100 lines
2.5 KiB
Python
100 lines
2.5 KiB
Python
# applesingle - a module to decode AppleSingle files
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import struct
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import MacOS
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import sys
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Error="applesingle.Error"
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verbose=0
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# File header format: magic, version, unused, number of entries
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AS_HEADER_FORMAT="ll16sh"
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AS_HEADER_LENGTH=26
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# The flag words for AppleSingle
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AS_MAGIC=0x00051600
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AS_VERSION=0x00020000
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# Entry header format: id, offset, length
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AS_ENTRY_FORMAT="lll"
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AS_ENTRY_LENGTH=12
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# The id values
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AS_DATAFORK=1
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AS_RESOURCEFORK=2
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AS_IGNORE=(3,4,5,6,8,9,10,11,12,13,14,15)
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def decode(input, output, resonly=0):
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if type(input) == type(''):
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input = open(input, 'rb')
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# Should we also test for FSSpecs or FSRefs?
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header = input.read(AS_HEADER_LENGTH)
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try:
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magic, version, dummy, nentry = struct.unpack(AS_HEADER_FORMAT, header)
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except ValueError, arg:
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raise Error, "Unpack header error: %s"%arg
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if verbose:
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print 'Magic: 0x%8.8x'%magic
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print 'Version: 0x%8.8x'%version
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print 'Entries: %d'%nentry
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if magic != AS_MAGIC:
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raise Error, 'Unknown AppleSingle magic number 0x%8.8x'%magic
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if version != AS_VERSION:
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raise Error, 'Unknown AppleSingle version number 0x%8.8x'%version
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if nentry <= 0:
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raise Error, "AppleSingle file contains no forks"
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headers = [input.read(AS_ENTRY_LENGTH) for i in range(nentry)]
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didwork = 0
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for hdr in headers:
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try:
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id, offset, length = struct.unpack(AS_ENTRY_FORMAT, hdr)
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except ValueError, arg:
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raise Error, "Unpack entry error: %s"%arg
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if verbose:
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print 'Fork %d, offset %d, length %d'%(id, offset, length)
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input.seek(offset)
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if length == 0:
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data = ''
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else:
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data = input.read(length)
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if len(data) != length:
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raise Error, 'Short read: expected %d bytes got %d'%(length, len(data))
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if id == AS_DATAFORK:
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if verbose:
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print ' (data fork)'
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if not resonly:
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didwork = 1
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fp = open(output, 'wb')
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fp.write(data)
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fp.close()
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elif id == AS_RESOURCEFORK:
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didwork = 1
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if verbose:
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print ' (resource fork)'
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if resonly:
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fp = open(output, 'wb')
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else:
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fp = MacOS.openrf(output, 'wb')
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fp.write(data)
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fp.close()
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elif id in AS_IGNORE:
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if verbose:
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print ' (ignored)'
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else:
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raise Error, 'Unknown fork type %d'%id
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if not didwork:
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raise Error, 'No useful forks found'
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def _test():
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if len(sys.argv) < 3 or sys.argv[1] == '-r' and len(sys.argv) != 4:
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print 'Usage: applesingle.py [-r] applesinglefile decodedfile'
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sys.exit(1)
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if sys.argv[1] == '-r':
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resonly = 1
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del sys.argv[1]
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else:
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resonly = 0
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decode(sys.argv[1], sys.argv[2], resonly=resonly)
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if __name__ == '__main__':
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_test()
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