;
if (code > CODE_CLEAR)
{
TIFFErrorExtR(
tif, tif->tif_name,
"LZWDecode: Corrupted LZW table at scanline %" PRIu32,
tif->tif_row);
return (0);
}
*op++ = (uint8_t)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])
{
TIFFErrorExtR(tif, 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])
{
TIFFErrorExtR(tif, 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)
{
TIFFErrorExtR(
tif, 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
{
*--tp = codep->value;
codep = codep->next;
} while (codep && tp > op);
assert(occ >= len);
op += len;
occ -= len;
}
else
{
*op++ = (uint8_t)code;
occ--;
}
}
tif->tif_rawcc -= (tmsize_t)((uint8_t *)bp - tif->tif_rawcp);
tif->tif_rawcp = (uint8_t *)bp;
sp->old_tif_rawcc = tif->tif_rawcc;
sp->dec_bitsleft = dec_bitsleft;