Pass IFDs to libtiff as TIFF_LONG8

[radarhere]

Resolves #8522

7053 found that "EXIFIFDOffset" tag 34665 was being unexpectedly treated as a TIFF_LONG8 by libtiff. To fix this, it cast many TIFF_LONGs to 64-bits.

This reverts that change. Instead, I found https://gitlab.com/libtiff/libtiff/-/blob/master/libtiff/tif_dirinfo.c#L152-164 explaining that this is special behaviour for the IFD tags.

/*--: EXIFIFD and GPSIFD specified as TIFF_LONG by Aware-Systems and not TIFF_IFD8 as in original LibTiff. However, for IFD-like tags,
 * libtiff uses the data type TIFF_IFD8 in tiffFields[]-tag definition combined with a special handling procedure in order to write either
 * a 32-bit value and the TIFF_IFD type-id into ClassicTIFF files or a 64-bit value and the TIFF_IFD8 type-id into BigTIFF files. */
{TIFFTAG_EXIFIFD, 1, 1, TIFF_IFD8, 0, TIFF_SETGET_IFD8, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "EXIFIFDOffset", (TIFFFieldArray *)&exifFieldArray},
{TIFFTAG_ICCPROFILE, -3, -3, TIFF_UNDEFINED, 0, TIFF_SETGET_C32_UINT8, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 1, "ICC Profile", NULL},
{TIFFTAG_GPSIFD, 1, 1, TIFF_IFD8, 0, TIFF_SETGET_IFD8, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "GPSIFDOffset", (TIFFFieldArray *)&gpsFieldArray},
{TIFFTAG_FAXRECVPARAMS, 1, 1, TIFF_LONG, 0, TIFF_SETGET_UINT32, TIFF_SETGET_UINT32, FIELD_CUSTOM, TRUE, FALSE, "FaxRecvParams", NULL},
{TIFFTAG_FAXSUBADDRESS, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_ASCII, TIFF_SETGET_ASCII, FIELD_CUSTOM, TRUE, FALSE, "FaxSubAddress", NULL},
{TIFFTAG_FAXRECVTIME, 1, 1, TIFF_LONG, 0, TIFF_SETGET_UINT32, TIFF_SETGET_UINT32, FIELD_CUSTOM, TRUE, FALSE, "FaxRecvTime", NULL},
{TIFFTAG_FAXDCS, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_ASCII, TIFF_SETGET_ASCII, FIELD_CUSTOM, TRUE, FALSE, "FaxDcs", NULL},
{TIFFTAG_STONITS, 1, 1, TIFF_DOUBLE, 0, TIFF_SETGET_DOUBLE, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "StoNits", NULL},
{TIFFTAG_IMAGESOURCEDATA, -3, -3, TIFF_UNDEFINED, 0, TIFF_SETGET_C32_UINT8, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 1, "Adobe Photoshop Document Data Block", NULL},
{TIFFTAG_INTEROPERABILITYIFD, 1, 1, TIFF_IFD8, 0, TIFF_SETGET_IFD8, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "InteroperabilityIFDOffset", NULL},

This PR passes the EXIF, GPSInfo and Interop IFDs to libtiff as TIFF_LONG8.

[mgorny]

Thanks. It fixes the regression, but it doesn't seem to get IFD right still, at least on PowerPC:

____________________________________________________ TestFileLibTiff.test_exif_ifd ____________________________________________________

self = <Tests.test_file_libtiff.TestFileLibTiff object at 0xf60a0c90>

    def test_exif_ifd(self) -> None:
        out = io.BytesIO()
        with Image.open("Tests/images/tiff_adobe_deflate.tif") as im:
            assert im.tag_v2[34665] == 125456
            im.save(out, "TIFF")

            with Image.open(out) as reloaded:
                assert 34665 not in reloaded.tag_v2

>           im.save(out, "TIFF", tiffinfo={34665: 125456})

Tests/test_file_libtiff.py:709: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
src/PIL/Image.py:2605: in save
    save_handler(self, fp, filename)
src/PIL/TiffImagePlugin.py:1954: in _save
    encoder = Image._getencoder(im.mode, "libtiff", a, encoderconfig)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

mode = 'RGB', encoder_name = 'libtiff'
args = ('RGB', 'tiff_adobe_deflate', 0, '', [(254, 0), (256, 278), (257, 374), (258, 8), (259, 8), (262, 2), ...], {254: 4, 273: 4, 279: 4, 305: 2, ...})
extra = ()

    def _getencoder(
        mode: str, encoder_name: str, args: Any, extra: tuple[Any, ...] = ()
    ) -> core.ImagingEncoder | ImageFile.PyEncoder:
        # tweak arguments
        if args is None:
            args = ()
        elif not isinstance(args, tuple):
            args = (args,)

        try:
            encoder = ENCODERS[encoder_name]
        except KeyError:
            pass
        else:
            return encoder(mode, *args + extra)

        try:
            # get encoder
            encoder = getattr(core, f"{encoder_name}_encoder")
        except AttributeError as e:
            msg = f"encoder {encoder_name} not available"
            raise OSError(msg) from e
>       return encoder(mode, *args + extra)
E       RuntimeError: Error setting from dictionary

src/PIL/Image.py:467: RuntimeError
-------------------------------------------------------- Captured stderr call ---------------------------------------------------------
_TIFFVSetField: : Bad LONG8 or IFD8 value 538833550496960 for "EXIFIFDOffset" tag 34665 in ClassicTIFF. Tag won't be written to file.

[mgorny]

Hmm:

125456 = 0x1EA10
538833550496960 = 0x1EA10F65ED4C0

So it's still getting some junk?

[radarhere]

Yes, I jumped the gun slightly.

I've updated the commit. Please try again.

[mgorny]

Thanks! With this change, all tests pass for me now.