text: #!/usr/bin/env python
  
  """
  c_zlib - zlib for Python using ctypes.
  
  This is a quick and nasty implementation of zlib using Python ctypes, in order
  to expose the ability to set a compression dictionary (which isn't available
  in the zlib module).
  """
  
  __license__ = """
  Copyright (c) 2009 Mark Nottingham <mnot@pobox.com>
   
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
   
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
   
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
  """
  
  
  import ctypes as C
  from ctypes import util
  
  _zlib = C.cdll.LoadLibrary(util.find_library('libz'))
  
  class _z_stream(C.Structure):
      _fields_ = [
          ("next_in", C.POINTER(C.c_ubyte)),
          ("avail_in", C.c_uint),
          ("total_in", C.c_ulong),
          ("next_out", C.POINTER(C.c_ubyte)),
          ("avail_out", C.c_uint),
          ("total_out", C.c_ulong),
          ("msg", C.c_char_p),
          ("state", C.c_void_p),
          ("zalloc", C.c_void_p),
          ("zfree", C.c_void_p),
          ("opaque", C.c_void_p),
          ("data_type", C.c_int),
          ("adler", C.c_ulong),
          ("reserved", C.c_ulong),
          
      ]
  
  # TODO: get zlib version with ctypes
  ZLIB_VERSION = C.c_char_p("1.2.3")
  Z_NULL = 0x00
  Z_OK = 0x00
  Z_STREAM_END = 0x01
  Z_NEED_DICT = 0x02
  Z_BUF_ERR = -0x05
  
  Z_NO_FLUSH = 0x00
  Z_SYNC_FLUSH = 0x02
  Z_FINISH = 0x04
  
  CHUNK = 1024 * 128  # FIXME: need to be smarter than this.
  
  class Compressor:
      def __init__(self, level=-1, dictionary=None):
          self.level = level
          self.st = _z_stream()
          err = _zlib.deflateInit_(C.byref(self.st), self.level, ZLIB_VERSION, C.sizeof(self.st))
          assert err == Z_OK, err # FIXME: specific error
          if dictionary:
              err = _zlib.deflateSetDictionary(
                  C.byref(self.st),
                  C.cast(C.c_char_p(dictionary), C.POINTER(C.c_ubyte)),
                  len(dictionary)
              )
              assert err == Z_OK, err # FIXME: more specific error
  
      def __call__(self, input):
          outbuf = C.create_string_buffer(CHUNK)
          self.st.avail_in  = len(input)
          self.st.next_in   = C.cast(C.c_char_p(input), C.POINTER(C.c_ubyte))
          self.st.next_out  = C.cast(outbuf, C.POINTER(C.c_ubyte))
          self.st.avail_out = CHUNK
          err = _zlib.deflate(C.byref(self.st), Z_SYNC_FLUSH)
          if err in [Z_OK, Z_STREAM_END]:
              return outbuf[:CHUNK-self.st.avail_out]
          else:
              raise AssertionError, err # FIXME: more specific errors?
  
      def __del__(self):
          err = _zlib.deflateEnd(C.byref(self.st))
          #assert err == Z_OK, err # FIXME: more specific error
  
      
  class Decompressor:
      def __init__(self, dictionary=None):
          self.dictionary = dictionary
          self.st = _z_stream()
          err = _zlib.inflateInit2_(C.byref(self.st), 15, ZLIB_VERSION, C.sizeof(self.st))
          assert err == Z_OK, err # FIXME: more specific error
  
      def __call__(self, input):
          outbuf = C.create_string_buffer(CHUNK)
          self.st.avail_in  = len(input)
          self.st.next_in   = C.cast(C.c_char_p(input), C.POINTER(C.c_ubyte))
          self.st.avail_out = CHUNK
          self.st.next_out  = C.cast(outbuf, C.POINTER(C.c_ubyte))
          err = _zlib.inflate(C.byref(self.st), Z_SYNC_FLUSH)
          if err == Z_NEED_DICT:
              assert self.dictionary, "no dictionary provided"  # FIXME: more specific error
              dict_id = _zlib.adler32(
                  0L,
                  C.cast(C.c_char_p(self.dictionary), C.POINTER(C.c_ubyte)),
                  len(self.dictionary)
              )
  #            assert dict_id == self.st.adler, 'incorrect dictionary (%s != %s)' % (dict_id, self.st.adler)
              err = _zlib.inflateSetDictionary(
                  C.byref(self.st),
                  C.cast(C.c_char_p(self.dictionary), C.POINTER(C.c_ubyte)),
                  len(self.dictionary)
              )
              assert err == Z_OK, err # FIXME: more specific error
              err = _zlib.inflate(C.byref(self.st), Z_SYNC_FLUSH)
          if err in [Z_OK, Z_STREAM_END]:
              return outbuf[:CHUNK-self.st.avail_out]
          else:
              raise AssertionError, err # FIXME: more specific error
  
      def __del__(self):
          err = _zlib.inflateEnd(C.byref(self.st))
          assert err == Z_OK, err # FIXME: more specific error
      
  