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authorLibravatarLibravatar Biswakalyan Bhuyan <biswa@surgot.in> 2022-11-13 23:46:45 +0530
committerLibravatarLibravatar Biswakalyan Bhuyan <biswa@surgot.in> 2022-11-13 23:46:45 +0530
commit9468226a9e2e2ab8cdd599f1d8538e860ca86120 (patch)
tree0a77ada226d6db80639f96b438bf83e4e756edb5 /env/lib/python3.10/site-packages/PIL/ImageFile.py
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+#
+# The Python Imaging Library.
+# $Id$
+#
+# base class for image file handlers
+#
+# history:
+# 1995-09-09 fl Created
+# 1996-03-11 fl Fixed load mechanism.
+# 1996-04-15 fl Added pcx/xbm decoders.
+# 1996-04-30 fl Added encoders.
+# 1996-12-14 fl Added load helpers
+# 1997-01-11 fl Use encode_to_file where possible
+# 1997-08-27 fl Flush output in _save
+# 1998-03-05 fl Use memory mapping for some modes
+# 1999-02-04 fl Use memory mapping also for "I;16" and "I;16B"
+# 1999-05-31 fl Added image parser
+# 2000-10-12 fl Set readonly flag on memory-mapped images
+# 2002-03-20 fl Use better messages for common decoder errors
+# 2003-04-21 fl Fall back on mmap/map_buffer if map is not available
+# 2003-10-30 fl Added StubImageFile class
+# 2004-02-25 fl Made incremental parser more robust
+#
+# Copyright (c) 1997-2004 by Secret Labs AB
+# Copyright (c) 1995-2004 by Fredrik Lundh
+#
+# See the README file for information on usage and redistribution.
+#
+
+import io
+import itertools
+import struct
+import sys
+
+from . import Image
+from ._util import is_path
+
+MAXBLOCK = 65536
+
+SAFEBLOCK = 1024 * 1024
+
+LOAD_TRUNCATED_IMAGES = False
+"""Whether or not to load truncated image files. User code may change this."""
+
+ERRORS = {
+ -1: "image buffer overrun error",
+ -2: "decoding error",
+ -3: "unknown error",
+ -8: "bad configuration",
+ -9: "out of memory error",
+}
+"""
+Dict of known error codes returned from :meth:`.PyDecoder.decode`,
+:meth:`.PyEncoder.encode` :meth:`.PyEncoder.encode_to_pyfd` and
+:meth:`.PyEncoder.encode_to_file`.
+"""
+
+
+#
+# --------------------------------------------------------------------
+# Helpers
+
+
+def raise_oserror(error):
+ try:
+ message = Image.core.getcodecstatus(error)
+ except AttributeError:
+ message = ERRORS.get(error)
+ if not message:
+ message = f"decoder error {error}"
+ raise OSError(message + " when reading image file")
+
+
+def _tilesort(t):
+ # sort on offset
+ return t[2]
+
+
+#
+# --------------------------------------------------------------------
+# ImageFile base class
+
+
+class ImageFile(Image.Image):
+ """Base class for image file format handlers."""
+
+ def __init__(self, fp=None, filename=None):
+ super().__init__()
+
+ self._min_frame = 0
+
+ self.custom_mimetype = None
+
+ self.tile = None
+ """ A list of tile descriptors, or ``None`` """
+
+ self.readonly = 1 # until we know better
+
+ self.decoderconfig = ()
+ self.decodermaxblock = MAXBLOCK
+
+ if is_path(fp):
+ # filename
+ self.fp = open(fp, "rb")
+ self.filename = fp
+ self._exclusive_fp = True
+ else:
+ # stream
+ self.fp = fp
+ self.filename = filename
+ # can be overridden
+ self._exclusive_fp = None
+
+ try:
+ try:
+ self._open()
+ except (
+ IndexError, # end of data
+ TypeError, # end of data (ord)
+ KeyError, # unsupported mode
+ EOFError, # got header but not the first frame
+ struct.error,
+ ) as v:
+ raise SyntaxError(v) from v
+
+ if not self.mode or self.size[0] <= 0 or self.size[1] <= 0:
+ raise SyntaxError("not identified by this driver")
+ except BaseException:
+ # close the file only if we have opened it this constructor
+ if self._exclusive_fp:
+ self.fp.close()
+ raise
+
+ def get_format_mimetype(self):
+ if self.custom_mimetype:
+ return self.custom_mimetype
+ if self.format is not None:
+ return Image.MIME.get(self.format.upper())
+
+ def verify(self):
+ """Check file integrity"""
+
+ # raise exception if something's wrong. must be called
+ # directly after open, and closes file when finished.
+ if self._exclusive_fp:
+ self.fp.close()
+ self.fp = None
+
+ def load(self):
+ """Load image data based on tile list"""
+
+ if self.tile is None:
+ raise OSError("cannot load this image")
+
+ pixel = Image.Image.load(self)
+ if not self.tile:
+ return pixel
+
+ self.map = None
+ use_mmap = self.filename and len(self.tile) == 1
+ # As of pypy 2.1.0, memory mapping was failing here.
+ use_mmap = use_mmap and not hasattr(sys, "pypy_version_info")
+
+ readonly = 0
+
+ # look for read/seek overrides
+ try:
+ read = self.load_read
+ # don't use mmap if there are custom read/seek functions
+ use_mmap = False
+ except AttributeError:
+ read = self.fp.read
+
+ try:
+ seek = self.load_seek
+ use_mmap = False
+ except AttributeError:
+ seek = self.fp.seek
+
+ if use_mmap:
+ # try memory mapping
+ decoder_name, extents, offset, args = self.tile[0]
+ if (
+ decoder_name == "raw"
+ and len(args) >= 3
+ and args[0] == self.mode
+ and args[0] in Image._MAPMODES
+ ):
+ try:
+ # use mmap, if possible
+ import mmap
+
+ with open(self.filename) as fp:
+ self.map = mmap.mmap(fp.fileno(), 0, access=mmap.ACCESS_READ)
+ if offset + self.size[1] * args[1] > self.map.size():
+ # buffer is not large enough
+ raise OSError
+ self.im = Image.core.map_buffer(
+ self.map, self.size, decoder_name, offset, args
+ )
+ readonly = 1
+ # After trashing self.im,
+ # we might need to reload the palette data.
+ if self.palette:
+ self.palette.dirty = 1
+ except (AttributeError, OSError, ImportError):
+ self.map = None
+
+ self.load_prepare()
+ err_code = -3 # initialize to unknown error
+ if not self.map:
+ # sort tiles in file order
+ self.tile.sort(key=_tilesort)
+
+ try:
+ # FIXME: This is a hack to handle TIFF's JpegTables tag.
+ prefix = self.tile_prefix
+ except AttributeError:
+ prefix = b""
+
+ # Remove consecutive duplicates that only differ by their offset
+ self.tile = [
+ list(tiles)[-1]
+ for _, tiles in itertools.groupby(
+ self.tile, lambda tile: (tile[0], tile[1], tile[3])
+ )
+ ]
+ for decoder_name, extents, offset, args in self.tile:
+ seek(offset)
+ decoder = Image._getdecoder(
+ self.mode, decoder_name, args, self.decoderconfig
+ )
+ try:
+ decoder.setimage(self.im, extents)
+ if decoder.pulls_fd:
+ decoder.setfd(self.fp)
+ err_code = decoder.decode(b"")[1]
+ else:
+ b = prefix
+ while True:
+ try:
+ s = read(self.decodermaxblock)
+ except (IndexError, struct.error) as e:
+ # truncated png/gif
+ if LOAD_TRUNCATED_IMAGES:
+ break
+ else:
+ raise OSError("image file is truncated") from e
+
+ if not s: # truncated jpeg
+ if LOAD_TRUNCATED_IMAGES:
+ break
+ else:
+ raise OSError(
+ "image file is truncated "
+ f"({len(b)} bytes not processed)"
+ )
+
+ b = b + s
+ n, err_code = decoder.decode(b)
+ if n < 0:
+ break
+ b = b[n:]
+ finally:
+ # Need to cleanup here to prevent leaks
+ decoder.cleanup()
+
+ self.tile = []
+ self.readonly = readonly
+
+ self.load_end()
+
+ if self._exclusive_fp and self._close_exclusive_fp_after_loading:
+ self.fp.close()
+ self.fp = None
+
+ if not self.map and not LOAD_TRUNCATED_IMAGES and err_code < 0:
+ # still raised if decoder fails to return anything
+ raise_oserror(err_code)
+
+ return Image.Image.load(self)
+
+ def load_prepare(self):
+ # create image memory if necessary
+ if not self.im or self.im.mode != self.mode or self.im.size != self.size:
+ self.im = Image.core.new(self.mode, self.size)
+ # create palette (optional)
+ if self.mode == "P":
+ Image.Image.load(self)
+
+ def load_end(self):
+ # may be overridden
+ pass
+
+ # may be defined for contained formats
+ # def load_seek(self, pos):
+ # pass
+
+ # may be defined for blocked formats (e.g. PNG)
+ # def load_read(self, bytes):
+ # pass
+
+ def _seek_check(self, frame):
+ if (
+ frame < self._min_frame
+ # Only check upper limit on frames if additional seek operations
+ # are not required to do so
+ or (
+ not (hasattr(self, "_n_frames") and self._n_frames is None)
+ and frame >= self.n_frames + self._min_frame
+ )
+ ):
+ raise EOFError("attempt to seek outside sequence")
+
+ return self.tell() != frame
+
+
+class StubImageFile(ImageFile):
+ """
+ Base class for stub image loaders.
+
+ A stub loader is an image loader that can identify files of a
+ certain format, but relies on external code to load the file.
+ """
+
+ def _open(self):
+ raise NotImplementedError("StubImageFile subclass must implement _open")
+
+ def load(self):
+ loader = self._load()
+ if loader is None:
+ raise OSError(f"cannot find loader for this {self.format} file")
+ image = loader.load(self)
+ assert image is not None
+ # become the other object (!)
+ self.__class__ = image.__class__
+ self.__dict__ = image.__dict__
+ return image.load()
+
+ def _load(self):
+ """(Hook) Find actual image loader."""
+ raise NotImplementedError("StubImageFile subclass must implement _load")
+
+
+class Parser:
+ """
+ Incremental image parser. This class implements the standard
+ feed/close consumer interface.
+ """
+
+ incremental = None
+ image = None
+ data = None
+ decoder = None
+ offset = 0
+ finished = 0
+
+ def reset(self):
+ """
+ (Consumer) Reset the parser. Note that you can only call this
+ method immediately after you've created a parser; parser
+ instances cannot be reused.
+ """
+ assert self.data is None, "cannot reuse parsers"
+
+ def feed(self, data):
+ """
+ (Consumer) Feed data to the parser.
+
+ :param data: A string buffer.
+ :exception OSError: If the parser failed to parse the image file.
+ """
+ # collect data
+
+ if self.finished:
+ return
+
+ if self.data is None:
+ self.data = data
+ else:
+ self.data = self.data + data
+
+ # parse what we have
+ if self.decoder:
+
+ if self.offset > 0:
+ # skip header
+ skip = min(len(self.data), self.offset)
+ self.data = self.data[skip:]
+ self.offset = self.offset - skip
+ if self.offset > 0 or not self.data:
+ return
+
+ n, e = self.decoder.decode(self.data)
+
+ if n < 0:
+ # end of stream
+ self.data = None
+ self.finished = 1
+ if e < 0:
+ # decoding error
+ self.image = None
+ raise_oserror(e)
+ else:
+ # end of image
+ return
+ self.data = self.data[n:]
+
+ elif self.image:
+
+ # if we end up here with no decoder, this file cannot
+ # be incrementally parsed. wait until we've gotten all
+ # available data
+ pass
+
+ else:
+
+ # attempt to open this file
+ try:
+ with io.BytesIO(self.data) as fp:
+ im = Image.open(fp)
+ except OSError:
+ # traceback.print_exc()
+ pass # not enough data
+ else:
+ flag = hasattr(im, "load_seek") or hasattr(im, "load_read")
+ if flag or len(im.tile) != 1:
+ # custom load code, or multiple tiles
+ self.decode = None
+ else:
+ # initialize decoder
+ im.load_prepare()
+ d, e, o, a = im.tile[0]
+ im.tile = []
+ self.decoder = Image._getdecoder(im.mode, d, a, im.decoderconfig)
+ self.decoder.setimage(im.im, e)
+
+ # calculate decoder offset
+ self.offset = o
+ if self.offset <= len(self.data):
+ self.data = self.data[self.offset :]
+ self.offset = 0
+
+ self.image = im
+
+ def __enter__(self):
+ return self
+
+ def __exit__(self, *args):
+ self.close()
+
+ def close(self):
+ """
+ (Consumer) Close the stream.
+
+ :returns: An image object.
+ :exception OSError: If the parser failed to parse the image file either
+ because it cannot be identified or cannot be
+ decoded.
+ """
+ # finish decoding
+ if self.decoder:
+ # get rid of what's left in the buffers
+ self.feed(b"")
+ self.data = self.decoder = None
+ if not self.finished:
+ raise OSError("image was incomplete")
+ if not self.image:
+ raise OSError("cannot parse this image")
+ if self.data:
+ # incremental parsing not possible; reopen the file
+ # not that we have all data
+ with io.BytesIO(self.data) as fp:
+ try:
+ self.image = Image.open(fp)
+ finally:
+ self.image.load()
+ return self.image
+
+
+# --------------------------------------------------------------------
+
+
+def _save(im, fp, tile, bufsize=0):
+ """Helper to save image based on tile list
+
+ :param im: Image object.
+ :param fp: File object.
+ :param tile: Tile list.
+ :param bufsize: Optional buffer size
+ """
+
+ im.load()
+ if not hasattr(im, "encoderconfig"):
+ im.encoderconfig = ()
+ tile.sort(key=_tilesort)
+ # FIXME: make MAXBLOCK a configuration parameter
+ # It would be great if we could have the encoder specify what it needs
+ # But, it would need at least the image size in most cases. RawEncode is
+ # a tricky case.
+ bufsize = max(MAXBLOCK, bufsize, im.size[0] * 4) # see RawEncode.c
+ try:
+ fh = fp.fileno()
+ fp.flush()
+ _encode_tile(im, fp, tile, bufsize, fh)
+ except (AttributeError, io.UnsupportedOperation) as exc:
+ _encode_tile(im, fp, tile, bufsize, None, exc)
+ if hasattr(fp, "flush"):
+ fp.flush()
+
+
+def _encode_tile(im, fp, tile, bufsize, fh, exc=None):
+ for e, b, o, a in tile:
+ if o > 0:
+ fp.seek(o)
+ encoder = Image._getencoder(im.mode, e, a, im.encoderconfig)
+ try:
+ encoder.setimage(im.im, b)
+ if encoder.pushes_fd:
+ encoder.setfd(fp)
+ l, s = encoder.encode_to_pyfd()
+ else:
+ if exc:
+ # compress to Python file-compatible object
+ while True:
+ l, s, d = encoder.encode(bufsize)
+ fp.write(d)
+ if s:
+ break
+ else:
+ # slight speedup: compress to real file object
+ s = encoder.encode_to_file(fh, bufsize)
+ if s < 0:
+ raise OSError(f"encoder error {s} when writing image file") from exc
+ finally:
+ encoder.cleanup()
+
+
+def _safe_read(fp, size):
+ """
+ Reads large blocks in a safe way. Unlike fp.read(n), this function
+ doesn't trust the user. If the requested size is larger than
+ SAFEBLOCK, the file is read block by block.
+
+ :param fp: File handle. Must implement a <b>read</b> method.
+ :param size: Number of bytes to read.
+ :returns: A string containing <i>size</i> bytes of data.
+
+ Raises an OSError if the file is truncated and the read cannot be completed
+
+ """
+ if size <= 0:
+ return b""
+ if size <= SAFEBLOCK:
+ data = fp.read(size)
+ if len(data) < size:
+ raise OSError("Truncated File Read")
+ return data
+ data = []
+ remaining_size = size
+ while remaining_size > 0:
+ block = fp.read(min(remaining_size, SAFEBLOCK))
+ if not block:
+ break
+ data.append(block)
+ remaining_size -= len(block)
+ if sum(len(d) for d in data) < size:
+ raise OSError("Truncated File Read")
+ return b"".join(data)
+
+
+class PyCodecState:
+ def __init__(self):
+ self.xsize = 0
+ self.ysize = 0
+ self.xoff = 0
+ self.yoff = 0
+
+ def extents(self):
+ return self.xoff, self.yoff, self.xoff + self.xsize, self.yoff + self.ysize
+
+
+class PyCodec:
+ def __init__(self, mode, *args):
+ self.im = None
+ self.state = PyCodecState()
+ self.fd = None
+ self.mode = mode
+ self.init(args)
+
+ def init(self, args):
+ """
+ Override to perform codec specific initialization
+
+ :param args: Array of args items from the tile entry
+ :returns: None
+ """
+ self.args = args
+
+ def cleanup(self):
+ """
+ Override to perform codec specific cleanup
+
+ :returns: None
+ """
+ pass
+
+ def setfd(self, fd):
+ """
+ Called from ImageFile to set the Python file-like object
+
+ :param fd: A Python file-like object
+ :returns: None
+ """
+ self.fd = fd
+
+ def setimage(self, im, extents=None):
+ """
+ Called from ImageFile to set the core output image for the codec
+
+ :param im: A core image object
+ :param extents: a 4 tuple of (x0, y0, x1, y1) defining the rectangle
+ for this tile
+ :returns: None
+ """
+
+ # following c code
+ self.im = im
+
+ if extents:
+ (x0, y0, x1, y1) = extents
+ else:
+ (x0, y0, x1, y1) = (0, 0, 0, 0)
+
+ if x0 == 0 and x1 == 0:
+ self.state.xsize, self.state.ysize = self.im.size
+ else:
+ self.state.xoff = x0
+ self.state.yoff = y0
+ self.state.xsize = x1 - x0
+ self.state.ysize = y1 - y0
+
+ if self.state.xsize <= 0 or self.state.ysize <= 0:
+ raise ValueError("Size cannot be negative")
+
+ if (
+ self.state.xsize + self.state.xoff > self.im.size[0]
+ or self.state.ysize + self.state.yoff > self.im.size[1]
+ ):
+ raise ValueError("Tile cannot extend outside image")
+
+
+class PyDecoder(PyCodec):
+ """
+ Python implementation of a format decoder. Override this class and
+ add the decoding logic in the :meth:`decode` method.
+
+ See :ref:`Writing Your Own File Codec in Python<file-codecs-py>`
+ """
+
+ _pulls_fd = False
+
+ @property
+ def pulls_fd(self):
+ return self._pulls_fd
+
+ def decode(self, buffer):
+ """
+ Override to perform the decoding process.
+
+ :param buffer: A bytes object with the data to be decoded.
+ :returns: A tuple of ``(bytes consumed, errcode)``.
+ If finished with decoding return -1 for the bytes consumed.
+ Err codes are from :data:`.ImageFile.ERRORS`.
+ """
+ raise NotImplementedError()
+
+ def set_as_raw(self, data, rawmode=None):
+ """
+ Convenience method to set the internal image from a stream of raw data
+
+ :param data: Bytes to be set
+ :param rawmode: The rawmode to be used for the decoder.
+ If not specified, it will default to the mode of the image
+ :returns: None
+ """
+
+ if not rawmode:
+ rawmode = self.mode
+ d = Image._getdecoder(self.mode, "raw", rawmode)
+ d.setimage(self.im, self.state.extents())
+ s = d.decode(data)
+
+ if s[0] >= 0:
+ raise ValueError("not enough image data")
+ if s[1] != 0:
+ raise ValueError("cannot decode image data")
+
+
+class PyEncoder(PyCodec):
+ """
+ Python implementation of a format encoder. Override this class and
+ add the decoding logic in the :meth:`encode` method.
+
+ See :ref:`Writing Your Own File Codec in Python<file-codecs-py>`
+ """
+
+ _pushes_fd = False
+
+ @property
+ def pushes_fd(self):
+ return self._pushes_fd
+
+ def encode(self, bufsize):
+ """
+ Override to perform the encoding process.
+
+ :param bufsize: Buffer size.
+ :returns: A tuple of ``(bytes encoded, errcode, bytes)``.
+ If finished with encoding return 1 for the error code.
+ Err codes are from :data:`.ImageFile.ERRORS`.
+ """
+ raise NotImplementedError()
+
+ def encode_to_pyfd(self):
+ """
+ If ``pushes_fd`` is ``True``, then this method will be used,
+ and ``encode()`` will only be called once.
+
+ :returns: A tuple of ``(bytes consumed, errcode)``.
+ Err codes are from :data:`.ImageFile.ERRORS`.
+ """
+ if not self.pushes_fd:
+ return 0, -8 # bad configuration
+ bytes_consumed, errcode, data = self.encode(0)
+ if data:
+ self.fd.write(data)
+ return bytes_consumed, errcode
+
+ def encode_to_file(self, fh, bufsize):
+ """
+ :param fh: File handle.
+ :param bufsize: Buffer size.
+
+ :returns: If finished successfully, return 0.
+ Otherwise, return an error code. Err codes are from
+ :data:`.ImageFile.ERRORS`.
+ """
+ errcode = 0
+ while errcode == 0:
+ status, errcode, buf = self.encode(bufsize)
+ if status > 0:
+ fh.write(buf[status:])
+ return errcode