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
|
# -*- tab-width: 4; indent-tabs-mode: nil -*-
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
from builtins import range
import sys, struct
class VBAStreamBase:
CHUNKSIZE = 4096
def __init__(self, chars, offset):
self.mnOffset = offset
self.chars = chars
def copyTokenHelp(self):
difference = self.DecompressedCurrent - self.DecompressedChunkStart
bitCount = 0
while( ( 1 << bitCount ) < difference ):
bitCount +=1
if bitCount < 4:
bitCount = 4;
lengthMask = 0xFFFF >> bitCount
offSetMask = ~lengthMask
maximumLength = ( 0xFFFF >> bitCount ) + 3
return lengthMask, offSetMask, bitCount, maximumLength
class UnCompressedVBAStream(VBAStreamBase):
def __packCopyToken(self, offset, length ):
lengthMask, offSetMask, bitCount, maximumLength = self.copyTokenHelp()
temp1 = offset - 1
temp2 = 16 - bitCount
temp3 = length - 3
copyToken = (temp1 << temp2) | temp3
return copyToken
def __compressRawChunk(self):
self.CompressedCurrent = self.CompressedChunkStart + 2
self.DecompressedCurrent = self.DecompressedChunkStart
padCount = self.CHUNKSIZE
lastByte = self.DecompressedChunkStart + padCount
if self.DecompressedBufferEnd < lastByte:
lastByte = self.DecompressedBufferEnd
for index in range( self.DecompressedChunkStart, lastByte ):
self.CompressedContainer[ self.CompressedCurrent ] = self.chars[ index ]
self.CompressedCurrent = self.CompressedCurrent + 1
self.DecompressedCurrent = self.DecompressedCurrent + 1
padCount = padCount - 1
for index in range( 0, padCount ):
self.CompressedContainer[ self.CompressedCurrent ] = 0x0;
self.CompressedCurrent = self.CompressedCurrent + 1
def __matching( self, decompressedEnd ):
candidate = self.DecompressedCurrent - 1
bestLength = 0
while candidate >= self.DecompressedChunkStart:
c = candidate
d = self.DecompressedCurrent
nLen = 0
while d < decompressedEnd and ( self.chars[ d ] == self.chars[ c ] ):
nLen = nLen + 1
c = c + 1
d = d + 1
if nLen > bestLength:
bestLength = nLen
bestCandidate = candidate
candidate = candidate - 1
if bestLength >= 3:
lengthMask, offSetMask, bitCount, maximumLength = self.copyTokenHelp()
length = bestLength
if ( maximumLength < bestLength ):
length = maximumLength
offset = self.DecompressedCurrent - bestCandidate
else:
length = 0
offset = 0
return offset, length
def __compressToken( self, compressedEnd, decompressedEnd, index, flags ):
offset = 0
offset, length = self.__matching( decompressedEnd )
if offset:
if (self.CompressedCurrent + 1) < compressedEnd:
copyToken = self.__packCopyToken( offset, length )
struct.pack_into("<H", self.CompressedContainer, self.CompressedCurrent, copyToken )
temp1 = ( 1 << index )
temp2 = flags & ~temp1
flags = temp2 | temp1
self.CompressedCurrent = self.CompressedCurrent + 2
self.DecompressedCurrent = self.DecompressedCurrent + length
else:
self.CompressedCurrent = compressedEnd
else:
if self.CompressedCurrent < compressedEnd:
self.CompressedContainer[ self.CompressedCurrent ] = self.chars[ self.DecompressedCurrent ]
self.CompressedCurrent = self.CompressedCurrent + 1
self.DecompressedCurrent = self.DecompressedCurrent + 1
else:
self.CompressedCurrent = compressedEnd
return flags
def __compressTokenSequence(self, compressedEnd, decompressedEnd ):
flagByteIndex = self.CompressedCurrent
tokenFlags = 0
self.CompressedCurrent = self.CompressedCurrent + 1
for index in range(0,8):
if ( ( self.DecompressedCurrent < decompressedEnd )
and (self.CompressedCurrent < compressedEnd) ):
tokenFlags = self.__compressToken( compressedEnd, decompressedEnd, index, tokenFlags )
self.CompressedContainer[ flagByteIndex ] = tokenFlags
def __CompressDecompressedChunk(self):
self.CompressedContainer.extend( bytearray(self.CHUNKSIZE + 2) )
compressedEnd = self.CompressedChunkStart + 4098
self.CompressedCurrent = self.CompressedChunkStart + 2
decompressedEnd = self.DecompressedBufferEnd
if (self.DecompressedChunkStart + self.CHUNKSIZE) < self.DecompressedBufferEnd:
decompressedEnd = (self.DecompressedChunkStart + self.CHUNKSIZE)
while (self.DecompressedCurrent < decompressedEnd) and (self.CompressedCurrent < compressedEnd):
self.__compressTokenSequence( compressedEnd, decompressedEnd)
if self.DecompressedCurrent < decompressedEnd:
self.__compressRawChunk( decompressedEnd - 1 )
compressedFlag = 0
else:
compressedFlag = 1
size = self.CompressedCurrent - self.CompressedChunkStart
header = 0x0000
#Pack CompressedChunkSize with Size and Header
temp1=header & 0xF000
temp2 = size - 3
header = temp1 | temp2
#Pack CompressedChunkFlag with CompressedFlag and Header
temp1 = header & 0x7FFF
temp2 = compressedFlag << 15
header = temp1 | temp2
#Pack CompressedChunkSignature with Header
temp1 = header & 0x8FFF
Header = temp1 | 0x3000
#CompressedChunkHeader located at CompressedChunkStart TO Header
struct.pack_into("<H", self.CompressedContainer, self.CompressedChunkStart, Header )
# trim buffer to size
if ( self.CompressedCurrent ):
self.CompressedContainer = self.CompressedContainer[ 0:self.CompressedCurrent ]
def compress(self):
self.CompressedContainer = bytearray()
self.CompressedCurrent = 0
self.CompressedChunkStart = 0
self.DecompressedCurrent = 0
self.DecompressedBufferEnd = len(self.chars)
self.DecompressedChunkStart = 0
SignatureByte = 0x01
self.CompressedContainer.append( SignatureByte )
self.CompressedCurrent = self.CompressedCurrent + 1
while self.DecompressedCurrent < self.DecompressedBufferEnd:
self.CompressedChunkStart = self.CompressedCurrent
self.DecompressedChunkStart = self.DecompressedCurrent
self.__CompressDecompressedChunk()
return self.CompressedContainer
class CompressedVBAStream(VBAStreamBase):
def __decompressRawChunk (self):
for i in range(0,self.CHUNKSIZE):
self.DecompressedChunk[ self.DecompressedCurrent + i ] = self.chars[self.CompressedCurrent + i ]
self.CompressedCurrent += self.CHUNKSIZE
self.DecompressedCurrent += self.CHUNKSIZE
def __unPackCopyToken (self, copyToken ):
lengthMask, offSetMask, bitCount, maximumLength = self.copyTokenHelp()
length = ( copyToken & lengthMask ) + 3
temp1 = copyToken & offSetMask
temp2 = 16 - bitCount
offSet = ( temp1 >> temp2 ) + 1
return offSet, length
def __byteCopy( self, srcOffSet, dstOffSet, length ):
destSize = len( self.DecompressedChunk )
srcCurrent = srcOffSet
dstCurrent = dstOffSet
for i in range( 0, length ):
self.DecompressedChunk[ dstCurrent ] = self.DecompressedChunk[ srcCurrent ]
srcCurrent +=1
dstCurrent +=1
def __decompressToken (self, index, flagByte):
flagBit = ( ( flagByte >> index ) & 1 )
if flagBit == 0:
self.DecompressedChunk[self.DecompressedCurrent] = self.chars[self.CompressedCurrent ]
self.CompressedCurrent += 1
self.DecompressedCurrent += 1
else:
copyToken = struct.unpack_from("<H", self.chars, self.CompressedCurrent)[0]
offSet, length = self.__unPackCopyToken( copyToken )
copySource = self.DecompressedCurrent - offSet
self.__byteCopy( copySource, self.DecompressedCurrent, length )
self.DecompressedCurrent += length
self.CompressedCurrent += 2
def __decompressTokenSequence (self):
flagByte = struct.unpack("b", self.chars[self.CompressedCurrent ])[0]
self.CompressedCurrent += 1
if self.CompressedCurrent < self.CompressedEnd:
for i in range(0,8):
if self.CompressedCurrent < self.CompressedEnd:
self.__decompressToken(i,flagByte)
def decompressCompressedChunk (self):
header = struct.unpack_from("<H",self.chars, self.CompressedChunkStart)[0]
#extract size from header
size = header & 0xFFF
size = size + 3
#extract chunk sig from header
sigflag = header >> 12
sig = sigflag & 0x7
#extract chunk flag from sig
compressedChunkFlag = (( sigflag & 0x8 ) == 0x8)
self.DecompressedChunk = bytearray(self.CHUNKSIZE);
self.DecompressedChunkStart = 0
self.DecompressedCurrent = 0
self.CompressedEnd = self.CompressedRecordEnd
if ( ( self.CompressedChunkStart + size ) < self.CompressedRecordEnd ):
self.CompressedEnd = ( self.CompressedChunkStart + size )
self.CompressedCurrent = self.CompressedChunkStart + 2
if compressedChunkFlag == 1:
while self.CompressedCurrent < self.CompressedEnd:
self.__decompressTokenSequence()
else:
self.__decompressRawChunk()
if self.DecompressedCurrent:
truncChunk = self.DecompressedChunk[0:self.DecompressedCurrent]
self.DecompressedContainer.extend( truncChunk )
def decompress (self):
self.DecompressedContainer = bytearray();
self.CompressedCurrent = self.mnOffset
self.CompressedRecordEnd = len(self.chars )
self.DeCompressedBufferEnd = 0
self.DecompressedChunkStart = 0
val = struct.unpack("b", self.chars[self.CompressedCurrent])[0]
if val == 1:
self.CompressedCurrent += 1
while self.CompressedCurrent < self.CompressedRecordEnd:
self.CompressedChunkStart = self.CompressedCurrent
self.decompressCompressedChunk()
return self.DecompressedContainer
else:
raise Exception("error decompressing container invalid signature byte %i"%val)
return None
# vim:set filetype=python shiftwidth=4 softtabstop=4 expandtab:
|
