mirror of
https://gitlab.freedesktop.org/dbus/dbus.git
synced 2025-12-28 01:30:09 +01:00
e20c311b13
* python/service.py: Heavy refactoring of method invocation, with
hopefully no effect on functionality. Nuked _dispatch_dbus_method_call
in favour of a new _message_cb that uses seperate functions for
looking up the method to call, marshalling the return values, and
sending exceptions as errors, and is easier to follow as a
consequence. Fixes some corner cases about returning things that
don't match your declared out_signature, allows exceptions to define
_dbus_error_name and have it be sent over the bus as the error name,
and paves the way for cool stuff like heeding the message no reply
flag, asynchronous method implementations, informing the method of the
sender, and including backtraces in the error messages.
* test/python/test-client.py: Catch and print exceptions thrown in the
async callback tests, rather than passing them to the low-level
bindings to be ignored in a noisy and frustrating manner.
317 lines
13 KiB
Python
317 lines
13 KiB
Python
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import dbus_bindings
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import _dbus
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import operator
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from exceptions import UnknownMethodException
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from decorators import method
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from decorators import signal
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class BusName:
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"""A base class for exporting your own Named Services across the Bus
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"""
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def __init__(self, named_service, bus=None):
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self._named_service = named_service
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if bus == None:
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# Get the default bus
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self._bus = _dbus.Bus()
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else:
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self._bus = bus
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dbus_bindings.bus_request_name(self._bus.get_connection(), named_service)
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def get_bus(self):
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"""Get the Bus this Service is on"""
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return self._bus
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def get_name(self):
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"""Get the name of this service"""
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return self._named_service
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def __repr__(self):
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return '<dbus.service.BusName %s on %r at %#x>' % (self._named_service, self._bus, id(self))
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__str__ = __repr__
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def _method_lookup(self, method_name, dbus_interface):
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"""Walks the Python MRO of the given class to find the method to invoke.
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Returns two methods, the one to call, and the one it inherits from which
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defines its D-Bus interface name, signature, and attributes.
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"""
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parent_method = None
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candidate_class = None
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successful = False
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# split up the cases when we do and don't have an interface because the
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# latter is much simpler
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if dbus_interface:
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# search through the class hierarchy in python MRO order
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for cls in self.__class__.__mro__:
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# if we haven't got a candidate class yet, and we find a class with a
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# suitably named member, save this as a candidate class
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if (not candidate_class and method_name in cls.__dict__):
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if ("_dbus_is_method" in cls.__dict__[method_name].__dict__
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and "_dbus_interface" in cls.__dict__[method_name].__dict__):
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# however if it is annotated for a different interface
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# than we are looking for, it cannot be a candidate
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if cls.__dict__[method_name]._dbus_interface == dbus_interface:
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candidate_class = cls
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parent_method = cls.__dict__[method_name]
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sucessful = True
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break
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else:
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pass
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else:
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candidate_class = cls
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# if we have a candidate class, carry on checking this and all
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# superclasses for a method annoated as a dbus method
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# on the correct interface
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if (candidate_class and method_name in cls.__dict__
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and "_dbus_is_method" in cls.__dict__[method_name].__dict__
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and "_dbus_interface" in cls.__dict__[method_name].__dict__
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and cls.__dict__[method_name]._dbus_interface == dbus_interface):
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# the candidate class has a dbus method on the correct interface,
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# or overrides a method that is, success!
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parent_method = cls.__dict__[method_name]
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sucessful = True
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break
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else:
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# simpler version of above
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for cls in self.__class__.__mro__:
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if (not candidate_class and method_name in cls.__dict__):
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candidate_class = cls
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if (candidate_class and method_name in cls.__dict__
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and "_dbus_is_method" in cls.__dict__[method_name].__dict__):
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parent_method = cls.__dict__[method_name]
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sucessful = True
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break
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if sucessful:
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return (candidate_class.__dict__[method_name], parent_method)
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else:
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if dbus_interface:
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raise UnknownMethodException('%s is not a valid method of interface %s' % (method_name, dbus_interface))
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else:
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raise UnknownMethodException('%s is not a valid method' % method_name)
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def _method_reply_return(connection, message, method_name, signature, *retval):
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reply = dbus_bindings.MethodReturn(message)
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iter = reply.get_iter(append=True)
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# do strict adding if an output signature was provided
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if signature:
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if len(signature) > len(retval):
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raise TypeError('output signature %s is longer than the number of values returned by %s' %
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(signature, method_name))
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elif len(retval) > len(signature):
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raise TypeError('output signature %s is shorter than the number of values returned by %s' %
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(signature, method_name))
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else:
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for (value, sig) in zip(retval, signature):
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iter.append_strict(value, sig)
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# no signature, try and guess the return type by inspection
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else:
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for value in retval:
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iter.append(value)
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connection.send(reply)
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def _method_reply_error(connection, message, exception):
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if '_dbus_error_name' in exception.__dict__:
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name = exception._dbus_error_name
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elif exception.__module__ == '__main__':
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name = 'org.freedesktop.DBus.Python.%s' % exception.__class__.__name__
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else:
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name = 'org.freedesktop.DBus.Python.%s.%s' % (exception.__module__, exception.__class__.__name__)
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contents = str(exception)
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reply = dbus_bindings.Error(message, name, contents)
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connection.send(reply)
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class InterfaceType(type):
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def __init__(cls, name, bases, dct):
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# these attributes are shared between all instances of the Interface
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# object, so this has to be a dictionary that maps class names to
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# the per-class introspection/interface data
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class_table = getattr(cls, '_dbus_class_table', {})
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cls._dbus_class_table = class_table
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interface_table = class_table[cls.__module__ + '.' + name] = {}
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# merge all the name -> method tables for all the interfaces
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# implemented by our base classes into our own
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for b in bases:
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base_name = b.__module__ + '.' + b.__name__
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if getattr(b, '_dbus_class_table', False):
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for (interface, method_table) in class_table[base_name].iteritems():
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our_method_table = interface_table.setdefault(interface, {})
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our_method_table.update(method_table)
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# add in all the name -> method entries for our own methods/signals
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for func in dct.values():
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if getattr(func, '_dbus_interface', False):
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method_table = interface_table.setdefault(func._dbus_interface, {})
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method_table[func.__name__] = func
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super(InterfaceType, cls).__init__(name, bases, dct)
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# methods are different to signals, so we have two functions... :)
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def _reflect_on_method(cls, func):
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args = func._dbus_args
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if func._dbus_in_signature:
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# convert signature into a tuple so length refers to number of
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# types, not number of characters
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in_sig = tuple(dbus_bindings.Signature(func._dbus_in_signature))
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if len(in_sig) > len(args):
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raise ValueError, 'input signature is longer than the number of arguments taken'
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elif len(in_sig) < len(args):
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raise ValueError, 'input signature is shorter than the number of arguments taken'
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else:
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# magic iterator which returns as many v's as we need
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in_sig = dbus_bindings.VariantSignature()
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if func._dbus_out_signature:
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out_sig = dbus_bindings.Signature(func._dbus_out_signature)
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else:
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# its tempting to default to dbus_bindings.Signature('v'), but
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# for methods that return nothing, providing incorrect
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# introspection data is worse than providing none at all
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out_sig = []
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reflection_data = ' <method name="%s">\n' % (func.__name__)
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for pair in zip(in_sig, args):
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reflection_data += ' <arg direction="in" type="%s" name="%s" />\n' % pair
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for type in out_sig:
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reflection_data += ' <arg direction="out" type="%s" />\n' % type
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reflection_data += ' </method>\n'
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return reflection_data
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def _reflect_on_signal(cls, func):
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args = func._dbus_args
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if func._dbus_signature:
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# convert signature into a tuple so length refers to number of
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# types, not number of characters
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sig = tuple(dbus_bindings.Signature(func._dbus_signature))
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if len(sig) > len(args):
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raise ValueError, 'signal signature is longer than the number of arguments provided'
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elif len(sig) < len(args):
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raise ValueError, 'signal signature is shorter than the number of arguments provided'
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else:
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# magic iterator which returns as many v's as we need
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sig = dbus_bindings.VariantSignature()
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reflection_data = ' <signal name="%s">\n' % (func.__name__)
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for pair in zip(sig, args):
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reflection_data = reflection_data + ' <arg type="%s" name="%s" />\n' % pair
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reflection_data = reflection_data + ' </signal>\n'
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return reflection_data
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class Interface(object):
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__metaclass__ = InterfaceType
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class Object(Interface):
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"""A base class for exporting your own Objects across the Bus.
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Just inherit from Object and provide a list of methods to share
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across the Bus
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"""
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def __init__(self, bus_name, object_path):
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self._object_path = object_path
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self._name = bus_name
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self._bus = bus_name.get_bus()
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self._connection = self._bus.get_connection()
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self._connection.register_object_path(object_path, self._unregister_cb, self._message_cb)
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def _unregister_cb(self, connection):
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print ("Unregister")
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def _message_cb(self, connection, message):
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try:
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# lookup candidate method and parent method
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method_name = message.get_member()
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interface_name = message.get_interface()
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(candidate_method, parent_method) = _method_lookup(self, method_name, interface_name)
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# call method
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args = message.get_args_list()
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retval = candidate_method(self, *args)
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# send return reply if it's not an asynchronous function
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# if we have a signature, use it to turn the return value into a tuple as appropriate
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if parent_method._dbus_out_signature:
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# iterate signature into list of complete types
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signature = tuple(dbus_bindings.Signature(parent_method._dbus_out_signature))
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# if we have zero or one return values we want make a tuple
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# for the _method_reply_return function, otherwise we need
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# to check we're passing it a sequence
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if len(signature) == 0:
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if retval == None:
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retval = ()
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else:
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raise TypeError('%s has an empty output signature but did not return None' %
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method_name)
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elif len(signature) == 1:
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retval = (retval,)
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else:
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if operator.isSequenceType(retval):
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# multi-value signature, multi-value return... proceed unchanged
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pass
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else:
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raise TypeError('%s has multiple output values in signature %s but did not return a sequence' %
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(method_name, signature))
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# no signature, so just turn the return into a tuple and send it as normal
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else:
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signature = None
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if retval == None:
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retval = ()
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else:
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retval = (retval,)
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print retval, signature
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_method_reply_return(connection, message, method_name, signature, *retval)
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except Exception, exception:
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# send error reply
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_method_reply_error(connection, message, exception)
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@method('org.freedesktop.DBus.Introspectable', in_signature='', out_signature='s')
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def Introspect(self):
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reflection_data = '<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">\n'
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reflection_data += '<node name="%s">\n' % (self._object_path)
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interfaces = self._dbus_class_table[self.__class__.__module__ + '.' + self.__class__.__name__]
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for (name, funcs) in interfaces.iteritems():
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reflection_data += ' <interface name="%s">\n' % (name)
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for func in funcs.values():
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if getattr(func, '_dbus_is_method', False):
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reflection_data += self.__class__._reflect_on_method(func)
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elif getattr(func, '_dbus_is_signal', False):
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reflection_data += self.__class__._reflect_on_signal(func)
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reflection_data += ' </interface>\n'
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reflection_data += '</node>\n'
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return reflection_data
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def __repr__(self):
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return '<dbus.service.Object %s on %r at %#x>' % (self._object_path, self._name, id(self))
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__str__ = __repr__
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