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src/Source/LibTIFF4/tif_open.c  view on Meta::CPAN

	 * use of memory-mapped files and strip chopping when
	 * a file is opened read-only.
	 */
	tif->tif_flags = FILLORDER_MSB2LSB;
	if (m == O_RDONLY )
		tif->tif_flags |= TIFF_MAPPED;

	#ifdef STRIPCHOP_DEFAULT
	if (m == O_RDONLY || m == O_RDWR)
		tif->tif_flags |= STRIPCHOP_DEFAULT;
	#endif

	/*
	 * Process library-specific flags in the open mode string.
	 * The following flags may be used to control intrinsic library
	 * behaviour that may or may not be desirable (usually for
	 * compatibility with some application that claims to support
	 * TIFF but only supports some braindead idea of what the
	 * vendor thinks TIFF is):
	 *
	 * 'l' use little-endian byte order for creating a file
	 * 'b' use big-endian byte order for creating a file
	 * 'L' read/write information using LSB2MSB bit order
	 * 'B' read/write information using MSB2LSB bit order
	 * 'H' read/write information using host bit order
	 * 'M' enable use of memory-mapped files when supported
	 * 'm' disable use of memory-mapped files
	 * 'C' enable strip chopping support when reading
	 * 'c' disable strip chopping support
	 * 'h' read TIFF header only, do not load the first IFD
	 * '4' ClassicTIFF for creating a file (default)
	 * '8' BigTIFF for creating a file
	 *
	 * The use of the 'l' and 'b' flags is strongly discouraged.
	 * These flags are provided solely because numerous vendors,
	 * typically on the PC, do not correctly support TIFF; they
	 * only support the Intel little-endian byte order.  This
	 * support is not configured by default because it supports
	 * the violation of the TIFF spec that says that readers *MUST*
	 * support both byte orders.  It is strongly recommended that
	 * you not use this feature except to deal with busted apps
	 * that write invalid TIFF.  And even in those cases you should
	 * bang on the vendors to fix their software.
	 *
	 * The 'L', 'B', and 'H' flags are intended for applications
	 * that can optimize operations on data by using a particular
	 * bit order.  By default the library returns data in MSB2LSB
	 * bit order for compatibiltiy with older versions of this
	 * library.  Returning data in the bit order of the native cpu
	 * makes the most sense but also requires applications to check
	 * the value of the FillOrder tag; something they probably do
	 * not do right now.
	 *
	 * The 'M' and 'm' flags are provided because some virtual memory
	 * systems exhibit poor behaviour when large images are mapped.
	 * These options permit clients to control the use of memory-mapped
	 * files on a per-file basis.
	 *
	 * The 'C' and 'c' flags are provided because the library support
	 * for chopping up large strips into multiple smaller strips is not
	 * application-transparent and as such can cause problems.  The 'c'
	 * option permits applications that only want to look at the tags,
	 * for example, to get the unadulterated TIFF tag information.
	 */
	for (cp = mode; *cp; cp++)
		switch (*cp) {
			case 'b':
				#ifndef WORDS_BIGENDIAN
				if (m&O_CREAT)
					tif->tif_flags |= TIFF_SWAB;
				#endif
				break;
			case 'l':
				#ifdef WORDS_BIGENDIAN
				if ((m&O_CREAT))
					tif->tif_flags |= TIFF_SWAB;
				#endif
				break;
			case 'B':
				tif->tif_flags = (tif->tif_flags &~ TIFF_FILLORDER) |
				    FILLORDER_MSB2LSB;
				break;
			case 'L':
				tif->tif_flags = (tif->tif_flags &~ TIFF_FILLORDER) |
				    FILLORDER_LSB2MSB;
				break;
			case 'H':
				tif->tif_flags = (tif->tif_flags &~ TIFF_FILLORDER) |
				    HOST_FILLORDER;
				break;
			case 'M':
				if (m == O_RDONLY)
					tif->tif_flags |= TIFF_MAPPED;
				break;
			case 'm':
				if (m == O_RDONLY)
					tif->tif_flags &= ~TIFF_MAPPED;
				break;
			case 'C':
				if (m == O_RDONLY)
					tif->tif_flags |= TIFF_STRIPCHOP;
				break;
			case 'c':
				if (m == O_RDONLY)
					tif->tif_flags &= ~TIFF_STRIPCHOP;
				break;
			case 'h':
				tif->tif_flags |= TIFF_HEADERONLY;
				break;
			case '8':
				if (m&O_CREAT)
					tif->tif_flags |= TIFF_BIGTIFF;
				break;
		}
	/*
	 * Read in TIFF header.
	 */
	if ((m & O_TRUNC) ||
	    !ReadOK(tif, &tif->tif_header, sizeof (TIFFHeaderClassic))) {
		if (tif->tif_mode == O_RDONLY) {
			TIFFErrorExt(tif->tif_clientdata, name,