xref: /aosp_15_r20/external/autotest/client/common_lib/cros/xmlrpc_types.py (revision 9c5db1993ded3edbeafc8092d69fe5de2ee02df7) 
1# Lint as: python2, python3
2# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5
6from __future__ import absolute_import
7from __future__ import division
8from __future__ import print_function
9try:
10    from inspect import getfullargspec as get_args
11except ImportError:
12    from inspect import getargspec as get_args
13import logging
14import six
15import sys
16
17
18TYPE_KEY = 'xmlrpc_struct_type_key'
19
20
21def deserialize(serialized, module=None):
22    """Deserialize an XmlRpcStruct.
23
24    Because Python XMLRPC doesn't understand anything more than basic
25    types, we're forced to reinvent type serialization.  This is one way
26    to do it.
27
28    This function looks at the constructor and figures out what subset of
29    |serialized| will be accepted as arguments.
30
31    @param serialized dict representing a serialized XmlRpcStruct.
32    @param module module object to pull classes from.  Defaults to
33            this file.
34    @return an XmlRpcStruct object built from |serialized|.
35
36    """
37    if TYPE_KEY not in serialized:
38        logging.error('Failed to deserialize XmlRpcStruct because of '
39                      'missing type.')
40        logging.error('Got serialized object: %r', serialized)
41        return None
42
43    if module is None:
44        module = sys.modules[__name__]
45    klass = getattr(module, serialized[TYPE_KEY])
46    constructor_args = get_args(klass.__init__)
47    optional_args = []
48    if constructor_args.defaults:
49        # Valid args should now be a list of all the parameters that have
50        # default values.
51        optional_args = constructor_args.args[-len(constructor_args.defaults):]
52        # skip to argument 1 because the first argument is always |self|.
53        required_args = constructor_args.args[1:-len(constructor_args.defaults)]
54    args = []
55    for arg in required_args:
56        if arg not in serialized:
57            logging.error('Failed to find non-keyword argument %s', arg)
58            return None
59
60        args.append(serialized[arg])
61    kwargs = dict([k_v for k_v in six.iteritems(serialized) if k_v[0] in optional_args])
62    logging.debug('Constructing %s object with args=%r, kwargs=%r',
63                  serialized[TYPE_KEY], args, kwargs)
64    return klass(*args, **kwargs)
65
66
67class XmlRpcStruct(object):
68    """Enables deserialization by injecting the proper class type.
69
70    To make deserilization work for you, write a constructor like:
71
72    def __init__(self, arg1, arg2='foo'):
73        # It is important that self.arg1 = arg1.  Otherwise arguments
74        # won't be sent over the wire correctly.
75        self.arg1 = arg1
76        self.arg2 = arg2
77
78    Serialization happens automatically when using XMLRPC proxies, since
79    Python's XMLRPC framework will take all fields from your object and drop
80    them into a dict to go over the wire.  To deserialize your object on the
81    other side, call deserialize() and pass in the module defining the
82    requisite class.
83
84    serialize() is provided to allow objects to fake that they are XMLRPC
85    proxies.
86
87    """
88
89    def __init__(self):
90        super(XmlRpcStruct, self).__init__()
91        setattr(self, TYPE_KEY, self.__class__.__name__)
92
93
94    def serialize(self):
95        """@return dict of object fields."""
96        return self.__dict__
97