tif_dirread.c

来自「支持各种栅格图像和矢量图像读取的库」· C语言 代码 · 共 1,972 行 · 第 1/4 页

			    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;
		}
	}
	/*
	 * Joris: 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;
	}
	/*
	 * Joris: 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 %lu",
			     tif->tif_name, diroff);
		return 0;
	}

	TIFFFreeDirectory(tif);

	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,
				    dp->tdir_type);

			TIFFMergeFieldInfo(tif,
					   _TIFFCreateAnonFieldInfo(tif,
						dp->tdir_tag,
						(TIFFDataType)dp->tdir_type),
					   1);

			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;
		}

		(void) TIFFFetchNormalTag(tif, dp);
	}
	
	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_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) {