Class: DBus::Connection

Inherits:
Object
  • Object
show all
Defined in:
lib/dbus/bus.rb

Overview

D-Bus main connection class

Main class that maintains a connection to a bus and can handle incoming and outgoing messages.

Direct Known Subclasses

RemoteBus, SessionBus, SystemBus

Defined Under Namespace

Classes: NameRequestError

Constant Summary collapse

NAME_FLAG_ALLOW_REPLACEMENT =

FIXME: describe the following names, flags and constants. See DBus spec for definition

0x1
NAME_FLAG_REPLACE_EXISTING = 
0x2
NAME_FLAG_DO_NOT_QUEUE = 
0x4
REQUEST_NAME_REPLY_PRIMARY_OWNER = 
0x1
REQUEST_NAME_REPLY_IN_QUEUE = 
0x2
REQUEST_NAME_REPLY_EXISTS = 
0x3
REQUEST_NAME_REPLY_ALREADY_OWNER = 
0x4
DBUSXMLINTRO = 
'<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
  <interface name="org.freedesktop.DBus.Introspectable">
    <method name="Introspect">
      <arg name="data" direction="out" type="s"/>
    </method>
  </interface>
  <interface name="org.freedesktop.DBus">
    <method name="RequestName">
      <arg direction="in" type="s"/>
      <arg direction="in" type="u"/>
      <arg direction="out" type="u"/>
    </method>
    <method name="ReleaseName">
      <arg direction="in" type="s"/>
      <arg direction="out" type="u"/>
    </method>
    <method name="StartServiceByName">
      <arg direction="in" type="s"/>
      <arg direction="in" type="u"/>
      <arg direction="out" type="u"/>
    </method>
    <method name="Hello">
      <arg direction="out" type="s"/>
    </method>
    <method name="NameHasOwner">
      <arg direction="in" type="s"/>
      <arg direction="out" type="b"/>
    </method>
    <method name="ListNames">
      <arg direction="out" type="as"/>
    </method>
    <method name="ListActivatableNames">
      <arg direction="out" type="as"/>
    </method>
    <method name="AddMatch">
      <arg direction="in" type="s"/>
    </method>
    <method name="RemoveMatch">
      <arg direction="in" type="s"/>
    </method>
    <method name="GetNameOwner">
      <arg direction="in" type="s"/>
      <arg direction="out" type="s"/>
    </method>
    <method name="ListQueuedOwners">
      <arg direction="in" type="s"/>
      <arg direction="out" type="as"/>
    </method>
    <method name="GetConnectionUnixUser">
      <arg direction="in" type="s"/>
      <arg direction="out" type="u"/>
    </method>
    <method name="GetConnectionUnixProcessID">
      <arg direction="in" type="s"/>
      <arg direction="out" type="u"/>
    </method>
    <method name="GetConnectionSELinuxSecurityContext">
      <arg direction="in" type="s"/>
      <arg direction="out" type="ay"/>
    </method>
    <method name="ReloadConfig">
    </method>
    <signal name="NameOwnerChanged">
      <arg type="s"/>
      <arg type="s"/>
      <arg type="s"/>
    </signal>
    <signal name="NameLost">
      <arg type="s"/>
    </signal>
    <signal name="NameAcquired">
      <arg type="s"/>
    </signal>
  </interface>
</node>
'
MSG_BUF_SIZE =

The buffer size for messages.

4096

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Connection

Create a new connection to the bus for a given connect path. path format is described in the D-Bus specification: dbus.freedesktop.org/doc/dbus-specification.html#addresses and is something like: “transport1:key1=value1,key2=value2;transport2:key1=value1,key2=value2” e.g. “unix:path=/tmp/dbus-test” or “tcp:host=localhost,port=2687”



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# File 'lib/dbus/bus.rb', line 197

def initialize(path)
  @path = path
  @unique_name = nil
  @buffer = ""
  @method_call_replies = Hash.new
  @method_call_msgs = Hash.new
  @signal_matchrules = Hash.new
  @proxy = nil
  @object_root = Node.new("/")
  @is_tcp = false
end

Instance Attribute Details

#socket ⇒ Object (readonly)

The socket that is used to connect with the bus.



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# File 'lib/dbus/bus.rb', line 189

def socket
  @socket
end

#unique_name ⇒ Object (readonly)

The unique name (by specification) of the message.



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# File 'lib/dbus/bus.rb', line 187

def unique_name
  @unique_name
end

Instance Method Details

#add_match(mr, &slot) ⇒ Object

Asks bus to send us messages matching mr, and execute slot when received



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# File 'lib/dbus/bus.rb', line 573

def add_match(mr, &slot)
  # check this is a signal.
  mrs = mr.to_s
  puts "#{@signal_matchrules.size} rules, adding #{mrs.inspect}" if $DEBUG
  # don't ask for the same match if we override it
  unless @signal_matchrules.key?(mrs)
    puts "Asked for a new match" if $DEBUG
    proxy.AddMatch(mrs)
  end
  @signal_matchrules[mrs] = slot
end

#connect ⇒ Object

Connect to the bus and initialize the connection.



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# File 'lib/dbus/bus.rb', line 210

def connect
  addresses = @path.split ";"
  # connect to first one that succeeds
  worked = addresses.find do |a|
    transport, keyvaluestring = a.split ":"
    kv_list = keyvaluestring.split ","
    kv_hash = Hash.new
    kv_list.each do |kv|
      key, escaped_value = kv.split "="
      value = escaped_value.gsub(/%(..)/) {|m| [$1].pack "H2" }
      kv_hash[key] = value
    end
    case transport
      when "unix"
      connect_to_unix kv_hash
      when "tcp"
      connect_to_tcp kv_hash
      else
      # ignore, report?
    end
  end
  worked
  # returns the address that worked or nil.
  # how to report failure?
end

#connect_to_tcp(params) ⇒ Object

Connect to a bus over tcp and initialize the connection.



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# File 'lib/dbus/bus.rb', line 237

def connect_to_tcp(params)
  #check if the path is sufficient
  if params.key?("host") and params.key?("port")
    begin
      #initialize the tcp socket
      @socket = TCPSocket.new(params["host"],params["port"].to_i)
      @socket.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
      init_connection
      @is_tcp = true
    rescue
      puts "Error: Could not establish connection to: #{@path}, will now exit."
      exit(0) #a little harsh
    end
  else
    #Danger, Will Robinson: the specified "path" is not usable
    puts "Error: supplied path: #{@path}, unusable! sorry."
  end
end

#connect_to_unix(params) ⇒ Object

Connect to an abstract unix bus and initialize the connection.



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# File 'lib/dbus/bus.rb', line 257

def connect_to_unix(params)
  @socket = Socket.new(Socket::Constants::PF_UNIX,Socket::Constants::SOCK_STREAM, 0)
  @socket.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
  if ! params['abstract'].nil?
    if HOST_END == LIL_END
      sockaddr = "\1\0\0#{params['abstract']}"
    else
      sockaddr = "\0\1\0#{params['abstract']}"
    end
  elsif ! params['path'].nil?
    sockaddr = Socket.pack_sockaddr_un(params['path'])
  end
  @socket.connect(sockaddr)
  init_connection
end

#emit(service, obj, intf, sig, *args) ⇒ Object

Emit a signal event for the given service, object obj, interface intf and signal sig with arguments args.



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# File 'lib/dbus/bus.rb', line 656

def emit(service, obj, intf, sig, *args)
  m = Message.new(DBus::Message::SIGNAL)
  m.path = obj.path
  m.interface = intf.name
  m.member = sig.name
  m.sender = service.name
  i = 0
  sig.params.each do |par|
    m.add_param(par.type, args[i])
    i += 1
  end
  send(m.marshall)
end

#glibize ⇒ Object

Tell a bus to register itself on the glib main loop



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# File 'lib/dbus/bus.rb', line 279

def glibize
  require 'glib2'
  # Circumvent a ruby-glib bug
  @channels ||= Array.new

  gio = GLib::IOChannel.new(@socket.fileno)
  @channels << gio
  gio.add_watch(GLib::IOChannel::IN) do |c, ch|
    update_buffer
    messages.each do |msg|
      process(msg)
    end
    true
  end
end

#introspect(dest, path) ⇒ Object

Issues a call to the org.freedesktop.DBus.Introspectable.Introspect method dest is the service and path the object path you want to introspect If a code block is given, the introspect call in asynchronous. If not data is returned

FIXME: link to ProxyObject data definition The returned object is a ProxyObject that has methods you can call to issue somme METHOD_CALL messages, and to setup to receive METHOD_RETURN



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# File 'lib/dbus/bus.rb', line 423

def introspect(dest, path)
  if not block_given?
    # introspect in synchronous !
    data = introspect_data(dest, path)
    pof = DBus::ProxyObjectFactory.new(data, self, dest, path)
    return pof.build
  else
    introspect_data(dest, path) do |async_data|
      yield(DBus::ProxyObjectFactory.new(async_data, self, dest, path).build)
    end
  end
end

#introspect_data(dest, path) ⇒ Object

This apostroph is for syntax highlighting editors confused by above xml: “



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# File 'lib/dbus/bus.rb', line 386

def introspect_data(dest, path)
  m = DBus::Message.new(DBus::Message::METHOD_CALL)
  m.path = path
  m.interface = "org.freedesktop.DBus.Introspectable"
  m.destination = dest
  m.member = "Introspect"
  m.sender = unique_name
  if not block_given?
    # introspect in synchronous !
    send_sync(m) do |rmsg|
      if rmsg.is_a?(Error)
        raise rmsg
      else
        return rmsg.params[0] # return value of introspect_data
      end
    end
  else
    send(m.marshall)
    on_return(m) do |rmsg|
      if rmsg.is_a?(Error)
        yield rmsg
      else
        yield rmsg.params[0]
      end
    end
  end
  nil
end

#messages ⇒ Object

Retrieve all the messages that are currently in the buffer.



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# File 'lib/dbus/bus.rb', line 500

def messages
  ret = Array.new
  while msg = pop_message
    ret << msg
  end
  ret
end

#on_return(m, &retc) ⇒ Object

Specify a code block that has to be executed when a reply for message m is received.



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# File 'lib/dbus/bus.rb', line 562

def on_return(m, &retc)
  # Have a better exception here
  if m.message_type != Message::METHOD_CALL
    raise "on_return should only get method_calls"
  end
  @method_call_msgs[m.serial] = m
  @method_call_replies[m.serial] = retc
end

#poll_messages ⇒ Object

Update the buffer and retrieve all messages using Connection#messages. Return the messages.



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# File 'lib/dbus/bus.rb', line 513

def poll_messages
  ret = nil
  r, d, d = IO.select([@socket], nil, nil, 0)
  if r and r.size > 0
    update_buffer
  end
  messages
end

#pop_message ⇒ Object

Get one message from the bus and remove it from the buffer. Return the message.



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# File 'lib/dbus/bus.rb', line 487

def pop_message
  return nil if @buffer.empty?
  ret = nil
  begin
    ret, size = Message.new.unmarshall_buffer(@buffer)
    @buffer.slice!(0, size)
  rescue IncompleteBufferException => e
    # fall through, let ret be null
  end
  ret
end

#process(m) ⇒ Object

Process a message m based on its type.



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# File 'lib/dbus/bus.rb', line 596

def process(m)
  return if m.nil? #check if somethings wrong
  case m.message_type
  when Message::ERROR, Message::METHOD_RETURN
    raise InvalidPacketException if m.reply_serial == nil
    mcs = @method_call_replies[m.reply_serial]
    if not mcs
      puts "DEBUG: no return code for mcs: #{mcs.inspect} m: #{m.inspect}" if $DEBUG
    else
      if m.message_type == Message::ERROR
        mcs.call(Error.new(m))
      else
        mcs.call(m)
      end
      @method_call_replies.delete(m.reply_serial)
      @method_call_msgs.delete(m.reply_serial)
    end
  when DBus::Message::METHOD_CALL
    if m.path == "/org/freedesktop/DBus"
      puts "DEBUG: Got method call on /org/freedesktop/DBus" if $DEBUG
    end
    node = @service.get_node(m.path)
    if not node
      reply = Message.error(m, "org.freedesktop.DBus.Error.UnknownObject",
                            "Object #{m.path} doesn't exist")
      send(reply.marshall)
    # handle introspectable as an exception:
    elsif m.interface == "org.freedesktop.DBus.Introspectable" and
        m.member == "Introspect"
      reply = Message.new(Message::METHOD_RETURN).reply_to(m)
      reply.sender = @unique_name
      reply.add_param(Type::STRING, node.to_xml)
      send(reply.marshall)
    else
      obj = node.object
      return if obj.nil?    # FIXME, sends no reply
      obj.dispatch(m) if obj
    end
  when DBus::Message::SIGNAL
    # the signal can match multiple different rules
    @signal_matchrules.each do |mrs, slot|
      if DBus::MatchRule.new.from_s(mrs).match(m)
        slot.call(m)
      end
    end
  else
    puts "DEBUG: Unknown message type: #{m.message_type}" if $DEBUG
  end
end

#proxy ⇒ Object

Set up a ProxyObject for the bus itself, since the bus is introspectable. Returns the object.



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# File 'lib/dbus/bus.rb', line 462

def proxy
  if @proxy == nil
    path = "/org/freedesktop/DBus"
    dest = "org.freedesktop.DBus"
    pof = DBus::ProxyObjectFactory.new(DBUSXMLINTRO, self, dest, path)
    @proxy = pof.build["org.freedesktop.DBus"]
  end
  @proxy
end

#remove_match(mr) ⇒ Object 



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# File 'lib/dbus/bus.rb', line 585

def remove_match(mr)
  mrs = mr.to_s
  unless @signal_matchrules.delete(mrs).nil?
    # don't remove nonexisting matches.
    # FIXME if we do try, the Error.MatchRuleNotFound is *not* raised
    # and instead is reported as "no return code for nil"
    proxy.RemoveMatch(mrs)
  end
end

#request_service(name) ⇒ Object

Attempt to request a service name.

FIXME, NameRequestError cannot really be rescued as it will be raised when dispatching a later call. Rework the API to better match the spec.



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# File 'lib/dbus/bus.rb', line 444

def request_service(name)
  # Use RequestName, but asynchronously!
  # A synchronous call would not work with service activation, where
  # method calls to be serviced arrive before the reply for RequestName
  # (Ticket#29).
  proxy.RequestName(name, NAME_FLAG_REPLACE_EXISTING) do |rmsg, r|
    if rmsg.is_a?(Error)  # check and report errors first
	  raise rmsg
	elsif r != REQUEST_NAME_REPLY_PRIMARY_OWNER
      raise NameRequestError
	end
  end
  @service = Service.new(name, self)
  @service
end

#send(buf) ⇒ Object

Send the buffer buf to the bus using Connection#writel.



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# File 'lib/dbus/bus.rb', line 274

def send(buf)
  @socket.write(buf) unless @socket.nil?
end

#send_sync(m, &retc) ⇒ Object

Send a message m on to the bus. This is done synchronously, thus the call will block until a reply message arrives.



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# File 'lib/dbus/bus.rb', line 541

def send_sync(m, &retc) # :yields: reply/return message
  return if m.nil? #check if somethings wrong
  send(m.marshall)
  @method_call_msgs[m.serial] = m
  @method_call_replies[m.serial] = retc

  retm = wait_for_message
  
  return if retm.nil? #check if somethings wrong
  
  process(retm)
  until [DBus::Message::ERROR,
      DBus::Message::METHOD_RETURN].include?(retm.message_type) and
      retm.reply_serial == m.serial
    retm = wait_for_message
    process(retm)
  end
end

#service(name) ⇒ Object Also known as: []

Retrieves the Service with the given name.



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# File 'lib/dbus/bus.rb', line 647

def service(name)
  # The service might not exist at this time so we cannot really check
  # anything
  Service.new(name, self)
end

#update_buffer ⇒ Object

Fill (append) the buffer from data that might be available on the socket.



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# File 'lib/dbus/bus.rb', line 474

def update_buffer
  @buffer += @socket.read_nonblock(MSG_BUF_SIZE)  
rescue EOFError
  raise                     # the caller expects it
rescue Exception => e
  puts "Oops:", e
  raise if @is_tcp          # why?
  puts "WARNING: read_nonblock failed, falling back to .recv"
  @buffer += @socket.recv(MSG_BUF_SIZE)  
end

#wait_for_message ⇒ Object

Wait for a message to arrive. Return it once it is available.



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# File 'lib/dbus/bus.rb', line 523

def wait_for_message
  if @socket.nil?
    puts "ERROR: Can't wait for messages, @socket is nil."
    return
  end
  ret = pop_message
  while ret == nil
    r, d, d = IO.select([@socket])
    if r and r[0] == @socket
      update_buffer
      ret = pop_message
    end
  end
  ret
end