tif_dirread.c

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		MissingRequired(tif, "PlanarConfiguration");
		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) {
		TIFFError(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)) {
		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, (int)v))
					goto bad;
			} else {
				if (!TIFFFetchPerSampleShorts(tif, dp, &iv) ||
				    !TIFFSetField(tif, dp->tdir_tag, iv))
					goto bad;
			}
			break;
		case TIFFTAG_SMINSAMPLEVALUE:
		case TIFFTAG_SMAXSAMPLEVALUE:
			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:
			/*
			 * 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 != (uint32) v) {
				if (!CheckDirCount(tif, dp, (uint32)(3*v)))
					break;
			}
			v *= sizeof (uint16);
			cp = CheckMalloc(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 =
					    (uint32)1 << td->td_bitspersample;
					if (dp->tdir_count == c)
						v = 0;
					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 = 0;
			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)
				(void) TIFFSetField(tif,
				    TIFFTAG_SUBFILETYPE, (int)v);
			break;
/* END REV 4.0 COMPATIBILITY */
		default:
			(void) TIFFFetchNormalTag(tif, dp);
			break;
		}
	}
	/*
	 * Verify Palette image has a Colormap.
	 */
	if (td->td_photometric == PHOTOMETRIC_PALETTE &&
	    !TIFFFieldSet(tif, FIELD_COLORMAP)) {
		MissingRequired(tif, "Colormap");
		goto bad;
	}
	/*
	 * 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;
		}
		TIFFWarning(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).
 */
#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]) )
	} else if (td->td_nstrips == 1 && BYTECOUNTLOOKSBAD) {
		/*
		 * 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.
		 */
		TIFFWarning(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;
	}
	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) {
		TIFFError(module, "%s: cannot handle zero scanline size",
			  tif->tif_name);
		return (0);
	}

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

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

	register TIFFDirEntry *dp;
	register TIFFDirectory *td = &tif->tif_dir;
	uint16 i;

	if (td->td_stripbytecount)
		_TIFFfree(td->td_stripbytecount);
	td->td_stripbytecount = (uint32*)
	    CheckMalloc(tif, td->td_nstrips, sizeof (uint32),
		"for \"StripByteCounts\" array");
	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) {
				TIFFError(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 (i = 0; i < td->td_nstrips; i++)
			td->td_stripbytecount[i] = 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.
		 */ 
		i--;
		if (((toff_t)(td->td_stripoffset[i]+td->td_stripbytecount[i]))
                                                               > filesize)
			td->td_stripbytecount[i] =
			    filesize - td->td_stripoffset[i];
	} else {
		uint32 rowbytes = TIFFScanlineSize(tif);
		uint32 rowsperstrip = td->td_imagelength/td->td_stripsperimage;
		for (i = 0; i < td->td_nstrips; i++)
			td->td_stripbytecount[i] = 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";

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

/*
 * 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) {
		TIFFWarning(tif->tif_name,
	"incorrect count for field \"%s\" (%lu, expecting %lu); tag ignored",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name,
		    dir->tdir_count, count);
		return (0);
	} else if (count < dir->tdir_count) {
		TIFFWarning(tif->tif_name,
	"incorrect count for field \"%s\" (%lu, expecting %lu); tag trimmed",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name,
		    dir->tdir_count, count);
		return (1);
	}
	return (1);
}

/*
 * Fetch a contiguous directory item.
 */
static tsize_t
TIFFFetchData(TIFF* tif, TIFFDirEntry* dir, char* cp)
{
	int w = TIFFDataWidth((TIFFDataType) dir->tdir_type);
	tsize_t cc = dir->tdir_count * w;