mirror of
https://github.com/elliotnunn/macresources.git
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69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
'''
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Handling of compressed MacOS resources.
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Author: Max Poliakovski 2018
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'''
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import struct
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import sys
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from GreggDecompress import GreggDecompress, GreggCompress
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def DecompressResource(inf):
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# get the extended resource header first
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hdrFields = struct.unpack(">IHBBI", inf.read(12))
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if hdrFields[0] != 0xA89F6572:
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print("Invalid extended resource header sig: 0x%X" % hdrFields[0])
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if hdrFields[1] != 18:
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print("Suspicious extended resource header length: %d" % hdrFields[1])
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if hdrFields[2] != 8 and hdrFields[2] != 9:
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print("Unknown ext res header format: %d" % hdrFields[2])
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if (hdrFields[3] & 1) == 0:
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print("extAttributes,bit0 isn't set. Treat this res as uncompressed.")
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print("Uncompressed length: %d" % hdrFields[4])
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if hdrFields[2] == 8:
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DonnSpecific = struct.unpack(">BBHH", inf.read(6))
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print("DonnDecompress isn't supported yet.")
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exit()
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else:
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GreggSpecific = struct.unpack(">HHBB", inf.read(6))
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fsize = inf.seek(0, 2)
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print("Compressed size: %d" % fsize)
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inf.seek(hdrFields[1], 0) # rewind to the start of compressed data
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dstBuf = bytearray()
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srcBuf = inf.read(fsize - hdrFields[1])
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# invoke GreggyBits decompressor and pass over required header data
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GreggDecompress(srcBuf, dstBuf, hdrFields[4], GreggSpecific[2], GreggSpecific[3])
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with open("Dump", 'wb') as outstream:
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outstream.write(dstBuf)
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# re-compress
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recompBuf = bytearray()
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# re-create extended resource header
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recompBuf.extend([0xA8, 0x9F, 0x65, 0x72, 0x00, 0x12, 0x09, 0x01])
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recompBuf.extend(hdrFields[4].to_bytes(4, 'big'))
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recompBuf.extend([0x00, 0x02, 0x00, 0x00])
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recompBuf.append(GreggSpecific[2])
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recompBuf.append(GreggSpecific[3])
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GreggCompress(dstBuf, recompBuf, hdrFields[4], customTab=True, isBitmapped=True)
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with open("RecompDump", 'wb') as outstream:
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outstream.write(recompBuf)
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if __name__ == "__main__":
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if len(sys.argv) < 2:
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file = "Compressed"
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else:
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file = sys.argv[1]
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with open(file, 'rb') as instream:
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DecompressResource(instream)
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