plugins/proxy.py

   1 #!/usr/bin/python
   2 # -*- coding: utf-8 -*-
   3 #
   4 # proxy.py — helper for Python-based external (xml-rpc) ikiwiki plugins
   5 #
   6 # Copyright © martin f. krafft <madduck@madduck.net>
   7 # Released under the terms of the GNU GPL version 2
   8 #
   9 __name__ = 'proxy.py'
  10 __description__ = 'helper for Python-based external (xml-rpc) ikiwiki plugins'
  11 __version__ = '0.1'
  12 __author__ = 'martin f. krafft <madduck@madduck.net>'
  13 __copyright__ = 'Copyright © ' + __author__
  14 __licence__ = 'GPLv2'
  15
  16 import sys
  17 import time
  18 import xmlrpclib
  19 import xml.parsers.expat
  20 from SimpleXMLRPCServer import SimpleXMLRPCDispatcher
  21
  22 class _IkiWikiExtPluginXMLRPCDispatcher(SimpleXMLRPCDispatcher):
  23
  24     def __init__(self, allow_none=False, encoding=None):
  25         try:
  26             SimpleXMLRPCDispatcher.__init__(self, allow_none, encoding)
  27         except TypeError:
  28             # see http://bugs.debian.org/470645
  29             # python2.4 and before only took one argument
  30             SimpleXMLRPCDispatcher.__init__(self)
  31
  32     def dispatch(self, method, params):
  33         return self._dispatch(method, params)
  34
  35 class _XMLStreamParser(object):
  36
  37     def __init__(self):
  38         self._parser = xml.parsers.expat.ParserCreate()
  39         self._parser.StartElementHandler = self._push_tag
  40         self._parser.EndElementHandler = self._pop_tag
  41         self._parser.XmlDeclHandler = self._check_pipelining
  42         self._reset()
  43
  44     def _reset(self):
  45         self._stack = list()
  46         self._acc = r''
  47         self._first_tag_received = False
  48
  49     def _push_tag(self, tag, attrs):
  50         self._stack.append(tag)
  51         self._first_tag_received = True
  52
  53     def _pop_tag(self, tag):
  54         top = self._stack.pop()
  55         if top != tag:
  56             raise ParseError, 'expected %s closing tag, got %s' % (top, tag)
  57
  58     def _request_complete(self):
  59         return self._first_tag_received and len(self._stack) == 0
  60
  61     def _check_pipelining(self, *args):
  62         if self._first_tag_received:
  63             raise PipeliningDetected, 'need a new line between XML documents'
  64
  65     def parse(self, data):
  66         self._parser.Parse(data, False)
  67         self._acc += data
  68         if self._request_complete():
  69             ret = self._acc
  70             self._reset()
  71             return ret
  72
  73     class ParseError(Exception):
  74         pass
  75
  76     class PipeliningDetected(Exception):
  77         pass
  78
  79 class _IkiWikiExtPluginXMLRPCHandler(object):
  80
  81     def __init__(self, debug_fn):
  82         self._dispatcher = _IkiWikiExtPluginXMLRPCDispatcher()
  83         self.register_function = self._dispatcher.register_function
  84         self._debug_fn = debug_fn
  85
  86     def register_function(self, function, name=None):
  87         # will be overwritten by __init__
  88         pass
  89
  90     @staticmethod
  91     def _write(out_fd, data):
  92         out_fd.write(str(data))
  93         out_fd.flush()
  94
  95     @staticmethod
  96     def _read(in_fd):
  97         ret = None
  98         parser = _XMLStreamParser()
  99         while True:
 100             line = in_fd.readline()
 101             if len(line) == 0:
 102                 # ikiwiki exited, EOF received
 103                 return None
 104
 105             ret = parser.parse(line)
 106             # unless this returns non-None, we need to loop again
 107             if ret is not None:
 108                 return ret
 109
 110     def send_rpc(self, cmd, in_fd, out_fd, **kwargs):
 111         xml = xmlrpclib.dumps(sum(kwargs.iteritems(), ()), cmd)
 112         self._debug_fn("calling ikiwiki procedure `%s': [%s]" % (cmd, xml))
 113         _IkiWikiExtPluginXMLRPCHandler._write(out_fd, xml)
 114
 115         self._debug_fn('reading response from ikiwiki...')
 116
 117         xml = _IkiWikiExtPluginXMLRPCHandler._read(in_fd)
 118         self._debug_fn('read response to procedure %s from ikiwiki: [%s]' % (cmd, xml))
 119         if xml is None:
 120             # ikiwiki is going down
 121             return None
 122
 123         data = xmlrpclib.loads(xml)[0]
 124         self._debug_fn('parsed data from response to procedure %s: [%s]' % (cmd, data))
 125         return data
 126
 127     def handle_rpc(self, in_fd, out_fd):
 128         self._debug_fn('waiting for procedure calls from ikiwiki...')
 129         xml = _IkiWikiExtPluginXMLRPCHandler._read(in_fd)
 130         if xml is None:
 131             # ikiwiki is going down
 132             self._debug_fn('ikiwiki is going down, and so are we...')
 133             return
 134
 135         self._debug_fn('received procedure call from ikiwiki: [%s]' % xml)
 136         params, method = xmlrpclib.loads(xml)
 137         ret = self._dispatcher.dispatch(method, params)
 138         xml = xmlrpclib.dumps((ret,), methodresponse=True)
 139         self._debug_fn('sending procedure response to ikiwiki: [%s]' % xml)
 140         _IkiWikiExtPluginXMLRPCHandler._write(out_fd, xml)
 141         return ret
 142
 143 class IkiWikiProcedureProxy(object):
 144
 145     # how to communicate None to ikiwiki
 146     _IKIWIKI_NIL_SENTINEL = {'null':''}
 147
 148     # sleep during each iteration
 149     _LOOP_DELAY = 0.1
 150
 151     def __init__(self, id, in_fd=sys.stdin, out_fd=sys.stdout, debug_fn=None):
 152         self._id = id
 153         self._in_fd = in_fd
 154         self._out_fd = out_fd
 155         self._hooks = list()
 156         if debug_fn is not None:
 157             self._debug_fn = debug_fn
 158         else:
 159             self._debug_fn = lambda s: None
 160         self._xmlrpc_handler = _IkiWikiExtPluginXMLRPCHandler(self._debug_fn)
 161         self._xmlrpc_handler.register_function(self._importme, name='import')
 162
 163     def hook(self, type, function, name=None):
 164         if name is None:
 165             name = function.__name__
 166         self._hooks.append((type, name))
 167
 168         def hook_proxy(*args):
 169 #            curpage = args[0]
 170 #            kwargs = dict([args[i:i+2] for i in xrange(1, len(args), 2)])
 171             ret = function(*args)
 172             self._debug_fn("%s hook `%s' returned: [%s]" % (type, name, ret))
 173             if ret == IkiWikiProcedureProxy._IKIWIKI_NIL_SENTINEL:
 174                 raise IkiWikiProcedureProxy.InvalidReturnValue, \
 175                         'hook functions are not allowed to return %s' \
 176                         % IkiWikiProcedureProxy._IKIWIKI_NIL_SENTINEL
 177             if ret is None:
 178                 ret = IkiWikiProcedureProxy._IKIWIKI_NIL_SENTINEL
 179             return ret
 180
 181         self._xmlrpc_handler.register_function(hook_proxy, name=name)
 182
 183     def _importme(self):
 184         self._debug_fn('importing...')
 185         for type, function in self._hooks:
 186             self._debug_fn('hooking %s into %s chain...' % (function, type))
 187             self._xmlrpc_handler.send_rpc('hook', self._in_fd, self._out_fd,
 188                                           id=self._id, type=type, call=function)
 189         return IkiWikiProcedureProxy._IKIWIKI_NIL_SENTINEL
 190
 191     def run(self):
 192         try:
 193             while True:
 194                 ret = self._xmlrpc_handler.handle_rpc(self._in_fd, self._out_fd)
 195                 if ret is None:
 196                     return
 197                 time.sleep(IkiWikiProcedureProxy._LOOP_DELAY)
 198         except Exception, e:
 199             print >>sys.stderr, 'uncaught exception: %s' % e
 200             import traceback
 201             print >>sys.stderr, traceback.format_exc(sys.exc_info()[2])
 202             import posix
 203             sys.exit(posix.EX_SOFTWARE)
 204
 205     class InvalidReturnValue(Exception):
 206         pass