TiffImagePlugin.py

#
# The Python Imaging Library.
# $Id$
#
# TIFF file handling
#
# TIFF is a flexible, if somewhat aged, image file format originally
# defined by Aldus.  Although TIFF supports a wide variety of pixel
# layouts and compression methods, the name doesn't really stand for
# "thousands of incompatible file formats," it just feels that way.
#
# To read TIFF data from a stream, the stream must be seekable.  For
# progressive decoding, make sure to use TIFF files where the tag
# directory is placed first in the file.
#
# History:
# 1995-09-01 fl   Created
# 1996-05-04 fl   Handle JPEGTABLES tag
# 1996-05-18 fl   Fixed COLORMAP support
# 1997-01-05 fl   Fixed PREDICTOR support
# 1997-08-27 fl   Added support for rational tags (from Perry Stoll)
# 1998-01-10 fl   Fixed seek/tell (from Jan Blom)
# 1998-07-15 fl   Use private names for internal variables
# 1999-06-13 fl   Rewritten for PIL 1.0 (1.0)
# 2000-10-11 fl   Additional fixes for Python 2.0 (1.1)
# 2001-04-17 fl   Fixed rewind support (seek to frame 0) (1.2)
# 2001-05-12 fl   Added write support for more tags (from Greg Couch) (1.3)
# 2001-12-18 fl   Added workaround for broken Matrox library
# 2002-01-18 fl   Don't mess up if photometric tag is missing (D. Alan Stewart)
# 2003-05-19 fl   Check FILLORDER tag
# 2003-09-26 fl   Added RGBa support
# 2004-02-24 fl   Added DPI support; fixed rational write support
# 2005-02-07 fl   Added workaround for broken Corel Draw 10 files
# 2006-01-09 fl   Added support for float/double tags (from Russell Nelson)
#
# Copyright (c) 1997-2006 by Secret Labs AB.  All rights reserved.
# Copyright (c) 1995-1997 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
import io
import itertools
import logging
import math
import os
import struct
import warnings
from collections.abc import MutableMapping
from fractions import Fraction
from numbers import Number, Rational

from . import Image, ImageFile, ImageOps, ImagePalette, TiffTags
from ._binary import i16be as i16
from ._binary import i32be as i32
from ._binary import o8
from .TiffTags import TYPES

logger = logging.getLogger(__name__)

# Set these to true to force use of libtiff for reading or writing.
READ_LIBTIFF = False
WRITE_LIBTIFF = False
IFD_LEGACY_API = True
STRIP_SIZE = 65536

II = b"II"  # little-endian (Intel style)
MM = b"MM"  # big-endian (Motorola style)

#
# --------------------------------------------------------------------
# Read TIFF files

# a few tag names, just to make the code below a bit more readable
IMAGEWIDTH = 256
IMAGELENGTH = 257
BITSPERSAMPLE = 258
COMPRESSION = 259
PHOTOMETRIC_INTERPRETATION = 262
FILLORDER = 266
IMAGEDESCRIPTION = 270
STRIPOFFSETS = 273
SAMPLESPERPIXEL = 277
ROWSPERSTRIP = 278
STRIPBYTECOUNTS = 279
X_RESOLUTION = 282
Y_RESOLUTION = 283
PLANAR_CONFIGURATION = 284
RESOLUTION_UNIT = 296
TRANSFERFUNCTION = 301
SOFTWARE = 305
DATE_TIME = 306
ARTIST = 315
PREDICTOR = 317
COLORMAP = 320
TILEWIDTH = 322
TILELENGTH = 323
TILEOFFSETS = 324
TILEBYTECOUNTS = 325
SUBIFD = 330
EXTRASAMPLES = 338
SAMPLEFORMAT = 339
JPEGTABLES = 347
YCBCRSUBSAMPLING = 530
REFERENCEBLACKWHITE = 532
COPYRIGHT = 33432
IPTC_NAA_CHUNK = 33723  # newsphoto properties
PHOTOSHOP_CHUNK = 34377  # photoshop properties
ICCPROFILE = 34675
EXIFIFD = 34665
XMP = 700
JPEGQUALITY = 65537  # pseudo-tag by libtiff

# https://github.com/imagej/ImageJA/blob/master/src/main/java/ij/io/TiffDecoder.java
IMAGEJ_META_DATA_BYTE_COUNTS = 50838
IMAGEJ_META_DATA = 50839

COMPRESSION_INFO = {
    # Compression => pil compression name
    1: "raw",
    2: "tiff_ccitt",
    3: "group3",
    4: "group4",
    5: "tiff_lzw",
    6: "tiff_jpeg",  # obsolete
    7: "jpeg",
    8: "tiff_adobe_deflate",
    32771: "tiff_raw_16",  # 16-bit padding
    32773: "packbits",
    32809: "tiff_thunderscan",
    32946: "tiff_deflate",
    34676: "tiff_sgilog",
    34677: "tiff_sgilog24",
    34925: "lzma",
    50000: "zstd",
    50001: "webp",
}

COMPRESSION_INFO_REV = {v: k for k, v in COMPRESSION_INFO.items()}

OPEN_INFO = {
    # (ByteOrder, PhotoInterpretation, SampleFormat, FillOrder, BitsPerSample,
    #  ExtraSamples) => mode, rawmode
    (II, 0, (1,), 1, (1,), ()): ("1", "1;I"),
    (MM, 0, (1,), 1, (1,), ()): ("1", "1;I"),
    (II, 0, (1,), 2, (1,), ()): ("1", "1;IR"),
    (MM, 0, (1,), 2, (1,), ()): ("1", "1;IR"),
    (II, 1, (1,), 1, (1,), ()): ("1", "1"),
    (MM, 1, (1,), 1, (1,), ()): ("1", "1"),
    (II, 1, (1,), 2, (1,), ()): ("1", "1;R"),
    (MM, 1, (1,), 2, (1,), ()): ("1", "1;R"),
    (II, 0, (1,), 1, (2,), ()): ("L", "L;2I"),
    (MM, 0, (1,), 1, (2,), ()): ("L", "L;2I"),
    (II, 0, (1,), 2, (2,), ()): ("L", "L;2IR"),
    (MM, 0, (1,), 2, (2,), ()): ("L", "L;2IR"),
    (II, 1, (1,), 1, (2,), ()): ("L", "L;2"),
    (MM, 1, (1,), 1, (2,), ()): ("L", "L;2"),
    (II, 1, (1,), 2, (2,), ()): ("L", "L;2R"),
    (MM, 1, (1,), 2, (2,), ()): ("L", "L;2R"),
    (II, 0, (1,), 1, (4,), ()): ("L", "L;4I"),
    (MM, 0, (1,), 1, (4,), ()): ("L", "L;4I"),
    (II, 0, (1,), 2, (4,), ()): ("L", "L;4IR"),
    (MM, 0, (1,), 2, (4,), ()): ("L", "L;4IR"),
    (II, 1, (1,), 1, (4,), ()): ("L", "L;4"),
    (MM, 1, (1,), 1, (4,), ()): ("L", "L;4"),
    (II, 1, (1,), 2, (4,), ()): ("L", "L;4R"),
    (MM, 1, (1,), 2, (4,), ()): ("L", "L;4R"),
    (II, 0, (1,), 1, (8,), ()): ("L", "L;I"),
    (MM, 0, (1,), 1, (8,), ()): ("L", "L;I"),
    (II, 0, (1,), 2, (8,), ()): ("L", "L;IR"),
    (MM, 0, (1,), 2, (8,), ()): ("L", "L;IR"),
    (II, 1, (1,), 1, (8,), ()): ("L", "L"),
    (MM, 1, (1,), 1, (8,), ()): ("L", "L"),
    (II, 1, (1,), 2, (8,), ()): ("L", "L;R"),
    (MM, 1, (1,), 2, (8,), ()): ("L", "L;R"),
    (II, 1, (1,), 1, (12,), ()): ("I;16", "I;12"),
    (II, 0, (1,), 1, (16,), ()): ("I;16", "I;16"),
    (II, 1, (1,), 1, (16,), ()): ("I;16", "I;16"),
    (MM, 1, (1,), 1, (16,), ()): ("I;16B", "I;16B"),
    (II, 1, (1,), 2, (16,), ()): ("I;16", "I;16R"),
    (II, 1, (2,), 1, (16,), ()): ("I", "I;16S"),
    (MM, 1, (2,), 1, (16,), ()): ("I", "I;16BS"),
    (II, 0, (3,), 1, (32,), ()): ("F", "F;32F"),
    (MM, 0, (3,), 1, (32,), ()): ("F", "F;32BF"),
    (II, 1, (1,), 1, (32,), ()): ("I", "I;32N"),
    (II, 1, (2,), 1, (32,), ()): ("I", "I;32S"),
    (MM, 1, (2,), 1, (32,), ()): ("I", "I;32BS"),
    (II, 1, (3,), 1, (32,), ()): ("F", "F;32F"),
    (MM, 1, (3,), 1, (32,), ()): ("F", "F;32BF"),
    (II, 1, (1,), 1, (8, 8), (2,)): ("LA", "LA"),
    (MM, 1, (1,), 1, (8, 8), (2,)): ("LA", "LA"),
    (II, 2, (1,), 1, (8, 8, 8), ()): ("RGB", "RGB"),
    (MM, 2, (1,), 1, (8, 8, 8), ()): ("RGB", "RGB"),
    (II, 2, (1,), 2, (8, 8, 8), ()): ("RGB", "RGB;R"),
    (MM, 2, (1,), 2, (8, 8, 8), ()): ("RGB", "RGB;R"),
    (II, 2, (1,), 1, (8, 8, 8, 8), ()): ("RGBA", "RGBA"),  # missing ExtraSamples
    (MM, 2, (1,), 1, (8, 8, 8, 8), ()): ("RGBA", "RGBA"),  # missing ExtraSamples
    (II, 2, (1,), 1, (8, 8, 8, 8), (0,)): ("RGBX", "RGBX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8), (0,)): ("RGBX", "RGBX"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8), (0, 0)): ("RGBX", "RGBXX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8), (0, 0)): ("RGBX", "RGBXX"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (0, 0, 0)): ("RGBX", "RGBXXX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (0, 0, 0)): ("RGBX", "RGBXXX"),
    (II, 2, (1,), 1, (8, 8, 8, 8), (1,)): ("RGBA", "RGBa"),
    (MM, 2, (1,), 1, (8, 8, 8, 8), (1,)): ("RGBA", "RGBa"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8), (1, 0)): ("RGBA", "RGBaX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8), (1, 0)): ("RGBA", "RGBaX"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (1, 0, 0)): ("RGBA", "RGBaXX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (1, 0, 0)): ("RGBA", "RGBaXX"),
    (II, 2, (1,), 1, (8, 8, 8, 8), (2,)): ("RGBA", "RGBA"),
    (MM, 2, (1,), 1, (8, 8, 8, 8), (2,)): ("RGBA", "RGBA"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8), (2, 0)): ("RGBA", "RGBAX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8), (2, 0)): ("RGBA", "RGBAX"),
    (II, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (2, 0, 0)): ("RGBA", "RGBAXX"),
    (MM, 2, (1,), 1, (8, 8, 8, 8, 8, 8), (2, 0, 0)): ("RGBA", "RGBAXX"),
    (II, 2, (1,), 1, (8, 8, 8, 8), (999,)): ("RGBA", "RGBA"),  # Corel Draw 10
    (MM, 2, (1,), 1, (8, 8, 8, 8), (999,)): ("RGBA", "RGBA"),  # Corel Draw 10
    (II, 2, (1,), 1, (16, 16, 16), ()): ("RGB", "RGB;16L"),
    (MM, 2, (1,), 1, (16, 16, 16), ()): ("RGB", "RGB;16B"),
    (II, 2, (1,), 1, (16, 16, 16, 16), ()): ("RGBA", "RGBA;16L"),
    (MM, 2, (1,), 1, (16, 16, 16, 16), ()): ("RGBA", "RGBA;16B"),
    (II, 2, (1,), 1, (16, 16, 16, 16), (0,)): ("RGBX", "RGBX;16L"),
    (MM, 2, (1,), 1, (16, 16, 16, 16), (0,)): ("RGBX", "RGBX;16B"),
    (II, 2, (1,), 1, (16, 16, 16, 16), (1,)): ("RGBA", "RGBa;16L"),
    (MM, 2, (1,), 1, (16, 16, 16, 16), (1,)): ("RGBA", "RGBa;16B"),
    (II, 2, (1,), 1, (16, 16, 16, 16), (2,)): ("RGBA", "RGBA;16L"),
    (MM, 2, (1,), 1, (16, 16, 16, 16), (2,)): ("RGBA", "RGBA;16B"),
    (II, 3, (1,), 1, (1,), ()): ("P", "P;1"),
    (MM, 3, (1,), 1, (1,), ()): ("P", "P;1"),
    (II, 3, (1,), 2, (1,), ()): ("P", "P;1R"),
    (MM, 3, (1,), 2, (1,), ()): ("P", "P;1R"),
    (II, 3, (1,), 1, (2,), ()): ("P", "P;2"),
    (MM, 3, (1,), 1, (2,), ()): ("P", "P;2"),
    (II, 3, (1,), 2, (2,), ()): ("P", "P;2R"),
    (MM, 3, (1,), 2, (2,), ()): ("P", "P;2R"),
    (II, 3, (1,), 1, (4,), ()): ("P", "P;4"),
    (MM, 3, (1,), 1, (4,), ()): ("P", "P;4"),
    (II, 3, (1,), 2, (4,), ()): ("P", "P;4R"),
    (MM, 3, (1,), 2, (4,), ()): ("P", "P;4R"),
    (II, 3, (1,), 1, (8,), ()): ("P", "P"),
    (MM, 3, (1,), 1, (8,), ()): ("P", "P"),
    (II, 3, (1,), 1, (8, 8), (2,)): ("PA", "PA"),
    (MM, 3, (1,), 1, (8, 8), (2,)): ("PA", "PA"),
    (II, 3, (1,), 2, (8,), ()): ("P", "P;R"),
    (MM, 3, (1,), 2, (8,), ()): ("P", "P;R"),
    (II, 5, (1,), 1, (8, 8, 8, 8), ()): ("CMYK", "CMYK"),
    (MM, 5, (1,), 1, (8, 8, 8, 8), ()): ("CMYK", "CMYK"),
    (II, 5, (1,), 1, (8, 8, 8, 8, 8), (0,)): ("CMYK", "CMYKX"),
    (MM, 5, (1,), 1, (8, 8, 8, 8, 8), (0,)): ("CMYK", "CMYKX"),
    (II, 5, (1,), 1, (8, 8, 8, 8, 8, 8), (0, 0)): ("CMYK", "CMYKXX"),
    (MM, 5, (1,), 1, (8, 8, 8, 8, 8, 8), (0, 0)): ("CMYK", "CMYKXX"),
    (II, 5, (1,), 1, (16, 16, 16, 16), ()): ("CMYK", "CMYK;16L"),
    # JPEG compressed images handled by LibTiff and auto-converted to RGBX
    # Minimal Baseline TIFF requires YCbCr images to have 3 SamplesPerPixel
    (II, 6, (1,), 1, (8, 8, 8), ()): ("RGB", "RGBX"),
    (MM, 6, (1,), 1, (8, 8, 8), ()): ("RGB", "RGBX"),
    (II, 8, (1,), 1, (8, 8, 8), ()): ("LAB", "LAB"),
    (MM, 8, (1,), 1, (8, 8, 8), ()): ("LAB", "LAB"),
}

MAX_SAMPLESPERPIXEL = max(len(key_tp[4]) for key_tp in OPEN_INFO.keys())

PREFIXES = [
    b"MM\x00\x2A",  # Valid TIFF header with big-endian byte order
    b"II\x2A\x00",  # Valid TIFF header with little-endian byte order
    b"MM\x2A\x00",  # Invalid TIFF header, assume big-endian
    b"II\x00\x2A",  # Invalid TIFF header, assume little-endian
    b"MM\x00\x2B",  # BigTIFF with big-endian byte order
    b"II\x2B\x00",  # BigTIFF with little-endian byte order
]


def _accept(prefix):
    return prefix[:4] in PREFIXES


def _limit_rational(val, max_val):
    inv = abs(val) > 1
    n_d = IFDRational(1 / val if inv else val).limit_rational(max_val)
    return n_d[::-1] if inv else n_d


def _limit_signed_rational(val, max_val, min_val):
    frac = Fraction(val)
    n_d = frac.numerator, frac.denominator

    if min(n_d) < min_val:
        n_d = _limit_rational(val, abs(min_val))

    if max(n_d) > max_val:
        val = Fraction(*n_d)
        n_d = _limit_rational(val, max_val)

    return n_d


##
# Wrapper for TIFF IFDs.

_load_dispatch = {}
_write_dispatch = {}


class IFDRational(Rational):
    """Implements a rational class where 0/0 is a legal value to match
    the in the wild use of exif rationals.

    e.g., DigitalZoomRatio - 0.00/0.00  indicates that no digital zoom was used
    """

    """ If the denominator is 0, store this as a float('nan'), otherwise store
    as a fractions.Fraction(). Delegate as appropriate

    """

    __slots__ = ("_numerator", "_denominator", "_val")

    def __init__(self, value, denominator=1):
        """
        :param value: either an integer numerator, a
        float/rational/other number, or an IFDRational
        :param denominator: Optional integer denominator
        """
        if isinstance(value, IFDRational):
            self._numerator = value.numerator
            self._denominator = value.denominator
            self._val = value._val
            return

        if isinstance(value, Fraction):
            self._numerator = value.numerator
            self._denominator = value.denominator
        else:
            self._numerator = value
            self._denominator = denominator

        if denominator == 0:
            self._val = float("nan")
        elif denominator == 1:
            self._val = Fraction(value)
        else:
            self._val = Fraction(value, denominator)

    @property
    def numerator(self):
        return self._numerator

    @property
    def denominator(self):
        return self._denominator

    def limit_rational(self, max_denominator):
        """

        :param max_denominator: Integer, the maximum denominator value
        :returns: Tuple of (numerator, denominator)
        """

        if self.denominator == 0:
            return self.numerator, self.denominator

        f = self._val.limit_denominator(max_denominator)
        return f.numerator, f.denominator

    def __repr__(self):
        return str(float(self._val))

    def __hash__(self):
        return self._val.__hash__()

    def __eq__(self, other):
        val = self._val
        if isinstance(other, IFDRational):
            other = other._val
        if isinstance(other, float):
            val = float(val)
        return val == other

    def __getstate__(self):
        return [self._val, self._numerator, self._denominator]

    def __setstate__(self, state):
        IFDRational.__init__(self, 0)
        _val, _numerator, _denominator = state
        self._val = _val
        self._numerator = _numerator
        self._denominator = _denominator

    def _delegate(op):
        def delegate(self, *args):
            return getattr(self._val, op)(*args)

        return delegate

    """ a = ['add','radd', 'sub', 'rsub', 'mul', 'rmul',
             'truediv', 'rtruediv', 'floordiv', 'rfloordiv',
             'mod','rmod', 'pow','rpow', 'pos', 'neg',
             'abs', 'trunc', 'lt', 'gt', 'le', 'ge', 'bool',
             'ceil', 'floor', 'round']
        print("\n".join("__%s__ = _delegate('__%s__')" % (s,s) for s in a))
        """

    __add__ = _delegate("__add__")
    __radd__ = _delegate("__radd__")
    __sub__ = _delegate("__sub__")
    __rsub__ = _delegate("__rsub__")
    __mul__ = _delegate("__mul__")
    __rmul__ = _delegate("__rmul__")
    __truediv__ = _delegate("__truediv__")
    __rtruediv__ = _delegate("__rtruediv__")
    __floordiv__ = _delegate("__floordiv__")
    __rfloordiv__ = _delegate("__rfloordiv__")
    __mod__ = _delegate("__mod__")
    __rmod__ = _delegate("__rmod__")
    __pow__ = _delegate("__pow__")
    __rpow__ = _delegate("__rpow__")
    __pos__ = _delegate("__pos__")
    __neg__ = _delegate("__neg__")
    __abs__ = _delegate("__abs__")
    __trunc__ = _delegate("__trunc__")
    __lt__ = _delegate("__lt__")
    __gt__ = _delegate("__gt__")
    __le__ = _delegate("__le__")
    __ge__ = _delegate("__ge__")
    __bool__ = _delegate("__bool__")
    __ceil__ = _delegate("__ceil__")
    __floor__ = _delegate("__floor__")
    __round__ = _delegate("__round__")


class ImageFileDirectory_v2(MutableMapping):
    """This class represents a TIFF tag directory.  To speed things up, we
    don't decode tags unless they're asked for.

    Exposes a dictionary interface of the tags in the directory::

        ifd = ImageFileDirectory_v2()
        ifd[key] = 'Some Data'
        ifd.tagtype[key] = TiffTags.ASCII
        print(ifd[key])
        'Some Data'

    Individual values are returned as the strings or numbers, sequences are
    returned as tuples of the values.

    The tiff metadata type of each item is stored in a dictionary of
    tag types in
    :attr:`~PIL.TiffImagePlugin.ImageFileDirectory_v2.tagtype`. The types
    are read from a tiff file, guessed from the type added, or added
    manually.

    Data Structures:

        * ``self.tagtype = {}``

          * Key: numerical TIFF tag number
          * Value: integer corresponding to the data type from
            :py:data:`.TiffTags.TYPES`

          .. versionadded:: 3.0.0

    'Internal' data structures:

        * ``self._tags_v2 = {}``

          * Key: numerical TIFF tag number
          * Value: decoded data, as tuple for multiple values

        * ``self._tagdata = {}``

          * Key: numerical TIFF tag number
          * Value: undecoded byte string from file

        * ``self._tags_v1 = {}``

          * Key: numerical TIFF tag number
          * Value: decoded data in the v1 format

    Tags will be found in the private attributes ``self._tagdata``, and in
    ``self._tags_v2`` once decoded.

    ``self.legacy_api`` is a value for internal use, and shouldn't be changed
    from outside code. In cooperation with
    :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v1`, if ``legacy_api``
    is true, then decoded tags will be populated into both ``_tags_v1`` and
    ``_tags_v2``. ``_tags_v2`` will be used if this IFD is used in the TIFF
    save routine. Tags should be read from ``_tags_v1`` if
    ``legacy_api == true``.

    """

    def __init__(self, ifh=b"II\052\0\0\0\0\0", prefix=None, group=None):
        """Initialize an ImageFileDirectory.

        To construct an ImageFileDirectory from a real file, pass the 8-byte
        magic header to the constructor.  To only set the endianness, pass it
        as the 'prefix' keyword argument.

        :param ifh: One of the accepted magic headers (cf. PREFIXES); also sets
              endianness.
        :param prefix: Override the endianness of the file.
        """
        if not _accept(ifh):
            raise SyntaxError(f"not a TIFF file (header {repr(ifh)} not valid)")
        self._prefix = prefix if prefix is not None else ifh[:2]
        if self._prefix == MM:
            self._endian = ">"
        elif self._prefix == II:
            self._endian = "<"
        else:
            raise SyntaxError("not a TIFF IFD")
        self._bigtiff = ifh[2] == 43
        self.group = group
        self.tagtype = {}
        """ Dictionary of tag types """
        self.reset()
        (self.next,) = (
            self._unpack("Q", ifh[8:]) if self._bigtiff else self._unpack("L", ifh[4:])
        )
        self._legacy_api = False

    prefix = property(lambda self: self._prefix)
    offset = property(lambda self: self._offset)
    legacy_api = property(lambda self: self._legacy_api)

    @legacy_api.setter
    def legacy_api(self, value):
        raise Exception("Not allowing setting of legacy api")

    def reset(self):
        self._tags_v1 = {}  # will remain empty if legacy_api is false
        self._tags_v2 = {}  # main tag storage
        self._tagdata = {}
        self.tagtype = {}  # added 2008-06-05 by Florian Hoech
        self._next = None
        self._offset = None

    def __str__(self):
        return str(dict(self))

    def named(self):
        """
        :returns: dict of name|key: value

        Returns the complete tag dictionary, with named tags where possible.
        """
        return {
            TiffTags.lookup(code, self.group).name: value
            for code, value in self.items()
        }

    def __len__(self):
        return len(set(self._tagdata) | set(self._tags_v2))

    def __getitem__(self, tag):
        if tag not in self._tags_v2:  # unpack on the fly
            data = self._tagdata[tag]
            typ = self.tagtype[tag]
            size, handler = self._load_dispatch[typ]
            self[tag] = handler(self, data, self.legacy_api)  # check type
        val = self._tags_v2[tag]
        if self.legacy_api and not isinstance(val, (tuple, bytes)):
            val = (val,)
        return val

    def __contains__(self, tag):
        return tag in self._tags_v2 or tag in self._tagdata

    def __setitem__(self, tag, value):
        self._setitem(tag, value, self.legacy_api)

    def _setitem(self, tag, value, legacy_api):
        basetypes = (Number, bytes, str)

        info = TiffTags.lookup(tag, self.group)
        values = [value] if isinstance(value, basetypes) else value

        if tag not in self.tagtype:
            if info.type:
                self.tagtype[tag] = info.type
            else:
                self.tagtype[tag] = TiffTags.UNDEFINED
                if all(isinstance(v, IFDRational) for v in values):
                    self.tagtype[tag] = (
                        TiffTags.RATIONAL
                        if all(v >= 0 for v in values)
                        else TiffTags.SIGNED_RATIONAL
                    )
                elif all(isinstance(v, int) for v in values):
                    if all(0 <= v < 2**16 for v in values):
                        self.tagtype[tag] = TiffTags.SHORT
                    elif all(-(2**15) < v < 2**15 for v in values):
                        self.tagtype[tag] = TiffTags.SIGNED_SHORT
                    else:
                        self.tagtype[tag] = (
                            TiffTags.LONG
                            if all(v >= 0 for v in values)
                            else TiffTags.SIGNED_LONG
                        )
                elif all(isinstance(v, float) for v in values):
                    self.tagtype[tag] = TiffTags.DOUBLE
                elif all(isinstance(v, str) for v in values):
                    self.tagtype[tag] = TiffTags.ASCII
                elif all(isinstance(v, bytes) for v in values):
                    self.tagtype[tag] = TiffTags.BYTE

        if self.tagtype[tag] == TiffTags.UNDEFINED:
            values = [
                v.encode("ascii", "replace") if isinstance(v, str) else v
                for v in values
            ]
        elif self.tagtype[tag] == TiffTags.RATIONAL:
            values = [float(v) if isinstance(v, int) else v for v in values]

        is_ifd = self.tagtype[tag] == TiffTags.LONG and isinstance(values, dict)
        if not is_ifd:
            values = tuple(info.cvt_enum(value) for value in values)

        dest = self._tags_v1 if legacy_api else self._tags_v2

        # Three branches:
        # Spec'd length == 1, Actual length 1, store as element
        # Spec'd length == 1, Actual > 1, Warn and truncate. Formerly barfed.
        # No Spec, Actual length 1, Formerly (<4.2) returned a 1 element tuple.
        # Don't mess with the legacy api, since it's frozen.
        if not is_ifd and (
            (info.length == 1)
            or self.tagtype[tag] == TiffTags.BYTE
            or (info.length is None and len(values) == 1 and not legacy_api)
        ):
            # Don't mess with the legacy api, since it's frozen.
            if legacy_api and self.tagtype[tag] in [
                TiffTags.RATIONAL,
                TiffTags.SIGNED_RATIONAL,
            ]:  # rationals
                values = (values,)
            try:
                (dest[tag],) = values
            except ValueError:
                # We've got a builtin tag with 1 expected entry
                warnings.warn(
                    f"Metadata Warning, tag {tag} had too many entries: "
                    f"{len(values)}, expected 1"
                )
                dest[tag] = values[0]

        else:
            # Spec'd length > 1 or undefined
            # Unspec'd, and length > 1
            dest[tag] = values

    def __delitem__(self, tag):
        self._tags_v2.pop(tag, None)
        self._tags_v1.pop(tag, None)
        self._tagdata.pop(tag, None)

    def __iter__(self):
        return iter(set(self._tagdata) | set(self._tags_v2))

    def _unpack(self, fmt, data):
        return struct.unpack(self._endian + fmt, data)

    def _pack(self, fmt, *values):
        return struct.pack(self._endian + fmt, *values)

    def _register_loader(idx, size):
        def decorator(func):
            from .TiffTags import TYPES

            if func.__name__.startswith("load_"):
                TYPES[idx] = func.__name__[5:].replace("_", " ")
            _load_dispatch[idx] = size, func  # noqa: F821
            return func

        return decorator

    def _register_writer(idx):
        def decorator(func):
            _write_dispatch[idx] = func  # noqa: F821
            return func

        return decorator

    def _register_basic(idx_fmt_name):
        from .TiffTags import TYPES

        idx, fmt, name = idx_fmt_name
        TYPES[idx] = name
        size = struct.calcsize("=" + fmt)
        _load_dispatch[idx] = (  # noqa: F821
            size,
            lambda self, data, legacy_api=True: (
                self._unpack(f"{len(data) // size}{fmt}", data)
            ),
        )
        _write_dispatch[idx] = lambda self, *values: (  # noqa: F821
            b"".join(self._pack(fmt, value) for value in values)
        )

    list(
        map(
            _register_basic,
            [
                (TiffTags.SHORT, "H", "short"),
                (TiffTags.LONG, "L", "long"),
                (TiffTags.SIGNED_BYTE, "b", "signed byte"),
                (TiffTags.SIGNED_SHORT, "h", "signed short"),
                (TiffTags.SIGNED_LONG, "l", "signed long"),
                (TiffTags.FLOAT, "f", "float"),
                (TiffTags.DOUBLE, "d", "double"),
                (TiffTags.IFD, "L", "long"),
                (TiffTags.LONG8, "Q", "long8"),
            ],
        )
    )

    @_register_loader(1, 1)  # Basic type, except for the legacy API.
    def load_byte(self, data, legacy_api=True):
        return data

    @_register_writer(1)  # Basic type, except for the legacy API.
    def write_byte(self, data):
        return data

    @_register_loader(2, 1)
    def load_string(self, data, legacy_api=True):
        if data.endswith(b"\0"):
            data = data[:-1]
        return data.decode("latin-1", "replace")

    @_register_writer(2)
    def write_string(self, value):
        # remerge of https://github.com/python-pillow/Pillow/pull/1416
        if not isinstance(value, bytes):
            value = value.encode("ascii", "replace")
        return value + b"\0"

    @_register_loader(5, 8)
    def load_rational(self, data, legacy_api=True):
        vals = self._unpack(f"{len(data) // 4}L", data)

        def combine(a, b):
            return (a, b) if legacy_api else IFDRational(a, b)

        return tuple(combine(num, denom) for num, denom in zip(vals[::2], vals[1::2]))

    @_register_writer(5)
    def write_rational(self, *values):
        return b"".join(
            self._pack("2L", *_limit_rational(frac, 2**32 - 1)) for frac in values
        )

    @_register_loader(7, 1)
    def load_undefined(self, data, legacy_api=True):
        return data

    @_register_writer(7)
    def write_undefined(self, value):
        return value

    @_register_loader(10, 8)
    def load_signed_rational(self, data, legacy_api=True):
        vals = self._unpack(f"{len(data) // 4}l", data)

        def combine(a, b):
            return (a, b) if legacy_api else IFDRational(a, b)

        return tuple(combine(num, denom) for num, denom in zip(vals[::2], vals[1::2]))

    @_register_writer(10)
    def write_signed_rational(self, *values):
        return b"".join(
            self._pack("2l", *_limit_signed_rational(frac, 2**31 - 1, -(2**31)))
            for frac in values
        )

    def _ensure_read(self, fp, size):
        ret = fp.read(size)
        if len(ret) != size:
            raise OSError(
                "Corrupt EXIF data.  "
                f"Expecting to read {size} bytes but only got {len(ret)}. "
            )
        return ret

    def load(self, fp):

        self.reset()
        self._offset = fp.tell()

        try:
            tag_count = (
                self._unpack("Q", self._ensure_read(fp, 8))
                if self._bigtiff
                else self._unpack("H", self._ensure_read(fp, 2))
            )[0]
            for i in range(tag_count):
                tag, typ, count, data = (
                    self._unpack("HHQ8s", self._ensure_read(fp, 20))
                    if self._bigtiff
                    else self._unpack("HHL4s", self._ensure_read(fp, 12))
                )

                tagname = TiffTags.lookup(tag, self.group).name
                typname = TYPES.get(typ, "unknown")
                msg = f"tag: {tagname} ({tag}) - type: {typname} ({typ})"

                try:
                    unit_size, handler = self._load_dispatch[typ]
                except KeyError:
                    logger.debug(msg + f" - unsupported type {typ}")
                    continue  # ignore unsupported type
                size = count * unit_size
                if size > (8 if self._bigtiff else 4):
                    here = fp.tell()
                    (offset,) = self._unpack("Q" if self._bigtiff else "L", data)
                    msg += f" Tag Location: {here} - Data Location: {offset}"
                    fp.seek(offset)
                    data = ImageFile._safe_read(fp, size)
                    fp.seek(here)
                else:
                    data = data[:size]

                if len(data) != size:
                    warnings.warn(
                        "Possibly corrupt EXIF data.  "
                        f"Expecting to read {size} bytes but only got {len(data)}."
                        f" Skipping tag {tag}"
                    )
                    logger.debug(msg)
                    continue

                if not data:
                    logger.debug(msg)
                    continue

                self._tagdata[tag] = data
                self.tagtype[tag] = typ

                msg += " - value: " + (
                    "<table: %d bytes>" % size if size > 32 else repr(data)
                )
                logger.debug(msg)

            (self.next,) = (
                self._unpack("Q", self._ensure_read(fp, 8))
                if self._bigtiff
                else self._unpack("L", self._ensure_read(fp, 4))
            )
        except OSError as msg:
            warnings.warn(str(msg))
            return

    def tobytes(self, offset=0):
        # FIXME What about tagdata?
        result = self._pack("H", len(self._tags_v2))

        entries = []
        offset = offset + len(result) + len(self._tags_v2) * 12 + 4
        stripoffsets = None

        # pass 1: convert tags to binary format
        # always write tags in ascending order
        for tag, value in sorted(self._tags_v2.items()):
            if tag == STRIPOFFSETS:
                stripoffsets = len(entries)
            typ = self.tagtype.get(tag)
            logger.debug(f"Tag {tag}, Type: {typ}, Value: {repr(value)}")
            is_ifd = typ == TiffTags.LONG and isinstance(value, dict)
            if is_ifd:
                if self._endian == "<":
                    ifh = b"II\x2A\x00\x08\x00\x00\x00"
                else:
                    ifh = b"MM\x00\x2A\x00\x00\x00\x08"
                ifd = ImageFileDirectory_v2(ifh, group=tag)
                values = self._tags_v2[tag]
                for ifd_tag, ifd_value in values.items():
                    ifd[ifd_tag] = ifd_value
                data = ifd.tobytes(offset)
            else:
                values = value if isinstance(value, tuple) else (value,)
                data = self._write_dispatch[typ](self, *values)

            tagname = TiffTags.lookup(tag, self.group).name
            typname = "ifd" if is_ifd else TYPES.get(typ, "unknown")
            msg = f"save: {tagname} ({tag}) - type: {typname} ({typ})"
            msg += " - value: " + (
                "<table: %d bytes>" % len(data) if len(data) >= 16 else str(values)
            )
            logger.debug(msg)

            # count is sum of lengths for string and arbitrary data
            if is_ifd:
                count = 1
            elif typ in [TiffTags.BYTE, TiffTags.ASCII, TiffTags.UNDEFINED]:
                count = len(data)
            else:
                count = len(values)
            # figure out if data fits into the entry
            if len(data) <= 4:
                entries.append((tag, typ, count, data.ljust(4, b"\0"), b""))
            else:
                entries.append((tag, typ, count, self._pack("L", offset), data))
                offset += (len(data) + 1) // 2 * 2  # pad to word

        # update strip offset data to point beyond auxiliary data
        if stripoffsets is not None:
            tag, typ, count, value, data = entries[stripoffsets]
            if data:
                raise NotImplementedError("multistrip support not yet implemented")
            value = self._pack("L", self._unpack("L", value)[0] + offset)
            entries[stripoffsets] = tag, typ, count, value, data

        # pass 2: write entries to file
        for tag, typ, count, value, data in entries:
            logger.debug(f"{tag} {typ} {count} {repr(value)} {repr(data)}")
            result += self._pack("HHL4s", tag, typ, count, value)

        # -- overwrite here for multi-page --
        result += b"\0\0\0\0"  # end of entries

        # pass 3: write auxiliary data to file
        for tag, typ, count, value, data in entries:
            result += data
            if len(data) & 1:
                result += b"\0"

        return result

    def save(self, fp):

        if fp.tell() == 0:  # skip TIFF header on subsequent pages
            # tiff header -- PIL always starts the first IFD at offset 8
            fp.write(self._prefix + self._pack("HL", 42, 8))

        offset = fp.tell()
        result = self.tobytes(offset)
        fp.write(result)
        return offset + len(result)


ImageFileDirectory_v2._load_dispatch = _load_dispatch
ImageFileDirectory_v2._write_dispatch = _write_dispatch
for idx, name in TYPES.items():
    name = name.replace(" ", "_")
    setattr(ImageFileDirectory_v2, "load_" + name, _load_dispatch[idx][1])
    setattr(ImageFileDirectory_v2, "write_" + name, _write_dispatch[idx])
del _load_dispatch, _write_dispatch, idx, name


# Legacy ImageFileDirectory support.
class ImageFileDirectory_v1(ImageFileDirectory_v2):
    """This class represents the **legacy** interface to a TIFF tag directory.

    Exposes a dictionary interface of the tags in the directory::

        ifd = ImageFileDirectory_v1()
        ifd[key] = 'Some Data'
        ifd.tagtype[key] = TiffTags.ASCII
        print(ifd[key])
        ('Some Data',)

    Also contains a dictionary of tag types as read from the tiff image file,
    :attr:`~PIL.TiffImagePlugin.ImageFileDirectory_v1.tagtype`.

    Values are returned as a tuple.

    ..  deprecated:: 3.0.0
    """

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._legacy_api = True

    tags = property(lambda self: self._tags_v1)
    tagdata = property(lambda self: self._tagdata)

    # defined in ImageFileDirectory_v2
    tagtype: dict
    """Dictionary of tag types"""

    @classmethod
    def from_v2(cls, original):
        """Returns an
        :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v1`
        instance with the same data as is contained in the original
        :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v2`
        instance.

        :returns: :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v1`

        """

        ifd = cls(prefix=original.prefix)
        ifd._tagdata = original._tagdata
        ifd.tagtype = original.tagtype
        ifd.next = original.next  # an indicator for multipage tiffs
        return ifd

    def to_v2(self):
        """Returns an
        :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v2`
        instance with the same data as is contained in the original
        :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v1`
        instance.

        :returns: :py:class:`~PIL.TiffImagePlugin.ImageFileDirectory_v2`

        """

        ifd = ImageFileDirectory_v2(prefix=self.prefix)
        ifd._tagdata = dict(self._tagdata)
        ifd.tagtype = dict(self.tagtype)
        ifd._tags_v2 = dict(self._tags_v2)
        return ifd

    def __contains__(self, tag):
        return tag in self._tags_v1 or tag in self._tagdata

    def __len__(self):
        return len(set(self._tagdata) | set(self._tags_v1))

    def __iter__(self):
        return iter(set(self._tagdata) | set(self._tags_v1))

    def __setitem__(self, tag, value):
        for legacy_api in (False, True):
            self._setitem(tag, value, legacy_api)

    def __getitem__(self, tag):
        if tag not in self._tags_v1:  # unpack on the fly
            data = self._tagdata[tag]
            typ = self.tagtype[tag]
            size, handler = self._load_dispatch[typ]
            for legacy in (False, True):
                self._setitem(tag, handler(self, data, legacy), legacy)
        val = self._tags_v1[tag]
        if not isinstance(val, (tuple, bytes)):
            val = (val,)
        return val


# undone -- switch this pointer when IFD_LEGACY_API == False
ImageFileDirectory = ImageFileDirectory_v1


##
# Image plugin for TIFF files.


class TiffImageFile(ImageFile.ImageFile):

    format = "TIFF"
    format_description = "Adobe TIFF"
    _close_exclusive_fp_after_loading = False

    def __init__(self, fp=None, filename=None):
        self.tag_v2 = None
        """ Image file directory (tag dictionary) """

        self.tag = None
        """ Legacy tag entries """

        super().__init__(fp, filename)

    def _open(self):
        """Open the first image in a TIFF file"""

        # Header
        ifh = self.fp.read(8)
        if ifh[2] == 43:
            ifh += self.fp.read(8)

        self.tag_v2 = ImageFileDirectory_v2(ifh)

        # legacy IFD entries will be filled in later
        self.ifd = None

        # setup frame pointers
        self.__first = self.__next = self.tag_v2.next
        self.__frame = -1
        self._fp = self.fp
        self._frame_pos = []
        self._n_frames = None

        logger.debug("*** TiffImageFile._open ***")
        logger.debug(f"- __first: {self.__first}")
        logger.debug(f"- ifh: {repr(ifh)}")  # Use repr to avoid str(bytes)

        # and load the first frame
        self._seek(0)

    @property
    def n_frames(self):
        if self._n_frames is None:
            current = self.tell()
            self._seek(len(self._frame_pos))
            while self._n_frames is None:
                self._seek(self.tell() + 1)
            self.seek(current)
        return self._n_frames

    def seek(self, frame):
        """Select a given frame as current image"""
        if not self._seek_check(frame):
            return
        self._seek(frame)
        # Create a new core image object on second and
        # subsequent frames in the image. Image may be
        # different size/mode.
        Image._decompression_bomb_check(self.size)
        self.im = Image.core.new(self.mode, self.size)

    def _seek(self, frame):
        self.fp = self._fp

        # reset buffered io handle in case fp
        # was passed to libtiff, invalidating the buffer
        self.fp.tell()

        while len(self._frame_pos) <= frame:
            if not self.__next:
                raise EOFError("no more images in TIFF file")
            logger.debug(
                f"Seeking to frame {frame}, on frame {self.__frame}, "
                f"__next {self.__next}, location: {self.fp.tell()}"
            )
            self.fp.seek(self.__next)
            self._frame_pos.append(self.__next)
            logger.debug("Loading tags, location: %s" % self.fp.tell())
            self.tag_v2.load(self.fp)
            if self.tag_v2.next in self._frame_pos:
                # This IFD has already been processed
                # Declare this to be the end of the image
                self.__next = 0
            else:
                self.__next = self.tag_v2.next
            if self.__next == 0:
                self._n_frames = frame + 1
            if len(self._frame_pos) == 1:
                self.is_animated = self.__next != 0
            self.__frame += 1
        self.fp.seek(self._frame_pos[frame])
        self.tag_v2.load(self.fp)
        self._reload_exif()
        # fill the legacy tag/ifd entries
        self.tag = self.ifd = ImageFileDirectory_v1.from_v2(self.tag_v2)
        self.__frame = frame
        self._setup()

    def tell(self):
        """Return the current frame number"""
        return self.__frame

    def get_child_images(self):
        if SUBIFD not in self.tag_v2:
            return []
        child_images = []
        exif = self.getexif()
        offset = None
        for im_offset in self.tag_v2[SUBIFD]:
            # reset buffered io handle in case fp
            # was passed to libtiff, invalidating the buffer
            current_offset = self._fp.tell()
            if offset is None:
                offset = current_offset

            fp = self._fp
            ifd = exif._get_ifd_dict(im_offset)
            jpegInterchangeFormat = ifd.get(513)
            if jpegInterchangeFormat is not None:
                fp.seek(jpegInterchangeFormat)
                jpeg_data = fp.read(ifd.get(514))

                fp = io.BytesIO(jpeg_data)

            with Image.open(fp) as im:
                if jpegInterchangeFormat is None:
                    im._frame_pos = [im_offset]
                    im._seek(0)
                im.load()
                child_images.append(im)

        if offset is not None:
            self._fp.seek(offset)
        return child_images

    def getxmp(self):
        """
        Returns a dictionary containing the XMP tags.
        Requires defusedxml to be installed.

        :returns: XMP tags in a dictionary.
        """
        return self._getxmp(self.tag_v2[XMP]) if XMP in self.tag_v2 else {}

    def get_photoshop_blocks(self):
        """
        Returns a dictionary of Photoshop "Image Resource Blocks".
        The keys are the image resource ID. For more information, see
        https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/#50577409_pgfId-1037727

        :returns: Photoshop "Image Resource Blocks" in a dictionary.
        """
        blocks = {}
        val = self.tag_v2.get(0x8649)
        if val:
            while val[:4] == b"8BIM":
                id = i16(val[4:6])
                n = math.ceil((val[6] + 1) / 2) * 2
                size = i32(val[6 + n : 10 + n])
                data = val[10 + n : 10 + n + size]
                blocks[id] = {"data": data}

                val = val[math.ceil((10 + n + size) / 2) * 2 :]
        return blocks

    def load(self):
        if self.tile and self.use_load_libtiff:
            return self._load_libtiff()
        return super().load()

    def load_end(self):
        if self._tile_orientation:
            method = {
                2: Image.Transpose.FLIP_LEFT_RIGHT,
                3: Image.Transpose.ROTATE_180,
                4: Image.Transpose.FLIP_TOP_BOTTOM,
                5: Image.Transpose.TRANSPOSE,
                6: Image.Transpose.ROTATE_270,
                7: Image.Transpose.TRANSVERSE,
                8: Image.Transpose.ROTATE_90,
            }.get(self._tile_orientation)
            if method is not None:
                self.im = self.im.transpose(method)
                self._size = self.im.size

        # allow closing if we're on the first frame, there's no next
        # This is the ImageFile.load path only, libtiff specific below.
        if not self.is_animated:
            self._close_exclusive_fp_after_loading = True

            # reset buffered io handle in case fp
            # was passed to libtiff, invalidating the buffer
            self.fp.tell()

            # load IFD data from fp before it is closed
            exif = self.getexif()
            for key in TiffTags.TAGS_V2_GROUPS.keys():
                if key not in exif:
                    continue
                exif.get_ifd(key)

    def _load_libtiff(self):
        """Overload method triggered when we detect a compressed tiff
        Calls out to libtiff"""

        Image.Image.load(self)

        self.load_prepare()

        if not len(self.tile) == 1:
            raise OSError("Not exactly one tile")

        # (self._compression, (extents tuple),
        #   0, (rawmode, self._compression, fp))
        extents = self.tile[0][1]
        args = list(self.tile[0][3])

        # To be nice on memory footprint, if there's a
        # file descriptor, use that instead of reading
        # into a string in python.
        # libtiff closes the file descriptor, so pass in a dup.
        try:
            fp = hasattr(self.fp, "fileno") and os.dup(self.fp.fileno())
            # flush the file descriptor, prevents error on pypy 2.4+
            # should also eliminate the need for fp.tell
            # in _seek
            if hasattr(self.fp, "flush"):
                self.fp.flush()
        except OSError:
            # io.BytesIO have a fileno, but returns an OSError if
            # it doesn't use a file descriptor.
            fp = False

        if fp:
            args[2] = fp

        decoder = Image._getdecoder(
            self.mode, "libtiff", tuple(args), self.decoderconfig
        )
        try:
            decoder.setimage(self.im, extents)
        except ValueError as e:
            raise OSError("Couldn't set the image") from e

        close_self_fp = self._exclusive_fp and not self.is_animated
        if hasattr(self.fp, "getvalue"):
            # We've got a stringio like thing passed in. Yay for all in memory.
            # The decoder needs the entire file in one shot, so there's not
            # a lot we can do here other than give it the entire file.
            # unless we could do something like get the address of the
            # underlying string for stringio.
            #
            # Rearranging for supporting byteio items, since they have a fileno
            # that returns an OSError if there's no underlying fp. Easier to
            # deal with here by reordering.
            logger.debug("have getvalue. just sending in a string from getvalue")
            n, err = decoder.decode(self.fp.getvalue())
        elif fp:
            # we've got a actual file on disk, pass in the fp.
            logger.debug("have fileno, calling fileno version of the decoder.")
            if not close_self_fp:
                self.fp.seek(0)
            # 4 bytes, otherwise the trace might error out
            n, err = decoder.decode(b"fpfp")
        else:
            # we have something else.
            logger.debug("don't have fileno or getvalue. just reading")
            self.fp.seek(0)
            # UNDONE -- so much for that buffer size thing.
            n, err = decoder.decode(self.fp.read())

        if fp:
            try:
                os.close(fp)
            except OSError:
                pass

        self.tile = []
        self.readonly = 0

        self.load_end()

        # libtiff closed the fp in a, we need to close self.fp, if possible
        if close_self_fp:
            self.fp.close()
            self.fp = None  # might be shared

        if err < 0:
            raise OSError(err)

        return Image.Image.load(self)

    def _setup(self):
        """Setup this image object based on current tags"""

        if 0xBC01 in self.tag_v2:
            raise OSError("Windows Media Photo files not yet supported")

        # extract relevant tags
        self._compression = COMPRESSION_INFO[self.tag_v2.get(COMPRESSION, 1)]
        self._planar_configuration = self.tag_v2.get(PLANAR_CONFIGURATION, 1)

        # photometric is a required tag, but not everyone is reading
        # the specification
        photo = self.tag_v2.get(PHOTOMETRIC_INTERPRETATION, 0)

        # old style jpeg compression images most certainly are YCbCr
        if self._compression == "tiff_jpeg":
            photo = 6

        fillorder = self.tag_v2.get(FILLORDER, 1)

        logger.debug("*** Summary ***")
        logger.debug(f"- compression: {self._compression}")
        logger.debug(f"- photometric_interpretation: {photo}")
        logger.debug(f"- planar_configuration: {self._planar_configuration}")
        logger.debug(f"- fill_order: {fillorder}")
        logger.debug(f"- YCbCr subsampling: {self.tag.get(YCBCRSUBSAMPLING)}")

        # size
        xsize = int(self.tag_v2.get(IMAGEWIDTH))
        ysize = int(self.tag_v2.get(IMAGELENGTH))
        self._size = xsize, ysize

        logger.debug(f"- size: {self.size}")

        sample_format = self.tag_v2.get(SAMPLEFORMAT, (1,))
        if len(sample_format) > 1 and max(sample_format) == min(sample_format) == 1:
            # SAMPLEFORMAT is properly per band, so an RGB image will
            # be (1,1,1).  But, we don't support per band pixel types,
            # and anything more than one band is a uint8. So, just
            # take the first element. Revisit this if adding support
            # for more exotic images.
            sample_format = (1,)

        bps_tuple = self.tag_v2.get(BITSPERSAMPLE, (1,))
        extra_tuple = self.tag_v2.get(EXTRASAMPLES, ())
        if photo in (2, 6, 8):  # RGB, YCbCr, LAB
            bps_count = 3
        elif photo == 5:  # CMYK
            bps_count = 4
        else:
            bps_count = 1
        bps_count += len(extra_tuple)
        bps_actual_count = len(bps_tuple)
        samples_per_pixel = self.tag_v2.get(
            SAMPLESPERPIXEL,
            3 if self._compression == "tiff_jpeg" and photo in (2, 6) else 1,
        )

        if samples_per_pixel > MAX_SAMPLESPERPIXEL:
            # DOS check, samples_per_pixel can be a Long, and we extend the tuple below
            logger.error("More samples per pixel than can be decoded: %s", samples_per_pixel)
            raise SyntaxError("Invalid value for samples per pixel")

        if samples_per_pixel < bps_actual_count:
            # If a file has more values in bps_tuple than expected,
            # remove the excess.
            bps_tuple = bps_tuple[:samples_per_pixel]
        elif samples_per_pixel > bps_actual_count and bps_actual_count == 1:
            # If a file has only one value in bps_tuple, when it should have more,
            # presume it is the same number of bits for all of the samples.
            bps_tuple = bps_tuple * samples_per_pixel

        if len(bps_tuple) != samples_per_pixel:
            raise SyntaxError("unknown data organization")

        # mode: check photometric interpretation and bits per pixel
        key = (
            self.tag_v2.prefix,
            photo,
            sample_format,
            fillorder,
            bps_tuple,
            extra_tuple,
        )
        logger.debug(f"format key: {key}")
        try:
            self.mode, rawmode = OPEN_INFO[key]
        except KeyError as e:
            logger.debug("- unsupported format")
            raise SyntaxError("unknown pixel mode") from e

        logger.debug(f"- raw mode: {rawmode}")
        logger.debug(f"- pil mode: {self.mode}")

        self.info["compression"] = self._compression

        xres = self.tag_v2.get(X_RESOLUTION, 1)
        yres = self.tag_v2.get(Y_RESOLUTION, 1)

        if xres and yres:
            resunit = self.tag_v2.get(RESOLUTION_UNIT)
            if resunit == 2:  # dots per inch
                self.info["dpi"] = (xres, yres)
            elif resunit == 3:  # dots per centimeter. convert to dpi
                self.info["dpi"] = (xres * 2.54, yres * 2.54)
            elif resunit is None:  # used to default to 1, but now 2)
                self.info["dpi"] = (xres, yres)
                # For backward compatibility,
                # we also preserve the old behavior
                self.info["resolution"] = xres, yres
            else:  # No absolute unit of measurement
                self.info["resolution"] = xres, yres

        # build tile descriptors
        x = y = layer = 0
        self.tile = []
        self.use_load_libtiff = READ_LIBTIFF or self._compression != "raw"
        if self.use_load_libtiff:
            # Decoder expects entire file as one tile.
            # There's a buffer size limit in load (64k)
            # so large g4 images will fail if we use that
            # function.
            #
            # Setup the one tile for the whole image, then
            # use the _load_libtiff function.

            # libtiff handles the fillmode for us, so 1;IR should
            # actually be 1;I. Including the R double reverses the
            # bits, so stripes of the image are reversed.  See
            # https://github.com/python-pillow/Pillow/issues/279
            if fillorder == 2:
                # Replace fillorder with fillorder=1
                key = key[:3] + (1,) + key[4:]
                logger.debug(f"format key: {key}")
                # this should always work, since all the
                # fillorder==2 modes have a corresponding
                # fillorder=1 mode
                self.mode, rawmode = OPEN_INFO[key]
            # libtiff always returns the bytes in native order.
            # we're expecting image byte order. So, if the rawmode
            # contains I;16, we need to convert from native to image
            # byte order.
            if rawmode == "I;16":
                rawmode = "I;16N"
            if ";16B" in rawmode:
                rawmode = rawmode.replace(";16B", ";16N")
            if ";16L" in rawmode:
                rawmode = rawmode.replace(";16L", ";16N")

            # YCbCr images with new jpeg compression with pixels in one plane
            # unpacked straight into RGB values
            if (
                photo == 6
                and self._compression == "jpeg"
                and self._planar_configuration == 1
            ):
                rawmode = "RGB"

            # Offset in the tile tuple is 0, we go from 0,0 to
            # w,h, and we only do this once -- eds
            a = (rawmode, self._compression, False, self.tag_v2.offset)
            self.tile.append(("libtiff", (0, 0, xsize, ysize), 0, a))

        elif STRIPOFFSETS in self.tag_v2 or TILEOFFSETS in self.tag_v2:
            # striped image
            if STRIPOFFSETS in self.tag_v2:
                offsets = self.tag_v2[STRIPOFFSETS]
                h = self.tag_v2.get(ROWSPERSTRIP, ysize)
                w = self.size[0]
            else:
                # tiled image
                offsets = self.tag_v2[TILEOFFSETS]
                w = self.tag_v2.get(TILEWIDTH)
                h = self.tag_v2.get(TILELENGTH)

            for offset in offsets:
                if x + w > xsize:
                    stride = w * sum(bps_tuple) / 8  # bytes per line
                else:
                    stride = 0

                tile_rawmode = rawmode
                if self._planar_configuration == 2:
                    # each band on it's own layer
                    tile_rawmode = rawmode[layer]
                    # adjust stride width accordingly
                    stride /= bps_count

                a = (tile_rawmode, int(stride), 1)
                self.tile.append(
                    (
                        self._compression,
                        (x, y, min(x + w, xsize), min(y + h, ysize)),
                        offset,
                        a,
                    )
                )
                x = x + w
                if x >= self.size[0]:
                    x, y = 0, y + h
                    if y >= self.size[1]:
                        x = y = 0
                        layer += 1
        else:
            logger.debug("- unsupported data organization")
            raise SyntaxError("unknown data organization")

        # Fix up info.
        if ICCPROFILE in self.tag_v2:
            self.info["icc_profile"] = self.tag_v2[ICCPROFILE]

        # fixup palette descriptor

        if self.mode in ["P", "PA"]:
            palette = [o8(b // 256) for b in self.tag_v2[COLORMAP]]
            self.palette = ImagePalette.raw("RGB;L", b"".join(palette))

        self._tile_orientation = self.tag_v2.get(0x0112)


#
# --------------------------------------------------------------------
# Write TIFF files

# little endian is default except for image modes with
# explicit big endian byte-order

SAVE_INFO = {
    # mode => rawmode, byteorder, photometrics,
    #           sampleformat, bitspersample, extra
    "1": ("1", II, 1, 1, (1,), None),
    "L": ("L", II, 1, 1, (8,), None),
    "LA": ("LA", II, 1, 1, (8, 8), 2),
    "P": ("P", II, 3, 1, (8,), None),
    "PA": ("PA", II, 3, 1, (8, 8), 2),
    "I": ("I;32S", II, 1, 2, (32,), None),
    "I;16": ("I;16", II, 1, 1, (16,), None),
    "I;16S": ("I;16S", II, 1, 2, (16,), None),
    "F": ("F;32F", II, 1, 3, (32,), None),
    "RGB": ("RGB", II, 2, 1, (8, 8, 8), None),
    "RGBX": ("RGBX", II, 2, 1, (8, 8, 8, 8), 0),
    "RGBA": ("RGBA", II, 2, 1, (8, 8, 8, 8), 2),
    "CMYK": ("CMYK", II, 5, 1, (8, 8, 8, 8), None),
    "YCbCr": ("YCbCr", II, 6, 1, (8, 8, 8), None),
    "LAB": ("LAB", II, 8, 1, (8, 8, 8), None),
    "I;32BS": ("I;32BS", MM, 1, 2, (32,), None),
    "I;16B": ("I;16B", MM, 1, 1, (16,), None),
    "I;16BS": ("I;16BS", MM, 1, 2, (16,), None),
    "F;32BF": ("F;32BF", MM, 1, 3, (32,), None),
}


def _save(im, fp, filename):

    try:
        rawmode, prefix, photo, format, bits, extra = SAVE_INFO[im.mode]
    except KeyError as e:
        raise OSError(f"cannot write mode {im.mode} as TIFF") from e

    ifd = ImageFileDirectory_v2(prefix=prefix)

    encoderinfo = im.encoderinfo
    encoderconfig = im.encoderconfig
    try:
        compression = encoderinfo["compression"]
    except KeyError:
        compression = im.info.get("compression")
        if isinstance(compression, int):
            # compression value may be from BMP. Ignore it
            compression = None
    if compression is None:
        compression = "raw"
    elif compression == "tiff_jpeg":
        # OJPEG is obsolete, so use new-style JPEG compression instead
        compression = "jpeg"
    elif compression == "tiff_deflate":
        compression = "tiff_adobe_deflate"

    libtiff = WRITE_LIBTIFF or compression != "raw"

    # required for color libtiff images
    ifd[PLANAR_CONFIGURATION] = 1

    ifd[IMAGEWIDTH] = im.size[0]
    ifd[IMAGELENGTH] = im.size[1]

    # write any arbitrary tags passed in as an ImageFileDirectory
    if "tiffinfo" in encoderinfo:
        info = encoderinfo["tiffinfo"]
    elif "exif" in encoderinfo:
        info = encoderinfo["exif"]
        if isinstance(info, bytes):
            exif = Image.Exif()
            exif.load(info)
            info = exif
    else:
        info = {}
    logger.debug("Tiffinfo Keys: %s" % list(info))
    if isinstance(info, ImageFileDirectory_v1):
        info = info.to_v2()
    for key in info:
        if isinstance(info, Image.Exif) and key in TiffTags.TAGS_V2_GROUPS.keys():
            ifd[key] = info.get_ifd(key)
        else:
            ifd[key] = info.get(key)
        try:
            ifd.tagtype[key] = info.tagtype[key]
        except Exception:
            pass  # might not be an IFD. Might not have populated type

    # additions written by Greg Couch, gregc@cgl.ucsf.edu
    # inspired by image-sig posting from Kevin Cazabon, kcazabon@home.com
    if hasattr(im, "tag_v2"):
        # preserve tags from original TIFF image file
        for key in (
            RESOLUTION_UNIT,
            X_RESOLUTION,
            Y_RESOLUTION,
            IPTC_NAA_CHUNK,
            PHOTOSHOP_CHUNK,
            XMP,
        ):
            if key in im.tag_v2:
                ifd[key] = im.tag_v2[key]
                ifd.tagtype[key] = im.tag_v2.tagtype[key]

    # preserve ICC profile (should also work when saving other formats
    # which support profiles as TIFF) -- 2008-06-06 Florian Hoech
    icc = encoderinfo.get("icc_profile", im.info.get("icc_profile"))
    if icc:
        ifd[ICCPROFILE] = icc

    for key, name in [
        (IMAGEDESCRIPTION, "description"),
        (X_RESOLUTION, "resolution"),
        (Y_RESOLUTION, "resolution"),
        (X_RESOLUTION, "x_resolution"),
        (Y_RESOLUTION, "y_resolution"),
        (RESOLUTION_UNIT, "resolution_unit"),
        (SOFTWARE, "software"),
        (DATE_TIME, "date_time"),
        (ARTIST, "artist"),
        (COPYRIGHT, "copyright"),
    ]:
        if name in encoderinfo:
            ifd[key] = encoderinfo[name]

    dpi = encoderinfo.get("dpi")
    if dpi:
        ifd[RESOLUTION_UNIT] = 2
        ifd[X_RESOLUTION] = dpi[0]
        ifd[Y_RESOLUTION] = dpi[1]

    if bits != (1,):
        ifd[BITSPERSAMPLE] = bits
        if len(bits) != 1:
            ifd[SAMPLESPERPIXEL] = len(bits)
    if extra is not None:
        ifd[EXTRASAMPLES] = extra
    if format != 1:
        ifd[SAMPLEFORMAT] = format

    if PHOTOMETRIC_INTERPRETATION not in ifd:
        ifd[PHOTOMETRIC_INTERPRETATION] = photo
    elif im.mode in ("1", "L") and ifd[PHOTOMETRIC_INTERPRETATION] == 0:
        if im.mode == "1":
            inverted_im = im.copy()
            px = inverted_im.load()
            for y in range(inverted_im.height):
                for x in range(inverted_im.width):
                    px[x, y] = 0 if px[x, y] == 255 else 255
            im = inverted_im
        else:
            im = ImageOps.invert(im)

    if im.mode in ["P", "PA"]:
        lut = im.im.getpalette("RGB", "RGB;L")
        colormap = []
        colors = len(lut) // 3
        for i in range(3):
            colormap += [v * 256 for v in lut[colors * i : colors * (i + 1)]]
            colormap += [0] * (256 - colors)
        ifd[COLORMAP] = colormap
    # data orientation
    stride = len(bits) * ((im.size[0] * bits[0] + 7) // 8)
    # aim for given strip size (64 KB by default) when using libtiff writer
    if libtiff:
        im_strip_size = encoderinfo.get("strip_size", STRIP_SIZE)
        rows_per_strip = 1 if stride == 0 else min(im_strip_size // stride, im.size[1])
        # JPEG encoder expects multiple of 8 rows
        if compression == "jpeg":
            rows_per_strip = min(((rows_per_strip + 7) // 8) * 8, im.size[1])
    else:
        rows_per_strip = im.size[1]
    if rows_per_strip == 0:
        rows_per_strip = 1
    strip_byte_counts = 1 if stride == 0 else stride * rows_per_strip
    strips_per_image = (im.size[1] + rows_per_strip - 1) // rows_per_strip
    ifd[ROWSPERSTRIP] = rows_per_strip
    if strip_byte_counts >= 2**16:
        ifd.tagtype[STRIPBYTECOUNTS] = TiffTags.LONG
    ifd[STRIPBYTECOUNTS] = (strip_byte_counts,) * (strips_per_image - 1) + (
        stride * im.size[1] - strip_byte_counts * (strips_per_image - 1),
    )
    ifd[STRIPOFFSETS] = tuple(
        range(0, strip_byte_counts * strips_per_image, strip_byte_counts)
    )  # this is adjusted by IFD writer
    # no compression by default:
    ifd[COMPRESSION] = COMPRESSION_INFO_REV.get(compression, 1)

    if im.mode == "YCbCr":
        for tag, value in {
            YCBCRSUBSAMPLING: (1, 1),
            REFERENCEBLACKWHITE: (0, 255, 128, 255, 128, 255),
        }.items():
            ifd.setdefault(tag, value)

    blocklist = [TILEWIDTH, TILELENGTH, TILEOFFSETS, TILEBYTECOUNTS]
    if libtiff:
        if "quality" in encoderinfo:
            quality = encoderinfo["quality"]
            if not isinstance(quality, int) or quality < 0 or quality > 100:
                raise ValueError("Invalid quality setting")
            if compression != "jpeg":
                raise ValueError(
                    "quality setting only supported for 'jpeg' compression"
                )
            ifd[JPEGQUALITY] = quality

        logger.debug("Saving using libtiff encoder")
        logger.debug("Items: %s" % sorted(ifd.items()))
        _fp = 0
        if hasattr(fp, "fileno"):
            try:
                fp.seek(0)
                _fp = os.dup(fp.fileno())
            except io.UnsupportedOperation:
                pass

        # optional types for non core tags
        types = {}
        # STRIPOFFSETS and STRIPBYTECOUNTS are added by the library
        # based on the data in the strip.
        # The other tags expect arrays with a certain length (fixed or depending on
        # BITSPERSAMPLE, etc), passing arrays with a different length will result in
        # segfaults. Block these tags until we add extra validation.
        # SUBIFD may also cause a segfault.
        blocklist += [
            REFERENCEBLACKWHITE,
            STRIPBYTECOUNTS,
            STRIPOFFSETS,
            TRANSFERFUNCTION,
            SUBIFD,
        ]

        # bits per sample is a single short in the tiff directory, not a list.
        atts = {BITSPERSAMPLE: bits[0]}
        # Merge the ones that we have with (optional) more bits from
        # the original file, e.g x,y resolution so that we can
        # save(load('')) == original file.
        legacy_ifd = {}
        if hasattr(im, "tag"):
            legacy_ifd = im.tag.to_v2()

        # SAMPLEFORMAT is determined by the image format and should not be copied
        # from legacy_ifd.
        supplied_tags = {**getattr(im, "tag_v2", {}), **legacy_ifd}
        if SAMPLEFORMAT in supplied_tags:
            del supplied_tags[SAMPLEFORMAT]

        for tag, value in itertools.chain(ifd.items(), supplied_tags.items()):
            # Libtiff can only process certain core items without adding
            # them to the custom dictionary.
            # Custom items are supported for int, float, unicode, string and byte
            # values. Other types and tuples require a tagtype.
            if tag not in TiffTags.LIBTIFF_CORE:
                if not Image.core.libtiff_support_custom_tags:
                    continue

                if tag in ifd.tagtype:
                    types[tag] = ifd.tagtype[tag]
                elif not (isinstance(value, (int, float, str, bytes))):
                    continue
                else:
                    type = TiffTags.lookup(tag).type
                    if type:
                        types[tag] = type
            if tag not in atts and tag not in blocklist:
                if isinstance(value, str):
                    atts[tag] = value.encode("ascii", "replace") + b"\0"
                elif isinstance(value, IFDRational):
                    atts[tag] = float(value)
                else:
                    atts[tag] = value

        if SAMPLEFORMAT in atts and len(atts[SAMPLEFORMAT]) == 1:
            atts[SAMPLEFORMAT] = atts[SAMPLEFORMAT][0]

        logger.debug("Converted items: %s" % sorted(atts.items()))

        # libtiff always expects the bytes in native order.
        # we're storing image byte order. So, if the rawmode
        # contains I;16, we need to convert from native to image
        # byte order.
        if im.mode in ("I;16B", "I;16"):
            rawmode = "I;16N"

        # Pass tags as sorted list so that the tags are set in a fixed order.
        # This is required by libtiff for some tags. For example, the JPEGQUALITY
        # pseudo tag requires that the COMPRESS tag was already set.
        tags = list(atts.items())
        tags.sort()
        a = (rawmode, compression, _fp, filename, tags, types)
        e = Image._getencoder(im.mode, "libtiff", a, encoderconfig)
        e.setimage(im.im, (0, 0) + im.size)
        while True:
            # undone, change to self.decodermaxblock:
            l, s, d = e.encode(16 * 1024)
            if not _fp:
                fp.write(d)
            if s:
                break
        if s < 0:
            raise OSError(f"encoder error {s} when writing image file")

    else:
        for tag in blocklist:
            del ifd[tag]
        offset = ifd.save(fp)

        ImageFile._save(
            im, fp, [("raw", (0, 0) + im.size, offset, (rawmode, stride, 1))]
        )

    # -- helper for multi-page save --
    if "_debug_multipage" in encoderinfo:
        # just to access o32 and o16 (using correct byte order)
        im._debug_multipage = ifd


class AppendingTiffWriter:
    fieldSizes = [
        0,  # None
        1,  # byte
        1,  # ascii
        2,  # short
        4,  # long
        8,  # rational
        1,  # sbyte
        1,  # undefined
        2,  # sshort
        4,  # slong
        8,  # srational
        4,  # float
        8,  # double
    ]

    #    StripOffsets = 273
    #    FreeOffsets = 288
    #    TileOffsets = 324
    #    JPEGQTables = 519
    #    JPEGDCTables = 520
    #    JPEGACTables = 521
    Tags = {273, 288, 324, 519, 520, 521}

    def __init__(self, fn, new=False):
        if hasattr(fn, "read"):
            self.f = fn
            self.close_fp = False
        else:
            self.name = fn
            self.close_fp = True
            try:
                self.f = open(fn, "w+b" if new else "r+b")
            except OSError:
                self.f = open(fn, "w+b")
        self.beginning = self.f.tell()
        self.setup()

    def setup(self):
        # Reset everything.
        self.f.seek(self.beginning, os.SEEK_SET)

        self.whereToWriteNewIFDOffset = None
        self.offsetOfNewPage = 0

        self.IIMM = iimm = self.f.read(4)
        if not iimm:
            # empty file - first page
            self.isFirst = True
            return

        self.isFirst = False
        if iimm == b"II\x2a\x00":
            self.setEndian("<")
        elif iimm == b"MM\x00\x2a":
            self.setEndian(">")
        else:
            raise RuntimeError("Invalid TIFF file header")

        self.skipIFDs()
        self.goToEnd()

    def finalize(self):
        if self.isFirst:
            return

        # fix offsets
        self.f.seek(self.offsetOfNewPage)

        iimm = self.f.read(4)
        if not iimm:
            # raise RuntimeError("nothing written into new page")
            # Make it easy to finish a frame without committing to a new one.
            return

        if iimm != self.IIMM:
            raise RuntimeError("IIMM of new page doesn't match IIMM of first page")

        ifd_offset = self.readLong()
        ifd_offset += self.offsetOfNewPage
        self.f.seek(self.whereToWriteNewIFDOffset)
        self.writeLong(ifd_offset)
        self.f.seek(ifd_offset)
        self.fixIFD()

    def newFrame(self):
        # Call this to finish a frame.
        self.finalize()
        self.setup()

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if self.close_fp:
            self.close()
        return False

    def tell(self):
        return self.f.tell() - self.offsetOfNewPage

    def seek(self, offset, whence=io.SEEK_SET):
        if whence == os.SEEK_SET:
            offset += self.offsetOfNewPage

        self.f.seek(offset, whence)
        return self.tell()

    def goToEnd(self):
        self.f.seek(0, os.SEEK_END)
        pos = self.f.tell()

        # pad to 16 byte boundary
        pad_bytes = 16 - pos % 16
        if 0 < pad_bytes < 16:
            self.f.write(bytes(pad_bytes))
        self.offsetOfNewPage = self.f.tell()

    def setEndian(self, endian):
        self.endian = endian
        self.longFmt = self.endian + "L"
        self.shortFmt = self.endian + "H"
        self.tagFormat = self.endian + "HHL"

    def skipIFDs(self):
        while True:
            ifd_offset = self.readLong()
            if ifd_offset == 0:
                self.whereToWriteNewIFDOffset = self.f.tell() - 4
                break

            self.f.seek(ifd_offset)
            num_tags = self.readShort()
            self.f.seek(num_tags * 12, os.SEEK_CUR)

    def write(self, data):
        return self.f.write(data)

    def readShort(self):
        (value,) = struct.unpack(self.shortFmt, self.f.read(2))
        return value

    def readLong(self):
        (value,) = struct.unpack(self.longFmt, self.f.read(4))
        return value

    def rewriteLastShortToLong(self, value):
        self.f.seek(-2, os.SEEK_CUR)
        bytes_written = self.f.write(struct.pack(self.longFmt, value))
        if bytes_written is not None and bytes_written != 4:
            raise RuntimeError(f"wrote only {bytes_written} bytes but wanted 4")

    def rewriteLastShort(self, value):
        self.f.seek(-2, os.SEEK_CUR)
        bytes_written = self.f.write(struct.pack(self.shortFmt, value))
        if bytes_written is not None and bytes_written != 2:
            raise RuntimeError(f"wrote only {bytes_written} bytes but wanted 2")

    def rewriteLastLong(self, value):
        self.f.seek(-4, os.SEEK_CUR)
        bytes_written = self.f.write(struct.pack(self.longFmt, value))
        if bytes_written is not None and bytes_written != 4:
            raise RuntimeError(f"wrote only {bytes_written} bytes but wanted 4")

    def writeShort(self, value):
        bytes_written = self.f.write(struct.pack(self.shortFmt, value))
        if bytes_written is not None and bytes_written != 2:
            raise RuntimeError(f"wrote only {bytes_written} bytes but wanted 2")

    def writeLong(self, value):
        bytes_written = self.f.write(struct.pack(self.longFmt, value))
        if bytes_written is not None and bytes_written != 4:
            raise RuntimeError(f"wrote only {bytes_written} bytes but wanted 4")

    def close(self):
        self.finalize()
        self.f.close()

    def fixIFD(self):
        num_tags = self.readShort()

        for i in range(num_tags):
            tag, field_type, count = struct.unpack(self.tagFormat, self.f.read(8))

            field_size = self.fieldSizes[field_type]
            total_size = field_size * count
            is_local = total_size <= 4
            if not is_local:
                offset = self.readLong()
                offset += self.offsetOfNewPage
                self.rewriteLastLong(offset)

            if tag in self.Tags:
                cur_pos = self.f.tell()

                if is_local:
                    self.fixOffsets(
                        count, isShort=(field_size == 2), isLong=(field_size == 4)
                    )
                    self.f.seek(cur_pos + 4)
                else:
                    self.f.seek(offset)
                    self.fixOffsets(
                        count, isShort=(field_size == 2), isLong=(field_size == 4)
                    )
                    self.f.seek(cur_pos)

                offset = cur_pos = None

            elif is_local:
                # skip the locally stored value that is not an offset
                self.f.seek(4, os.SEEK_CUR)

    def fixOffsets(self, count, isShort=False, isLong=False):
        if not isShort and not isLong:
            raise RuntimeError("offset is neither short nor long")

        for i in range(count):
            offset = self.readShort() if isShort else self.readLong()
            offset += self.offsetOfNewPage
            if isShort and offset >= 65536:
                # offset is now too large - we must convert shorts to longs
                if count != 1:
                    raise RuntimeError("not implemented")  # XXX TODO

                # simple case - the offset is just one and therefore it is
                # local (not referenced with another offset)
                self.rewriteLastShortToLong(offset)
                self.f.seek(-10, os.SEEK_CUR)
                self.writeShort(TiffTags.LONG)  # rewrite the type to LONG
                self.f.seek(8, os.SEEK_CUR)
            elif isShort:
                self.rewriteLastShort(offset)
            else:
                self.rewriteLastLong(offset)


def _save_all(im, fp, filename):
    encoderinfo = im.encoderinfo.copy()
    encoderconfig = im.encoderconfig
    append_images = list(encoderinfo.get("append_images", []))
    if not hasattr(im, "n_frames") and not append_images:
        return _save(im, fp, filename)

    cur_idx = im.tell()
    try:
        with AppendingTiffWriter(fp) as tf:
            for ims in [im] + append_images:
                ims.encoderinfo = encoderinfo
                ims.encoderconfig = encoderconfig
                if not hasattr(ims, "n_frames"):
                    nfr = 1
                else:
                    nfr = ims.n_frames

                for idx in range(nfr):
                    ims.seek(idx)
                    ims.load()
                    _save(ims, tf, filename)
                    tf.newFrame()
    finally:
        im.seek(cur_idx)


#
# --------------------------------------------------------------------
# Register

Image.register_open(TiffImageFile.format, TiffImageFile, _accept)
Image.register_save(TiffImageFile.format, _save)
Image.register_save_all(TiffImageFile.format, _save_all)

Image.register_extensions(TiffImageFile.format, [".tif", ".tiff"])

Image.register_mime(TiffImageFile.format, "image/tiff")