/usr/lib/python2.7/dist-packages/PyPDF2/filters.py is in python-pypdf2 1.26.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 | # vim: sw=4:expandtab:foldmethod=marker
#
# Copyright (c) 2006, Mathieu Fenniak
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
"""
Implementation of stream filters for PDF.
"""
__author__ = "Mathieu Fenniak"
__author_email__ = "biziqe@mathieu.fenniak.net"
from .utils import PdfReadError, ord_, chr_
from sys import version_info
if version_info < ( 3, 0 ):
from cStringIO import StringIO
else:
from io import StringIO
import struct
try:
import zlib
def decompress(data):
return zlib.decompress(data)
def compress(data):
return zlib.compress(data)
except ImportError:
# Unable to import zlib. Attempt to use the System.IO.Compression
# library from the .NET framework. (IronPython only)
import System
from System import IO, Collections, Array
def _string_to_bytearr(buf):
retval = Array.CreateInstance(System.Byte, len(buf))
for i in range(len(buf)):
retval[i] = ord(buf[i])
return retval
def _bytearr_to_string(bytes):
retval = ""
for i in range(bytes.Length):
retval += chr(bytes[i])
return retval
def _read_bytes(stream):
ms = IO.MemoryStream()
buf = Array.CreateInstance(System.Byte, 2048)
while True:
bytes = stream.Read(buf, 0, buf.Length)
if bytes == 0:
break
else:
ms.Write(buf, 0, bytes)
retval = ms.ToArray()
ms.Close()
return retval
def decompress(data):
bytes = _string_to_bytearr(data)
ms = IO.MemoryStream()
ms.Write(bytes, 0, bytes.Length)
ms.Position = 0 # fseek 0
gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Decompress)
bytes = _read_bytes(gz)
retval = _bytearr_to_string(bytes)
gz.Close()
return retval
def compress(data):
bytes = _string_to_bytearr(data)
ms = IO.MemoryStream()
gz = IO.Compression.DeflateStream(ms, IO.Compression.CompressionMode.Compress, True)
gz.Write(bytes, 0, bytes.Length)
gz.Close()
ms.Position = 0 # fseek 0
bytes = ms.ToArray()
retval = _bytearr_to_string(bytes)
ms.Close()
return retval
class FlateDecode(object):
def decode(data, decodeParms):
data = decompress(data)
predictor = 1
if decodeParms:
try:
predictor = decodeParms.get("/Predictor", 1)
except AttributeError:
pass # usually an array with a null object was read
# predictor 1 == no predictor
if predictor != 1:
columns = decodeParms["/Columns"]
# PNG prediction:
if predictor >= 10 and predictor <= 15:
output = StringIO()
# PNG prediction can vary from row to row
rowlength = columns + 1
assert len(data) % rowlength == 0
prev_rowdata = (0,) * rowlength
for row in range(len(data) // rowlength):
rowdata = [ord_(x) for x in data[(row*rowlength):((row+1)*rowlength)]]
filterByte = rowdata[0]
if filterByte == 0:
pass
elif filterByte == 1:
for i in range(2, rowlength):
rowdata[i] = (rowdata[i] + rowdata[i-1]) % 256
elif filterByte == 2:
for i in range(1, rowlength):
rowdata[i] = (rowdata[i] + prev_rowdata[i]) % 256
else:
# unsupported PNG filter
raise PdfReadError("Unsupported PNG filter %r" % filterByte)
prev_rowdata = rowdata
output.write(''.join([chr(x) for x in rowdata[1:]]))
data = output.getvalue()
else:
# unsupported predictor
raise PdfReadError("Unsupported flatedecode predictor %r" % predictor)
return data
decode = staticmethod(decode)
def encode(data):
return compress(data)
encode = staticmethod(encode)
class ASCIIHexDecode(object):
def decode(data, decodeParms=None):
retval = ""
char = ""
x = 0
while True:
c = data[x]
if c == ">":
break
elif c.isspace():
x += 1
continue
char += c
if len(char) == 2:
retval += chr(int(char, base=16))
char = ""
x += 1
assert char == ""
return retval
decode = staticmethod(decode)
class LZWDecode(object):
"""Taken from:
http://www.java2s.com/Open-Source/Java-Document/PDF/PDF-Renderer/com/sun/pdfview/decode/LZWDecode.java.htm
"""
class decoder(object):
def __init__(self, data):
self.STOP=257
self.CLEARDICT=256
self.data=data
self.bytepos=0
self.bitpos=0
self.dict=[""]*4096
for i in range(256):
self.dict[i]=chr(i)
self.resetDict()
def resetDict(self):
self.dictlen=258
self.bitspercode=9
def nextCode(self):
fillbits=self.bitspercode
value=0
while fillbits>0 :
if self.bytepos >= len(self.data):
return -1
nextbits=ord(self.data[self.bytepos])
bitsfromhere=8-self.bitpos
if bitsfromhere>fillbits:
bitsfromhere=fillbits
value |= (((nextbits >> (8-self.bitpos-bitsfromhere)) &
(0xff >> (8-bitsfromhere))) <<
(fillbits-bitsfromhere))
fillbits -= bitsfromhere
self.bitpos += bitsfromhere
if self.bitpos >=8:
self.bitpos=0
self.bytepos = self.bytepos+1
return value
def decode(self):
""" algorithm derived from:
http://www.rasip.fer.hr/research/compress/algorithms/fund/lz/lzw.html
and the PDFReference
"""
cW = self.CLEARDICT;
baos=""
while True:
pW = cW;
cW = self.nextCode();
if cW == -1:
raise PdfReadError("Missed the stop code in LZWDecode!")
if cW == self.STOP:
break;
elif cW == self.CLEARDICT:
self.resetDict();
elif pW == self.CLEARDICT:
baos+=self.dict[cW]
else:
if cW < self.dictlen:
baos += self.dict[cW]
p=self.dict[pW]+self.dict[cW][0]
self.dict[self.dictlen]=p
self.dictlen+=1
else:
p=self.dict[pW]+self.dict[pW][0]
baos+=p
self.dict[self.dictlen] = p;
self.dictlen+=1
if (self.dictlen >= (1 << self.bitspercode) - 1 and
self.bitspercode < 12):
self.bitspercode+=1
return baos
@staticmethod
def decode(data,decodeParams=None):
return LZWDecode.decoder(data).decode()
class ASCII85Decode(object):
def decode(data, decodeParms=None):
if version_info < ( 3, 0 ):
retval = ""
group = []
x = 0
hitEod = False
# remove all whitespace from data
data = [y for y in data if not (y in ' \n\r\t')]
while not hitEod:
c = data[x]
if len(retval) == 0 and c == "<" and data[x+1] == "~":
x += 2
continue
#elif c.isspace():
# x += 1
# continue
elif c == 'z':
assert len(group) == 0
retval += '\x00\x00\x00\x00'
x += 1
continue
elif c == "~" and data[x+1] == ">":
if len(group) != 0:
# cannot have a final group of just 1 char
assert len(group) > 1
cnt = len(group) - 1
group += [ 85, 85, 85 ]
hitEod = cnt
else:
break
else:
c = ord(c) - 33
assert c >= 0 and c < 85
group += [ c ]
if len(group) >= 5:
b = group[0] * (85**4) + \
group[1] * (85**3) + \
group[2] * (85**2) + \
group[3] * 85 + \
group[4]
assert b < (2**32 - 1)
c4 = chr((b >> 0) % 256)
c3 = chr((b >> 8) % 256)
c2 = chr((b >> 16) % 256)
c1 = chr(b >> 24)
retval += (c1 + c2 + c3 + c4)
if hitEod:
retval = retval[:-4+hitEod]
group = []
x += 1
return retval
else:
if isinstance(data, str):
data = data.encode('ascii')
n = b = 0
out = bytearray()
for c in data:
if ord('!') <= c and c <= ord('u'):
n += 1
b = b*85+(c-33)
if n == 5:
out += struct.pack(b'>L',b)
n = b = 0
elif c == ord('z'):
assert n == 0
out += b'\0\0\0\0'
elif c == ord('~'):
if n:
for _ in range(5-n):
b = b*85+84
out += struct.pack(b'>L',b)[:n-1]
break
return bytes(out)
decode = staticmethod(decode)
def decodeStreamData(stream):
from .generic import NameObject
filters = stream.get("/Filter", ())
if len(filters) and not isinstance(filters[0], NameObject):
# we have a single filter instance
filters = (filters,)
data = stream._data
# If there is not data to decode we should not try to decode the data.
if data:
for filterType in filters:
if filterType == "/FlateDecode" or filterType == "/Fl":
data = FlateDecode.decode(data, stream.get("/DecodeParms"))
elif filterType == "/ASCIIHexDecode" or filterType == "/AHx":
data = ASCIIHexDecode.decode(data)
elif filterType == "/LZWDecode" or filterType == "/LZW":
data = LZWDecode.decode(data, stream.get("/DecodeParms"))
elif filterType == "/ASCII85Decode" or filterType == "/A85":
data = ASCII85Decode.decode(data)
elif filterType == "/Crypt":
decodeParams = stream.get("/DecodeParams", {})
if "/Name" not in decodeParams and "/Type" not in decodeParams:
pass
else:
raise NotImplementedError("/Crypt filter with /Name or /Type not supported yet")
else:
# unsupported filter
raise NotImplementedError("unsupported filter %s" % filterType)
return data
|