diff options
| -rw-r--r-- | FuseArchive/Chunk.py | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/FuseArchive/Chunk.py b/FuseArchive/Chunk.py index 2ceb7ed..9f12f83 100644 --- a/FuseArchive/Chunk.py +++ b/FuseArchive/Chunk.py @@ -1,13 +1,17 @@ -import struct, zlib +import struct, zlib, logging # Format version # Payload block size (so you don't have to uncompress it to see) # Data compression type (0 = none, 1 = zlib) # Ref count (number of files that use this) # filler to pad out ot 64 bytes for future expansion -hformat = 'HHBL52x' +hformat = 'HLBL48x' compress_level = 6 +assert struct.calcsize( hformat ) == 64, \ + "Header struct must be 64 bytes not %d bytes" % \ + struct.calcsize( hformat ) + # This handles serialization and deserialization of compressed chunks with # some header data class Chunk: @@ -24,25 +28,35 @@ class Chunk: # Returns a string representing the serialized class to be sent to a # file def serialize(self, compression = 1): + l = len( self.chunk ) + + logging.debug( "Packing header: len: %d compression: %d count: %d" % + ( l, compression, self.count ) ) + data = struct.pack( hformat, 0, - len( self.chunk ), + l, compression, self.count ) if compression == 0: + logging.debug( "Saving chunk data raw" ) data += self.chunk elif compression == 1: + logging.debug( "Saving chunk data using zlib" ) data += zlib.compress( self.chunk, compress_level ) else: raise ValueError( "Invalid compression type: %d" % compression ) + logging.debug( "Returning serialized block, size is %d" % len( data) ) + return data # Converts the output of serialize back to a chunk object @staticmethod def deserialize(data): + logging.debug( "Deserializing data of length %d" % len( data ) ) hd = Chunk.parse_header( data[ :64 ] ) obj = Chunk() obj.count = hd[ 'count' ] @@ -62,6 +76,7 @@ class Chunk: # involve potentially uncompressing some data @staticmethod def parse_header(data): + logging.debug( "Parsing header of length %d" % len( data ) ) fields = struct.unpack( hformat, data ) return { 'version': fields[ 0 ], |