tif_pdsdirread.c

TIFF文件格式读取及生成的源代码

		if (!ReadOK(tif, cp, cc))
			goto bad;
	} else {
		if (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:
	TIFFError(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) {
		TIFFError(tif->tif_name,
		    "%s: Rational with zero denominator (num = %lu)",
		    _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)
{
	/* This appears to be a flagrant bug in the TIFF library, yet I
	   actually don't understand how it could have ever worked the old
	   way. Look at the comments in my new code and you'll understand. */
#if (0)
	float v = (float)
	    TIFFExtractData(tif, dir->tdir_type, dir->tdir_offset);
	TIFFCvtIEEEFloatToNative(tif, 1, &v);
#else
	float v;
	/* This is a little bit tricky - if we just cast the uint32 to a float,
	   C will perform a numerical conversion, which is not what we want.
	   We want to take the actual bit pattern in the uint32 and interpret
	   it as a float. Thus we cast a uint32 * into a float * and then
	   dereference to get v. */
	uint32 l = (uint32)
	    TIFFExtractData(tif, dir->tdir_type, dir->tdir_offset);
	v = * (float *) &l;
	TIFFCvtIEEEFloatToNative(tif, 1, &v);
#endif
	return (v);

}

/*
 * Fetch an array of BYTE or SBYTE values.
 */
static int
TIFFFetchByteArray(TIFF* tif, TIFFDirEntry* dir, uint16* v)
{
	if (dir->tdir_count <= 4) {
		/*
		 * Extract data from offset field.
		 */
		if (tif->tif_header.tiff_magic == TIFF_BIGENDIAN) {
			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 >> 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] = dir->tdir_offset & 0xffff;
			case 1: v[0] = dir->tdir_offset >> 16;
			}
		} else {
			switch (dir->tdir_count) {
			case 2: v[1] = dir->tdir_offset >> 16;
			case 1: v[0] = dir->tdir_offset & 0xffff;
			}
		}
		return (1);
	} else
		return (TIFFFetchData(tif, dir, (char *)v) != 0);
}

/*
 * Fetch a pair of SHORT or BYTE values.
 */
static int
TIFFFetchShortPair(TIFF* tif, TIFFDirEntry* dir)
{
	uint16 v[2];
	int ok = 0;

	switch (dir->tdir_type) {
	case TIFF_SHORT:
	case TIFF_SSHORT:
		ok = TIFFFetchShortArray(tif, dir, v);
		break;
	case TIFF_BYTE:
	case TIFF_SBYTE:
		ok  = TIFFFetchByteArray(tif, dir, v);
		break;
	}
	if (ok)
		TIFFSetField(tif, dir->tdir_tag, v[0], v[1]);
	return (ok);
}

/*
 * 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*)CheckMalloc(tif,
	    dir->tdir_count*TIFFDataWidth(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) {
		v[0] = *(float*) &dir->tdir_offset;
		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, (uint16*) v))
			return (0);
		if (dir->tdir_type == TIFF_BYTE) {
			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_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 */
		TIFFError(tif->tif_name,
		    "Cannot read TIFF_ANY type %d for field \"%s\"",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
		return (0);
	}
	return (1);
}


/*
 * Fetch a tag that is not handled by special case code.
 */
/* The standard function TIFFFetchNormalTag() could definitely be replaced
   with a simple call to this function, just adding TIFFSetField() as the
   last argument. */
static int
TIFFFetchNormalSubTag(TIFF* tif, TIFFDirEntry* dp, const TIFFFieldInfo* fip,
		      int (*setFieldFn)(TIFF *tif, ttag_t tag, ...))
{
	static char mesg[] = "to fetch tag value";
	int ok = 0;

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

		switch (dp->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
			/* NB: always expand BYTE values to shorts */