test_file_png.py

import re
import sys
import zlib
from io import BytesIO

import pytest

from PIL import Image, ImageFile, PngImagePlugin, features

from .helper import (
    PillowLeakTestCase,
    assert_image,
    assert_image_equal,
    assert_image_equal_tofile,
    hopper,
    is_win32,
    mark_if_feature_version,
    skip_unless_feature,
)

try:
    import defusedxml.ElementTree as ElementTree
except ImportError:
    ElementTree = None

# sample png stream

TEST_PNG_FILE = "Tests/images/hopper.png"

# stuff to create inline PNG images

MAGIC = PngImagePlugin._MAGIC


def chunk(cid, *data):
    test_file = BytesIO()
    PngImagePlugin.putchunk(*(test_file, cid) + data)
    return test_file.getvalue()


o32 = PngImagePlugin.o32

IHDR = chunk(b"IHDR", o32(1), o32(1), b"\x08\x02", b"\0\0\0")
IDAT = chunk(b"IDAT")
IEND = chunk(b"IEND")

HEAD = MAGIC + IHDR
TAIL = IDAT + IEND


def load(data):
    return Image.open(BytesIO(data))


def roundtrip(im, **options):
    out = BytesIO()
    im.save(out, "PNG", **options)
    out.seek(0)
    return Image.open(out)


@skip_unless_feature("zlib")
class TestFilePng:
    def get_chunks(self, filename):
        chunks = []
        with open(filename, "rb") as fp:
            fp.read(8)
            with PngImagePlugin.PngStream(fp) as png:
                while True:
                    cid, pos, length = png.read()
                    chunks.append(cid)
                    try:
                        s = png.call(cid, pos, length)
                    except EOFError:
                        break
                    png.crc(cid, s)
        return chunks

    def test_sanity(self, tmp_path):

        # internal version number
        assert re.search(r"\d+\.\d+\.\d+(\.\d+)?$", features.version_codec("zlib"))

        test_file = str(tmp_path / "temp.png")

        hopper("RGB").save(test_file)

        with Image.open(test_file) as im:
            im.load()
            assert im.mode == "RGB"
            assert im.size == (128, 128)
            assert im.format == "PNG"
            assert im.get_format_mimetype() == "image/png"

        for mode in ["1", "L", "P", "RGB", "I", "I;16"]:
            im = hopper(mode)
            im.save(test_file)
            with Image.open(test_file) as reloaded:
                if mode == "I;16":
                    reloaded = reloaded.convert(mode)
                assert_image_equal(reloaded, im)

    def test_invalid_file(self):
        invalid_file = "Tests/images/flower.jpg"

        with pytest.raises(SyntaxError):
            PngImagePlugin.PngImageFile(invalid_file)

    def test_broken(self):
        # Check reading of totally broken files.  In this case, the test
        # file was checked into Subversion as a text file.

        test_file = "Tests/images/broken.png"
        with pytest.raises(OSError):
            with Image.open(test_file):
                pass

    def test_bad_text(self):
        # Make sure PIL can read malformed tEXt chunks (@PIL152)

        im = load(HEAD + chunk(b"tEXt") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"tEXt", b"spam") + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"tEXt", b"spam\0") + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"tEXt", b"spam\0egg") + TAIL)
        assert im.info == {"spam": "egg"}

        im = load(HEAD + chunk(b"tEXt", b"spam\0egg\0") + TAIL)
        assert im.info == {"spam": "egg\x00"}

    def test_bad_ztxt(self):
        # Test reading malformed zTXt chunks (python-pillow/Pillow#318)

        im = load(HEAD + chunk(b"zTXt") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"zTXt", b"spam") + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"zTXt", b"spam\0") + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"zTXt", b"spam\0\0") + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"zTXt", b"spam\0\0" + zlib.compress(b"egg")[:1]) + TAIL)
        assert im.info == {"spam": ""}

        im = load(HEAD + chunk(b"zTXt", b"spam\0\0" + zlib.compress(b"egg")) + TAIL)
        assert im.info == {"spam": "egg"}

    def test_bad_itxt(self):

        im = load(HEAD + chunk(b"iTXt") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"iTXt", b"spam") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"iTXt", b"spam\0") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"iTXt", b"spam\0\x02") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"iTXt", b"spam\0\0\0foo\0") + TAIL)
        assert im.info == {}

        im = load(HEAD + chunk(b"iTXt", b"spam\0\0\0en\0Spam\0egg") + TAIL)
        assert im.info == {"spam": "egg"}
        assert im.info["spam"].lang == "en"
        assert im.info["spam"].tkey == "Spam"

        im = load(
            HEAD
            + chunk(b"iTXt", b"spam\0\1\0en\0Spam\0" + zlib.compress(b"egg")[:1])
            + TAIL
        )
        assert im.info == {"spam": ""}

        im = load(
            HEAD
            + chunk(b"iTXt", b"spam\0\1\1en\0Spam\0" + zlib.compress(b"egg"))
            + TAIL
        )
        assert im.info == {}

        im = load(
            HEAD
            + chunk(b"iTXt", b"spam\0\1\0en\0Spam\0" + zlib.compress(b"egg"))
            + TAIL
        )
        assert im.info == {"spam": "egg"}
        assert im.info["spam"].lang == "en"
        assert im.info["spam"].tkey == "Spam"

    def test_interlace(self):

        test_file = "Tests/images/pil123p.png"
        with Image.open(test_file) as im:
            assert_image(im, "P", (162, 150))
            assert im.info.get("interlace")

            im.load()

        test_file = "Tests/images/pil123rgba.png"
        with Image.open(test_file) as im:
            assert_image(im, "RGBA", (162, 150))
            assert im.info.get("interlace")

            im.load()

    def test_load_transparent_p(self):
        test_file = "Tests/images/pil123p.png"
        with Image.open(test_file) as im:
            assert_image(im, "P", (162, 150))
            im = im.convert("RGBA")
        assert_image(im, "RGBA", (162, 150))

        # image has 124 unique alpha values
        assert len(im.getchannel("A").getcolors()) == 124

    def test_load_transparent_rgb(self):
        test_file = "Tests/images/rgb_trns.png"
        with Image.open(test_file) as im:
            assert im.info["transparency"] == (0, 255, 52)

            assert_image(im, "RGB", (64, 64))
            im = im.convert("RGBA")
        assert_image(im, "RGBA", (64, 64))

        # image has 876 transparent pixels
        assert im.getchannel("A").getcolors()[0][0] == 876

    def test_save_p_transparent_palette(self, tmp_path):
        in_file = "Tests/images/pil123p.png"
        with Image.open(in_file) as im:
            # 'transparency' contains a byte string with the opacity for
            # each palette entry
            assert len(im.info["transparency"]) == 256

            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

        # check if saved image contains same transparency
        with Image.open(test_file) as im:
            assert len(im.info["transparency"]) == 256

            assert_image(im, "P", (162, 150))
            im = im.convert("RGBA")
        assert_image(im, "RGBA", (162, 150))

        # image has 124 unique alpha values
        assert len(im.getchannel("A").getcolors()) == 124

    def test_save_p_single_transparency(self, tmp_path):
        in_file = "Tests/images/p_trns_single.png"
        with Image.open(in_file) as im:
            # pixel value 164 is full transparent
            assert im.info["transparency"] == 164
            assert im.getpixel((31, 31)) == 164

            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

        # check if saved image contains same transparency
        with Image.open(test_file) as im:
            assert im.info["transparency"] == 164
            assert im.getpixel((31, 31)) == 164
            assert_image(im, "P", (64, 64))
            im = im.convert("RGBA")
        assert_image(im, "RGBA", (64, 64))

        assert im.getpixel((31, 31)) == (0, 255, 52, 0)

        # image has 876 transparent pixels
        assert im.getchannel("A").getcolors()[0][0] == 876

    def test_save_p_transparent_black(self, tmp_path):
        # check if solid black image with full transparency
        # is supported (check for #1838)
        im = Image.new("RGBA", (10, 10), (0, 0, 0, 0))
        assert im.getcolors() == [(100, (0, 0, 0, 0))]

        im = im.convert("P")
        test_file = str(tmp_path / "temp.png")
        im.save(test_file)

        # check if saved image contains same transparency
        with Image.open(test_file) as im:
            assert len(im.info["transparency"]) == 256
            assert_image(im, "P", (10, 10))
            im = im.convert("RGBA")
        assert_image(im, "RGBA", (10, 10))
        assert im.getcolors() == [(100, (0, 0, 0, 0))]

    def test_save_greyscale_transparency(self, tmp_path):
        for mode, num_transparent in {"1": 1994, "L": 559, "I": 559}.items():
            in_file = "Tests/images/" + mode.lower() + "_trns.png"
            with Image.open(in_file) as im:
                assert im.mode == mode
                assert im.info["transparency"] == 255

                im_rgba = im.convert("RGBA")
            assert im_rgba.getchannel("A").getcolors()[0][0] == num_transparent

            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

            with Image.open(test_file) as test_im:
                assert test_im.mode == mode
                assert test_im.info["transparency"] == 255
                assert_image_equal(im, test_im)

            test_im_rgba = test_im.convert("RGBA")
            assert test_im_rgba.getchannel("A").getcolors()[0][0] == num_transparent

    def test_save_rgb_single_transparency(self, tmp_path):
        in_file = "Tests/images/caption_6_33_22.png"
        with Image.open(in_file) as im:
            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

    def test_load_verify(self):
        # Check open/load/verify exception (@PIL150)

        with Image.open(TEST_PNG_FILE) as im:
            # Assert that there is no unclosed file warning
            with pytest.warns(None) as record:
                im.verify()
            assert not record

        with Image.open(TEST_PNG_FILE) as im:
            im.load()
            with pytest.raises(RuntimeError):
                im.verify()

    def test_verify_struct_error(self):
        # Check open/load/verify exception (#1755)

        # offsets to test, -10: breaks in i32() in read. (OSError)
        #                  -13: breaks in crc, txt chunk.
        #                  -14: malformed chunk

        for offset in (-10, -13, -14):
            with open(TEST_PNG_FILE, "rb") as f:
                test_file = f.read()[:offset]

            with Image.open(BytesIO(test_file)) as im:
                assert im.fp is not None
                with pytest.raises((OSError, SyntaxError)):
                    im.verify()

    def test_verify_ignores_crc_error(self):
        # check ignores crc errors in ancillary chunks

        chunk_data = chunk(b"tEXt", b"spam")
        broken_crc_chunk_data = chunk_data[:-1] + b"q"  # break CRC

        image_data = HEAD + broken_crc_chunk_data + TAIL
        with pytest.raises(SyntaxError):
            PngImagePlugin.PngImageFile(BytesIO(image_data))

        ImageFile.LOAD_TRUNCATED_IMAGES = True
        try:
            im = load(image_data)
            assert im is not None
        finally:
            ImageFile.LOAD_TRUNCATED_IMAGES = False

    def test_verify_not_ignores_crc_error_in_required_chunk(self):
        # check does not ignore crc errors in required chunks

        image_data = MAGIC + IHDR[:-1] + b"q" + TAIL

        ImageFile.LOAD_TRUNCATED_IMAGES = True
        try:
            with pytest.raises(SyntaxError):
                PngImagePlugin.PngImageFile(BytesIO(image_data))
        finally:
            ImageFile.LOAD_TRUNCATED_IMAGES = False

    def test_roundtrip_dpi(self):
        # Check dpi roundtripping

        with Image.open(TEST_PNG_FILE) as im:
            im = roundtrip(im, dpi=(100.33, 100.33))
        assert im.info["dpi"] == (100.33, 100.33)

    def test_load_float_dpi(self):
        with Image.open(TEST_PNG_FILE) as im:
            assert im.info["dpi"] == (95.9866, 95.9866)

    def test_roundtrip_text(self):
        # Check text roundtripping

        with Image.open(TEST_PNG_FILE) as im:
            info = PngImagePlugin.PngInfo()
            info.add_text("TXT", "VALUE")
            info.add_text("ZIP", "VALUE", zip=True)

            im = roundtrip(im, pnginfo=info)
        assert im.info == {"TXT": "VALUE", "ZIP": "VALUE"}
        assert im.text == {"TXT": "VALUE", "ZIP": "VALUE"}

    def test_roundtrip_itxt(self):
        # Check iTXt roundtripping

        im = Image.new("RGB", (32, 32))
        info = PngImagePlugin.PngInfo()
        info.add_itxt("spam", "Eggs", "en", "Spam")
        info.add_text("eggs", PngImagePlugin.iTXt("Spam", "en", "Eggs"), zip=True)

        im = roundtrip(im, pnginfo=info)
        assert im.info == {"spam": "Eggs", "eggs": "Spam"}
        assert im.text == {"spam": "Eggs", "eggs": "Spam"}
        assert im.text["spam"].lang == "en"
        assert im.text["spam"].tkey == "Spam"
        assert im.text["eggs"].lang == "en"
        assert im.text["eggs"].tkey == "Eggs"

    def test_nonunicode_text(self):
        # Check so that non-Unicode text is saved as a tEXt rather than iTXt

        im = Image.new("RGB", (32, 32))
        info = PngImagePlugin.PngInfo()
        info.add_text("Text", "Ascii")
        im = roundtrip(im, pnginfo=info)
        assert isinstance(im.info["Text"], str)

    def test_unicode_text(self):
        # Check preservation of non-ASCII characters

        def rt_text(value):
            im = Image.new("RGB", (32, 32))
            info = PngImagePlugin.PngInfo()
            info.add_text("Text", value)
            im = roundtrip(im, pnginfo=info)
            assert im.info == {"Text": value}

        rt_text(" Aa" + chr(0xA0) + chr(0xC4) + chr(0xFF))  # Latin1
        rt_text(chr(0x400) + chr(0x472) + chr(0x4FF))  # Cyrillic
        # CJK:
        rt_text(chr(0x4E00) + chr(0x66F0) + chr(0x9FBA) + chr(0x3042) + chr(0xAC00))
        rt_text("A" + chr(0xC4) + chr(0x472) + chr(0x3042))  # Combined

    def test_scary(self):
        # Check reading of evil PNG file.  For information, see:
        # http://scary.beasts.org/security/CESA-2004-001.txt
        # The first byte is removed from pngtest_bad.png
        # to avoid classification as malware.

        with open("Tests/images/pngtest_bad.png.bin", "rb") as fd:
            data = b"\x89" + fd.read()

        pngfile = BytesIO(data)
        with pytest.raises(OSError):
            with Image.open(pngfile):
                pass

    def test_trns_rgb(self):
        # Check writing and reading of tRNS chunks for RGB images.
        # Independent file sample provided by Sebastian Spaeth.

        test_file = "Tests/images/caption_6_33_22.png"
        with Image.open(test_file) as im:
            assert im.info["transparency"] == (248, 248, 248)

            # check saving transparency by default
            im = roundtrip(im)
        assert im.info["transparency"] == (248, 248, 248)

        im = roundtrip(im, transparency=(0, 1, 2))
        assert im.info["transparency"] == (0, 1, 2)

    def test_trns_p(self, tmp_path):
        # Check writing a transparency of 0, issue #528
        im = hopper("P")
        im.info["transparency"] = 0

        f = str(tmp_path / "temp.png")
        im.save(f)

        with Image.open(f) as im2:
            assert "transparency" in im2.info

            assert_image_equal(im2.convert("RGBA"), im.convert("RGBA"))

    def test_trns_null(self):
        # Check reading images with null tRNS value, issue #1239
        test_file = "Tests/images/tRNS_null_1x1.png"
        with Image.open(test_file) as im:

            assert im.info["transparency"] == 0

    def test_save_icc_profile(self):
        with Image.open("Tests/images/icc_profile_none.png") as im:
            assert im.info["icc_profile"] is None

            with Image.open("Tests/images/icc_profile.png") as with_icc:
                expected_icc = with_icc.info["icc_profile"]

                im = roundtrip(im, icc_profile=expected_icc)
                assert im.info["icc_profile"] == expected_icc

    def test_discard_icc_profile(self):
        with Image.open("Tests/images/icc_profile.png") as im:
            assert "icc_profile" in im.info

            im = roundtrip(im, icc_profile=None)
        assert "icc_profile" not in im.info

    def test_roundtrip_icc_profile(self):
        with Image.open("Tests/images/icc_profile.png") as im:
            expected_icc = im.info["icc_profile"]

            im = roundtrip(im)
        assert im.info["icc_profile"] == expected_icc

    def test_roundtrip_no_icc_profile(self):
        with Image.open("Tests/images/icc_profile_none.png") as im:
            assert im.info["icc_profile"] is None

            im = roundtrip(im)
        assert "icc_profile" not in im.info

    def test_repr_png(self):
        im = hopper()

        with Image.open(BytesIO(im._repr_png_())) as repr_png:
            assert repr_png.format == "PNG"
            assert_image_equal(im, repr_png)

    def test_repr_png_error(self):
        im = hopper("F")

        with pytest.raises(ValueError):
            im._repr_png_()

    def test_chunk_order(self, tmp_path):
        with Image.open("Tests/images/icc_profile.png") as im:
            test_file = str(tmp_path / "temp.png")
            im.convert("P").save(test_file, dpi=(100, 100))

        chunks = self.get_chunks(test_file)

        # https://www.w3.org/TR/PNG/#5ChunkOrdering
        # IHDR - shall be first
        assert chunks.index(b"IHDR") == 0
        # PLTE - before first IDAT
        assert chunks.index(b"PLTE") < chunks.index(b"IDAT")
        # iCCP - before PLTE and IDAT
        assert chunks.index(b"iCCP") < chunks.index(b"PLTE")
        assert chunks.index(b"iCCP") < chunks.index(b"IDAT")
        # tRNS - after PLTE, before IDAT
        assert chunks.index(b"tRNS") > chunks.index(b"PLTE")
        assert chunks.index(b"tRNS") < chunks.index(b"IDAT")
        # pHYs - before IDAT
        assert chunks.index(b"pHYs") < chunks.index(b"IDAT")

    def test_getchunks(self):
        im = hopper()

        chunks = PngImagePlugin.getchunks(im)
        assert len(chunks) == 3

    def test_read_private_chunks(self):
        with Image.open("Tests/images/exif.png") as im:
            assert im.private_chunks == [(b"orNT", b"\x01")]

    def test_roundtrip_private_chunk(self):
        # Check private chunk roundtripping

        with Image.open(TEST_PNG_FILE) as im:
            info = PngImagePlugin.PngInfo()
            info.add(b"prIV", b"VALUE")
            info.add(b"atEC", b"VALUE2")
            info.add(b"prIV", b"VALUE3", True)

            im = roundtrip(im, pnginfo=info)
        assert im.private_chunks == [(b"prIV", b"VALUE"), (b"atEC", b"VALUE2")]
        im.load()
        assert im.private_chunks == [
            (b"prIV", b"VALUE"),
            (b"atEC", b"VALUE2"),
            (b"prIV", b"VALUE3", True),
        ]

    def test_textual_chunks_after_idat(self):
        with Image.open("Tests/images/hopper.png") as im:
            assert "comment" in im.text.keys()
            for k, v in {
                "date:create": "2014-09-04T09:37:08+03:00",
                "date:modify": "2014-09-04T09:37:08+03:00",
            }.items():
                assert im.text[k] == v

        # Raises a SyntaxError in load_end
        with Image.open("Tests/images/broken_data_stream.png") as im:
            with pytest.raises(OSError):
                assert isinstance(im.text, dict)

        # Raises a UnicodeDecodeError in load_end
        with Image.open("Tests/images/truncated_image.png") as im:
            # The file is truncated
            with pytest.raises(OSError):
                im.text()
            ImageFile.LOAD_TRUNCATED_IMAGES = True
            assert isinstance(im.text, dict)
            ImageFile.LOAD_TRUNCATED_IMAGES = False

        # Raises an EOFError in load_end
        with Image.open("Tests/images/hopper_idat_after_image_end.png") as im:
            assert im.text == {"TXT": "VALUE", "ZIP": "VALUE"}

    def test_padded_idat(self):
        # This image has been manually hexedited
        # so that the IDAT chunk has padding at the end
        # Set MAXBLOCK to the length of the actual data
        # so that the decoder finishes reading before the chunk ends
        MAXBLOCK = ImageFile.MAXBLOCK
        ImageFile.MAXBLOCK = 45
        ImageFile.LOAD_TRUNCATED_IMAGES = True

        with Image.open("Tests/images/padded_idat.png") as im:
            im.load()

            ImageFile.MAXBLOCK = MAXBLOCK
            ImageFile.LOAD_TRUNCATED_IMAGES = False

            assert_image_equal_tofile(im, "Tests/images/bw_gradient.png")

    def test_specify_bits(self, tmp_path):
        im = hopper("P")

        out = str(tmp_path / "temp.png")
        im.save(out, bits=4)

        with Image.open(out) as reloaded:
            assert len(reloaded.png.im_palette[1]) == 48

    def test_plte_length(self, tmp_path):
        im = Image.new("P", (1, 1))
        im.putpalette((1, 1, 1))

        out = str(tmp_path / "temp.png")
        im.save(str(tmp_path / "temp.png"))

        with Image.open(out) as reloaded:
            assert len(reloaded.png.im_palette[1]) == 3

    def test_getxmp(self):
        with Image.open("Tests/images/color_snakes.png") as im:
            if ElementTree is None:
                with pytest.warns(UserWarning):
                    assert im.getxmp() == {}
            else:
                xmp = im.getxmp()

                description = xmp["xmpmeta"]["RDF"]["Description"]
                assert description["PixelXDimension"] == "10"
                assert description["subject"]["Seq"] is None

    def test_exif(self):
        # With an EXIF chunk
        with Image.open("Tests/images/exif.png") as im:
            exif = im._getexif()
        assert exif[274] == 1

        # With an ImageMagick zTXt chunk
        with Image.open("Tests/images/exif_imagemagick.png") as im:
            exif = im._getexif()
            assert exif[274] == 1

            # Assert that info still can be extracted
            # when the image is no longer a PngImageFile instance
            exif = im.copy().getexif()
            assert exif[274] == 1

        # With a tEXt chunk
        with Image.open("Tests/images/exif_text.png") as im:
            exif = im._getexif()
        assert exif[274] == 1

        # With XMP tags
        with Image.open("Tests/images/xmp_tags_orientation.png") as im:
            exif = im.getexif()
        assert exif[274] == 3

    def test_exif_save(self, tmp_path):
        with Image.open("Tests/images/exif.png") as im:
            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

        with Image.open(test_file) as reloaded:
            exif = reloaded._getexif()
        assert exif[274] == 1

    @mark_if_feature_version(
        pytest.mark.valgrind_known_error, "libjpeg_turbo", "2.0", reason="Known Failing"
    )
    def test_exif_from_jpg(self, tmp_path):
        with Image.open("Tests/images/pil_sample_rgb.jpg") as im:
            test_file = str(tmp_path / "temp.png")
            im.save(test_file)

        with Image.open(test_file) as reloaded:
            exif = reloaded._getexif()
        assert exif[305] == "Adobe Photoshop CS Macintosh"

    def test_exif_argument(self, tmp_path):
        with Image.open(TEST_PNG_FILE) as im:
            test_file = str(tmp_path / "temp.png")
            im.save(test_file, exif=b"exifstring")

        with Image.open(test_file) as reloaded:
            assert reloaded.info["exif"] == b"Exif\x00\x00exifstring"

    def test_tell(self):
        with Image.open(TEST_PNG_FILE) as im:
            assert im.tell() == 0

    def test_seek(self):
        with Image.open(TEST_PNG_FILE) as im:
            im.seek(0)

            with pytest.raises(EOFError):
                im.seek(1)

    @pytest.mark.parametrize("buffer", (True, False))
    def test_save_stdout(self, buffer):
        old_stdout = sys.stdout

        if buffer:

            class MyStdOut:
                buffer = BytesIO()

            mystdout = MyStdOut()
        else:
            mystdout = BytesIO()

        sys.stdout = mystdout

        with Image.open(TEST_PNG_FILE) as im:
            im.save(sys.stdout, "PNG")

        # Reset stdout
        sys.stdout = old_stdout

        if buffer:
            mystdout = mystdout.buffer
        with Image.open(mystdout) as reloaded:
            assert_image_equal_tofile(reloaded, TEST_PNG_FILE)


@pytest.mark.skipif(is_win32(), reason="Requires Unix or macOS")
@skip_unless_feature("zlib")
class TestTruncatedPngPLeaks(PillowLeakTestCase):
    mem_limit = 2 * 1024  # max increase in K
    iterations = 100  # Leak is 56k/iteration, this will leak 5.6megs

    def test_leak_load(self):
        with open("Tests/images/hopper.png", "rb") as f:
            DATA = BytesIO(f.read(16 * 1024))

        ImageFile.LOAD_TRUNCATED_IMAGES = True
        with Image.open(DATA) as im:
            im.load()

        def core():
            with Image.open(DATA) as im:
                im.load()

        try:
            self._test_leak(core)
        finally:
            ImageFile.LOAD_TRUNCATED_IMAGES = False