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@@ -1,79 +1,80 b'' | |||||
1 | # base85.py: pure python base85 codec |
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1 | # base85.py: pure python base85 codec | |
2 | # |
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2 | # | |
3 | # Copyright (C) 2009 Brendan Cully <brendan@kublai.com> |
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3 | # Copyright (C) 2009 Brendan Cully <brendan@kublai.com> | |
4 | # |
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4 | # | |
5 | # This software may be used and distributed according to the terms of the |
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5 | # This software may be used and distributed according to the terms of the | |
6 | # GNU General Public License version 2 or any later version. |
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6 | # GNU General Public License version 2 or any later version. | |
7 |
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7 | |||
8 | from __future__ import absolute_import |
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8 | from __future__ import absolute_import | |
9 |
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9 | |||
10 | import struct |
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10 | import struct | |
11 |
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11 | |||
12 | from .. import pycompat |
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12 | from .. import pycompat | |
13 |
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13 | |||
14 | _b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef" |
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14 | _b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef" | |
15 | "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~") |
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15 | "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~") | |
16 | _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] |
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16 | _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] | |
17 | _b85dec = {} |
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17 | _b85dec = {} | |
18 |
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18 | |||
19 | def _mkb85dec(): |
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19 | def _mkb85dec(): | |
20 | for i, c in enumerate(_b85chars): |
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20 | for i, c in enumerate(_b85chars): | |
21 | _b85dec[c] = i |
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21 | _b85dec[c] = i | |
22 |
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22 | |||
23 | def b85encode(text, pad=False): |
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23 | def b85encode(text, pad=False): | |
24 | """encode text in base85 format""" |
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24 | """encode text in base85 format""" | |
25 | l = len(text) |
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25 | l = len(text) | |
26 | r = l % 4 |
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26 | r = l % 4 | |
27 | if r: |
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27 | if r: | |
28 | text += '\0' * (4 - r) |
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28 | text += '\0' * (4 - r) | |
29 | longs = len(text) >> 2 |
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29 | longs = len(text) >> 2 | |
30 | words = struct.unpack('>%dL' % (longs), text) |
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30 | words = struct.unpack('>%dL' % (longs), text) | |
31 |
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31 | |||
32 | out = ''.join(_b85chars[(word // 52200625) % 85] + |
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32 | out = ''.join(_b85chars[(word // 52200625) % 85] + | |
33 | _b85chars2[(word // 7225) % 7225] + |
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33 | _b85chars2[(word // 7225) % 7225] + | |
34 | _b85chars2[word % 7225] |
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34 | _b85chars2[word % 7225] | |
35 | for word in words) |
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35 | for word in words) | |
36 |
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36 | |||
37 | if pad: |
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37 | if pad: | |
38 | return out |
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38 | return out | |
39 |
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39 | |||
40 | # Trim padding |
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40 | # Trim padding | |
41 | olen = l % 4 |
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41 | olen = l % 4 | |
42 | if olen: |
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42 | if olen: | |
43 | olen += 1 |
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43 | olen += 1 | |
44 | olen += l // 4 * 5 |
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44 | olen += l // 4 * 5 | |
45 | return out[:olen] |
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45 | return out[:olen] | |
46 |
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46 | |||
47 | def b85decode(text): |
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47 | def b85decode(text): | |
48 | """decode base85-encoded text""" |
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48 | """decode base85-encoded text""" | |
49 | if not _b85dec: |
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49 | if not _b85dec: | |
50 | _mkb85dec() |
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50 | _mkb85dec() | |
51 |
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51 | |||
52 | l = len(text) |
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52 | l = len(text) | |
53 | out = [] |
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53 | out = [] | |
54 | for i in range(0, len(text), 5): |
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54 | for i in range(0, len(text), 5): | |
55 | chunk = text[i:i + 5] |
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55 | chunk = text[i:i + 5] | |
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56 | chunk = pycompat.bytestr(chunk) | |||
56 | acc = 0 |
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57 | acc = 0 | |
57 | for j, c in enumerate(chunk): |
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58 | for j, c in enumerate(chunk): | |
58 | try: |
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59 | try: | |
59 | acc = acc * 85 + _b85dec[c] |
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60 | acc = acc * 85 + _b85dec[c] | |
60 | except KeyError: |
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61 | except KeyError: | |
61 | raise ValueError('bad base85 character at position %d' |
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62 | raise ValueError('bad base85 character at position %d' | |
62 | % (i + j)) |
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63 | % (i + j)) | |
63 | if acc > 4294967295: |
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64 | if acc > 4294967295: | |
64 | raise ValueError('Base85 overflow in hunk starting at byte %d' % i) |
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65 | raise ValueError('Base85 overflow in hunk starting at byte %d' % i) | |
65 | out.append(acc) |
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66 | out.append(acc) | |
66 |
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67 | |||
67 | # Pad final chunk if necessary |
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68 | # Pad final chunk if necessary | |
68 | cl = l % 5 |
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69 | cl = l % 5 | |
69 | if cl: |
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70 | if cl: | |
70 | acc *= 85 ** (5 - cl) |
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71 | acc *= 85 ** (5 - cl) | |
71 | if cl > 1: |
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72 | if cl > 1: | |
72 | acc += 0xffffff >> (cl - 2) * 8 |
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73 | acc += 0xffffff >> (cl - 2) * 8 | |
73 | out[-1] = acc |
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74 | out[-1] = acc | |
74 |
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75 | |||
75 | out = struct.pack('>%dL' % (len(out)), *out) |
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76 | out = struct.pack('>%dL' % (len(out)), *out) | |
76 | if cl: |
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77 | if cl: | |
77 | out = out[:-(5 - cl)] |
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78 | out = out[:-(5 - cl)] | |
78 |
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79 | |||
79 | return out |
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80 | return out |
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