├── .gitignore
├── LICENSE
├── README.md
└── gogextract.py


/.gitignore:
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1 | extract
2 | 


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/LICENSE:
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 1 | MIT License
 2 | 
 3 | Copyright (c) 2016 Gabriel Huber
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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 1 | # GOG Extract
 2 | 
 3 | Script for unpacking GOG Linux installers.
 4 | 
 5 | Explanation of how it works is in my [blog post].
 6 | 
 7 | ## Usage
 8 | 
 9 | `gogextract.py <input file> <output dir>`
10 | 
11 | Output files will be named `unpacker.sh`, `mojosetup.tar.gz` and `data.zip`.
12 | 
13 | ## License
14 | 
15 | [MIT](LICENSE)
16 | 
17 | [blog post]: https://yepoleb.github.io/blog/2016/10/09/how-the-gog-linux-installers-work/
18 | 


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/gogextract.py:
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 1 | #!/usr/bin/env python3
 2 | import io
 3 | import re
 4 | import shutil
 5 | import os
 6 | from os import path
 7 | import sys
 8 | 
 9 | FILESIZE_RE = re.compile(r'filesizes="(\d+?)"')
10 | OFFSET_RE = re.compile(r'offset=`head -n (\d+?) "\$0"')
11 | 
12 | if len(sys.argv) == 2:
13 |     input_path = sys.argv[1]
14 |     output_path = "./"
15 | elif len(sys.argv) == 3:
16 |     input_path = sys.argv[1]
17 |     output_path = sys.argv[2]
18 | else:
19 |     print("Usage: {} <input file> <output dir>".format(sys.argv[0]))
20 |     exit(1)
21 | 
22 | game_bin = open(input_path, "rb")
23 | os.makedirs(output_path, exist_ok=True)
24 | 
25 | # Read the first 10kb so we can determine the script line number
26 | beginning = game_bin.read(10240).decode("utf-8", errors="ignore")
27 | offset_match = OFFSET_RE.search(beginning)
28 | script_lines = int(offset_match.group(1))
29 | 
30 | # Read the number of lines to determine the script size
31 | game_bin.seek(0, io.SEEK_SET)
32 | for l in range(0, script_lines):
33 |     game_bin.readline()
34 | script_size = game_bin.tell()
35 | print("Makeself script size:", script_size)
36 | 
37 | # Read the script
38 | game_bin.seek(0, io.SEEK_SET)
39 | script_bin = game_bin.read(script_size)
40 | with open(path.join(output_path, "unpacker.sh"), "wb") as script_f:
41 |     script_f.write(script_bin)
42 | script = script_bin.decode("utf-8")
43 | 
44 | # Filesize is for the MojoSetup archive, not the actual game data
45 | filesize_match = FILESIZE_RE.search(script)
46 | filesize = int(filesize_match.group(1))
47 | print("MojoSetup archive size:", filesize)
48 | 
49 | # Extract the setup archive
50 | game_bin.seek(script_size, io.SEEK_SET)
51 | with open(path.join(output_path, "mojosetup.tar.gz"), "wb") as setup_f:
52 |     setup_f.write(game_bin.read(filesize))
53 | 
54 | # Extract the game data archive
55 | dataoffset = script_size + filesize
56 | game_bin.seek(dataoffset, io.SEEK_SET)
57 | with open(path.join(output_path, "data.zip"), "wb") as datafile:
58 |     shutil.copyfileobj(game_bin, datafile)
59 | 


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