Lib/plat-mac/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         try:
  32                 magic, version, dummy, nentry = struct.unpack(AS_HEADER_FORMAT, header)
  33         except ValueError, arg:
  34                 raise Error, "Unpack header error: %s"%arg
  35         if verbose:
  36                 print 'Magic:   0x%8.8x'%magic
  37                 print 'Version: 0x%8.8x'%version
  38                 print 'Entries: %d'%nentry
  39         if magic != AS_MAGIC:
  40                 raise Error, 'Unknown AppleSingle magic number 0x%8.8x'%magic
  41         if version != AS_VERSION:
  42                 raise Error, 'Unknown AppleSingle version number 0x%8.8x'%version
  43         if nentry <= 0:
  44                 raise Error, "AppleSingle file contains no forks"
  45         headers = [input.read(AS_ENTRY_LENGTH) for i in range(nentry)]
  46         didwork = 0
  47         for hdr in headers:
  48                 try:
  49                         id, offset, length = struct.unpack(AS_ENTRY_FORMAT, hdr)
  50                 except ValueError, arg:
  51                         raise Error, "Unpack entry error: %s"%arg
  52                 if verbose:
  53                         print 'Fork %d, offset %d, length %d'%(id, offset, length)
  54                 input.seek(offset)
  55                 if length == 0:
  56                         data = ''
  57                 else:
  58                         data = input.read(length)
  59                 if len(data) != length:
  60                         raise Error, 'Short read: expected %d bytes got %d'%(length, len(data))
  61                 if id == AS_DATAFORK:
  62                         if verbose:
  63                                 print '  (data fork)'
  64                         if not resonly:
  65                                 didwork = 1
  66                                 fp = open(output, 'wb')
  67                                 fp.write(data)
  68                                 fp.close()
  69                 elif id == AS_RESOURCEFORK:
  70                         didwork = 1
  71                         if verbose:
  72                                 print '  (resource fork)'
  73                         if resonly:
  74                                 fp = open(output, 'wb')
  75                         else:
  76                                 fp = MacOS.openrf(output, 'wb')
  77                         fp.write(data)
  78                         fp.close()
  79                 elif id in AS_IGNORE:
  80                         if verbose:
  81                                 print '  (ignored)'
  82                 else:
  83                         raise Error, 'Unknown fork type %d'%id
  84         if not didwork:
  85                 raise Error, 'No useful forks found'
  86
  87 def _test():
  88         if len(sys.argv) < 3 or sys.argv[1] == '-r' and len(sys.argv) != 4:
  89                 print 'Usage: applesingle.py [-r] applesinglefile decodedfile'
  90                 sys.exit(1)
  91         if sys.argv[1] == '-r':
  92                 resonly = 1
  93                 del sys.argv[1]
  94         else:
  95                 resonly = 0
  96         decode(sys.argv[1], sys.argv[2], resonly=resonly)
  97
  98 if __name__ == '__main__':
  99         _test()
 100