Mac/Lib/applesingle.py

   1 # applesingle - a module to decode AppleSingle files
   2 import struct
   3 import MacOS
   4 import sys
   5
   6 Error="applesingle.Error"
   7
   8 verbose=0
   9
  10 # File header format: magic, version, unused, number of entries
  11 AS_HEADER_FORMAT="ll16sh"
  12 AS_HEADER_LENGTH=26
  13 # The flag words for AppleSingle
  14 AS_MAGIC=0x00051600
  15 AS_VERSION=0x00020000
  16
  17 # Entry header format: id, offset, length
  18 AS_ENTRY_FORMAT="lll"
  19 AS_ENTRY_LENGTH=12
  20
  21 # The id values
  22 AS_DATAFORK=1
  23 AS_RESOURCEFORK=2
  24 AS_IGNORE=(3,4,5,6,8,9,10,11,12,13,14,15)
  25
  26 def decode(input, output, resonly=0):
  27         if type(input) == type(''):
  28                 input = open(input, 'rb')
  29         # Should we also test for FSSpecs or FSRefs?
  30         header = input.read(AS_HEADER_LENGTH)
  31         print `header`
  32         try:
  33                 magic, version, dummy, nentry = struct.unpack(AS_HEADER_FORMAT, header)
  34         except ValueError, arg:
  35                 raise Error, "Unpack header error: %s"%arg
  36         if verbose:
  37                 print 'Magic:   0x%8.8x'%magic
  38                 print 'Version: 0x%8.8x'%version
  39                 print 'Entries: %d'%nentry
  40         if magic != AS_MAGIC:
  41                 raise Error, 'Unknown AppleSingle magic number 0x%8.8x'%magic
  42         if version != AS_VERSION:
  43                 raise Error, 'Unknown AppleSingle version number 0x%8.8x'%version
  44         if nentry <= 0:
  45                 raise Error, "AppleSingle file contains no forks"
  46         headers = [input.read(AS_ENTRY_LENGTH) for i in range(nentry)]
  47         didwork = 0
  48         for hdr in headers:
  49                 try:
  50                         id, offset, length = struct.unpack(AS_ENTRY_FORMAT, hdr)
  51                 except ValueError, arg:
  52                         raise Error, "Unpack entry error: %s"%arg
  53                 if verbose:
  54                         print 'Fork %d, offset %d, length %d'%(id, offset, length)
  55                 input.seek(offset)
  56                 if length == 0:
  57                         data = ''
  58                 else:
  59                         data = input.read(length)
  60                 if len(data) != length:
  61                         raise Error, 'Short read: expected %d bytes got %d'%(length, len(data))
  62                 if id == AS_DATAFORK:
  63                         if verbose:
  64                                 print '  (data fork)'
  65                         if not resonly:
  66                                 didwork = 1
  67                                 fp = open(output, 'wb')
  68                                 fp.write(data)
  69                                 fp.close()
  70                 elif id == AS_RESOURCEFORK:
  71                         didwork = 1
  72                         if verbose:
  73                                 print '  (resource fork)'
  74                         if resonly:
  75                                 fp = open(output, 'wb')
  76                         else:
  77                                 fp = MacOS.openrf(output, 'wb')
  78                         fp.write(data)
  79                         fp.close()
  80                 elif id in AS_IGNORE:
  81                         if verbose:
  82                                 print '  (ignored)'
  83                 else:
  84                         raise Error, 'Unknown fork type %d'%id
  85         if not didwork:
  86                 raise Error, 'No useful forks found'
  87
  88 def _test():
  89         if len(sys.argv) < 3 or sys.argv[1] == '-r' and len(sys.argv) != 4:
  90                 print 'Usage: applesingle.py [-r] applesinglefile decodedfile'
  91                 sys.exit(1)
  92         if sys.argv[1] == '-r':
  93                 resonly = 1
  94                 del sys.argv[1]
  95         else:
  96                 resonly = 0
  97         decode(sys.argv[1], sys.argv[2], resonly=resonly)
  98
  99 if __name__ == '__main__':
 100         _test()
 101