annotate pytouhou/formats/pbg3.py @ 716:5016c09e5d7c

Fix some warnings.
author Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
date Mon, 23 Sep 2019 13:49:07 +0200
parents d1f0bb0b7a17
children d18c0bf11138
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1 # -*- encoding: utf-8 -*-
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2 ##
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3 ## Copyright (C) 2011 Thibaut Girka <thib@sitedethib.com>
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4 ##
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5 ## This program is free software; you can redistribute it and/or modify
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6 ## it under the terms of the GNU General Public License as published
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7 ## by the Free Software Foundation; version 3 only.
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8 ##
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9 ## This program is distributed in the hope that it will be useful,
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10 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 ## GNU General Public License for more details.
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13 ##
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14
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15 """PBG3 archive files handling.
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16
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17 This module provides classes for handling the PBG3 file format.
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18 The PBG3 format is the archive format used by Touhou: EoSD.
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19
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20 PBG3 files are merely a bitstream composed of a header,
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21 a file table, and LZSS-compressed files.
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22 """
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23
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24 from collections import namedtuple
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25 from io import BytesIO
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26
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27 from pytouhou.utils.bitstream import BitStream
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28 from pytouhou.utils import lzss
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29
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30 from pytouhou.utils.helpers import get_logger
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31
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32 from pytouhou.formats import WrongFormatError
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33
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34 logger = get_logger(__name__)
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36
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37 class PBG3BitStream(BitStream):
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38 """Helper class to handle strings and integers in PBG3 bitstreams."""
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39
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40 def read_int(self):
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41 """Read an integer from the bitstream.
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42
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43 Integers have variable sizes. They begin with a two-bit value indicating
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44 the number of (non-aligned) bytes to read.
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45 """
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46
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47 size = self.read(2)
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48 return self.read((size + 1) * 8)
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49
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50
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51 def read_string(self, maxsize):
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52 """Read a string from the bitstream.
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53
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54 Strings are stored as standard NULL-termianted sequences of bytes.
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55 The only catch is that they are not byte-aligned.
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56 """
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57
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58 string = []
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59 for i in range(maxsize):
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60 byte = self.read(8)
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61 if byte == 0:
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62 break
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63 string.append(byte)
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64 return ''.join(chr(byte) for byte in string)
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65
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66
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67
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68 PBG3Entry = namedtuple('PBG3Entry', 'unknown1 unknown2 checksum offset size')
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69
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70
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71
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72 class PBG3:
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73 """Handle PBG3 archive files.
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74
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75 PBG3 is a file archive format used in Touhou 6: EoSD.
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76 This class provides a representation of such files, as well as functions to
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77 read and extract files from a PBG3 archive.
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78
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79 Instance variables:
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80 entries -- list of PBG3Entry objects describing files present in the archive
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81 bitstream -- PBG3BitStream object
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82 """
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83
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84 def __init__(self, entries=None, bitstream=None):
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85 self.entries = entries or {}
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86 self.bitstream = bitstream #TODO
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87
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88
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89 def __enter__(self):
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90 return self
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91
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92
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93 def __exit__(self, type, value, traceback):
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94 return self.bitstream.__exit__(type, value, traceback)
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95
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96
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97 @classmethod
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98 def read(cls, file):
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99 """Read a PBG3 file.
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100
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101 Raise an exception if the file is invalid.
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102 Return a PBG3 instance otherwise.
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103 """
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104
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105 magic = file.read(4)
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106 if magic != b'PBG3':
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107 raise WrongFormatError(magic)
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108
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109 bitstream = PBG3BitStream(file)
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110 entries = {}
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111
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112 nb_entries = bitstream.read_int()
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113 offset = bitstream.read_int()
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114 bitstream.seek(offset)
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115 for i in range(nb_entries):
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116 unknown1 = bitstream.read_int()
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117 unknown2 = bitstream.read_int()
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118 checksum = bitstream.read_int() # Checksum of *compressed data*
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119 offset = bitstream.read_int()
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120 size = bitstream.read_int()
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121 name = bitstream.read_string(255)
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122 entries[name] = PBG3Entry(unknown1, unknown2, checksum, offset, size)
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123
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124 return PBG3(entries, bitstream)
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125
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126
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127 def list_files(self):
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128 """List files present in the archive."""
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129 return self.entries.keys()
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130
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131
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132 def get_file(self, filename, check=False):
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133 """Extract a given file.
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134
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135 If “filename” is in the archive, extract it and return its contents.
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136 Otherwise, raise an exception.
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137
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138 By default, the checksum of the file won't be verified,
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139 you can however force the verification using the “check” argument.
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140 """
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141
0
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142 unkwn1, unkwn2, checksum, offset, size = self.entries[filename]
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143 self.bitstream.seek(offset)
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144 data = lzss.decompress(self.bitstream, size)
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145 if check:
204
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146 # Verify the checksum
0
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147 compressed_size = self.bitstream.io.tell() - offset
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148 self.bitstream.seek(offset)
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149 value = 0
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150 for c in self.bitstream.io.read(compressed_size):
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151 value += c
0
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152 value &= 0xFFFFFFFF
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153 if value != checksum:
58
3da4de9decd0 Use logging module
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154 logger.warn('corrupted data!')
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155 return BytesIO(data)