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500 lines
14 KiB
Python
500 lines
14 KiB
Python
#
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# The Python Imaging Library.
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# $Id$
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#
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# base class for image file handlers
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#
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# history:
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# 1995-09-09 fl Created
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# 1996-03-11 fl Fixed load mechanism.
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# 1996-04-15 fl Added pcx/xbm decoders.
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# 1996-04-30 fl Added encoders.
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# 1996-12-14 fl Added load helpers
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# 1997-01-11 fl Use encode_to_file where possible
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# 1997-08-27 fl Flush output in _save
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# 1998-03-05 fl Use memory mapping for some modes
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# 1999-02-04 fl Use memory mapping also for "I;16" and "I;16B"
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# 1999-05-31 fl Added image parser
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# 2000-10-12 fl Set readonly flag on memory-mapped images
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# 2002-03-20 fl Use better messages for common decoder errors
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# 2003-04-21 fl Fall back on mmap/map_buffer if map is not available
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# 2003-10-30 fl Added StubImageFile class
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# 2004-02-25 fl Made incremental parser more robust
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#
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# Copyright (c) 1997-2004 by Secret Labs AB
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# Copyright (c) 1995-2004 by Fredrik Lundh
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#
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# See the README file for information on usage and redistribution.
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#
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from PIL import Image
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import traceback, os
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import io
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MAXBLOCK = 65536
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SAFEBLOCK = 1024*1024
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LOAD_TRUNCATED_IMAGES = False
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ERRORS = {
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-1: "image buffer overrun error",
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-2: "decoding error",
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-3: "unknown error",
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-8: "bad configuration",
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-9: "out of memory error"
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}
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def raise_ioerror(error):
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try:
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message = Image.core.getcodecstatus(error)
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except AttributeError:
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message = ERRORS.get(error)
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if not message:
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message = "decoder error %d" % error
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raise IOError(message + " when reading image file")
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#
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# --------------------------------------------------------------------
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# Helpers
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def _tilesort(t):
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# sort on offset
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return t[2]
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#
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# --------------------------------------------------------------------
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# ImageFile base class
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##
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# Base class for image file handlers.
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class ImageFile(Image.Image):
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"Base class for image file format handlers."
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def __init__(self, fp=None, filename=None):
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Image.Image.__init__(self)
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self.tile = None
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self.readonly = 1 # until we know better
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self.decoderconfig = ()
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self.decodermaxblock = MAXBLOCK
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if Image.isStringType(fp):
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# filename
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self.fp = open(fp, "rb")
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self.filename = fp
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else:
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# stream
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self.fp = fp
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self.filename = filename
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try:
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self._open()
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except IndexError as v: # end of data
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if Image.DEBUG > 1:
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traceback.print_exc()
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raise SyntaxError(v)
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except TypeError as v: # end of data (ord)
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if Image.DEBUG > 1:
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traceback.print_exc()
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raise SyntaxError(v)
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except KeyError as v: # unsupported mode
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if Image.DEBUG > 1:
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traceback.print_exc()
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raise SyntaxError(v)
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except EOFError as v: # got header but not the first frame
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if Image.DEBUG > 1:
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traceback.print_exc()
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raise SyntaxError(v)
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if not self.mode or self.size[0] <= 0:
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raise SyntaxError("not identified by this driver")
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def draft(self, mode, size):
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"Set draft mode"
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pass
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def verify(self):
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"Check file integrity"
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# raise exception if something's wrong. must be called
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# directly after open, and closes file when finished.
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self.fp = None
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def load(self):
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"Load image data based on tile list"
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pixel = Image.Image.load(self)
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if self.tile is None:
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raise IOError("cannot load this image")
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if not self.tile:
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return pixel
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self.map = None
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readonly = 0
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if self.filename and len(self.tile) == 1:
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# try memory mapping
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d, e, o, a = self.tile[0]
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if d == "raw" and a[0] == self.mode and a[0] in Image._MAPMODES:
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try:
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if hasattr(Image.core, "map"):
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# use built-in mapper
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self.map = Image.core.map(self.filename)
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self.map.seek(o)
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self.im = self.map.readimage(
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self.mode, self.size, a[1], a[2]
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)
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else:
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# use mmap, if possible
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import mmap
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file = open(self.filename, "r+")
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size = os.path.getsize(self.filename)
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# FIXME: on Unix, use PROT_READ etc
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self.map = mmap.mmap(file.fileno(), size)
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self.im = Image.core.map_buffer(
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self.map, self.size, d, e, o, a
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)
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readonly = 1
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except (AttributeError, EnvironmentError, ImportError):
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self.map = None
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self.load_prepare()
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# look for read/seek overrides
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try:
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read = self.load_read
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except AttributeError:
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read = self.fp.read
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try:
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seek = self.load_seek
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except AttributeError:
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seek = self.fp.seek
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if not self.map:
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# sort tiles in file order
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self.tile.sort(key=_tilesort)
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try:
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# FIXME: This is a hack to handle TIFF's JpegTables tag.
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prefix = self.tile_prefix
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except AttributeError:
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prefix = b""
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for d, e, o, a in self.tile:
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d = Image._getdecoder(self.mode, d, a, self.decoderconfig)
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seek(o)
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try:
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d.setimage(self.im, e)
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except ValueError:
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continue
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b = prefix
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t = len(b)
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while True:
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try:
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s = read(self.decodermaxblock)
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except IndexError as ie: # truncated png/gif
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if LOAD_TRUNCATED_IMAGES:
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break
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else:
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raise IndexError(ie)
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if not s: # truncated jpeg
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self.tile = []
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if LOAD_TRUNCATED_IMAGES:
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break
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else:
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raise IOError("image file is truncated (%d bytes not processed)" % len(b))
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b = b + s
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n, e = d.decode(b)
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if n < 0:
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break
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b = b[n:]
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t = t + n
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self.tile = []
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self.readonly = readonly
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self.fp = None # might be shared
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if (not LOAD_TRUNCATED_IMAGES or t == 0) and not self.map and e < 0:
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# still raised if decoder fails to return anything
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raise_ioerror(e)
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# post processing
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if hasattr(self, "tile_post_rotate"):
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# FIXME: This is a hack to handle rotated PCD's
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self.im = self.im.rotate(self.tile_post_rotate)
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self.size = self.im.size
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self.load_end()
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return Image.Image.load(self)
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def load_prepare(self):
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# create image memory if necessary
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if not self.im or\
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self.im.mode != self.mode or self.im.size != self.size:
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self.im = Image.core.new(self.mode, self.size)
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# create palette (optional)
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if self.mode == "P":
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Image.Image.load(self)
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def load_end(self):
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# may be overridden
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pass
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# may be defined for contained formats
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# def load_seek(self, pos):
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# pass
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# may be defined for blocked formats (e.g. PNG)
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# def load_read(self, bytes):
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# pass
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##
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# Base class for stub image loaders.
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# <p>
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# A stub loader is an image loader that can identify files of a
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# certain format, but relies on external code to load the file.
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class StubImageFile(ImageFile):
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"Base class for stub image loaders."
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def _open(self):
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raise NotImplementedError(
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"StubImageFile subclass must implement _open"
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)
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def load(self):
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loader = self._load()
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if loader is None:
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raise IOError("cannot find loader for this %s file" % self.format)
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image = loader.load(self)
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assert image is not None
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# become the other object (!)
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self.__class__ = image.__class__
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self.__dict__ = image.__dict__
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##
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# (Hook) Find actual image loader.
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def _load(self):
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raise NotImplementedError(
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"StubImageFile subclass must implement _load"
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)
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##
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# Incremental image parser. This class implements the standard
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# feed/close consumer interface.
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class Parser:
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incremental = None
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image = None
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data = None
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decoder = None
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finished = 0
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##
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# (Consumer) Reset the parser. Note that you can only call this
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# method immediately after you've created a parser; parser
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# instances cannot be reused.
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def reset(self):
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assert self.data is None, "cannot reuse parsers"
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##
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# (Consumer) Feed data to the parser.
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#
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# @param data A string buffer.
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# @exception IOError If the parser failed to parse the image file.
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def feed(self, data):
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# collect data
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if self.finished:
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return
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if self.data is None:
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self.data = data
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else:
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self.data = self.data + data
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# parse what we have
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if self.decoder:
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if self.offset > 0:
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# skip header
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skip = min(len(self.data), self.offset)
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self.data = self.data[skip:]
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self.offset = self.offset - skip
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if self.offset > 0 or not self.data:
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return
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n, e = self.decoder.decode(self.data)
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if n < 0:
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# end of stream
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self.data = None
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self.finished = 1
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if e < 0:
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# decoding error
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self.image = None
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raise_ioerror(e)
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else:
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# end of image
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return
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self.data = self.data[n:]
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elif self.image:
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# if we end up here with no decoder, this file cannot
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# be incrementally parsed. wait until we've gotten all
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# available data
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pass
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else:
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# attempt to open this file
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try:
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try:
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fp = io.BytesIO(self.data)
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im = Image.open(fp)
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finally:
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fp.close() # explicitly close the virtual file
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except IOError:
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# traceback.print_exc()
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pass # not enough data
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else:
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flag = hasattr(im, "load_seek") or hasattr(im, "load_read")
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if flag or len(im.tile) != 1:
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# custom load code, or multiple tiles
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self.decode = None
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else:
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# initialize decoder
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im.load_prepare()
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d, e, o, a = im.tile[0]
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im.tile = []
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self.decoder = Image._getdecoder(
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im.mode, d, a, im.decoderconfig
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)
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self.decoder.setimage(im.im, e)
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# calculate decoder offset
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self.offset = o
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if self.offset <= len(self.data):
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self.data = self.data[self.offset:]
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self.offset = 0
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self.image = im
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##
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# (Consumer) Close the stream.
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#
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# @return An image object.
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# @exception IOError If the parser failed to parse the image file.
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def close(self):
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# finish decoding
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if self.decoder:
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# get rid of what's left in the buffers
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self.feed(b"")
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self.data = self.decoder = None
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if not self.finished:
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raise IOError("image was incomplete")
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if not self.image:
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raise IOError("cannot parse this image")
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if self.data:
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# incremental parsing not possible; reopen the file
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# not that we have all data
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try:
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fp = io.BytesIO(self.data)
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self.image = Image.open(fp)
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finally:
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self.image.load()
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fp.close() # explicitly close the virtual file
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return self.image
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# --------------------------------------------------------------------
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##
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# (Helper) Save image body to file.
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#
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# @param im Image object.
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# @param fp File object.
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# @param tile Tile list.
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def _save(im, fp, tile):
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"Helper to save image based on tile list"
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im.load()
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if not hasattr(im, "encoderconfig"):
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im.encoderconfig = ()
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tile.sort(key=_tilesort)
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# FIXME: make MAXBLOCK a configuration parameter
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bufsize = max(MAXBLOCK, im.size[0] * 4) # see RawEncode.c
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try:
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fh = fp.fileno()
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fp.flush()
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except (AttributeError, io.UnsupportedOperation):
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# compress to Python file-compatible object
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for e, b, o, a in tile:
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e = Image._getencoder(im.mode, e, a, im.encoderconfig)
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if o > 0:
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fp.seek(o, 0)
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e.setimage(im.im, b)
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while True:
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l, s, d = e.encode(bufsize)
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fp.write(d)
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if s:
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break
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if s < 0:
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raise IOError("encoder error %d when writing image file" % s)
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else:
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# slight speedup: compress to real file object
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for e, b, o, a in tile:
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e = Image._getencoder(im.mode, e, a, im.encoderconfig)
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if o > 0:
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fp.seek(o, 0)
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e.setimage(im.im, b)
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s = e.encode_to_file(fh, bufsize)
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if s < 0:
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raise IOError("encoder error %d when writing image file" % s)
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try:
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fp.flush()
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except: pass
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##
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# Reads large blocks in a safe way. Unlike fp.read(n), this function
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# doesn't trust the user. If the requested size is larger than
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# SAFEBLOCK, the file is read block by block.
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#
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# @param fp File handle. Must implement a <b>read</b> method.
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# @param size Number of bytes to read.
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# @return A string containing up to <i>size</i> bytes of data.
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def _safe_read(fp, size):
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if size <= 0:
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return b""
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if size <= SAFEBLOCK:
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return fp.read(size)
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data = []
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while size > 0:
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block = fp.read(min(size, SAFEBLOCK))
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if not block:
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break
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data.append(block)
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size = size - len(block)
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return b"".join(data)
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