/* $Id: tif_dirread.c,v 1.92.2.9 2010-06-14 00:21:46 fwarmerdam Exp $ */

/*
 * 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.
 */

/*
 * TIFF Library.
 *
 * Directory Read Support Routines.
 */
#include "tiffiop.h"

#define	IGNORE	0		/* tag placeholder used below */

#ifdef HAVE_IEEEFP
# define	TIFFCvtIEEEFloatToNative(tif, n, fp)
# define	TIFFCvtIEEEDoubleToNative(tif, n, dp)
#else
extern	void TIFFCvtIEEEFloatToNative(TIFF*, uint32, float*);
extern	void TIFFCvtIEEEDoubleToNative(TIFF*, uint32, double*);
#endif

static  TIFFDirEntry* TIFFReadDirectoryFind(TIFFDirEntry* dir,
					    uint16 dircount, uint16 tagid);
static	int EstimateStripByteCounts(TIFF*, TIFFDirEntry*, uint16);
static	void MissingRequired(TIFF*, const char*);
static	int TIFFCheckDirOffset(TIFF*, toff_t);
static	int CheckDirCount(TIFF*, TIFFDirEntry*, uint32);
static	uint16 TIFFFetchDirectory(TIFF*, toff_t, TIFFDirEntry**, toff_t *);
static	tsize_t TIFFFetchData(TIFF*, TIFFDirEntry*, char*);
static	tsize_t TIFFFetchString(TIFF*, TIFFDirEntry*, char*);
static	float TIFFFetchRational(TIFF*, TIFFDirEntry*);
static	int TIFFFetchNormalTag(TIFF*, TIFFDirEntry*);
static	int TIFFFetchPerSampleShorts(TIFF*, TIFFDirEntry*, uint16*);
static	int TIFFFetchPerSampleLongs(TIFF*, TIFFDirEntry*, uint32*);
static	int TIFFFetchPerSampleAnys(TIFF*, TIFFDirEntry*, double*);
static	int TIFFFetchShortArray(TIFF*, TIFFDirEntry*, uint16*);
static	int TIFFFetchStripThing(TIFF*, TIFFDirEntry*, long, uint32**);
static	int TIFFFetchRefBlackWhite(TIFF*, TIFFDirEntry*);
static	int TIFFFetchSubjectDistance(TIFF*, TIFFDirEntry*);
static	float TIFFFetchFloat(TIFF*, TIFFDirEntry*);
static	int TIFFFetchFloatArray(TIFF*, TIFFDirEntry*, float*);
static	int TIFFFetchDoubleArray(TIFF*, TIFFDirEntry*, double*);
static	int TIFFFetchAnyArray(TIFF*, TIFFDirEntry*, double*);
static	int TIFFFetchShortPair(TIFF*, TIFFDirEntry*);
static	void ChopUpSingleUncompressedStrip(TIFF*);

/*
 * Read the next TIFF directory from a file and convert it to the internal
 * format. We read directories sequentially.
 */
int
TIFFReadDirectory(TIFF* tif)
{
	static const char module[] = "TIFFReadDirectory";

	int n;
	TIFFDirectory* td;
	TIFFDirEntry *dp, *dir = NULL;
	uint16 iv;
	uint32 v;
	const TIFFFieldInfo* fip;
	size_t fix;
	uint16 dircount;
	int diroutoforderwarning = 0, compressionknown = 0;
	int haveunknowntags = 0;

	tif->tif_diroff = tif->tif_nextdiroff;
	/*
	 * Check whether we have the last offset or bad offset (IFD looping).
	 */
	if (!TIFFCheckDirOffset(tif, tif->tif_nextdiroff))
		return 0;
	/*
	 * Cleanup any previous compression state.
	 */
	(*tif->tif_cleanup)(tif);
	tif->tif_curdir++;
	dircount = TIFFFetchDirectory(tif, tif->tif_nextdiroff,
				      &dir, &tif->tif_nextdiroff);
	if (!dircount) {
		TIFFErrorExt(tif->tif_clientdata, module,
			     "%s: Failed to read directory at offset %u",
			     tif->tif_name, tif->tif_nextdiroff);
		return 0;
	}

	tif->tif_flags &= ~TIFF_BEENWRITING;	/* reset before new dir */
	/*
	 * Setup default value and then make a pass over
	 * the fields to check type and tag information,
	 * and to extract info required to size data
	 * structures.  A second pass is made afterwards
	 * to read in everthing not taken in the first pass.
	 */
	td = &tif->tif_dir;
	/* free any old stuff and reinit */
	TIFFFreeDirectory(tif);
	TIFFDefaultDirectory(tif);
	/*
	 * Electronic Arts writes gray-scale TIFF files
	 * without a PlanarConfiguration directory entry.
	 * Thus we setup a default value here, even though
	 * the TIFF spec says there is no default value.
	 */
	TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);

	/*
	 * Sigh, we must make a separate pass through the
	 * directory for the following reason:
	 *
	 * We must process the Compression tag in the first pass
	 * in order to merge in codec-private tag definitions (otherwise
	 * we may get complaints about unknown tags).  However, the
	 * Compression tag may be dependent on the SamplesPerPixel
	 * tag value because older TIFF specs permited Compression
	 * to be written as a SamplesPerPixel-count tag entry.
	 * Thus if we don't first figure out the correct SamplesPerPixel
	 * tag value then we may end up ignoring the Compression tag
	 * value because it has an incorrect count value (if the
	 * true value of SamplesPerPixel is not 1).
	 *
	 * It sure would have been nice if Aldus had really thought
	 * this stuff through carefully.
	 */
	for (dp = dir, n = dircount; n > 0; n--, dp++) {
		if (tif->tif_flags & TIFF_SWAB) {
			TIFFSwabArrayOfShort(&dp->tdir_tag, 2);
			TIFFSwabArrayOfLong(&dp->tdir_count, 2);
		}
		if (dp->tdir_tag == TIFFTAG_SAMPLESPERPIXEL) {
			if (!TIFFFetchNormalTag(tif, dp))
				goto bad;
			dp->tdir_tag = IGNORE;
		}
	}
	/*
	 * First real pass over the directory.
	 */
	fix = 0;
	for (dp = dir, n = dircount; n > 0; n--, dp++) {

		if (dp->tdir_tag == IGNORE)
			continue;
		if (fix >= tif->tif_nfields)
			fix = 0;

		/*
		 * Silicon Beach (at least) writes unordered
		 * directory tags (violating the spec).  Handle
		 * it here, but be obnoxious (maybe they'll fix it?).
		 */
		if (dp->tdir_tag < tif->tif_fieldinfo[fix]->field_tag) {
			if (!diroutoforderwarning) {
				TIFFWarningExt(tif->tif_clientdata, module,
	"%s: invalid TIFF directory; tags are not sorted in ascending order",
					    tif->tif_name);
				diroutoforderwarning = 1;
			}
			fix = 0;			/* O(n^2) */
		}
		while (fix < tif->tif_nfields &&
		    tif->tif_fieldinfo[fix]->field_tag < dp->tdir_tag)
			fix++;
		if (fix >= tif->tif_nfields ||
		    tif->tif_fieldinfo[fix]->field_tag != dp->tdir_tag) {
			/* Unknown tag ... we'll deal with it below */
			haveunknowntags = 1;
			continue;
		}
		/*
		 * Null out old tags that we ignore.
		 */
		if (tif->tif_fieldinfo[fix]->field_bit == FIELD_IGNORE) {
	ignore:
			dp->tdir_tag = IGNORE;
			continue;
		}
		/*
		 * Check data type.
		 */
		fip = tif->tif_fieldinfo[fix];
		while (dp->tdir_type != (unsigned short) fip->field_type
		    && fix < tif->tif_nfields) {
			if (fip->field_type == TIFF_ANY)	/* wildcard */
				break;
			fip = tif->tif_fieldinfo[++fix];
			if (fix >= tif->tif_nfields ||
			    fip->field_tag != dp->tdir_tag) {
				TIFFWarningExt(tif->tif_clientdata, module,
			"%s: wrong data type %d for \"%s\"; tag ignored",
					    tif->tif_name, dp->tdir_type,
					    tif->tif_fieldinfo[fix-1]->field_name);
				goto ignore;
			}
		}
		/*
		 * Check count if known in advance.
		 */
		if (fip->field_readcount != TIFF_VARIABLE
		    && fip->field_readcount != TIFF_VARIABLE2) {
			uint32 expected = (fip->field_readcount == TIFF_SPP) ?
			    (uint32) td->td_samplesperpixel :
			    (uint32) fip->field_readcount;
			if (!CheckDirCount(tif, dp, expected))
				goto ignore;
		}

		switch (dp->tdir_tag) {
		case TIFFTAG_COMPRESSION:
			/*
			 * The 5.0 spec says the Compression tag has
			 * one value, while earlier specs say it has
			 * one value per sample.  Because of this, we
			 * accept the tag if one value is supplied.
			 */
			if (dp->tdir_count == 1) {
				v = TIFFExtractData(tif,
				    dp->tdir_type, dp->tdir_offset);
				if (!TIFFSetField(tif, dp->tdir_tag, (uint16)v))
					goto bad;
				else
					compressionknown = 1;
				break;
			/* XXX: workaround for broken TIFFs */
			} else if (dp->tdir_type == TIFF_LONG) {
				if (!TIFFFetchPerSampleLongs(tif, dp, &v) ||
				    !TIFFSetField(tif, dp->tdir_tag, (uint16)v))
					goto bad;
			} else {
				if (!TIFFFetchPerSampleShorts(tif, dp, &iv)
				    || !TIFFSetField(tif, dp->tdir_tag, iv))
					goto bad;
			}
			dp->tdir_tag = IGNORE;
			break;
		case TIFFTAG_STRIPOFFSETS:
		case TIFFTAG_STRIPBYTECOUNTS:
		case TIFFTAG_TILEOFFSETS:
		case TIFFTAG_TILEBYTECOUNTS:
			TIFFSetFieldBit(tif, fip->field_bit);
			break;
		case TIFFTAG_IMAGEWIDTH:
		case TIFFTAG_IMAGELENGTH:
		case TIFFTAG_IMAGEDEPTH:
		case TIFFTAG_TILELENGTH:
		case TIFFTAG_TILEWIDTH:
		case TIFFTAG_TILEDEPTH:
		case TIFFTAG_PLANARCONFIG:
		case TIFFTAG_ROWSPERSTRIP:
		case TIFFTAG_EXTRASAMPLES:
			if (!TIFFFetchNormalTag(tif, dp))
				goto bad;
			dp->tdir_tag = IGNORE;
			break;
		}
	}

	/*
	 * If we saw any unknown tags, make an extra pass over the directory
	 * to deal with them.  This must be done separately because the tags
	 * could have become known when we registered a codec after finding
	 * the Compression tag.  In a correctly-sorted directory there's
	 * no problem because Compression will come before any codec-private
	 * tags, but if the sorting is wrong that might not hold.
	 */
	if (haveunknowntags) {
	    fix = 0;
	    for (dp = dir, n = dircount; n > 0; n--, dp++) {
		if (dp->tdir_tag == IGNORE)
			continue;
		if (fix >= tif->tif_nfields ||
		    dp->tdir_tag < tif->tif_fieldinfo[fix]->field_tag)
			fix = 0;			/* O(n^2) */
		while (fix < tif->tif_nfields &&
		    tif->tif_fieldinfo[fix]->field_tag < dp->tdir_tag)
			fix++;
		if (fix >= tif->tif_nfields ||
		    tif->tif_fieldinfo[fix]->field_tag != dp->tdir_tag) {

					TIFFWarningExt(tif->tif_clientdata,
						       module,
                        "%s: unknown field with tag %d (0x%x) encountered",
						       tif->tif_name,
						       dp->tdir_tag,
						       dp->tdir_tag);

					if (!_TIFFMergeFieldInfo(tif,
						_TIFFCreateAnonFieldInfo(tif,
						dp->tdir_tag,
						(TIFFDataType) dp->tdir_type),
						1))
					{
					TIFFWarningExt(tif->tif_clientdata,
						       module,
			"Registering anonymous field with tag %d (0x%x) failed",
						       dp->tdir_tag,
						       dp->tdir_tag);
					dp->tdir_tag = IGNORE;
					continue;
					}
			fix = 0;
			while (fix < tif->tif_nfields &&
			       tif->tif_fieldinfo[fix]->field_tag < dp->tdir_tag)
				fix++;
		}
		/*
		 * Check data type.
		 */
		fip = tif->tif_fieldinfo[fix];
		while (dp->tdir_type != (unsigned short) fip->field_type
		    && fix < tif->tif_nfields) {
			if (fip->field_type == TIFF_ANY)	/* wildcard */
				break;
			fip = tif->tif_fieldinfo[++fix];
			if (fix >= tif->tif_nfields ||
			    fip->field_tag != dp->tdir_tag) {
				TIFFWarningExt(tif->tif_clientdata, module,
			"%s: wrong data type %d for \"%s\"; tag ignored",
					    tif->tif_name, dp->tdir_type,
					    tif->tif_fieldinfo[fix-1]->field_name);
				dp->tdir_tag = IGNORE;
				break;
			}
		}
	    }
	}

	/*
	 * XXX: OJPEG hack.
	 * If a) compression is OJPEG, b) planarconfig tag says it's separate,
	 * c) strip offsets/bytecounts tag are both present and
	 * d) both contain exactly one value, then we consistently find
	 * that the buggy implementation of the buggy compression scheme
	 * matches contig planarconfig best. So we 'fix-up' the tag here
	 */
	if ((td->td_compression==COMPRESSION_OJPEG) &&
	    (td->td_planarconfig==PLANARCONFIG_SEPARATE)) {
		dp = TIFFReadDirectoryFind(dir,dircount,TIFFTAG_STRIPOFFSETS);
		if ((dp!=0) && (dp->tdir_count==1)) {
			dp = TIFFReadDirectoryFind(dir, dircount,
						   TIFFTAG_STRIPBYTECOUNTS);
			if ((dp!=0) && (dp->tdir_count==1)) {
				td->td_planarconfig=PLANARCONFIG_CONTIG;
				TIFFWarningExt(tif->tif_clientdata,
					       "TIFFReadDirectory",
				"Planarconfig tag value assumed incorrect, "
				"assuming data is contig instead of chunky");
			}
		}
	}

	/*
	 * Allocate directory structure and setup defaults.
	 */
	if (!TIFFFieldSet(tif, FIELD_IMAGEDIMENSIONS)) {
		MissingRequired(tif, "ImageLength");
		goto bad;
	}
	/* 
	 * Setup appropriate structures (by strip or by tile)
	 */
	if (!TIFFFieldSet(tif, FIELD_TILEDIMENSIONS)) {
		td->td_nstrips = TIFFNumberOfStrips(tif);
		td->td_tilewidth = td->td_imagewidth;
		td->td_tilelength = td->td_rowsperstrip;
		td->td_tiledepth = td->td_imagedepth;
		tif->tif_flags &= ~TIFF_ISTILED;
	} else {
		td->td_nstrips = TIFFNumberOfTiles(tif);
		tif->tif_flags |= TIFF_ISTILED;
	}
	if (!td->td_nstrips) {
		TIFFErrorExt(tif->tif_clientdata, module,
			     "%s: cannot handle zero number of %s",
			     tif->tif_name, isTiled(tif) ? "tiles" : "strips");
		goto bad;
	}
	td->td_stripsperimage = td->td_nstrips;
	if (td->td_planarconfig == PLANARCONFIG_SEPARATE)
		td->td_stripsperimage /= td->td_samplesperpixel;
	if (!TIFFFieldSet(tif, FIELD_STRIPOFFSETS)) {
		if ((td->td_compression==COMPRESSION_OJPEG) &&
		    (isTiled(tif)==0) &&
		    (td->td_nstrips==1)) {
			/*
			 * XXX: OJPEG hack.
			 * If a) compression is OJPEG, b) it's not a tiled TIFF,
			 * and c) the number of strips is 1,
			 * then we tolerate the absence of stripoffsets tag,
			 * because, presumably, all required data is in the
			 * JpegInterchangeFormat stream.
			 */
			TIFFSetFieldBit(tif, FIELD_STRIPOFFSETS);
		} else {
			MissingRequired(tif,
				isTiled(tif) ? "TileOffsets" : "StripOffsets");
			goto bad;
		}
	}

	/*
	 * Second pass: extract other information.
	 */
	for (dp = dir, n = dircount; n > 0; n--, dp++) {
		if (dp->tdir_tag == IGNORE)
			continue;
		switch (dp->tdir_tag) {
		case TIFFTAG_MINSAMPLEVALUE:
		case TIFFTAG_MAXSAMPLEVALUE:
		case TIFFTAG_BITSPERSAMPLE:
		case TIFFTAG_DATATYPE:
		case TIFFTAG_SAMPLEFORMAT:
			/*
			 * The 5.0 spec says the Compression tag has
			 * one value, while earlier specs say it has
			 * one value per sample.  Because of this, we
			 * accept the tag if one value is supplied.
			 *
			 * The MinSampleValue, MaxSampleValue, BitsPerSample
			 * DataType and SampleFormat tags are supposed to be
			 * written as one value/sample, but some vendors
			 * incorrectly write one value only -- so we accept
			 * that as well (yech). Other vendors write correct
			 * value for NumberOfSamples, but incorrect one for
			 * BitsPerSample and friends, and we will read this
			 * too.
			 */
			if (dp->tdir_count == 1) {
				v = TIFFExtractData(tif,
				    dp->tdir_type, dp->tdir_offset);
				if (!TIFFSetField(tif, dp->tdir_tag, (uint16)v))
					goto bad;
			/* XXX: workaround for broken TIFFs */
			} else if (dp->tdir_tag == TIFFTAG_BITSPERSAMPLE
				   && dp->tdir_type == TIFF_LONG) {
				if (!TIFFFetchPerSampleLongs(tif, dp, &v) ||
				    !TIFFSetField(tif, dp->tdir_tag, (uint16)v))
					goto bad;
			} else {
				if (!TIFFFetchPerSampleShorts(tif, dp, &iv) ||
				    !TIFFSetField(tif, dp->tdir_tag, iv))
					goto bad;
			}
			break;
		case TIFFTAG_SMINSAMPLEVALUE:
		case TIFFTAG_SMAXSAMPLEVALUE:
			{
				double dv = 0.0;
				if (!TIFFFetchPerSampleAnys(tif, dp, &dv) ||
				    !TIFFSetField(tif, dp->tdir_tag, dv))
					goto bad;
			}
			break;
		case TIFFTAG_STRIPOFFSETS:
		case TIFFTAG_TILEOFFSETS:
			if (!TIFFFetchStripThing(tif, dp,
			    td->td_nstrips, &td->td_stripoffset))
				goto bad;
			break;
		case TIFFTAG_STRIPBYTECOUNTS:
		case TIFFTAG_TILEBYTECOUNTS:
			if (!TIFFFetchStripThing(tif, dp,
			    td->td_nstrips, &td->td_stripbytecount))
				goto bad;
			break;
		case TIFFTAG_COLORMAP:
		case TIFFTAG_TRANSFERFUNCTION:
			{
				char* cp;
				/*
				 * TransferFunction can have either 1x or 3x
				 * data values; Colormap can have only 3x
				 * items.
				 */
				v = 1L<<td->td_bitspersample;
				if (dp->tdir_tag == TIFFTAG_COLORMAP ||
				    dp->tdir_count != v) {
					if (!CheckDirCount(tif, dp, 3 * v))
						break;
				}
				v *= sizeof(uint16);
				cp = (char *)_TIFFCheckMalloc(tif,
							      dp->tdir_count,
							      sizeof (uint16),
					"to read \"TransferFunction\" tag");
				if (cp != NULL) {
					if (TIFFFetchData(tif, dp, cp)) {
						/*
						 * This deals with there being
						 * only one array to apply to
						 * all samples.
						 */
						uint32 c = 1L << td->td_bitspersample;
						if (dp->tdir_count == c)
							v = 0L;
						TIFFSetField(tif, dp->tdir_tag,
						    cp, cp+v, cp+2*v);
					}
					_TIFFfree(cp);
				}
				break;
			}
		case TIFFTAG_PAGENUMBER:
		case TIFFTAG_HALFTONEHINTS:
		case TIFFTAG_YCBCRSUBSAMPLING:
		case TIFFTAG_DOTRANGE:
			(void) TIFFFetchShortPair(tif, dp);
			break;
		case TIFFTAG_REFERENCEBLACKWHITE:
			(void) TIFFFetchRefBlackWhite(tif, dp);
			break;
/* BEGIN REV 4.0 COMPATIBILITY */
		case TIFFTAG_OSUBFILETYPE:
			v = 0L;
			switch (TIFFExtractData(tif, dp->tdir_type,
			    dp->tdir_offset)) {
			case OFILETYPE_REDUCEDIMAGE:
				v = FILETYPE_REDUCEDIMAGE;
				break;
			case OFILETYPE_PAGE:
				v = FILETYPE_PAGE;
				break;
			}
			if (v)
				TIFFSetField(tif, TIFFTAG_SUBFILETYPE, v);
			break;
/* END REV 4.0 COMPATIBILITY */
		default:
			(void) TIFFFetchNormalTag(tif, dp);
			break;
		}
	}
	/*
	 * OJPEG hack:
	 * - If a) compression is OJPEG, and b) photometric tag is missing,
	 * then we consistently find that photometric should be YCbCr
	 * - If a) compression is OJPEG, and b) photometric tag says it's RGB,
	 * then we consistently find that the buggy implementation of the
	 * buggy compression scheme matches photometric YCbCr instead.
	 * - If a) compression is OJPEG, and b) bitspersample tag is missing,
	 * then we consistently find bitspersample should be 8.
	 * - If a) compression is OJPEG, b) samplesperpixel tag is missing,
	 * and c) photometric is RGB or YCbCr, then we consistently find
	 * samplesperpixel should be 3
	 * - If a) compression is OJPEG, b) samplesperpixel tag is missing,
	 * and c) photometric is MINISWHITE or MINISBLACK, then we consistently
	 * find samplesperpixel should be 3
	 */
	if (td->td_compression==COMPRESSION_OJPEG)
	{
		if (!TIFFFieldSet(tif,FIELD_PHOTOMETRIC))
		{
			TIFFWarningExt(tif->tif_clientdata, "TIFFReadDirectory",
			"Photometric tag is missing, assuming data is YCbCr");
			if (!TIFFSetField(tif,TIFFTAG_PHOTOMETRIC,PHOTOMETRIC_YCBCR))
				goto bad;
		}
		else if (td->td_photometric==PHOTOMETRIC_RGB)
		{
			td->td_photometric=PHOTOMETRIC_YCBCR;
			TIFFWarningExt(tif->tif_clientdata, "TIFFReadDirectory",
			"Photometric tag value assumed incorrect, "
			"assuming data is YCbCr instead of RGB");
		}
		if (!TIFFFieldSet(tif,FIELD_BITSPERSAMPLE))
		{
			TIFFWarningExt(tif->tif_clientdata,"TIFFReadDirectory",
		"BitsPerSample tag is missing, assuming 8 bits per sample");
			if (!TIFFSetField(tif,TIFFTAG_BITSPERSAMPLE,8))
				goto bad;
		}
		if (!TIFFFieldSet(tif,FIELD_SAMPLESPERPIXEL))
		{
			if ((td->td_photometric==PHOTOMETRIC_RGB)
			    || (td->td_photometric==PHOTOMETRIC_YCBCR))
			{
				TIFFWarningExt(tif->tif_clientdata,
					       "TIFFReadDirectory",
				"SamplesPerPixel tag is missing, "
				"assuming correct SamplesPerPixel value is 3");
				if (!TIFFSetField(tif,TIFFTAG_SAMPLESPERPIXEL,3))
					goto bad;
			}
			else if ((td->td_photometric==PHOTOMETRIC_MINISWHITE)
				 || (td->td_photometric==PHOTOMETRIC_MINISBLACK))
			{
				TIFFWarningExt(tif->tif_clientdata,
					       "TIFFReadDirectory",
				"SamplesPerPixel tag is missing, "
				"assuming correct SamplesPerPixel value is 1");
				if (!TIFFSetField(tif,TIFFTAG_SAMPLESPERPIXEL,1))
					goto bad;
			}
		}
	}
	/*
	 * Verify Palette image has a Colormap.
	 */
	if (td->td_photometric == PHOTOMETRIC_PALETTE &&
	    !TIFFFieldSet(tif, FIELD_COLORMAP)) {
		MissingRequired(tif, "Colormap");
		goto bad;
	}
	/*
	 * OJPEG hack:
	 * We do no further messing with strip/tile offsets/bytecounts in OJPEG
	 * TIFFs
	 */
	if (td->td_compression!=COMPRESSION_OJPEG)
	{
		/*
		 * Attempt to deal with a missing StripByteCounts tag.
		 */
		if (!TIFFFieldSet(tif, FIELD_STRIPBYTECOUNTS)) {
			/*
			 * Some manufacturers violate the spec by not giving
			 * the size of the strips.  In this case, assume there
			 * is one uncompressed strip of data.
			 */
			if ((td->td_planarconfig == PLANARCONFIG_CONTIG &&
			    td->td_nstrips > 1) ||
			    (td->td_planarconfig == PLANARCONFIG_SEPARATE &&
			     td->td_nstrips != td->td_samplesperpixel)) {
			    MissingRequired(tif, "StripByteCounts");
			    goto bad;
			}
			TIFFWarningExt(tif->tif_clientdata, module,
				"%s: TIFF directory is missing required "
				"\"%s\" field, calculating from imagelength",
				tif->tif_name,
				_TIFFFieldWithTag(tif,TIFFTAG_STRIPBYTECOUNTS)->field_name);
			if (EstimateStripByteCounts(tif, dir, dircount) < 0)
			    goto bad;
		/*
		 * Assume we have wrong StripByteCount value (in case
		 * of single strip) in following cases:
		 *   - it is equal to zero along with StripOffset;
		 *   - it is larger than file itself (in case of uncompressed
		 *     image);
		 *   - it is smaller than the size of the bytes per row
		 *     multiplied on the number of rows.  The last case should
		 *     not be checked in the case of writing new image,
		 *     because we may do not know the exact strip size
		 *     until the whole image will be written and directory
		 *     dumped out.
		 */
		#define	BYTECOUNTLOOKSBAD \
		    ( (td->td_stripbytecount[0] == 0 && td->td_stripoffset[0] != 0) || \
		      (td->td_compression == COMPRESSION_NONE && \
		       td->td_stripbytecount[0] > TIFFGetFileSize(tif) - td->td_stripoffset[0]) || \
		      (tif->tif_mode == O_RDONLY && \
		       td->td_compression == COMPRESSION_NONE && \
		       td->td_stripbytecount[0] < TIFFScanlineSize(tif) * td->td_imagelength) )

		} else if (td->td_nstrips == 1
			   && td->td_stripoffset[0] != 0
			   && BYTECOUNTLOOKSBAD) {
			/*
			 * XXX: Plexus (and others) sometimes give a value of
			 * zero for a tag when they don't know what the
			 * correct value is!  Try and handle the simple case
			 * of estimating the size of a one strip image.
			 */
			TIFFWarningExt(tif->tif_clientdata, module,
	"%s: Bogus \"%s\" field, ignoring and calculating from imagelength",
				    tif->tif_name,
				    _TIFFFieldWithTag(tif,TIFFTAG_STRIPBYTECOUNTS)->field_name);
			if(EstimateStripByteCounts(tif, dir, dircount) < 0)
			    goto bad;
		} else if (td->td_planarconfig == PLANARCONFIG_CONTIG
			   && td->td_nstrips > 2
			   && td->td_compression == COMPRESSION_NONE
			   && td->td_stripbytecount[0] != td->td_stripbytecount[1]
                           && td->td_stripbytecount[0] != 0 
                           && td->td_stripbytecount[1] != 0 ) {
			/*
			 * XXX: Some vendors fill StripByteCount array with 
                         * absolutely wrong values (it can be equal to 
                         * StripOffset array, for example). Catch this case 
                         * here.
			 */
			TIFFWarningExt(tif->tif_clientdata, module,
	"%s: Wrong \"%s\" field, ignoring and calculating from imagelength",
				    tif->tif_name,
				    _TIFFFieldWithTag(tif,TIFFTAG_STRIPBYTECOUNTS)->field_name);
			if (EstimateStripByteCounts(tif, dir, dircount) < 0)
			    goto bad;
		}
	}
	if (dir) {
		_TIFFfree((char *)dir);
		dir = NULL;
	}
	if (!TIFFFieldSet(tif, FIELD_MAXSAMPLEVALUE))
		td->td_maxsamplevalue = (uint16)((1L<<td->td_bitspersample)-1);
	/*
	 * Setup default compression scheme.
	 */

	/*
	 * XXX: We can optimize checking for the strip bounds using the sorted
	 * bytecounts array. See also comments for TIFFAppendToStrip()
	 * function in tif_write.c.
	 */
	if (td->td_nstrips > 1) {
		tstrip_t strip;

		td->td_stripbytecountsorted = 1;
		for (strip = 1; strip < td->td_nstrips; strip++) {
			if (td->td_stripoffset[strip - 1] >
			    td->td_stripoffset[strip]) {
				td->td_stripbytecountsorted = 0;
				break;
			}
		}
	}

	if (!TIFFFieldSet(tif, FIELD_COMPRESSION))
		TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_NONE);
	/*
	 * Some manufacturers make life difficult by writing
	 * large amounts of uncompressed data as a single strip.
	 * This is contrary to the recommendations of the spec.
	 * The following makes an attempt at breaking such images
	 * into strips closer to the recommended 8k bytes.  A
	 * side effect, however, is that the RowsPerStrip tag
	 * value may be changed.
	 */
	if (td->td_nstrips == 1 && td->td_compression == COMPRESSION_NONE &&
	    (tif->tif_flags & (TIFF_STRIPCHOP|TIFF_ISTILED)) == TIFF_STRIPCHOP)
		ChopUpSingleUncompressedStrip(tif);

	/*
	 * Reinitialize i/o since we are starting on a new directory.
	 */
	tif->tif_row = (uint32) -1;
	tif->tif_curstrip = (tstrip_t) -1;
	tif->tif_col = (uint32) -1;
	tif->tif_curtile = (ttile_t) -1;
	tif->tif_tilesize = (tsize_t) -1;

	tif->tif_scanlinesize = TIFFScanlineSize(tif);
	if (!tif->tif_scanlinesize) {
		TIFFErrorExt(tif->tif_clientdata, module,
			     "%s: cannot handle zero scanline size",
			     tif->tif_name);
		return (0);
	}

	if (isTiled(tif)) {
		tif->tif_tilesize = TIFFTileSize(tif);
		if (!tif->tif_tilesize) {
			TIFFErrorExt(tif->tif_clientdata, module,
				     "%s: cannot handle zero tile size",
				     tif->tif_name);
			return (0);
		}
	} else {
		if (!TIFFStripSize(tif)) {
			TIFFErrorExt(tif->tif_clientdata, module,
				     "%s: cannot handle zero strip size",
				     tif->tif_name);
			return (0);
		}
	}
	return (1);
bad:
	if (dir)
		_TIFFfree(dir);
	return (0);
}

static TIFFDirEntry*
TIFFReadDirectoryFind(TIFFDirEntry* dir, uint16 dircount, uint16 tagid)
{
	TIFFDirEntry* m;
	uint16 n;
	for (m=dir, n=0; n<dircount; m++, n++)
	{
		if (m->tdir_tag==tagid)
			return(m);
	}
	return(0);
}

/*
 * Read custom directory from the arbitarry offset.
 * The code is very similar to TIFFReadDirectory().
 */
int
TIFFReadCustomDirectory(TIFF* tif, toff_t diroff,
			const TIFFFieldInfo info[], size_t n)
{
	static const char module[] = "TIFFReadCustomDirectory";

	TIFFDirectory* td = &tif->tif_dir;
	TIFFDirEntry *dp, *dir = NULL;
	const TIFFFieldInfo* fip;
	size_t fix;
	uint16 i, dircount;

	_TIFFSetupFieldInfo(tif, info, n);

	dircount = TIFFFetchDirectory(tif, diroff, &dir, NULL);
	if (!dircount) {
		TIFFErrorExt(tif->tif_clientdata, module,
			"%s: Failed to read custom directory at offset %u",
			     tif->tif_name, diroff);
		return 0;
	}

	TIFFFreeDirectory(tif);
        _TIFFmemset(&tif->tif_dir, 0, sizeof(TIFFDirectory));

	fix = 0;
	for (dp = dir, i = dircount; i > 0; i--, dp++) {
		if (tif->tif_flags & TIFF_SWAB) {
			TIFFSwabArrayOfShort(&dp->tdir_tag, 2);
			TIFFSwabArrayOfLong(&dp->tdir_count, 2);
		}

		if (fix >= tif->tif_nfields || dp->tdir_tag == IGNORE)
			continue;

		while (fix < tif->tif_nfields &&
		       tif->tif_fieldinfo[fix]->field_tag < dp->tdir_tag)
			fix++;

		if (fix >= tif->tif_nfields ||
		    tif->tif_fieldinfo[fix]->field_tag != dp->tdir_tag) {

			TIFFWarningExt(tif->tif_clientdata, module,
                        "%s: unknown field with tag %d (0x%x) encountered",
				    tif->tif_name, dp->tdir_tag, dp->tdir_tag);
			if (!_TIFFMergeFieldInfo(tif,
						 _TIFFCreateAnonFieldInfo(tif,
						 dp->tdir_tag,
						 (TIFFDataType) dp->tdir_type),
						 1))
			{
				TIFFWarningExt(tif->tif_clientdata, module,
			"Registering anonymous field with tag %d (0x%x) failed",
						dp->tdir_tag, dp->tdir_tag);
				goto ignore;
			}

			fix = 0;
			while (fix < tif->tif_nfields &&
			       tif->tif_fieldinfo[fix]->field_tag < dp->tdir_tag)
				fix++;
		}
		/*
		 * Null out old tags that we ignore.
		 */
		if (tif->tif_fieldinfo[fix]->field_bit == FIELD_IGNORE) {
	ignore:
			dp->tdir_tag = IGNORE;
			continue;
		}
		/*
		 * Check data type.
		 */
		fip = tif->tif_fieldinfo[fix];
		while (dp->tdir_type != (unsigned short) fip->field_type
                       && fix < tif->tif_nfields) {
			if (fip->field_type == TIFF_ANY)	/* wildcard */
				break;
                        fip = tif->tif_fieldinfo[++fix];
			if (fix >= tif->tif_nfields ||
			    fip->field_tag != dp->tdir_tag) {
				TIFFWarningExt(tif->tif_clientdata, module,
			"%s: wrong data type %d for \"%s\"; tag ignored",
					    tif->tif_name, dp->tdir_type,
					    tif->tif_fieldinfo[fix-1]->field_name);
				goto ignore;
			}
		}
		/*
		 * Check count if known in advance.
		 */
		if (fip->field_readcount != TIFF_VARIABLE
		    && fip->field_readcount != TIFF_VARIABLE2) {
			uint32 expected = (fip->field_readcount == TIFF_SPP) ?
			    (uint32) td->td_samplesperpixel :
			    (uint32) fip->field_readcount;
			if (!CheckDirCount(tif, dp, expected))
				goto ignore;
		}

		/*
		 * EXIF tags which need to be specifically processed.
		 */
		switch (dp->tdir_tag) {
			case EXIFTAG_SUBJECTDISTANCE:
				(void) TIFFFetchSubjectDistance(tif, dp);
				break;
			default:
				(void) TIFFFetchNormalTag(tif, dp);
				break;
		}
	}
	
	if (dir)
		_TIFFfree(dir);
	return 1;
}

/*
 * EXIF is important special case of custom IFD, so we have a special
 * function to read it.
 */
int
TIFFReadEXIFDirectory(TIFF* tif, toff_t diroff)
{
	size_t exifFieldInfoCount;
	const TIFFFieldInfo *exifFieldInfo =
		_TIFFGetExifFieldInfo(&exifFieldInfoCount);
	return TIFFReadCustomDirectory(tif, diroff, exifFieldInfo,
				       exifFieldInfoCount);
}

static int
EstimateStripByteCounts(TIFF* tif, TIFFDirEntry* dir, uint16 dircount)
{
	static const char module[] = "EstimateStripByteCounts";

	TIFFDirEntry *dp;
	TIFFDirectory *td = &tif->tif_dir;
	uint32 strip;

	if (td->td_stripbytecount)
		_TIFFfree(td->td_stripbytecount);
	td->td_stripbytecount = (uint32*)
	    _TIFFCheckMalloc(tif, td->td_nstrips, sizeof (uint32),
		"for \"StripByteCounts\" array");
        if( td->td_stripbytecount == NULL )
            return -1;

	if (td->td_compression != COMPRESSION_NONE) {
		uint32 space = (uint32)(sizeof (TIFFHeader)
		    + sizeof (uint16)
		    + (dircount * sizeof (TIFFDirEntry))
		    + sizeof (uint32));
		toff_t filesize = TIFFGetFileSize(tif);
		uint16 n;

		/* calculate amount of space used by indirect values */
		for (dp = dir, n = dircount; n > 0; n--, dp++)
		{
			uint32 cc = TIFFDataWidth((TIFFDataType) dp->tdir_type);
			if (cc == 0) {
				TIFFErrorExt(tif->tif_clientdata, module,
			"%s: Cannot determine size of unknown tag type %d",
					  tif->tif_name, dp->tdir_type);
				return -1;
			}
			cc = cc * dp->tdir_count;
			if (cc > sizeof (uint32))
				space += cc;
		}
		space = filesize - space;
		if (td->td_planarconfig == PLANARCONFIG_SEPARATE)
			space /= td->td_samplesperpixel;
		for (strip = 0; strip < td->td_nstrips; strip++)
			td->td_stripbytecount[strip] = space;
		/*
		 * This gross hack handles the case were the offset to
		 * the last strip is past the place where we think the strip
		 * should begin.  Since a strip of data must be contiguous,
		 * it's safe to assume that we've overestimated the amount
		 * of data in the strip and trim this number back accordingly.
		 */ 
		strip--;
		if (((toff_t)(td->td_stripoffset[strip]+
			      td->td_stripbytecount[strip])) > filesize)
			td->td_stripbytecount[strip] =
			    filesize - td->td_stripoffset[strip];
	} else if (isTiled(tif)) {
		uint32 bytespertile = TIFFTileSize(tif);

		for (strip = 0; strip < td->td_nstrips; strip++)
                    td->td_stripbytecount[strip] = bytespertile;
	} else {
		uint32 rowbytes = TIFFScanlineSize(tif);
		uint32 rowsperstrip = td->td_imagelength/td->td_stripsperimage;
		for (strip = 0; strip < td->td_nstrips; strip++)
			td->td_stripbytecount[strip] = rowbytes * rowsperstrip;
	}
	TIFFSetFieldBit(tif, FIELD_STRIPBYTECOUNTS);
	if (!TIFFFieldSet(tif, FIELD_ROWSPERSTRIP))
		td->td_rowsperstrip = td->td_imagelength;
	return 1;
}

static void
MissingRequired(TIFF* tif, const char* tagname)
{
	static const char module[] = "MissingRequired";

	TIFFErrorExt(tif->tif_clientdata, module,
		  "%s: TIFF directory is missing required \"%s\" field",
		  tif->tif_name, tagname);
}

/*
 * Check the directory offset against the list of already seen directory
 * offsets. This is a trick to prevent IFD looping. The one can create TIFF
 * file with looped directory pointers. We will maintain a list of already
 * seen directories and check every IFD offset against that list.
 */
static int
TIFFCheckDirOffset(TIFF* tif, toff_t diroff)
{
	uint16 n;

	if (diroff == 0)			/* no more directories */
		return 0;

	for (n = 0; n < tif->tif_dirnumber && tif->tif_dirlist; n++) {
		if (tif->tif_dirlist[n] == diroff)
			return 0;
	}

	tif->tif_dirnumber++;

	if (tif->tif_dirnumber > tif->tif_dirlistsize) {
		toff_t* new_dirlist;

		/*
		 * XXX: Reduce memory allocation granularity of the dirlist
		 * array.
		 */
		new_dirlist = (toff_t *)_TIFFCheckRealloc(tif,
							  tif->tif_dirlist,
							  tif->tif_dirnumber,
							  2 * sizeof(toff_t),
							  "for IFD list");
		if (!new_dirlist)
			return 0;
		tif->tif_dirlistsize = 2 * tif->tif_dirnumber;
		tif->tif_dirlist = new_dirlist;
	}

	tif->tif_dirlist[tif->tif_dirnumber - 1] = diroff;

	return 1;
}

/*
 * Check the count field of a directory entry against a known value.  The
 * caller is expected to skip/ignore the tag if there is a mismatch.
 */
static int
CheckDirCount(TIFF* tif, TIFFDirEntry* dir, uint32 count)
{
	if (count > dir->tdir_count) {
		TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
	"incorrect count for field \"%s\" (%u, expecting %u); tag ignored",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name,
		    dir->tdir_count, count);
		return (0);
	} else if (count < dir->tdir_count) {
		TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
	"incorrect count for field \"%s\" (%u, expecting %u); tag trimmed",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name,
		    dir->tdir_count, count);
		return (1);
	}
	return (1);
}

/*
 * Read IFD structure from the specified offset. If the pointer to
 * nextdiroff variable has been specified, read it too. Function returns a
 * number of fields in the directory or 0 if failed.
 */
static uint16
TIFFFetchDirectory(TIFF* tif, toff_t diroff, TIFFDirEntry **pdir,
		   toff_t *nextdiroff)
{
	static const char module[] = "TIFFFetchDirectory";

	TIFFDirEntry *dir;
	uint16 dircount;

	assert(pdir);

	tif->tif_diroff = diroff;
	if (nextdiroff)
		*nextdiroff = 0;
	if (!isMapped(tif)) {
		if (!SeekOK(tif, tif->tif_diroff)) {
			TIFFErrorExt(tif->tif_clientdata, module,
				"%s: Seek error accessing TIFF directory",
				tif->tif_name);
			return 0;
		}
		if (!ReadOK(tif, &dircount, sizeof (uint16))) {
			TIFFErrorExt(tif->tif_clientdata, module,
				"%s: Can not read TIFF directory count",
				tif->tif_name);
			return 0;
		}
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabShort(&dircount);
		dir = (TIFFDirEntry *)_TIFFCheckMalloc(tif, dircount,
						sizeof (TIFFDirEntry),
						"to read TIFF directory");
		if (dir == NULL)
			return 0;
		if (!ReadOK(tif, dir, dircount*sizeof (TIFFDirEntry))) {
			TIFFErrorExt(tif->tif_clientdata, module,
				"%.100s: Can not read TIFF directory",
				tif->tif_name);
			_TIFFfree(dir);
			return 0;
		}
		/*
		 * Read offset to next directory for sequential scans if
		 * needed.
		 */
		if (nextdiroff)
			(void) ReadOK(tif, nextdiroff, sizeof(uint32));
	} else {
		toff_t off = tif->tif_diroff;

		/*
		 * Check for integer overflow when validating the dir_off,
		 * otherwise a very high offset may cause an OOB read and
		 * crash the client. Make two comparisons instead of
		 *
		 *  off + sizeof(uint16) > tif->tif_size
		 *
		 * to avoid overflow.
		 */
		if (tif->tif_size < sizeof (uint16) ||
		    off > tif->tif_size - sizeof(uint16)) {
			TIFFErrorExt(tif->tif_clientdata, module,
				"%s: Can not read TIFF directory count",
				tif->tif_name);
			return 0;
		} else {
			_TIFFmemcpy(&dircount, tif->tif_base + off,
				    sizeof(uint16));
		}
		off += sizeof (uint16);
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabShort(&dircount);
		dir = (TIFFDirEntry *)_TIFFCheckMalloc(tif, dircount,
						sizeof(TIFFDirEntry),
						"to read TIFF directory");
		if (dir == NULL)
			return 0;
		if (off + dircount * sizeof (TIFFDirEntry) > tif->tif_size) {
			TIFFErrorExt(tif->tif_clientdata, module,
				     "%s: Can not read TIFF directory",
				     tif->tif_name);
			_TIFFfree(dir);
			return 0;
		} else {
			_TIFFmemcpy(dir, tif->tif_base + off,
				    dircount * sizeof(TIFFDirEntry));
		}
		if (nextdiroff) {
			off += dircount * sizeof (TIFFDirEntry);
			if (off + sizeof (uint32) <= tif->tif_size) {
				_TIFFmemcpy(nextdiroff, tif->tif_base + off,
					    sizeof (uint32));
			}
		}
	}
	if (nextdiroff && tif->tif_flags & TIFF_SWAB)
		TIFFSwabLong(nextdiroff);
	*pdir = dir;
	return dircount;
}

/*
 * Fetch a contiguous directory item.
 */
static tsize_t
TIFFFetchData(TIFF* tif, TIFFDirEntry* dir, char* cp)
{
	uint32 w = TIFFDataWidth((TIFFDataType) dir->tdir_type);
	/* 
	 * FIXME: butecount should have tsize_t type, but for now libtiff
	 * defines tsize_t as a signed 32-bit integer and we are losing
	 * ability to read arrays larger than 2^31 bytes. So we are using
	 * uint32 instead of tsize_t here.
	 */
	uint32 cc = dir->tdir_count * w;

	/* Check for overflow. */
	if (!dir->tdir_count || !w || cc / w != dir->tdir_count)
		goto bad;

	if (!isMapped(tif)) {
		if (!SeekOK(tif, dir->tdir_offset))
			goto bad;
		if (!ReadOK(tif, cp, cc))
			goto bad;
	} else {
		/* Check for overflow. */
		if (dir->tdir_offset + cc < dir->tdir_offset
		    || dir->tdir_offset + cc < cc
		    || dir->tdir_offset + cc > tif->tif_size)
			goto bad;
		_TIFFmemcpy(cp, tif->tif_base + dir->tdir_offset, cc);
	}
	if (tif->tif_flags & TIFF_SWAB) {
		switch (dir->tdir_type) {
		case TIFF_SHORT:
		case TIFF_SSHORT:
			TIFFSwabArrayOfShort((uint16*) cp, dir->tdir_count);
			break;
		case TIFF_LONG:
		case TIFF_SLONG:
		case TIFF_FLOAT:
			TIFFSwabArrayOfLong((uint32*) cp, dir->tdir_count);
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
			TIFFSwabArrayOfLong((uint32*) cp, 2*dir->tdir_count);
			break;
		case TIFF_DOUBLE:
			TIFFSwabArrayOfDouble((double*) cp, dir->tdir_count);
			break;
		}
	}
	return (cc);
bad:
	TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
		     "Error fetching data for field \"%s\"",
		     _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
	return (tsize_t) 0;
}

/*
 * Fetch an ASCII item from the file.
 */
static tsize_t
TIFFFetchString(TIFF* tif, TIFFDirEntry* dir, char* cp)
{
	if (dir->tdir_count <= 4) {
		uint32 l = dir->tdir_offset;
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabLong(&l);
		_TIFFmemcpy(cp, &l, dir->tdir_count);
		return (1);
	}
	return (TIFFFetchData(tif, dir, cp));
}

/*
 * Convert numerator+denominator to float.
 */
static int
cvtRational(TIFF* tif, TIFFDirEntry* dir, uint32 num, uint32 denom, float* rv)
{
	if (denom == 0) {
		TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
		    "%s: Rational with zero denominator (num = %u)",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name, num);
		return (0);
	} else {
		if (dir->tdir_type == TIFF_RATIONAL)
			*rv = ((float)num / (float)denom);
		else
			*rv = ((float)(int32)num / (float)(int32)denom);
		return (1);
	}
}

/*
 * Fetch a rational item from the file at offset off and return the value as a
 * floating point number.
 */
static float
TIFFFetchRational(TIFF* tif, TIFFDirEntry* dir)
{
	uint32 l[2];
	float v;

	return (!TIFFFetchData(tif, dir, (char *)l) ||
	    !cvtRational(tif, dir, l[0], l[1], &v) ? 1.0f : v);
}

/*
 * Fetch a single floating point value from the offset field and return it as
 * a native float.
 */
static float
TIFFFetchFloat(TIFF* tif, TIFFDirEntry* dir)
{
	float v;
	int32 l = TIFFExtractData(tif, dir->tdir_type, dir->tdir_offset);
        _TIFFmemcpy(&v, &l, sizeof(float));
	TIFFCvtIEEEFloatToNative(tif, 1, &v);
	return (v);
}

/*
 * Fetch an array of BYTE or SBYTE values.
 */
static int
TIFFFetchByteArray(TIFF* tif, TIFFDirEntry* dir, uint8* v)
{
    if (dir->tdir_count <= 4) {
        /*
         * Extract data from offset field.
         */
        if (tif->tif_header.tiff_magic == TIFF_BIGENDIAN) {
	    if (dir->tdir_type == TIFF_SBYTE)
                switch (dir->tdir_count) {
                    case 4: v[3] = dir->tdir_offset & 0xff;
                    case 3: v[2] = (dir->tdir_offset >> 8) & 0xff;
                    case 2: v[1] = (dir->tdir_offset >> 16) & 0xff;
		    case 1: v[0] = dir->tdir_offset >> 24;
                }
	    else
                switch (dir->tdir_count) {
                    case 4: v[3] = dir->tdir_offset & 0xff;
                    case 3: v[2] = (dir->tdir_offset >> 8) & 0xff;
                    case 2: v[1] = (dir->tdir_offset >> 16) & 0xff;
		    case 1: v[0] = dir->tdir_offset >> 24;
                }
	} else {
	    if (dir->tdir_type == TIFF_SBYTE)
                switch (dir->tdir_count) {
                    case 4: v[3] = dir->tdir_offset >> 24;
                    case 3: v[2] = (dir->tdir_offset >> 16) & 0xff;
                    case 2: v[1] = (dir->tdir_offset >> 8) & 0xff;
                    case 1: v[0] = dir->tdir_offset & 0xff;
		}
	    else
                switch (dir->tdir_count) {
                    case 4: v[3] = dir->tdir_offset >> 24;
                    case 3: v[2] = (dir->tdir_offset >> 16) & 0xff;
                    case 2: v[1] = (dir->tdir_offset >> 8) & 0xff;
                    case 1: v[0] = dir->tdir_offset & 0xff;
		}
	}
        return (1);
    } else
        return (TIFFFetchData(tif, dir, (char*) v) != 0);	/* XXX */
}

/*
 * Fetch an array of SHORT or SSHORT values.
 */
static int
TIFFFetchShortArray(TIFF* tif, TIFFDirEntry* dir, uint16* v)
{
	if (dir->tdir_count <= 2) {
		if (tif->tif_header.tiff_magic == TIFF_BIGENDIAN) {
			switch (dir->tdir_count) {
			case 2: v[1] = (uint16) (dir->tdir_offset & 0xffff);
			case 1: v[0] = (uint16) (dir->tdir_offset >> 16);
			}
		} else {
			switch (dir->tdir_count) {
			case 2: v[1] = (uint16) (dir->tdir_offset >> 16);
			case 1: v[0] = (uint16) (dir->tdir_offset & 0xffff);
			}
		}
		return (1);
	} else
		return (TIFFFetchData(tif, dir, (char *)v) != 0);
}

/*
 * Fetch a pair of SHORT or BYTE values. Some tags may have either BYTE
 * or SHORT type and this function works with both ones.
 */
static int
TIFFFetchShortPair(TIFF* tif, TIFFDirEntry* dir)
{
	/*
	 * Prevent overflowing the v stack arrays below by performing a sanity
	 * check on tdir_count, this should never be greater than two.
	 */
	if (dir->tdir_count > 2) {
		TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
		"unexpected count for field \"%s\", %u, expected 2; ignored",
			_TIFFFieldWithTag(tif, dir->tdir_tag)->field_name,
			dir->tdir_count);
		return 0;
	}

	switch (dir->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
			{
			uint8 v[4];
			return TIFFFetchByteArray(tif, dir, v)
				&& TIFFSetField(tif, dir->tdir_tag, v[0], v[1]);
			}
		case TIFF_SHORT:
		case TIFF_SSHORT:
			{
			uint16 v[2];
			return TIFFFetchShortArray(tif, dir, v)
				&& TIFFSetField(tif, dir->tdir_tag, v[0], v[1]);
			}
		default:
			return 0;
	}
}

/*
 * Fetch an array of LONG or SLONG values.
 */
static int
TIFFFetchLongArray(TIFF* tif, TIFFDirEntry* dir, uint32* v)
{
	if (dir->tdir_count == 1) {
		v[0] = dir->tdir_offset;
		return (1);
	} else
		return (TIFFFetchData(tif, dir, (char*) v) != 0);
}

/*
 * Fetch an array of RATIONAL or SRATIONAL values.
 */
static int
TIFFFetchRationalArray(TIFF* tif, TIFFDirEntry* dir, float* v)
{
	int ok = 0;
	uint32* l;

	l = (uint32*)_TIFFCheckMalloc(tif,
	    dir->tdir_count, TIFFDataWidth((TIFFDataType) dir->tdir_type),
	    "to fetch array of rationals");
	if (l) {
		if (TIFFFetchData(tif, dir, (char *)l)) {
			uint32 i;
			for (i = 0; i < dir->tdir_count; i++) {
				ok = cvtRational(tif, dir,
				    l[2*i+0], l[2*i+1], &v[i]);
				if (!ok)
					break;
			}
		}
		_TIFFfree((char *)l);
	}
	return (ok);
}

/*
 * Fetch an array of FLOAT values.
 */
static int
TIFFFetchFloatArray(TIFF* tif, TIFFDirEntry* dir, float* v)
{

	if (dir->tdir_count == 1) {
	        union
		{
		  float  f;
		  uint32 i;
		} float_union;

		float_union.i=dir->tdir_offset;
		v[0]=float_union.f;
		TIFFCvtIEEEFloatToNative(tif, dir->tdir_count, v);
		return (1);
	} else	if (TIFFFetchData(tif, dir, (char*) v)) {
		TIFFCvtIEEEFloatToNative(tif, dir->tdir_count, v);
		return (1);
	} else
		return (0);
}

/*
 * Fetch an array of DOUBLE values.
 */
static int
TIFFFetchDoubleArray(TIFF* tif, TIFFDirEntry* dir, double* v)
{
	if (TIFFFetchData(tif, dir, (char*) v)) {
		TIFFCvtIEEEDoubleToNative(tif, dir->tdir_count, v);
		return (1);
	} else
		return (0);
}

/*
 * Fetch an array of ANY values.  The actual values are returned as doubles
 * which should be able hold all the types.  Yes, there really should be an
 * tany_t to avoid this potential non-portability ...  Note in particular that
 * we assume that the double return value vector is large enough to read in
 * any fundamental type.  We use that vector as a buffer to read in the base
 * type vector and then convert it in place to double (from end to front of
 * course).
 */
static int
TIFFFetchAnyArray(TIFF* tif, TIFFDirEntry* dir, double* v)
{
	int i;

	switch (dir->tdir_type) {
	case TIFF_BYTE:
	case TIFF_SBYTE:
		if (!TIFFFetchByteArray(tif, dir, (uint8*) v))
			return (0);
		if (dir->tdir_type == TIFF_BYTE) {
			uint8* vp = (uint8*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int8* vp = (int8*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_SHORT:
	case TIFF_SSHORT:
		if (!TIFFFetchShortArray(tif, dir, (uint16*) v))
			return (0);
		if (dir->tdir_type == TIFF_SHORT) {
			uint16* vp = (uint16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int16* vp = (int16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_LONG:
	case TIFF_SLONG:
		if (!TIFFFetchLongArray(tif, dir, (uint32*) v))
			return (0);
		if (dir->tdir_type == TIFF_LONG) {
			uint32* vp = (uint32*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int32* vp = (int32*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_RATIONAL:
	case TIFF_SRATIONAL:
		if (!TIFFFetchRationalArray(tif, dir, (float*) v))
			return (0);
		{ float* vp = (float*) v;
		  for (i = dir->tdir_count-1; i >= 0; i--)
			v[i] = vp[i];
		}
		break;
	case TIFF_FLOAT:
		if (!TIFFFetchFloatArray(tif, dir, (float*) v))
			return (0);
		{ float* vp = (float*) v;
		  for (i = dir->tdir_count-1; i >= 0; i--)
			v[i] = vp[i];
		}
		break;
	case TIFF_DOUBLE:
		return (TIFFFetchDoubleArray(tif, dir, (double*) v));
	default:
		/* TIFF_NOTYPE */
		/* TIFF_ASCII */
		/* TIFF_UNDEFINED */
		TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
			     "cannot read TIFF_ANY type %d for field \"%s\"",
			     dir->tdir_type,
			     _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
		return (0);
	}
	return (1);
}

/*
 * Fetch a tag that is not handled by special case code.
 */
static int
TIFFFetchNormalTag(TIFF* tif, TIFFDirEntry* dp)
{
	static const char mesg[] = "to fetch tag value";
	int ok = 0;
	const TIFFFieldInfo* fip = _TIFFFieldWithTag(tif, dp->tdir_tag);

	if (dp->tdir_count > 1) {		/* array of values */
		char* cp = NULL;

		switch (dp->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (uint8), mesg);
			ok = cp && TIFFFetchByteArray(tif, dp, (uint8*) cp);
			break;
		case TIFF_SHORT:
		case TIFF_SSHORT:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (uint16), mesg);
			ok = cp && TIFFFetchShortArray(tif, dp, (uint16*) cp);
			break;
		case TIFF_LONG:
		case TIFF_SLONG:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (uint32), mesg);
			ok = cp && TIFFFetchLongArray(tif, dp, (uint32*) cp);
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (float), mesg);
			ok = cp && TIFFFetchRationalArray(tif, dp, (float*) cp);
			break;
		case TIFF_FLOAT:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (float), mesg);
			ok = cp && TIFFFetchFloatArray(tif, dp, (float*) cp);
			break;
		case TIFF_DOUBLE:
			cp = (char *)_TIFFCheckMalloc(tif,
			    dp->tdir_count, sizeof (double), mesg);
			ok = cp && TIFFFetchDoubleArray(tif, dp, (double*) cp);
			break;
		case TIFF_ASCII:
		case TIFF_UNDEFINED:		/* bit of a cheat... */
			/*
			 * Some vendors write strings w/o the trailing
			 * NULL byte, so always append one just in case.
			 */
			cp = (char *)_TIFFCheckMalloc(tif, dp->tdir_count + 1,
						      1, mesg);
			if( (ok = (cp && TIFFFetchString(tif, dp, cp))) != 0 )
				cp[dp->tdir_count] = '\0';	/* XXX */
			break;
		}
		if (ok) {
			ok = (fip->field_passcount ?
			    TIFFSetField(tif, dp->tdir_tag, dp->tdir_count, cp)
			  : TIFFSetField(tif, dp->tdir_tag, cp));
		}
		if (cp != NULL)
			_TIFFfree(cp);
	} else if (CheckDirCount(tif, dp, 1)) {	/* singleton value */
		switch (dp->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
		case TIFF_SHORT:
		case TIFF_SSHORT:
			/*
			 * If the tag is also acceptable as a LONG or SLONG
			 * then TIFFSetField will expect an uint32 parameter
			 * passed to it (through varargs).  Thus, for machines
			 * where sizeof (int) != sizeof (uint32) we must do
			 * a careful check here.  It's hard to say if this
			 * is worth optimizing.
			 *
			 * NB: We use TIFFFieldWithTag here knowing that
			 *     it returns us the first entry in the table
			 *     for the tag and that that entry is for the
			 *     widest potential data type the tag may have.
			 */
			{ TIFFDataType type = fip->field_type;
			  if (type != TIFF_LONG && type != TIFF_SLONG) {
				uint16 v = (uint16)
			   TIFFExtractData(tif, dp->tdir_type, dp->tdir_offset);
				ok = (fip->field_passcount ?
				    TIFFSetField(tif, dp->tdir_tag, 1, &v)
				  : TIFFSetField(tif, dp->tdir_tag, v));
				break;
			  }
			}
			/* fall thru... */
		case TIFF_LONG:
		case TIFF_SLONG:
			{ uint32 v32 =
		    TIFFExtractData(tif, dp->tdir_type, dp->tdir_offset);
			  ok = (fip->field_passcount ? 
			      TIFFSetField(tif, dp->tdir_tag, 1, &v32)
			    : TIFFSetField(tif, dp->tdir_tag, v32));
			}
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
		case TIFF_FLOAT:
			{ float v = (dp->tdir_type == TIFF_FLOAT ? 
			      TIFFFetchFloat(tif, dp)
			    : TIFFFetchRational(tif, dp));
			  ok = (fip->field_passcount ?
			      TIFFSetField(tif, dp->tdir_tag, 1, &v)
			    : TIFFSetField(tif, dp->tdir_tag, v));
			}
			break;
		case TIFF_DOUBLE:
			{ double v;
			  ok = (TIFFFetchDoubleArray(tif, dp, &v) &&
			    (fip->field_passcount ?
			      TIFFSetField(tif, dp->tdir_tag, 1, &v)
			    : TIFFSetField(tif, dp->tdir_tag, v))
			  );
			}
			break;
		case TIFF_ASCII:
		case TIFF_UNDEFINED:		/* bit of a cheat... */
			{ char c[2];
			  if( (ok = (TIFFFetchString(tif, dp, c) != 0)) != 0 ) {
				c[1] = '\0';		/* XXX paranoid */
				ok = (fip->field_passcount ?
					TIFFSetField(tif, dp->tdir_tag, 1, c)
				      : TIFFSetField(tif, dp->tdir_tag, c));
			  }
			}
			break;
		}
	}
	return (ok);
}

#define	NITEMS(x)	(sizeof (x) / sizeof (x[0]))
/*
 * Fetch samples/pixel short values for 
 * the specified tag and verify that
 * all values are the same.
 */
static int
TIFFFetchPerSampleShorts(TIFF* tif, TIFFDirEntry* dir, uint16* pl)
{
    uint16 samples = tif->tif_dir.td_samplesperpixel;
    int status = 0;

    if (CheckDirCount(tif, dir, (uint32) samples)) {
        uint16 buf[10];
        uint16* v = buf;

        if (dir->tdir_count > NITEMS(buf))
            v = (uint16*) _TIFFCheckMalloc(tif, dir->tdir_count, sizeof(uint16),
                                      "to fetch per-sample values");
        if (v && TIFFFetchShortArray(tif, dir, v)) {
            uint16 i;
            int check_count = dir->tdir_count;
            if( samples < check_count )
                check_count = samples;

            for (i = 1; i < check_count; i++)
                if (v[i] != v[0]) {
			TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                "Cannot handle different per-sample values for field \"%s\"",
			_TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
			goto bad;
                }
            *pl = v[0];
            status = 1;
        }
      bad:
        if (v && v != buf)
            _TIFFfree(v);
    }
    return (status);
}

/*
 * Fetch samples/pixel long values for 
 * the specified tag and verify that
 * all values are the same.
 */
static int
TIFFFetchPerSampleLongs(TIFF* tif, TIFFDirEntry* dir, uint32* pl)
{
    uint16 samples = tif->tif_dir.td_samplesperpixel;
    int status = 0;

    if (CheckDirCount(tif, dir, (uint32) samples)) {
        uint32 buf[10];
        uint32* v = buf;

        if (dir->tdir_count > NITEMS(buf))
            v = (uint32*) _TIFFCheckMalloc(tif, dir->tdir_count, sizeof(uint32),
                                      "to fetch per-sample values");
        if (v && TIFFFetchLongArray(tif, dir, v)) {
            uint16 i;
            int check_count = dir->tdir_count;

            if( samples < check_count )
                check_count = samples;
            for (i = 1; i < check_count; i++)
                if (v[i] != v[0]) {
			TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                "Cannot handle different per-sample values for field \"%s\"",
			_TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
			goto bad;
                }
            *pl = v[0];
            status = 1;
        }
      bad:
        if (v && v != buf)
            _TIFFfree(v);
    }
    return (status);
}

/*
 * Fetch samples/pixel ANY values for the specified tag and verify that all
 * values are the same.
 */
static int
TIFFFetchPerSampleAnys(TIFF* tif, TIFFDirEntry* dir, double* pl)
{
    uint16 samples = tif->tif_dir.td_samplesperpixel;
    int status = 0;

    if (CheckDirCount(tif, dir, (uint32) samples)) {
        double buf[10];
        double* v = buf;

        if (dir->tdir_count > NITEMS(buf))
            v = (double*) _TIFFCheckMalloc(tif, dir->tdir_count, sizeof (double),
                                      "to fetch per-sample values");
        if (v && TIFFFetchAnyArray(tif, dir, v)) {
            uint16 i;
            int check_count = dir->tdir_count;
            if( samples < check_count )
                check_count = samples;

            for (i = 1; i < check_count; i++)
                if (v[i] != v[0]) {
			TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
		"Cannot handle different per-sample values for field \"%s\"",
			_TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
			goto bad;
                }
            *pl = v[0];
            status = 1;
        }
      bad:
        if (v && v != buf)
            _TIFFfree(v);
    }
    return (status);
}
#undef NITEMS

/*
 * Fetch a set of offsets or lengths.
 * While this routine says "strips", in fact it's also used for tiles.
 */
static int
TIFFFetchStripThing(TIFF* tif, TIFFDirEntry* dir, long nstrips, uint32** lpp)
{
	register uint32* lp;
	int status;

        CheckDirCount(tif, dir, (uint32) nstrips);

	/*
	 * Allocate space for strip information.
	 */
	if (*lpp == NULL &&
	    (*lpp = (uint32 *)_TIFFCheckMalloc(tif,
	      nstrips, sizeof (uint32), "for strip array")) == NULL)
		return (0);
	lp = *lpp;
        _TIFFmemset( lp, 0, sizeof(uint32) * nstrips );

	if (dir->tdir_type == (int)TIFF_SHORT) {
		/*
		 * Handle uint16->uint32 expansion.
		 */
		uint16* dp = (uint16*) _TIFFCheckMalloc(tif,
		    dir->tdir_count, sizeof (uint16), "to fetch strip tag");
		if (dp == NULL)
			return (0);
		if( (status = TIFFFetchShortArray(tif, dir, dp)) != 0 ) {
                    int i;
                    
                    for( i = 0; i < nstrips && i < (int) dir->tdir_count; i++ )
                    {
                        lp[i] = dp[i];
                    }
		}
		_TIFFfree((char*) dp);

        } else if( nstrips != (int) dir->tdir_count ) {
            /* Special case to correct length */

            uint32* dp = (uint32*) _TIFFCheckMalloc(tif,
		    dir->tdir_count, sizeof (uint32), "to fetch strip tag");
            if (dp == NULL)
                return (0);

            status = TIFFFetchLongArray(tif, dir, dp);
            if( status != 0 ) {
                int i;

                for( i = 0; i < nstrips && i < (int) dir->tdir_count; i++ )
                {
                    lp[i] = dp[i];
                }
            }

            _TIFFfree( (char *) dp );
	} else
            status = TIFFFetchLongArray(tif, dir, lp);
        
	return (status);
}

/*
 * Fetch and set the RefBlackWhite tag.
 */
static int
TIFFFetchRefBlackWhite(TIFF* tif, TIFFDirEntry* dir)
{
	static const char mesg[] = "for \"ReferenceBlackWhite\" array";
	char* cp;
	int ok;

	if (dir->tdir_type == TIFF_RATIONAL)
		return (TIFFFetchNormalTag(tif, dir));
	/*
	 * Handle LONG's for backward compatibility.
	 */
	cp = (char *)_TIFFCheckMalloc(tif, dir->tdir_count,
				      sizeof (uint32), mesg);
	if( (ok = (cp && TIFFFetchLongArray(tif, dir, (uint32*) cp))) != 0) {
		float* fp = (float*)
		    _TIFFCheckMalloc(tif, dir->tdir_count, sizeof (float), mesg);
		if( (ok = (fp != NULL)) != 0 ) {
			uint32 i;
			for (i = 0; i < dir->tdir_count; i++)
				fp[i] = (float)((uint32*) cp)[i];
			ok = TIFFSetField(tif, dir->tdir_tag, fp);
			_TIFFfree((char*) fp);
		}
	}
	if (cp)
		_TIFFfree(cp);
	return (ok);
}

/*
 * Fetch and set the SubjectDistance EXIF tag.
 */
static int
TIFFFetchSubjectDistance(TIFF* tif, TIFFDirEntry* dir)
{
	uint32 l[2];
	float v;
	int ok = 0;

    if( dir->tdir_count != 1 || dir->tdir_type != TIFF_RATIONAL )
    {
		TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
                       "incorrect count or type for SubjectDistance, tag ignored" );
		return (0);
    }

	if (TIFFFetchData(tif, dir, (char *)l)
	    && cvtRational(tif, dir, l[0], l[1], &v)) {
		/*
		 * XXX: Numerator 0xFFFFFFFF means that we have infinite
		 * distance. Indicate that with a negative floating point
		 * SubjectDistance value.
		 */
		ok = TIFFSetField(tif, dir->tdir_tag,
				  (l[0] != 0xFFFFFFFF) ? v : -v);
	}

	return ok;
}

/*
 * Replace a single strip (tile) of uncompressed data by multiple strips
 * (tiles), each approximately STRIP_SIZE_DEFAULT bytes. This is useful for
 * dealing with large images or for dealing with machines with a limited
 * amount memory.
 */
static void
ChopUpSingleUncompressedStrip(TIFF* tif)
{
	register TIFFDirectory *td = &tif->tif_dir;
	uint32 bytecount = td->td_stripbytecount[0];
	uint32 offset = td->td_stripoffset[0];
	tsize_t rowbytes = TIFFVTileSize(tif, 1), stripbytes;
	tstrip_t strip, nstrips, rowsperstrip;
	uint32* newcounts;
	uint32* newoffsets;

	/*
	 * Make the rows hold at least one scanline, but fill specified amount
	 * of data if possible.
	 */
	if (rowbytes > STRIP_SIZE_DEFAULT) {
		stripbytes = rowbytes;
		rowsperstrip = 1;
	} else if (rowbytes > 0 ) {
		rowsperstrip = STRIP_SIZE_DEFAULT / rowbytes;
		stripbytes = rowbytes * rowsperstrip;
	}
        else
            return;

	/* 
	 * never increase the number of strips in an image
	 */
	if (rowsperstrip >= td->td_rowsperstrip)
		return;
	nstrips = (tstrip_t) TIFFhowmany(bytecount, stripbytes);
        if( nstrips == 0 ) /* something is wonky, do nothing. */
            return;

	newcounts = (uint32*) _TIFFCheckMalloc(tif, nstrips, sizeof (uint32),
				"for chopped \"StripByteCounts\" array");
	newoffsets = (uint32*) _TIFFCheckMalloc(tif, nstrips, sizeof (uint32),
				"for chopped \"StripOffsets\" array");
	if (newcounts == NULL || newoffsets == NULL) {
	        /*
		 * Unable to allocate new strip information, give up and use
		 * the original one strip information.
		 */
		if (newcounts != NULL)
			_TIFFfree(newcounts);
		if (newoffsets != NULL)
			_TIFFfree(newoffsets);
		return;
	}
	/*
	 * Fill the strip information arrays with new bytecounts and offsets
	 * that reflect the broken-up format.
	 */
	for (strip = 0; strip < nstrips; strip++) {
		if ((uint32)stripbytes > bytecount)
			stripbytes = bytecount;
		newcounts[strip] = stripbytes;
		newoffsets[strip] = offset;
		offset += stripbytes;
		bytecount -= stripbytes;
	}
	/*
	 * Replace old single strip info with multi-strip info.
	 */
	td->td_stripsperimage = td->td_nstrips = nstrips;
	TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP, rowsperstrip);

	_TIFFfree(td->td_stripbytecount);
	_TIFFfree(td->td_stripoffset);
	td->td_stripbytecount = newcounts;
	td->td_stripoffset = newoffsets;
	td->td_stripbytecountsorted = 1;
}

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