Added script
Leo Coogan
5 years ago
parent
6ca2616a52
commit
6a08f348ed
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MIT License
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Copyright (c) 2010 magical
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#!/usr/bin/env python3
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import sys
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from sys import stdin, stdout, stderr, exit
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from os import SEEK_SET, SEEK_CUR, SEEK_END
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from errno import EPIPE
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from struct import pack, unpack
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__all__ = ('decompress', 'decompress_file', 'decompress_bytes',
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'decompress_overlay', 'DecompressionError')
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class DecompressionError(ValueError):
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pass
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def bits(byte):
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return ((byte >> 7) & 1,
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(byte >> 6) & 1,
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(byte >> 5) & 1,
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(byte >> 4) & 1,
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(byte >> 3) & 1,
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(byte >> 2) & 1,
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(byte >> 1) & 1,
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(byte) & 1)
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def decompress_raw_lzss10(indata, decompressed_size, _overlay=False):
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"""Decompress LZSS-compressed bytes. Returns a bytearray."""
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data = bytearray()
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it = iter(indata)
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if _overlay:
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disp_extra = 3
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else:
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disp_extra = 1
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def writebyte(b):
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data.append(b)
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def readbyte():
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return next(it)
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def readshort():
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# big-endian
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a = next(it)
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b = next(it)
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return (a << 8) | b
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def copybyte():
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data.append(next(it))
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while len(data) < decompressed_size:
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b = readbyte()
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flags = bits(b)
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for flag in flags:
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if flag == 0:
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copybyte()
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elif flag == 1:
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sh = readshort()
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count = (sh >> 0xc) + 3
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disp = (sh & 0xfff) + disp_extra
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for _ in range(count):
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writebyte(data[-disp])
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else:
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raise ValueError(flag)
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if decompressed_size <= len(data):
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break
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if len(data) != decompressed_size:
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raise DecompressionError("decompressed size does not match the expected size")
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return data
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def decompress_raw_lzss11(indata, decompressed_size):
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"""Decompress LZSS-compressed bytes. Returns a bytearray."""
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data = bytearray()
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it = iter(indata)
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def writebyte(b):
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data.append(b)
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def readbyte():
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return next(it)
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def copybyte():
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data.append(next(it))
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while len(data) < decompressed_size:
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b = readbyte()
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flags = bits(b)
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for flag in flags:
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if flag == 0:
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copybyte()
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elif flag == 1:
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b = readbyte()
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indicator = b >> 4
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if indicator == 0:
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# 8 bit count, 12 bit disp
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# indicator is 0, don't need to mask b
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count = (b << 4)
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b = readbyte()
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count += b >> 4
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count += 0x11
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elif indicator == 1:
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# 16 bit count, 12 bit disp
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count = ((b & 0xf) << 12) + (readbyte() << 4)
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b = readbyte()
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count += b >> 4
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count += 0x111
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else:
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# indicator is count (4 bits), 12 bit disp
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count = indicator
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count += 1
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disp = ((b & 0xf) << 8) + readbyte()
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disp += 1
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try:
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for _ in range(count):
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writebyte(data[-disp])
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except IndexError:
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raise Exception(count, disp, len(data), sum(1 for x in it) )
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else:
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raise ValueError(flag)
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if decompressed_size <= len(data):
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break
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if len(data) != decompressed_size:
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raise DecompressionError("decompressed size does not match the expected size")
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return data
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def decompress_overlay(f, out):
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# the compression header is at the end of the file
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f.seek(-8, SEEK_END)
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header = f.read(8)
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# decompression goes backwards.
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# end < here < start
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# end_delta == here - decompression end address
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# start_delta == decompression start address - here
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end_delta, start_delta = unpack("<LL", header)
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filelen = f.tell()
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padding = end_delta >> 0x18
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end_delta &= 0xFFFFFF
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decompressed_size = start_delta + end_delta
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f.seek(-end_delta, SEEK_END)
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data = bytearray()
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data.extend(f.read(end_delta - padding))
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data.reverse()
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#stdout.write(data.tostring())
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uncompressed_data = decompress_raw_lzss10(data, decompressed_size,
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_overlay=True)
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uncompressed_data.reverse()
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# first we write up to the portion of the file which was "overwritten" by
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# the decompressed data, then the decompressed data itself.
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# i wonder if it's possible for decompression to overtake the compressed
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# data, so that the decompression code is reading its own output...
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f.seek(0, SEEK_SET)
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out.write(f.read(filelen - end_delta))
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out.write(uncompressed_data)
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def decompress(obj):
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"""Decompress LZSS-compressed bytes or a file-like object.
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Shells out to decompress_file() or decompress_bytes() depending on
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whether or not the passed-in object has a 'read' attribute or not.
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Returns a bytearray."""
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if hasattr(obj, 'read'):
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return decompress_file(obj)
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else:
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return decompress_bytes(obj)
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def decompress_bytes(data):
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"""Decompress LZSS-compressed bytes. Returns a bytearray."""
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header = data[:4]
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if header[0] == 0x10:
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decompress_raw = decompress_raw_lzss10
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elif header[0] == 0x11:
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decompress_raw = decompress_raw_lzss11
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else:
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raise DecompressionError("not as lzss-compressed file")
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decompressed_size, = unpack("<L", header[1:] + b'\x00')
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data = data[4:]
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return decompress_raw(data, decompressed_size)
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def decompress_file(f):
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"""Decompress an LZSS-compressed file. Returns a bytearray.
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This isn't any more efficient than decompress_bytes, as it reads
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the entire file into memory. It is offered as a convenience.
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"""
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header = f.read(4)
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if header[0] == 0x10:
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decompress_raw = decompress_raw_lzss10
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elif header[0] == 0x11:
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decompress_raw = decompress_raw_lzss11
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else:
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raise DecompressionError("not as lzss-compressed file")
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decompressed_size, = unpack("<L", header[1:] + b'\x00')
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data = f.read()
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return decompress_raw(data, decompressed_size)
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def main(args=None):
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if args is None:
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args = sys.argv[1:]
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if '--overlay' in args:
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args.remove('--overlay')
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overlay = True
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else:
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overlay = False
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if len(args) < 1 or args[0] == '-':
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if overlay:
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print("Can't decompress overlays from stdin", file=stderr)
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return 2
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if hasattr(stdin, 'buffer'):
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f = stdin.buffer
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else:
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f = stdin
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else:
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try:
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f = open(args[0], "rb")
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except IOError as e:
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print(e, file=stderr)
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return 2
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stdout = sys.stdout
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if hasattr(stdout, 'buffer'):
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# grab the underlying binary stream
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stdout = stdout.buffer
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try:
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if overlay:
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decompress_overlay(f, stdout)
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else:
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stdout.write(decompress_file(f))
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except IOError as e:
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if e.errno == EPIPE:
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# don't complain about a broken pipe
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pass
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else:
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raise
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except (DecompressionError,) as e:
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print(e, file=stderr)
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return 1
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return 0
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if __name__ == '__main__':
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exit(main())
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