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moby--moby/vendor/github.com/godbus/dbus/conn.go
Alexander Morozov f2614f2107 project: use vndr for vendoring
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
2016-11-03 15:31:46 -07:00

634 lines
17 KiB
Go

package dbus
import (
"errors"
"io"
"os"
"reflect"
"strings"
"sync"
)
const defaultSystemBusAddress = "unix:path=/var/run/dbus/system_bus_socket"
var (
systemBus *Conn
systemBusLck sync.Mutex
sessionBus *Conn
sessionBusLck sync.Mutex
sessionEnvLck sync.Mutex
)
// ErrClosed is the error returned by calls on a closed connection.
var ErrClosed = errors.New("dbus: connection closed by user")
// Conn represents a connection to a message bus (usually, the system or
// session bus).
//
// Connections are either shared or private. Shared connections
// are shared between calls to the functions that return them. As a result,
// the methods Close, Auth and Hello must not be called on them.
//
// Multiple goroutines may invoke methods on a connection simultaneously.
type Conn struct {
transport
busObj BusObject
unixFD bool
uuid string
names []string
namesLck sync.RWMutex
serialLck sync.Mutex
nextSerial uint32
serialUsed map[uint32]bool
calls map[uint32]*Call
callsLck sync.RWMutex
handlers map[ObjectPath]map[string]exportedObj
handlersLck sync.RWMutex
out chan *Message
closed bool
outLck sync.RWMutex
signals []chan<- *Signal
signalsLck sync.Mutex
eavesdropped chan<- *Message
eavesdroppedLck sync.Mutex
}
// SessionBus returns a shared connection to the session bus, connecting to it
// if not already done.
func SessionBus() (conn *Conn, err error) {
sessionBusLck.Lock()
defer sessionBusLck.Unlock()
if sessionBus != nil {
return sessionBus, nil
}
defer func() {
if conn != nil {
sessionBus = conn
}
}()
conn, err = SessionBusPrivate()
if err != nil {
return
}
if err = conn.Auth(nil); err != nil {
conn.Close()
conn = nil
return
}
if err = conn.Hello(); err != nil {
conn.Close()
conn = nil
}
return
}
// SessionBusPrivate returns a new private connection to the session bus.
func SessionBusPrivate() (*Conn, error) {
sessionEnvLck.Lock()
defer sessionEnvLck.Unlock()
address := os.Getenv("DBUS_SESSION_BUS_ADDRESS")
if address != "" && address != "autolaunch:" {
return Dial(address)
}
return sessionBusPlatform()
}
// SystemBus returns a shared connection to the system bus, connecting to it if
// not already done.
func SystemBus() (conn *Conn, err error) {
systemBusLck.Lock()
defer systemBusLck.Unlock()
if systemBus != nil {
return systemBus, nil
}
defer func() {
if conn != nil {
systemBus = conn
}
}()
conn, err = SystemBusPrivate()
if err != nil {
return
}
if err = conn.Auth(nil); err != nil {
conn.Close()
conn = nil
return
}
if err = conn.Hello(); err != nil {
conn.Close()
conn = nil
}
return
}
// SystemBusPrivate returns a new private connection to the system bus.
func SystemBusPrivate() (*Conn, error) {
address := os.Getenv("DBUS_SYSTEM_BUS_ADDRESS")
if address != "" {
return Dial(address)
}
return Dial(defaultSystemBusAddress)
}
// Dial establishes a new private connection to the message bus specified by address.
func Dial(address string) (*Conn, error) {
tr, err := getTransport(address)
if err != nil {
return nil, err
}
return newConn(tr)
}
// NewConn creates a new private *Conn from an already established connection.
func NewConn(conn io.ReadWriteCloser) (*Conn, error) {
return newConn(genericTransport{conn})
}
// newConn creates a new *Conn from a transport.
func newConn(tr transport) (*Conn, error) {
conn := new(Conn)
conn.transport = tr
conn.calls = make(map[uint32]*Call)
conn.out = make(chan *Message, 10)
conn.handlers = make(map[ObjectPath]map[string]exportedObj)
conn.nextSerial = 1
conn.serialUsed = map[uint32]bool{0: true}
conn.busObj = conn.Object("org.freedesktop.DBus", "/org/freedesktop/DBus")
return conn, nil
}
// BusObject returns the object owned by the bus daemon which handles
// administrative requests.
func (conn *Conn) BusObject() BusObject {
return conn.busObj
}
// Close closes the connection. Any blocked operations will return with errors
// and the channels passed to Eavesdrop and Signal are closed. This method must
// not be called on shared connections.
func (conn *Conn) Close() error {
conn.outLck.Lock()
if conn.closed {
// inWorker calls Close on read error, the read error may
// be caused by another caller calling Close to shutdown the
// dbus connection, a double-close scenario we prevent here.
conn.outLck.Unlock()
return nil
}
close(conn.out)
conn.closed = true
conn.outLck.Unlock()
conn.signalsLck.Lock()
for _, ch := range conn.signals {
close(ch)
}
conn.signalsLck.Unlock()
conn.eavesdroppedLck.Lock()
if conn.eavesdropped != nil {
close(conn.eavesdropped)
}
conn.eavesdroppedLck.Unlock()
return conn.transport.Close()
}
// Eavesdrop causes conn to send all incoming messages to the given channel
// without further processing. Method replies, errors and signals will not be
// sent to the appropiate channels and method calls will not be handled. If nil
// is passed, the normal behaviour is restored.
//
// The caller has to make sure that ch is sufficiently buffered;
// if a message arrives when a write to ch is not possible, the message is
// discarded.
func (conn *Conn) Eavesdrop(ch chan<- *Message) {
conn.eavesdroppedLck.Lock()
conn.eavesdropped = ch
conn.eavesdroppedLck.Unlock()
}
// getSerial returns an unused serial.
func (conn *Conn) getSerial() uint32 {
conn.serialLck.Lock()
defer conn.serialLck.Unlock()
n := conn.nextSerial
for conn.serialUsed[n] {
n++
}
conn.serialUsed[n] = true
conn.nextSerial = n + 1
return n
}
// Hello sends the initial org.freedesktop.DBus.Hello call. This method must be
// called after authentication, but before sending any other messages to the
// bus. Hello must not be called for shared connections.
func (conn *Conn) Hello() error {
var s string
err := conn.busObj.Call("org.freedesktop.DBus.Hello", 0).Store(&s)
if err != nil {
return err
}
conn.namesLck.Lock()
conn.names = make([]string, 1)
conn.names[0] = s
conn.namesLck.Unlock()
return nil
}
// inWorker runs in an own goroutine, reading incoming messages from the
// transport and dispatching them appropiately.
func (conn *Conn) inWorker() {
for {
msg, err := conn.ReadMessage()
if err == nil {
conn.eavesdroppedLck.Lock()
if conn.eavesdropped != nil {
select {
case conn.eavesdropped <- msg:
default:
}
conn.eavesdroppedLck.Unlock()
continue
}
conn.eavesdroppedLck.Unlock()
dest, _ := msg.Headers[FieldDestination].value.(string)
found := false
if dest == "" {
found = true
} else {
conn.namesLck.RLock()
if len(conn.names) == 0 {
found = true
}
for _, v := range conn.names {
if dest == v {
found = true
break
}
}
conn.namesLck.RUnlock()
}
if !found {
// Eavesdropped a message, but no channel for it is registered.
// Ignore it.
continue
}
switch msg.Type {
case TypeMethodReply, TypeError:
serial := msg.Headers[FieldReplySerial].value.(uint32)
conn.callsLck.Lock()
if c, ok := conn.calls[serial]; ok {
if msg.Type == TypeError {
name, _ := msg.Headers[FieldErrorName].value.(string)
c.Err = Error{name, msg.Body}
} else {
c.Body = msg.Body
}
c.Done <- c
conn.serialLck.Lock()
delete(conn.serialUsed, serial)
conn.serialLck.Unlock()
delete(conn.calls, serial)
}
conn.callsLck.Unlock()
case TypeSignal:
iface := msg.Headers[FieldInterface].value.(string)
member := msg.Headers[FieldMember].value.(string)
// as per http://dbus.freedesktop.org/doc/dbus-specification.html ,
// sender is optional for signals.
sender, _ := msg.Headers[FieldSender].value.(string)
if iface == "org.freedesktop.DBus" && sender == "org.freedesktop.DBus" {
if member == "NameLost" {
// If we lost the name on the bus, remove it from our
// tracking list.
name, ok := msg.Body[0].(string)
if !ok {
panic("Unable to read the lost name")
}
conn.namesLck.Lock()
for i, v := range conn.names {
if v == name {
conn.names = append(conn.names[:i],
conn.names[i+1:]...)
}
}
conn.namesLck.Unlock()
} else if member == "NameAcquired" {
// If we acquired the name on the bus, add it to our
// tracking list.
name, ok := msg.Body[0].(string)
if !ok {
panic("Unable to read the acquired name")
}
conn.namesLck.Lock()
conn.names = append(conn.names, name)
conn.namesLck.Unlock()
}
}
signal := &Signal{
Sender: sender,
Path: msg.Headers[FieldPath].value.(ObjectPath),
Name: iface + "." + member,
Body: msg.Body,
}
conn.signalsLck.Lock()
for _, ch := range conn.signals {
ch <- signal
}
conn.signalsLck.Unlock()
case TypeMethodCall:
go conn.handleCall(msg)
}
} else if _, ok := err.(InvalidMessageError); !ok {
// Some read error occured (usually EOF); we can't really do
// anything but to shut down all stuff and returns errors to all
// pending replies.
conn.Close()
conn.callsLck.RLock()
for _, v := range conn.calls {
v.Err = err
v.Done <- v
}
conn.callsLck.RUnlock()
return
}
// invalid messages are ignored
}
}
// Names returns the list of all names that are currently owned by this
// connection. The slice is always at least one element long, the first element
// being the unique name of the connection.
func (conn *Conn) Names() []string {
conn.namesLck.RLock()
// copy the slice so it can't be modified
s := make([]string, len(conn.names))
copy(s, conn.names)
conn.namesLck.RUnlock()
return s
}
// Object returns the object identified by the given destination name and path.
func (conn *Conn) Object(dest string, path ObjectPath) BusObject {
return &Object{conn, dest, path}
}
// outWorker runs in an own goroutine, encoding and sending messages that are
// sent to conn.out.
func (conn *Conn) outWorker() {
for msg := range conn.out {
err := conn.SendMessage(msg)
conn.callsLck.RLock()
if err != nil {
if c := conn.calls[msg.serial]; c != nil {
c.Err = err
c.Done <- c
}
conn.serialLck.Lock()
delete(conn.serialUsed, msg.serial)
conn.serialLck.Unlock()
} else if msg.Type != TypeMethodCall {
conn.serialLck.Lock()
delete(conn.serialUsed, msg.serial)
conn.serialLck.Unlock()
}
conn.callsLck.RUnlock()
}
}
// Send sends the given message to the message bus. You usually don't need to
// use this; use the higher-level equivalents (Call / Go, Emit and Export)
// instead. If msg is a method call and NoReplyExpected is not set, a non-nil
// call is returned and the same value is sent to ch (which must be buffered)
// once the call is complete. Otherwise, ch is ignored and a Call structure is
// returned of which only the Err member is valid.
func (conn *Conn) Send(msg *Message, ch chan *Call) *Call {
var call *Call
msg.serial = conn.getSerial()
if msg.Type == TypeMethodCall && msg.Flags&FlagNoReplyExpected == 0 {
if ch == nil {
ch = make(chan *Call, 5)
} else if cap(ch) == 0 {
panic("dbus: unbuffered channel passed to (*Conn).Send")
}
call = new(Call)
call.Destination, _ = msg.Headers[FieldDestination].value.(string)
call.Path, _ = msg.Headers[FieldPath].value.(ObjectPath)
iface, _ := msg.Headers[FieldInterface].value.(string)
member, _ := msg.Headers[FieldMember].value.(string)
call.Method = iface + "." + member
call.Args = msg.Body
call.Done = ch
conn.callsLck.Lock()
conn.calls[msg.serial] = call
conn.callsLck.Unlock()
conn.outLck.RLock()
if conn.closed {
call.Err = ErrClosed
call.Done <- call
} else {
conn.out <- msg
}
conn.outLck.RUnlock()
} else {
conn.outLck.RLock()
if conn.closed {
call = &Call{Err: ErrClosed}
} else {
conn.out <- msg
call = &Call{Err: nil}
}
conn.outLck.RUnlock()
}
return call
}
// sendError creates an error message corresponding to the parameters and sends
// it to conn.out.
func (conn *Conn) sendError(e Error, dest string, serial uint32) {
msg := new(Message)
msg.Type = TypeError
msg.serial = conn.getSerial()
msg.Headers = make(map[HeaderField]Variant)
if dest != "" {
msg.Headers[FieldDestination] = MakeVariant(dest)
}
msg.Headers[FieldErrorName] = MakeVariant(e.Name)
msg.Headers[FieldReplySerial] = MakeVariant(serial)
msg.Body = e.Body
if len(e.Body) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(e.Body...))
}
conn.outLck.RLock()
if !conn.closed {
conn.out <- msg
}
conn.outLck.RUnlock()
}
// sendReply creates a method reply message corresponding to the parameters and
// sends it to conn.out.
func (conn *Conn) sendReply(dest string, serial uint32, values ...interface{}) {
msg := new(Message)
msg.Type = TypeMethodReply
msg.serial = conn.getSerial()
msg.Headers = make(map[HeaderField]Variant)
if dest != "" {
msg.Headers[FieldDestination] = MakeVariant(dest)
}
msg.Headers[FieldReplySerial] = MakeVariant(serial)
msg.Body = values
if len(values) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(values...))
}
conn.outLck.RLock()
if !conn.closed {
conn.out <- msg
}
conn.outLck.RUnlock()
}
// Signal registers the given channel to be passed all received signal messages.
// The caller has to make sure that ch is sufficiently buffered; if a message
// arrives when a write to c is not possible, it is discarded.
//
// Multiple of these channels can be registered at the same time.
//
// These channels are "overwritten" by Eavesdrop; i.e., if there currently is a
// channel for eavesdropped messages, this channel receives all signals, and
// none of the channels passed to Signal will receive any signals.
func (conn *Conn) Signal(ch chan<- *Signal) {
conn.signalsLck.Lock()
conn.signals = append(conn.signals, ch)
conn.signalsLck.Unlock()
}
// RemoveSignal removes the given channel from the list of the registered channels.
func (conn *Conn) RemoveSignal(ch chan<- *Signal) {
conn.signalsLck.Lock()
for i := len(conn.signals) - 1; i >= 0; i-- {
if ch == conn.signals[i] {
copy(conn.signals[i:], conn.signals[i+1:])
conn.signals[len(conn.signals)-1] = nil
conn.signals = conn.signals[:len(conn.signals)-1]
}
}
conn.signalsLck.Unlock()
}
// SupportsUnixFDs returns whether the underlying transport supports passing of
// unix file descriptors. If this is false, method calls containing unix file
// descriptors will return an error and emitted signals containing them will
// not be sent.
func (conn *Conn) SupportsUnixFDs() bool {
return conn.unixFD
}
// Error represents a D-Bus message of type Error.
type Error struct {
Name string
Body []interface{}
}
func NewError(name string, body []interface{}) *Error {
return &Error{name, body}
}
func (e Error) Error() string {
if len(e.Body) >= 1 {
s, ok := e.Body[0].(string)
if ok {
return s
}
}
return e.Name
}
// Signal represents a D-Bus message of type Signal. The name member is given in
// "interface.member" notation, e.g. org.freedesktop.D-Bus.NameLost.
type Signal struct {
Sender string
Path ObjectPath
Name string
Body []interface{}
}
// transport is a D-Bus transport.
type transport interface {
// Read and Write raw data (for example, for the authentication protocol).
io.ReadWriteCloser
// Send the initial null byte used for the EXTERNAL mechanism.
SendNullByte() error
// Returns whether this transport supports passing Unix FDs.
SupportsUnixFDs() bool
// Signal the transport that Unix FD passing is enabled for this connection.
EnableUnixFDs()
// Read / send a message, handling things like Unix FDs.
ReadMessage() (*Message, error)
SendMessage(*Message) error
}
var (
transports = make(map[string]func(string) (transport, error))
)
func getTransport(address string) (transport, error) {
var err error
var t transport
addresses := strings.Split(address, ";")
for _, v := range addresses {
i := strings.IndexRune(v, ':')
if i == -1 {
err = errors.New("dbus: invalid bus address (no transport)")
continue
}
f := transports[v[:i]]
if f == nil {
err = errors.New("dbus: invalid bus address (invalid or unsupported transport)")
continue
}
t, err = f(v[i+1:])
if err == nil {
return t, nil
}
}
return nil, err
}
// dereferenceAll returns a slice that, assuming that vs is a slice of pointers
// of arbitrary types, containes the values that are obtained from dereferencing
// all elements in vs.
func dereferenceAll(vs []interface{}) []interface{} {
for i := range vs {
v := reflect.ValueOf(vs[i])
v = v.Elem()
vs[i] = v.Interface()
}
return vs
}
// getKey gets a key from a the list of keys. Returns "" on error / not found...
func getKey(s, key string) string {
for _, keyEqualsValue := range strings.Split(s, ",") {
keyValue := strings.SplitN(keyEqualsValue, "=", 2)
if len(keyValue) == 2 && keyValue[0] == key {
return keyValue[1]
}
}
return ""
}