253 lines
9.4 KiB
Python
253 lines
9.4 KiB
Python
# vim: sw=4:expandtab:foldmethod=marker
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#
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# Copyright (c) 2006, Mathieu Fenniak
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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# * The name of the author may not be used to endorse or promote products
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# derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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"""
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Implementation of stream filters for PDF.
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"""
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__author__ = "Mathieu Fenniak"
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__author_email__ = "biziqe@mathieu.fenniak.net"
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from utils import PdfReadError
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try:
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from cStringIO import StringIO
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except ImportError:
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from StringIO import StringIO
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try:
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import zlib
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def decompress(data):
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return zlib.decompress(data)
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def compress(data):
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return zlib.compress(data)
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except ImportError:
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# Unable to import zlib. Attempt to use the System.IO.Compression
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# library from the .NET framework. (IronPython only)
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import System
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from System import IO, Collections, Array
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def _string_to_bytearr(buf):
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retval = Array.CreateInstance(System.Byte, len(buf))
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for i in range(len(buf)):
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retval[i] = ord(buf[i])
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return retval
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def _bytearr_to_string(bytes):
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retval = ""
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for i in range(bytes.Length):
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retval += chr(bytes[i])
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return retval
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def _read_bytes(stream):
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ms = IO.MemoryStream()
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buf = Array.CreateInstance(System.Byte, 2048)
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while True:
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bytes = stream.Read(buf, 0, buf.Length)
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if bytes == 0:
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break
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else:
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ms.Write(buf, 0, bytes)
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retval = ms.ToArray()
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ms.Close()
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return retval
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def decompress(data):
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bytes = _string_to_bytearr(data)
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ms = IO.MemoryStream()
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ms.Write(bytes, 0, bytes.Length)
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ms.Position = 0 # fseek 0
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gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Decompress)
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bytes = _read_bytes(gz)
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retval = _bytearr_to_string(bytes)
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gz.Close()
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return retval
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def compress(data):
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bytes = _string_to_bytearr(data)
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ms = IO.MemoryStream()
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gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Compress, True)
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gz.Write(bytes, 0, bytes.Length)
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gz.Close()
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ms.Position = 0 # fseek 0
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bytes = ms.ToArray()
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retval = _bytearr_to_string(bytes)
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ms.Close()
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return retval
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class FlateDecode(object):
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def decode(data, decodeParms):
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data = decompress(data)
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predictor = 1
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if decodeParms:
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predictor = decodeParms.get("/Predictor", 1)
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# predictor 1 == no predictor
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if predictor != 1:
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columns = decodeParms["/Columns"]
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# PNG prediction:
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if predictor >= 10 and predictor <= 15:
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output = StringIO()
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# PNG prediction can vary from row to row
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rowlength = columns + 1
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assert len(data) % rowlength == 0
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prev_rowdata = (0,) * rowlength
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for row in xrange(len(data) / rowlength):
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rowdata = [ord(x) for x in data[(row*rowlength):((row+1)*rowlength)]]
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filterByte = rowdata[0]
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if filterByte == 0:
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pass
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elif filterByte == 1:
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for i in range(2, rowlength):
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rowdata[i] = (rowdata[i] + rowdata[i-1]) % 256
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elif filterByte == 2:
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for i in range(1, rowlength):
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rowdata[i] = (rowdata[i] + prev_rowdata[i]) % 256
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else:
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# unsupported PNG filter
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raise PdfReadError("Unsupported PNG filter %r" % filterByte)
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prev_rowdata = rowdata
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output.write(''.join([chr(x) for x in rowdata[1:]]))
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data = output.getvalue()
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else:
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# unsupported predictor
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raise PdfReadError("Unsupported flatedecode predictor %r" % predictor)
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return data
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decode = staticmethod(decode)
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def encode(data):
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return compress(data)
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encode = staticmethod(encode)
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class ASCIIHexDecode(object):
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def decode(data, decodeParms=None):
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retval = ""
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char = ""
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x = 0
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while True:
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c = data[x]
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if c == ">":
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break
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elif c.isspace():
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x += 1
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continue
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char += c
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if len(char) == 2:
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retval += chr(int(char, base=16))
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char = ""
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x += 1
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assert char == ""
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return retval
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decode = staticmethod(decode)
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class ASCII85Decode(object):
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def decode(data, decodeParms=None):
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retval = ""
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group = []
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x = 0
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hitEod = False
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# remove all whitespace from data
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data = [y for y in data if not (y in ' \n\r\t')]
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while not hitEod:
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c = data[x]
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if len(retval) == 0 and c == "<" and data[x+1] == "~":
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x += 2
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continue
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#elif c.isspace():
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# x += 1
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# continue
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elif c == 'z':
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assert len(group) == 0
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retval += '\x00\x00\x00\x00'
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continue
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elif c == "~" and data[x+1] == ">":
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if len(group) != 0:
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# cannot have a final group of just 1 char
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assert len(group) > 1
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cnt = len(group) - 1
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group += [ 85, 85, 85 ]
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hitEod = cnt
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else:
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break
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else:
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c = ord(c) - 33
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assert c >= 0 and c < 85
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group += [ c ]
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if len(group) >= 5:
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b = group[0] * (85**4) + \
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group[1] * (85**3) + \
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group[2] * (85**2) + \
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group[3] * 85 + \
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group[4]
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assert b < (2**32 - 1)
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c4 = chr((b >> 0) % 256)
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c3 = chr((b >> 8) % 256)
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c2 = chr((b >> 16) % 256)
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c1 = chr(b >> 24)
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retval += (c1 + c2 + c3 + c4)
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if hitEod:
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retval = retval[:-4+hitEod]
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group = []
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x += 1
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return retval
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decode = staticmethod(decode)
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def decodeStreamData(stream):
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from generic import NameObject
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filters = stream.get("/Filter", ())
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if len(filters) and not isinstance(filters[0], NameObject):
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# we have a single filter instance
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filters = (filters,)
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data = stream._data
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for filterType in filters:
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if filterType == "/FlateDecode":
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data = FlateDecode.decode(data, stream.get("/DecodeParms"))
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elif filterType == "/ASCIIHexDecode":
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data = ASCIIHexDecode.decode(data)
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elif filterType == "/ASCII85Decode":
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data = ASCII85Decode.decode(data)
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elif filterType == "/Crypt":
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decodeParams = stream.get("/DecodeParams", {})
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if "/Name" not in decodeParams and "/Type" not in decodeParams:
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pass
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else:
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raise NotImplementedError("/Crypt filter with /Name or /Type not supported yet")
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else:
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# unsupported filter
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raise NotImplementedError("unsupported filter %s" % filterType)
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return data
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if __name__ == "__main__":
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assert "abc" == ASCIIHexDecode.decode('61\n626\n3>')
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ascii85Test = """
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<~9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,
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O<DJ+*.@<*K0@<6L(Df-\\0Ec5e;DffZ(EZee.Bl.9pF"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY
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i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa
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l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G
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>uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c~>
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"""
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ascii85_originalText="Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure."
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assert ASCII85Decode.decode(ascii85Test) == ascii85_originalText
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