/* $Id: tif_dir.c,v 1.100 2009-01-23 05:25:19 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 Tag Get & Set Routines.
 * (and also some miscellaneous stuff)
 */
#include "tiffiop.h"

/*
 * These are used in the backwards compatibility code...
 */
#define DATATYPE_VOID		0       /* !untyped data */
#define DATATYPE_INT		1       /* !signed integer data */
#define DATATYPE_UINT		2       /* !unsigned integer data */
#define DATATYPE_IEEEFP		3       /* !IEEE floating point data */

static void
setByteArray(void** vpp, void* vp, size_t nmemb, size_t elem_size)
{
	if (*vpp)
		_TIFFfree(*vpp), *vpp = 0;
	if (vp) {
		tmsize_t bytes = (tmsize_t)(nmemb * elem_size);
		if (elem_size && bytes / elem_size == nmemb)
			*vpp = (void*) _TIFFmalloc(bytes);
		if (*vpp)
			_TIFFmemcpy(*vpp, vp, bytes);
	}
}
void _TIFFsetByteArray(void** vpp, void* vp, uint32 n)
    { setByteArray(vpp, vp, n, 1); }
void _TIFFsetString(char** cpp, char* cp)
    { setByteArray((void**) cpp, (void*) cp, strlen(cp)+1, 1); }
void _TIFFsetNString(char** cpp, char* cp, uint32 n)
    { setByteArray((void**) cpp, (void*) cp, n, 1); }
void _TIFFsetShortArray(uint16** wpp, uint16* wp, uint32 n)
    { setByteArray((void**) wpp, (void*) wp, n, sizeof (uint16)); }
void _TIFFsetLongArray(uint32** lpp, uint32* lp, uint32 n)
    { setByteArray((void**) lpp, (void*) lp, n, sizeof (uint32)); }
void _TIFFsetLong8Array(uint64** lpp, uint64* lp, uint32 n)
    { setByteArray((void**) lpp, (void*) lp, n, sizeof (uint64)); }
void _TIFFsetFloatArray(float** fpp, float* fp, uint32 n)
    { setByteArray((void**) fpp, (void*) fp, n, sizeof (float)); }
void _TIFFsetDoubleArray(double** dpp, double* dp, uint32 n)
    { setByteArray((void**) dpp, (void*) dp, n, sizeof (double)); }

/*
 * Install extra samples information.
 */
static int
setExtraSamples(TIFFDirectory* td, va_list ap, uint32* v)
{
/* XXX: Unassociated alpha data == 999 is a known Corel Draw bug, see below */
#define EXTRASAMPLE_COREL_UNASSALPHA 999 

	uint16* va;
	uint32 i;

	*v = (uint16) va_arg(ap, uint16_vap);
	if ((uint16) *v > td->td_samplesperpixel)
		return 0;
	va = va_arg(ap, uint16*);
	if (*v > 0 && va == NULL)		/* typically missing param */
		return 0;
	for (i = 0; i < *v; i++) {
		if (va[i] > EXTRASAMPLE_UNASSALPHA) {
			/*
			 * XXX: Corel Draw is known to produce incorrect
			 * ExtraSamples tags which must be patched here if we
			 * want to be able to open some of the damaged TIFF
			 * files: 
			 */
			if (va[i] == EXTRASAMPLE_COREL_UNASSALPHA)
				va[i] = EXTRASAMPLE_UNASSALPHA;
			else
				return 0;
		}
	}
	td->td_extrasamples = (uint16) *v;
	_TIFFsetShortArray(&td->td_sampleinfo, va, td->td_extrasamples);
	return 1;

#undef EXTRASAMPLE_COREL_UNASSALPHA
}

static uint32
checkInkNamesString(TIFF* tif, uint32 slen, const char* s)
{
	TIFFDirectory* td = &tif->tif_dir;
	uint16 i = td->td_samplesperpixel;

	if (slen > 0) {
		const char* ep = s+slen;
		const char* cp = s;
		for (; i > 0; i--) {
			for (; *cp != '\0'; cp++)
				if (cp >= ep)
					goto bad;
			cp++;				/* skip \0 */
		}
		return ((uint32)(cp-s));
	}
bad:
	TIFFErrorExt(tif->tif_clientdata, "TIFFSetField",
	    "%s: Invalid InkNames value; expecting %d names, found %d",
	    tif->tif_name,
	    td->td_samplesperpixel,
	    td->td_samplesperpixel-i);
	return (0);
}

static int
_TIFFVSetField(TIFF* tif, uint32 tag, va_list ap)
{
	static const char module[] = "_TIFFVSetField";

	TIFFDirectory* td = &tif->tif_dir;
	int status = 1;
	uint32 v32, i, v;
	char* s;

	switch (tag) {
	case TIFFTAG_SUBFILETYPE:
		td->td_subfiletype = (uint32) va_arg(ap, uint32);
		break;
	case TIFFTAG_IMAGEWIDTH:
		td->td_imagewidth = (uint32) va_arg(ap, uint32);
		break;
	case TIFFTAG_IMAGELENGTH:
		td->td_imagelength = (uint32) va_arg(ap, uint32);
		break;
	case TIFFTAG_BITSPERSAMPLE:
		td->td_bitspersample = (uint16) va_arg(ap, uint16_vap);
		/*
		 * If the data require post-decoding processing to byte-swap
		 * samples, set it up here.  Note that since tags are required
		 * to be ordered, compression code can override this behaviour
		 * in the setup method if it wants to roll the post decoding
		 * work in with its normal work.
		 */
		if (tif->tif_flags & TIFF_SWAB) {
			if (td->td_bitspersample == 16)
				tif->tif_postdecode = _TIFFSwab16BitData;
			else if (td->td_bitspersample == 24)
				tif->tif_postdecode = _TIFFSwab24BitData;
			else if (td->td_bitspersample == 32)
				tif->tif_postdecode = _TIFFSwab32BitData;
			else if (td->td_bitspersample == 64)
				tif->tif_postdecode = _TIFFSwab64BitData;
			else if (td->td_bitspersample == 128) /* two 64's */
				tif->tif_postdecode = _TIFFSwab64BitData;
		}
		break;
	case TIFFTAG_COMPRESSION:
		v = (uint16) va_arg(ap, uint16_vap);
		/*
		 * If we're changing the compression scheme, the notify the
		 * previous module so that it can cleanup any state it's
		 * setup.
		 */
		if (TIFFFieldSet(tif, FIELD_COMPRESSION)) {
			if ((uint32)td->td_compression == v)
				break;
			(*tif->tif_cleanup)(tif);
			tif->tif_flags &= ~TIFF_CODERSETUP;
		}
		/*
		 * Setup new compression routine state.
		 */
		if( (status = TIFFSetCompressionScheme(tif, v)) != 0 )
		    td->td_compression = (uint16) v;
		else
		    status = 0;
		break;
	case TIFFTAG_PHOTOMETRIC:
		td->td_photometric = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_THRESHHOLDING:
		td->td_threshholding = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_FILLORDER:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v != FILLORDER_LSB2MSB && v != FILLORDER_MSB2LSB)
			goto badvalue;
		td->td_fillorder = (uint16) v;
		break;
	case TIFFTAG_ORIENTATION:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v < ORIENTATION_TOPLEFT || ORIENTATION_LEFTBOT < v)
			goto badvalue;
		else
			td->td_orientation = (uint16) v;
		break;
	case TIFFTAG_SAMPLESPERPIXEL:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v == 0)
			goto badvalue;
		td->td_samplesperpixel = (uint16) v;
		break;
	case TIFFTAG_ROWSPERSTRIP:
		v32 = (uint32) va_arg(ap, uint32);
		if (v32 == 0)
			goto badvalue32;
		td->td_rowsperstrip = v32;
		if (!TIFFFieldSet(tif, FIELD_TILEDIMENSIONS)) {
			td->td_tilelength = v32;
			td->td_tilewidth = td->td_imagewidth;
		}
		break;
	case TIFFTAG_MINSAMPLEVALUE:
		td->td_minsamplevalue = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_MAXSAMPLEVALUE:
		td->td_maxsamplevalue = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_SMINSAMPLEVALUE:
		td->td_sminsamplevalue = (double) va_arg(ap, double);
		break;
	case TIFFTAG_SMAXSAMPLEVALUE:
		td->td_smaxsamplevalue = (double) va_arg(ap, double);
		break;
	case TIFFTAG_XRESOLUTION:
		td->td_xresolution = (float) va_arg(ap, double);
		break;
	case TIFFTAG_YRESOLUTION:
		td->td_yresolution = (float) va_arg(ap, double);
		break;
	case TIFFTAG_PLANARCONFIG:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v != PLANARCONFIG_CONTIG && v != PLANARCONFIG_SEPARATE)
			goto badvalue;
		td->td_planarconfig = (uint16) v;
		break;
	case TIFFTAG_XPOSITION:
		td->td_xposition = (float) va_arg(ap, double);
		break;
	case TIFFTAG_YPOSITION:
		td->td_yposition = (float) va_arg(ap, double);
		break;
	case TIFFTAG_RESOLUTIONUNIT:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v < RESUNIT_NONE || RESUNIT_CENTIMETER < v)
			goto badvalue;
		td->td_resolutionunit = (uint16) v;
		break;
	case TIFFTAG_PAGENUMBER:
		td->td_pagenumber[0] = (uint16) va_arg(ap, uint16_vap);
		td->td_pagenumber[1] = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_HALFTONEHINTS:
		td->td_halftonehints[0] = (uint16) va_arg(ap, uint16_vap);
		td->td_halftonehints[1] = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_COLORMAP:
		v32 = (uint32)(1L<<td->td_bitspersample);
		_TIFFsetShortArray(&td->td_colormap[0], va_arg(ap, uint16*), v32);
		_TIFFsetShortArray(&td->td_colormap[1], va_arg(ap, uint16*), v32);
		_TIFFsetShortArray(&td->td_colormap[2], va_arg(ap, uint16*), v32);
		break;
	case TIFFTAG_EXTRASAMPLES:
		if (!setExtraSamples(td, ap, &v))
			goto badvalue;
		break;
	case TIFFTAG_MATTEING:
		td->td_extrasamples =  (((uint16) va_arg(ap, uint16_vap)) != 0);
		if (td->td_extrasamples) {
			uint16 sv = EXTRASAMPLE_ASSOCALPHA;
			_TIFFsetShortArray(&td->td_sampleinfo, &sv, 1);
		}
		break;
	case TIFFTAG_TILEWIDTH:
		v32 = (uint32) va_arg(ap, uint32);
		if (v32 % 16) {
			if (tif->tif_mode != O_RDONLY)
				goto badvalue32;
			TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
				"Nonstandard tile width %d, convert file", v32);
		}
		td->td_tilewidth = v32;
		tif->tif_flags |= TIFF_ISTILED;
		break;
	case TIFFTAG_TILELENGTH:
		v32 = (uint32) va_arg(ap, uint32);
		if (v32 % 16) {
			if (tif->tif_mode != O_RDONLY)
				goto badvalue32;
			TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
			    "Nonstandard tile length %d, convert file", v32);
		}
		td->td_tilelength = v32;
		tif->tif_flags |= TIFF_ISTILED;
		break;
	case TIFFTAG_TILEDEPTH:
		v32 = (uint32) va_arg(ap, uint32);
		if (v32 == 0)
			goto badvalue32;
		td->td_tiledepth = v32;
		break;
	case TIFFTAG_DATATYPE:
		v = (uint16) va_arg(ap, uint16_vap);
		switch (v) {
		case DATATYPE_VOID:	v = SAMPLEFORMAT_VOID;	break;
		case DATATYPE_INT:	v = SAMPLEFORMAT_INT;	break;
		case DATATYPE_UINT:	v = SAMPLEFORMAT_UINT;	break;
		case DATATYPE_IEEEFP:	v = SAMPLEFORMAT_IEEEFP;break;
		default:		goto badvalue;
		}
		td->td_sampleformat = (uint16) v;
		break;
	case TIFFTAG_SAMPLEFORMAT:
		v = (uint16) va_arg(ap, uint16_vap);
		if (v < SAMPLEFORMAT_UINT || SAMPLEFORMAT_COMPLEXIEEEFP < v)
			goto badvalue;
		td->td_sampleformat = (uint16) v;

		/*  Try to fix up the SWAB function for complex data. */
		if( td->td_sampleformat == SAMPLEFORMAT_COMPLEXINT
		    && td->td_bitspersample == 32
		    && tif->tif_postdecode == _TIFFSwab32BitData )
		    tif->tif_postdecode = _TIFFSwab16BitData;
		else if( (td->td_sampleformat == SAMPLEFORMAT_COMPLEXINT
			  || td->td_sampleformat == SAMPLEFORMAT_COMPLEXIEEEFP)
			 && td->td_bitspersample == 64
			 && tif->tif_postdecode == _TIFFSwab64BitData )
		    tif->tif_postdecode = _TIFFSwab32BitData;
		break;
	case TIFFTAG_IMAGEDEPTH:
		td->td_imagedepth = (uint32) va_arg(ap, uint32);
		break;
	case TIFFTAG_SUBIFD:
		if ((tif->tif_flags & TIFF_INSUBIFD) == 0) {
			td->td_nsubifd = (uint16) va_arg(ap, uint16_vap);
			_TIFFsetLong8Array(&td->td_subifd, (uint64*) va_arg(ap, uint64*),
			    (long) td->td_nsubifd);
		} else {
			TIFFErrorExt(tif->tif_clientdata, module,
				     "%s: Sorry, cannot nest SubIFDs",
				     tif->tif_name);
			status = 0;
		}
		break;
	case TIFFTAG_YCBCRPOSITIONING:
		td->td_ycbcrpositioning = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_YCBCRSUBSAMPLING:
		td->td_ycbcrsubsampling[0] = (uint16) va_arg(ap, uint16_vap);
		td->td_ycbcrsubsampling[1] = (uint16) va_arg(ap, uint16_vap);
		break;
	case TIFFTAG_TRANSFERFUNCTION:
		v = (td->td_samplesperpixel - td->td_extrasamples) > 1 ? 3 : 1;
		for (i = 0; i < v; i++)
			_TIFFsetShortArray(&td->td_transferfunction[i],
			    va_arg(ap, uint16*), 1L<<td->td_bitspersample);
		break;
	case TIFFTAG_INKNAMES:
		v = (uint16) va_arg(ap, uint16_vap);
		s = va_arg(ap, char*);
		v = checkInkNamesString(tif, v, s);
		status = v > 0;
		if( v > 0 ) {
			_TIFFsetNString(&td->td_inknames, s, v);
			td->td_inknameslen = v;
		}
		break;
	default: {
		TIFFTagValue *tv;
		int tv_size, iCustom;
		const TIFFField *fip = TIFFFindField(tif, tag, TIFF_ANY);

		/*
		 * This can happen if multiple images are open with different
		 * codecs which have private tags.  The global tag information
		 * table may then have tags that are valid for one file but not
		 * the other. If the client tries to set a tag that is not valid
		 * for the image's codec then we'll arrive here.  This
		 * happens, for example, when tiffcp is used to convert between
		 * compression schemes and codec-specific tags are blindly copied.
		 */
		if(fip == NULL || fip->field_bit != FIELD_CUSTOM) {
			TIFFErrorExt(tif->tif_clientdata, module,
			    "%s: Invalid %stag \"%s\" (not supported by codec)",
			    tif->tif_name, isPseudoTag(tag) ? "pseudo-" : "",
			    fip ? fip->field_name : "Unknown");
			status = 0;
			break;
		}

		/*
		 * Find the existing entry for this custom value.
		 */
		tv = NULL;
		for (iCustom = 0; iCustom < td->td_customValueCount; iCustom++) {
			if (td->td_customValues[iCustom].info->field_tag == tag) {
				tv = td->td_customValues + iCustom;
				if (tv->value != NULL) {
					_TIFFfree(tv->value);
					tv->value = NULL;
				}
				break;
			}
		}

		/*
		 * Grow the custom list if the entry was not found.
		 */
		if(tv == NULL) {
			TIFFTagValue *new_customValues;

			td->td_customValueCount++;
			new_customValues = (TIFFTagValue *)
			    _TIFFrealloc(td->td_customValues,
			    sizeof(TIFFTagValue) * td->td_customValueCount);
			if (!new_customValues) {
				TIFFErrorExt(tif->tif_clientdata, module,
				    "%s: Failed to allocate space for list of custom values",
				    tif->tif_name);
				status = 0;
				goto end;
			}

			td->td_customValues = new_customValues;

			tv = td->td_customValues + (td->td_customValueCount - 1);
			tv->info = fip;
			tv->value = NULL;
			tv->count = 0;
		}

		/*
		 * Set custom value ... save a copy of the custom tag value.
		 */
		tv_size = _TIFFDataSize(fip->field_type);
		if (tv_size == 0) {
			status = 0;
			TIFFErrorExt(tif->tif_clientdata, module,
			    "%s: Bad field type %d for \"%s\"",
			    tif->tif_name, fip->field_type,
			    fip->field_name);
			goto end;
		}

		if (fip->field_type == TIFF_ASCII)
		{
			uint32 ma;
			char* mb;
			if (fip->field_passcount)
			{
				assert(fip->field_writecount==TIFF_VARIABLE2);
				ma=(uint32)va_arg(ap,uint32);
				mb=(char*)va_arg(ap,char*);
			}
			else
			{
				mb=(char*)va_arg(ap,char*);
				ma=(uint32)(strlen(mb)+1);
			}
			tv->count=ma;
			setByteArray(&tv->value,mb,ma,1);
		}
		else
		{
			if(fip->field_passcount) {
				if (fip->field_writecount == TIFF_VARIABLE2)
					tv->count = (uint32) va_arg(ap, uint32);
				else
					tv->count = (int) va_arg(ap, int);
			} else if (fip->field_writecount == TIFF_VARIABLE
			   || fip->field_writecount == TIFF_VARIABLE2)
				tv->count = 1;
			else if (fip->field_writecount == TIFF_SPP)
				tv->count = td->td_samplesperpixel;
			else
				tv->count = fip->field_writecount;


			tv->value = _TIFFCheckMalloc(tif, tv_size, tv->count,
			    "Tag Value");
			if (!tv->value) {
				status = 0;
				goto end;
			}

			if ((fip->field_passcount
			    || fip->field_writecount == TIFF_VARIABLE
			    || fip->field_writecount == TIFF_VARIABLE2
			    || fip->field_writecount == TIFF_SPP
			    || tv->count > 1)
			    && fip->field_tag != TIFFTAG_PAGENUMBER
			    && fip->field_tag != TIFFTAG_HALFTONEHINTS
			    && fip->field_tag != TIFFTAG_YCBCRSUBSAMPLING
			    && fip->field_tag != TIFFTAG_DOTRANGE) {
				_TIFFmemcpy(tv->value, va_arg(ap, void *),
				    tv->count * tv_size);
			} else {
				/*
				 * XXX: The following loop required to handle
				 * TIFFTAG_PAGENUMBER, TIFFTAG_HALFTONEHINTS,
				 * TIFFTAG_YCBCRSUBSAMPLING and TIFFTAG_DOTRANGE tags.
				 * These tags are actually arrays and should be passed as
				 * array pointers to TIFFSetField() function, but actually
				 * passed as a list of separate values. This behaviour
				 * must be changed in the future!
				 */
				int i;
				char *val = (char *)tv->value;

				for (i = 0; i < tv->count; i++, val += tv_size) {
					switch (fip->field_type) {
						case TIFF_BYTE:
						case TIFF_UNDEFINED:
							{
								uint8 v = (uint8)va_arg(ap, int);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_SBYTE:
							{
								int8 v = (int8)va_arg(ap, int);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_SHORT:
							{
								uint16 v = (uint16)va_arg(ap, int);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_SSHORT:
							{
								int16 v = (int16)va_arg(ap, int);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_LONG:
						case TIFF_IFD:
							{
								uint32 v = va_arg(ap, uint32);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_SLONG:
							{
								int32 v = va_arg(ap, int32);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_LONG8:
						case TIFF_IFD8:
							{
								uint64 v = va_arg(ap, uint64);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_SLONG8:
							{
								int64 v = va_arg(ap, int64);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_RATIONAL:
						case TIFF_SRATIONAL:
						case TIFF_FLOAT:
							{
								float v = (float)va_arg(ap, double);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						case TIFF_DOUBLE:
							{
								double v = va_arg(ap, double);
								_TIFFmemcpy(val, &v, tv_size);
							}
							break;
						default:
							_TIFFmemset(val, 0, tv_size);
							status = 0;
							break;
					}
				}
			}
		}
	}
	}
	if (status) {
		TIFFSetFieldBit(tif, TIFFFieldWithTag(tif, tag)->field_bit);
		tif->tif_flags |= TIFF_DIRTYDIRECT;
	}

end:
	va_end(ap);
	return (status);
badvalue:
	TIFFErrorExt(tif->tif_clientdata, module,
		     "%s: Bad value %u for \"%s\" tag",
		     tif->tif_name, v,
		     TIFFFieldWithTag(tif, tag)->field_name);
	va_end(ap);
	return (0);
badvalue32:
	TIFFErrorExt(tif->tif_clientdata, module,
		     "%s: Bad value %u for \"%s\" tag",
		     tif->tif_name, v32,
		     TIFFFieldWithTag(tif, tag)->field_name);
	va_end(ap);
	return (0);
}

/*
 * Return 1/0 according to whether or not
 * it is permissible to set the tag's value.
 * Note that we allow ImageLength to be changed
 * so that we can append and extend to images.
 * Any other tag may not be altered once writing
 * has commenced, unless its value has no effect
 * on the format of the data that is written.
 */
static int
OkToChangeTag(TIFF* tif, uint32 tag)
{
	const TIFFField* fip = TIFFFindField(tif, tag, TIFF_ANY);
	if (!fip) {			/* unknown tag */
		TIFFErrorExt(tif->tif_clientdata, "TIFFSetField", "%s: Unknown %stag %u",
		    tif->tif_name, isPseudoTag(tag) ? "pseudo-" : "", tag);
		return (0);
	}
	if (tag != TIFFTAG_IMAGELENGTH && (tif->tif_flags & TIFF_BEENWRITING) &&
	    !fip->field_oktochange) {
		/*
		 * Consult info table to see if tag can be changed
		 * after we've started writing.  We only allow changes
		 * to those tags that don't/shouldn't affect the
		 * compression and/or format of the data.
		 */
		TIFFErrorExt(tif->tif_clientdata, "TIFFSetField",
		    "%s: Cannot modify tag \"%s\" while writing",
		    tif->tif_name, fip->field_name);
		return (0);
	}
	return (1);
}

/*
 * Record the value of a field in the
 * internal directory structure.  The
 * field will be written to the file
 * when/if the directory structure is
 * updated.
 */
int
TIFFSetField(TIFF* tif, uint32 tag, ...)
{
	va_list ap;
	int status;

	va_start(ap, tag);
	status = TIFFVSetField(tif, tag, ap);
	va_end(ap);
	return (status);
}

/*
 * Clear the contents of the field in the internal structure.
 */
int
TIFFUnsetField(TIFF* tif, uint32 tag)
{
    const TIFFField *fip =  TIFFFieldWithTag(tif, tag);
    TIFFDirectory* td = &tif->tif_dir;

    if( !fip )
        return 0;

    if( fip->field_bit != FIELD_CUSTOM )
        TIFFClrFieldBit(tif, fip->field_bit);
    else
    {
        TIFFTagValue *tv = NULL;
        int i;

        for (i = 0; i < td->td_customValueCount; i++) {
                
            tv = td->td_customValues + i;
            if( tv->info->field_tag == tag )
                break;
        }

        if( i < td->td_customValueCount )
        {
            _TIFFfree(tv->value);
            for( ; i < td->td_customValueCount-1; i++) {
                td->td_customValues[i] = td->td_customValues[i+1];
            }
            td->td_customValueCount--;
        }
    }
        
    tif->tif_flags |= TIFF_DIRTYDIRECT;

    return (1);
}

/*
 * Like TIFFSetField, but taking a varargs
 * parameter list.  This routine is useful
 * for building higher-level interfaces on
 * top of the library.
 */
int
TIFFVSetField(TIFF* tif, uint32 tag, va_list ap)
{
	return OkToChangeTag(tif, tag) ?
	    (*tif->tif_tagmethods.vsetfield)(tif, tag, ap) : 0;
}

static int
_TIFFVGetField(TIFF* tif, uint32 tag, va_list ap)
{
	TIFFDirectory* td = &tif->tif_dir;
	int ret_val = 1;

	switch (tag) {
		case TIFFTAG_SUBFILETYPE:
			*va_arg(ap, uint32*) = td->td_subfiletype;
			break;
		case TIFFTAG_IMAGEWIDTH:
			*va_arg(ap, uint32*) = td->td_imagewidth;
			break;
		case TIFFTAG_IMAGELENGTH:
			*va_arg(ap, uint32*) = td->td_imagelength;
			break;
		case TIFFTAG_BITSPERSAMPLE:
			*va_arg(ap, uint16*) = td->td_bitspersample;
			break;
		case TIFFTAG_COMPRESSION:
			*va_arg(ap, uint16*) = td->td_compression;
			break;
		case TIFFTAG_PHOTOMETRIC:
			*va_arg(ap, uint16*) = td->td_photometric;
			break;
		case TIFFTAG_THRESHHOLDING:
			*va_arg(ap, uint16*) = td->td_threshholding;
			break;
		case TIFFTAG_FILLORDER:
			*va_arg(ap, uint16*) = td->td_fillorder;
			break;
		case TIFFTAG_ORIENTATION:
			*va_arg(ap, uint16*) = td->td_orientation;
			break;
		case TIFFTAG_SAMPLESPERPIXEL:
			*va_arg(ap, uint16*) = td->td_samplesperpixel;
			break;
		case TIFFTAG_ROWSPERSTRIP:
			*va_arg(ap, uint32*) = td->td_rowsperstrip;
			break;
		case TIFFTAG_MINSAMPLEVALUE:
			*va_arg(ap, uint16*) = td->td_minsamplevalue;
			break;
		case TIFFTAG_MAXSAMPLEVALUE:
			*va_arg(ap, uint16*) = td->td_maxsamplevalue;
			break;
		case TIFFTAG_SMINSAMPLEVALUE:
			*va_arg(ap, double*) = td->td_sminsamplevalue;
			break;
		case TIFFTAG_SMAXSAMPLEVALUE:
			*va_arg(ap, double*) = td->td_smaxsamplevalue;
			break;
		case TIFFTAG_XRESOLUTION:
			*va_arg(ap, float*) = td->td_xresolution;
			break;
		case TIFFTAG_YRESOLUTION:
			*va_arg(ap, float*) = td->td_yresolution;
			break;
		case TIFFTAG_PLANARCONFIG:
			*va_arg(ap, uint16*) = td->td_planarconfig;
			break;
		case TIFFTAG_XPOSITION:
			*va_arg(ap, float*) = td->td_xposition;
			break;
		case TIFFTAG_YPOSITION:
			*va_arg(ap, float*) = td->td_yposition;
			break;
		case TIFFTAG_RESOLUTIONUNIT:
			*va_arg(ap, uint16*) = td->td_resolutionunit;
			break;
		case TIFFTAG_PAGENUMBER:
			*va_arg(ap, uint16*) = td->td_pagenumber[0];
			*va_arg(ap, uint16*) = td->td_pagenumber[1];
			break;
		case TIFFTAG_HALFTONEHINTS:
			*va_arg(ap, uint16*) = td->td_halftonehints[0];
			*va_arg(ap, uint16*) = td->td_halftonehints[1];
			break;
		case TIFFTAG_COLORMAP:
			*va_arg(ap, uint16**) = td->td_colormap[0];
			*va_arg(ap, uint16**) = td->td_colormap[1];
			*va_arg(ap, uint16**) = td->td_colormap[2];
			break;
		case TIFFTAG_STRIPOFFSETS:
		case TIFFTAG_TILEOFFSETS:
			*va_arg(ap, uint64**) = td->td_stripoffset;
			break;
		case TIFFTAG_STRIPBYTECOUNTS:
		case TIFFTAG_TILEBYTECOUNTS:
			*va_arg(ap, uint64**) = td->td_stripbytecount;
			break;
		case TIFFTAG_MATTEING:
			*va_arg(ap, uint16*) =
			    (td->td_extrasamples == 1 &&
			    td->td_sampleinfo[0] == EXTRASAMPLE_ASSOCALPHA);
			break;
		case TIFFTAG_EXTRASAMPLES:
			*va_arg(ap, uint16*) = td->td_extrasamples;
			*va_arg(ap, uint16**) = td->td_sampleinfo;
			break;
		case TIFFTAG_TILEWIDTH:
			*va_arg(ap, uint32*) = td->td_tilewidth;
			break;
		case TIFFTAG_TILELENGTH:
			*va_arg(ap, uint32*) = td->td_tilelength;
			break;
		case TIFFTAG_TILEDEPTH:
			*va_arg(ap, uint32*) = td->td_tiledepth;
			break;
		case TIFFTAG_DATATYPE:
			switch (td->td_sampleformat) {
				case SAMPLEFORMAT_UINT:
					*va_arg(ap, uint16*) = DATATYPE_UINT;
					break;
				case SAMPLEFORMAT_INT:
					*va_arg(ap, uint16*) = DATATYPE_INT;
					break;
				case SAMPLEFORMAT_IEEEFP:
					*va_arg(ap, uint16*) = DATATYPE_IEEEFP;
					break;
				case SAMPLEFORMAT_VOID:
					*va_arg(ap, uint16*) = DATATYPE_VOID;
					break;
			}
			break;
		case TIFFTAG_SAMPLEFORMAT:
			*va_arg(ap, uint16*) = td->td_sampleformat;
			break;
		case TIFFTAG_IMAGEDEPTH:
			*va_arg(ap, uint32*) = td->td_imagedepth;
			break;
		case TIFFTAG_SUBIFD:
			*va_arg(ap, uint16*) = td->td_nsubifd;
			*va_arg(ap, uint64**) = td->td_subifd;
			break;
		case TIFFTAG_YCBCRPOSITIONING:
			*va_arg(ap, uint16*) = td->td_ycbcrpositioning;
			break;
		case TIFFTAG_YCBCRSUBSAMPLING:
			*va_arg(ap, uint16*) = td->td_ycbcrsubsampling[0];
			*va_arg(ap, uint16*) = td->td_ycbcrsubsampling[1];
			break;
		case TIFFTAG_TRANSFERFUNCTION:
			*va_arg(ap, uint16**) = td->td_transferfunction[0];
			if (td->td_samplesperpixel - td->td_extrasamples > 1) {
				*va_arg(ap, uint16**) = td->td_transferfunction[1];
				*va_arg(ap, uint16**) = td->td_transferfunction[2];
			}
			break;
		case TIFFTAG_INKNAMES:
			*va_arg(ap, char**) = td->td_inknames;
			break;
		default:
			{
				const TIFFField* fip =
					TIFFFindField(tif, tag, TIFF_ANY);
				int i;

				/*
				 * This can happen if multiple images are open
				 * with different codecs which have private
				 * tags.  The global tag information table may
				 * then have tags that are valid for one file
				 * but not the other. If the client tries to
				 * get a tag that is not valid for the image's
				 * codec then we'll arrive here.
				 */
				if( fip == NULL || fip->field_bit != FIELD_CUSTOM )
				{
					TIFFErrorExt(tif->tif_clientdata, "_TIFFVGetField",
					    "%s: Invalid %stag \"%s\" "
					    "(not supported by codec)",
					    tif->tif_name,
					    isPseudoTag(tag) ? "pseudo-" : "",
					    fip ? fip->field_name : "Unknown");
					ret_val = 0;
					break;
				}

				/*
				 * Do we have a custom value?
				 */
				ret_val = 0;
				for (i = 0; i < td->td_customValueCount; i++) {
					TIFFTagValue *tv = td->td_customValues + i;

					if (tv->info->field_tag != tag)
						continue;

					if (fip->field_passcount) {
						if (fip->field_readcount == TIFF_VARIABLE2)
							*va_arg(ap, uint32*) = (uint32)tv->count;
						else  /* Assume TIFF_VARIABLE */
							*va_arg(ap, uint16*) = (uint16)tv->count;
						*va_arg(ap, void **) = tv->value;
						ret_val = 1;
					} else {
						if ((fip->field_type == TIFF_ASCII
						    || fip->field_readcount == TIFF_VARIABLE
						    || fip->field_readcount == TIFF_VARIABLE2
						    || fip->field_readcount == TIFF_SPP
						    || tv->count > 1)
						    && fip->field_tag != TIFFTAG_PAGENUMBER
						    && fip->field_tag != TIFFTAG_HALFTONEHINTS
						    && fip->field_tag != TIFFTAG_YCBCRSUBSAMPLING
						    && fip->field_tag != TIFFTAG_DOTRANGE) {
							*va_arg(ap, void **) = tv->value;
							ret_val = 1;
						} else {
							int j;
							char *val = (char *)tv->value;

							for (j = 0; j < tv->count;
							    j++, val += _TIFFDataSize(tv->info->field_type)) {
								switch (fip->field_type) {
									case TIFF_BYTE:
									case TIFF_UNDEFINED:
										*va_arg(ap, uint8*) =
										    *(uint8 *)val;
										ret_val = 1;
										break;
									case TIFF_SBYTE:
										*va_arg(ap, int8*) =
										    *(int8 *)val;
										ret_val = 1;
										break;
									case TIFF_SHORT:
										*va_arg(ap, uint16*) =
										    *(uint16 *)val;
										ret_val = 1;
										break;
									case TIFF_SSHORT:
										*va_arg(ap, int16*) =
										    *(int16 *)val;
										ret_val = 1;
										break;
									case TIFF_LONG:
									case TIFF_IFD:
										*va_arg(ap, uint32*) =
										    *(uint32 *)val;
										ret_val = 1;
										break;
									case TIFF_SLONG:
										*va_arg(ap, int32*) =
										    *(int32 *)val;
										ret_val = 1;
										break;
									case TIFF_LONG8:
									case TIFF_IFD8:
										*va_arg(ap, uint64*) =
										    *(uint64 *)val;
										ret_val = 1;
										break;
									case TIFF_SLONG8:
										*va_arg(ap, int64*) =
										    *(int64 *)val;
										ret_val = 1;
										break;
									case TIFF_RATIONAL:
									case TIFF_SRATIONAL:
									case TIFF_FLOAT:
										*va_arg(ap, float*) =
										    *(float *)val;
										ret_val = 1;
										break;
									case TIFF_DOUBLE:
										*va_arg(ap, double*) =
										    *(double *)val;
										ret_val = 1;
										break;
									default:
										ret_val = 0;
										break;
								}
							}
						}
					}
					break;
				}
			}
	}
	return(ret_val);
}

/*
 * Return the value of a field in the
 * internal directory structure.
 */
int
TIFFGetField(TIFF* tif, uint32 tag, ...)
{
	int status;
	va_list ap;

	va_start(ap, tag);
	status = TIFFVGetField(tif, tag, ap);
	va_end(ap);
	return (status);
}

/*
 * Like TIFFGetField, but taking a varargs
 * parameter list.  This routine is useful
 * for building higher-level interfaces on
 * top of the library.
 */
int
TIFFVGetField(TIFF* tif, uint32 tag, va_list ap)
{
	const TIFFField* fip = TIFFFindField(tif, tag, TIFF_ANY);
	return (fip && (isPseudoTag(tag) || TIFFFieldSet(tif, fip->field_bit)) ?
	    (*tif->tif_tagmethods.vgetfield)(tif, tag, ap) : 0);
}

#define	CleanupField(member) {		\
    if (td->member) {			\
	_TIFFfree(td->member);		\
	td->member = 0;			\
    }					\
}

/*
 * Release storage associated with a directory.
 */
void
TIFFFreeDirectory(TIFF* tif)
{
	TIFFDirectory *td = &tif->tif_dir;
	int            i;

	_TIFFmemset(td->td_fieldsset, 0, FIELD_SETLONGS);
	CleanupField(td_colormap[0]);
	CleanupField(td_colormap[1]);
	CleanupField(td_colormap[2]);
	CleanupField(td_sampleinfo);
	CleanupField(td_subifd);
	CleanupField(td_inknames);
	CleanupField(td_transferfunction[0]);
	CleanupField(td_transferfunction[1]);
	CleanupField(td_transferfunction[2]);
	CleanupField(td_stripoffset);
	CleanupField(td_stripbytecount);
	TIFFClrFieldBit(tif, FIELD_YCBCRSUBSAMPLING);
	TIFFClrFieldBit(tif, FIELD_YCBCRPOSITIONING);

	/* Cleanup custom tag values */
	for( i = 0; i < td->td_customValueCount; i++ ) {
		if (td->td_customValues[i].value)
			_TIFFfree(td->td_customValues[i].value);
	}

	td->td_customValueCount = 0;
	CleanupField(td_customValues);
}
#undef CleanupField

/*
 * Client Tag extension support (from Niles Ritter).
 */
static TIFFExtendProc _TIFFextender = (TIFFExtendProc) NULL;

TIFFExtendProc
TIFFSetTagExtender(TIFFExtendProc extender)
{
	TIFFExtendProc prev = _TIFFextender;
	_TIFFextender = extender;
	return (prev);
}

/*
 * Setup for a new directory.  Should we automatically call
 * TIFFWriteDirectory() if the current one is dirty?
 *
 * The newly created directory will not exist on the file till
 * TIFFWriteDirectory(), TIFFFlush() or TIFFClose() is called.
 */
int
TIFFCreateDirectory(TIFF* tif)
{
	TIFFDefaultDirectory(tif);
	tif->tif_diroff = 0;
	tif->tif_nextdiroff = 0;
	tif->tif_curoff = 0;
	tif->tif_row = (uint32) -1;
	tif->tif_curstrip = (uint32) -1;

	return 0;
}

/*
 * Setup a default directory structure.
 */
int
TIFFDefaultDirectory(TIFF* tif)
{
	register TIFFDirectory* td = &tif->tif_dir;
	const TIFFFieldArray* tiffFieldArray;

	tiffFieldArray = _TIFFGetFields();
	_TIFFSetupFields(tif, tiffFieldArray);   

	_TIFFmemset(td, 0, sizeof (*td));
	td->td_fillorder = FILLORDER_MSB2LSB;
	td->td_bitspersample = 1;
	td->td_threshholding = THRESHHOLD_BILEVEL;
	td->td_orientation = ORIENTATION_TOPLEFT;
	td->td_samplesperpixel = 1;
	td->td_rowsperstrip = (uint32) -1;
	td->td_tilewidth = 0;
	td->td_tilelength = 0;
	td->td_tiledepth = 1;
	td->td_stripbytecountsorted = 1; /* Our own arrays always sorted. */  
	td->td_resolutionunit = RESUNIT_INCH;
	td->td_sampleformat = SAMPLEFORMAT_UINT;
	td->td_imagedepth = 1;
	td->td_ycbcrsubsampling[0] = 2;
	td->td_ycbcrsubsampling[1] = 2;
	td->td_ycbcrpositioning = YCBCRPOSITION_CENTERED;
	tif->tif_postdecode = _TIFFNoPostDecode;  
	tif->tif_foundfield = NULL;
	tif->tif_tagmethods.vsetfield = _TIFFVSetField;  
	tif->tif_tagmethods.vgetfield = _TIFFVGetField;
	tif->tif_tagmethods.printdir = NULL;
	/*
	 *  Give client code a chance to install their own
	 *  tag extensions & methods, prior to compression overloads.
	 */
	if (_TIFFextender)
		(*_TIFFextender)(tif);
	(void) TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_NONE);
	/*
	 * NB: The directory is marked dirty as a result of setting
	 * up the default compression scheme.  However, this really
	 * isn't correct -- we want TIFF_DIRTYDIRECT to be set only
	 * if the user does something.  We could just do the setup
	 * by hand, but it seems better to use the normal mechanism
	 * (i.e. TIFFSetField).
	 */
	tif->tif_flags &= ~TIFF_DIRTYDIRECT;

	/*
	 * As per http://bugzilla.remotesensing.org/show_bug.cgi?id=19
	 * we clear the ISTILED flag when setting up a new directory.
	 * Should we also be clearing stuff like INSUBIFD?
	 */
	tif->tif_flags &= ~TIFF_ISTILED;

	return (1);
}

static int
TIFFAdvanceDirectory(TIFF* tif, uint64* nextdir, uint64* off)
{
	static const char module[] = "TIFFAdvanceDirectory";
	if (isMapped(tif))
	{
		uint64 poff=*nextdir;
		if (!(tif->tif_flags&TIFF_BIGTIFF))
		{
			tmsize_t poffa,poffb,poffc,poffd;
			uint16 dircount;
			uint32 nextdir32;
			poffa=(tmsize_t)poff;
			poffb=poffa+sizeof(uint16);
			if (((uint64)poffa!=poff)||(poffb<poffa)||(poffb<(tmsize_t)sizeof(uint16))||(poffb>tif->tif_size))
			{
				TIFFErrorExt(tif->tif_clientdata,module,"Error fetching directory count");
				return(0);
			}
			_TIFFmemcpy(&dircount,tif->tif_base+poffa,sizeof(uint16));
			if (tif->tif_flags&TIFF_SWAB)
				TIFFSwabShort(&dircount);
			poffc=poffb+dircount*12;
			poffd=poffc+sizeof(uint32);
			if ((poffc<poffb)||(poffc<dircount*12)||(poffd<poffc)||(poffd<(tmsize_t)sizeof(uint32))||(poffd>tif->tif_size))
			{
				TIFFErrorExt(tif->tif_clientdata,module,"Error fetching directory link");
				return(0);
			}
			if (off!=NULL)
				*off=(uint64)poffc;
			_TIFFmemcpy(&nextdir32,tif->tif_base+poffc,sizeof(uint32));
			if (tif->tif_flags&TIFF_SWAB)
				TIFFSwabLong(&nextdir32);
			*nextdir=nextdir32;
		}
		else
		{
			tmsize_t poffa,poffb,poffc,poffd;
			uint64 dircount64;
			uint16 dircount16;
			poffa=(tmsize_t)poff;
			poffb=poffa+sizeof(uint64);
			if (((uint64)poffa!=poff)||(poffb<poffa)||(poffb<(tmsize_t)sizeof(uint64))||(poffb>tif->tif_size))
			{
				TIFFErrorExt(tif->tif_clientdata,module,"Error fetching directory count");
				return(0);
			}
			_TIFFmemcpy(&dircount64,tif->tif_base+poffa,sizeof(uint64));
			if (tif->tif_flags&TIFF_SWAB)
				TIFFSwabLong8(&dircount64);
			if (dircount64>0xFFFF)
			{
				TIFFErrorExt(tif->tif_clientdata,module,"Sanity check on directory count failed");
				return(0);
			}
			dircount16=(uint16)dircount64;
			poffc=poffb+dircount16*20;
			poffd=poffc+sizeof(uint64);
			if ((poffc<poffb)||(poffc<dircount16*20)||(poffd<poffc)||(poffd<(tmsize_t)sizeof(uint64))||(poffd>tif->tif_size))
			{
				TIFFErrorExt(tif->tif_clientdata,module,"Error fetching directory link");
				return(0);
			}
			if (off!=NULL)
				*off=(uint64)poffc;
			_TIFFmemcpy(nextdir,tif->tif_base+poffc,sizeof(uint64));
			if (tif->tif_flags&TIFF_SWAB)
				TIFFSwabLong8(nextdir);
		}
		return(1);
	}
	else
	{
		if (!(tif->tif_flags&TIFF_BIGTIFF))
		{
			uint16 dircount;
			uint32 nextdir32;
			if (!SeekOK(tif, *nextdir) ||
			    !ReadOK(tif, &dircount, sizeof (uint16))) {
				TIFFErrorExt(tif->tif_clientdata, module, "%s: Error fetching directory count",
				    tif->tif_name);
				return (0);
			}
			if (tif->tif_flags & TIFF_SWAB)
				TIFFSwabShort(&dircount);
			if (off != NULL)
				*off = TIFFSeekFile(tif,
				    dircount*12, SEEK_CUR);
			else
				(void) TIFFSeekFile(tif,
				    dircount*12, SEEK_CUR);
			if (!ReadOK(tif, &nextdir32, sizeof (uint32))) {
				TIFFErrorExt(tif->tif_clientdata, module, "%s: Error fetching directory link",
				    tif->tif_name);
				return (0);
			}
			if (tif->tif_flags & TIFF_SWAB)
				TIFFSwabLong(&nextdir32);
			*nextdir=nextdir32;
		}
		else
		{
			uint64 dircount64;
			uint16 dircount16;
			if (!SeekOK(tif, *nextdir) ||
			    !ReadOK(tif, &dircount64, sizeof (uint64))) {
				TIFFErrorExt(tif->tif_clientdata, module, "%s: Error fetching directory count",
				    tif->tif_name);
				return (0);
			}
			if (tif->tif_flags & TIFF_SWAB)
				TIFFSwabLong8(&dircount64);
			if (dircount64>0xFFFF)
			{
				TIFFErrorExt(tif->tif_clientdata, module, "Error fetching directory count");
				return(0);
			}
			dircount16 = (uint16)dircount64;
			if (off != NULL)
				*off = TIFFSeekFile(tif,
				    dircount16*20, SEEK_CUR);
			else
				(void) TIFFSeekFile(tif,
				    dircount16*20, SEEK_CUR);
			if (!ReadOK(tif, nextdir, sizeof (uint64))) {
				TIFFErrorExt(tif->tif_clientdata, module, "%s: Error fetching directory link",
				    tif->tif_name);
				return (0);
			}
			if (tif->tif_flags & TIFF_SWAB)
				TIFFSwabLong8(nextdir);
		}
		return (1);
	}
}

/*
 * Count the number of directories in a file.
 */
uint16
TIFFNumberOfDirectories(TIFF* tif)
{
	uint64 nextdir;
	uint16 n;
	if (!(tif->tif_flags&TIFF_BIGTIFF))
		nextdir = tif->tif_header.classic.tiff_diroff;
	else
		nextdir = tif->tif_header.big.tiff_diroff;
	n = 0;
	while (nextdir != 0 && TIFFAdvanceDirectory(tif, &nextdir, NULL))
		n++;
	return (n);
}

/*
 * Set the n-th directory as the current directory.
 * NB: Directories are numbered starting at 0.
 */
int
TIFFSetDirectory(TIFF* tif, uint16 dirn)
{
	uint64 nextdir;
	uint16 n;

	if (!(tif->tif_flags&TIFF_BIGTIFF))
		nextdir = tif->tif_header.classic.tiff_diroff;
	else
		nextdir = tif->tif_header.big.tiff_diroff;
	for (n = dirn; n > 0 && nextdir != 0; n--)
		if (!TIFFAdvanceDirectory(tif, &nextdir, NULL))
			return (0);
	tif->tif_nextdiroff = nextdir;
	/*
	 * Set curdir to the actual directory index.  The
	 * -1 is because TIFFReadDirectory will increment
	 * tif_curdir after successfully reading the directory.
	 */
	tif->tif_curdir = (dirn - n) - 1;
	/*
	 * Reset tif_dirnumber counter and start new list of seen directories.
	 * We need this to prevent IFD loops.
	 */
	tif->tif_dirnumber = 0;
	return (TIFFReadDirectory(tif));
}

/*
 * Set the current directory to be the directory
 * located at the specified file offset.  This interface
 * is used mainly to access directories linked with
 * the SubIFD tag (e.g. thumbnail images).
 */
int
TIFFSetSubDirectory(TIFF* tif, uint64 diroff)
{
	tif->tif_nextdiroff = diroff;
	/*
	 * Reset tif_dirnumber counter and start new list of seen directories.
	 * We need this to prevent IFD loops.
	 */
	tif->tif_dirnumber = 0;
	return (TIFFReadDirectory(tif));
}

/*
 * Return file offset of the current directory.
 */
uint64
TIFFCurrentDirOffset(TIFF* tif)
{
	return (tif->tif_diroff);
}

/*
 * Return an indication of whether or not we are
 * at the last directory in the file.
 */
int
TIFFLastDirectory(TIFF* tif)
{
	return (tif->tif_nextdiroff == 0);
}

/*
 * Unlink the specified directory from the directory chain.
 */
int
TIFFUnlinkDirectory(TIFF* tif, uint16 dirn)
{
	static const char module[] = "TIFFUnlinkDirectory";
	uint64 nextdir;
	uint64 off;
	uint16 n;

	if (tif->tif_mode == O_RDONLY) {
		TIFFErrorExt(tif->tif_clientdata, module,
                             "Can not unlink directory in read-only file");
		return (0);
	}
	/*
	 * Go to the directory before the one we want
	 * to unlink and nab the offset of the link
	 * field we'll need to patch.
	 */
	if (!(tif->tif_flags&TIFF_BIGTIFF))
	{
		nextdir = tif->tif_header.classic.tiff_diroff;
		off = 4;
	}
	else
	{
		nextdir = tif->tif_header.big.tiff_diroff;
		off = 8;
	}
	for (n = dirn-1; n > 0; n--) {
		if (nextdir == 0) {
			TIFFErrorExt(tif->tif_clientdata, module, "Directory %d does not exist", dirn);
			return (0);
		}
		if (!TIFFAdvanceDirectory(tif, &nextdir, &off))
			return (0);
	}
	/*
	 * Advance to the directory to be unlinked and fetch
	 * the offset of the directory that follows.
	 */
	if (!TIFFAdvanceDirectory(tif, &nextdir, NULL))
		return (0);
	/*
	 * Go back and patch the link field of the preceding
	 * directory to point to the offset of the directory
	 * that follows.
	 */
	(void) TIFFSeekFile(tif, off, SEEK_SET);
	if (!(tif->tif_flags&TIFF_BIGTIFF))
	{
		uint32 nextdir32;
		nextdir32=(uint32)nextdir;
		assert((uint64)nextdir32==nextdir);
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabLong(&nextdir32);
		if (!WriteOK(tif, &nextdir32, sizeof (uint32))) {
			TIFFErrorExt(tif->tif_clientdata, module, "Error writing directory link");
			return (0);
		}
	}
	else
	{
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabLong8(&nextdir);
		if (!WriteOK(tif, &nextdir, sizeof (uint64))) {
			TIFFErrorExt(tif->tif_clientdata, module, "Error writing directory link");
			return (0);
		}
	}
	/*
	 * Leave directory state setup safely.  We don't have
	 * facilities for doing inserting and removing directories,
	 * so it's safest to just invalidate everything.  This
	 * means that the caller can only append to the directory
	 * chain.
	 */
	(*tif->tif_cleanup)(tif);
	if ((tif->tif_flags & TIFF_MYBUFFER) && tif->tif_rawdata) {
		_TIFFfree(tif->tif_rawdata);
		tif->tif_rawdata = NULL;
		tif->tif_rawcc = 0;
	}
	tif->tif_flags &= ~(TIFF_BEENWRITING|TIFF_BUFFERSETUP|TIFF_POSTENCODE|TIFF_BUF4WRITE);
	TIFFFreeDirectory(tif);
	TIFFDefaultDirectory(tif);
	tif->tif_diroff = 0;			/* force link on next write */
	tif->tif_nextdiroff = 0;		/* next write must be at end */
	tif->tif_curoff = 0;
	tif->tif_row = (uint32) -1;
	tif->tif_curstrip = (uint32) -1;
	return (1);
}

/* vim: set ts=8 sts=8 sw=8 noet: */
