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moby--moby/vendor/github.com/godbus/dbus/export.go

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package dbus
import (
"bytes"
"errors"
"fmt"
"reflect"
"strings"
)
var (
errmsgInvalidArg = Error{
"org.freedesktop.DBus.Error.InvalidArgs",
[]interface{}{"Invalid type / number of args"},
}
errmsgNoObject = Error{
"org.freedesktop.DBus.Error.NoSuchObject",
[]interface{}{"No such object"},
}
errmsgUnknownMethod = Error{
"org.freedesktop.DBus.Error.UnknownMethod",
[]interface{}{"Unknown / invalid method"},
}
)
// exportedObj represents an exported object. It stores a precomputed
// method table that represents the methods exported on the bus.
type exportedObj struct {
methods map[string]reflect.Value
// Whether or not this export is for the entire subtree
includeSubtree bool
}
func (obj exportedObj) Method(name string) (reflect.Value, bool) {
out, exists := obj.methods[name]
return out, exists
}
// Sender is a type which can be used in exported methods to receive the message
// sender.
type Sender string
func computeMethodName(name string, mapping map[string]string) string {
newname, ok := mapping[name]
if ok {
name = newname
}
return name
}
func getMethods(in interface{}, mapping map[string]string) map[string]reflect.Value {
if in == nil {
return nil
}
methods := make(map[string]reflect.Value)
val := reflect.ValueOf(in)
typ := val.Type()
for i := 0; i < typ.NumMethod(); i++ {
methtype := typ.Method(i)
method := val.Method(i)
t := method.Type()
// only track valid methods must return *Error as last arg
// and must be exported
if t.NumOut() == 0 ||
t.Out(t.NumOut()-1) != reflect.TypeOf(&errmsgInvalidArg) ||
methtype.PkgPath != "" {
continue
}
// map names while building table
methods[computeMethodName(methtype.Name, mapping)] = method
}
return methods
}
// searchHandlers will look through all registered handlers looking for one
// to handle the given path. If a verbatim one isn't found, it will check for
// a subtree registration for the path as well.
func (conn *Conn) searchHandlers(path ObjectPath) (map[string]exportedObj, bool) {
conn.handlersLck.RLock()
defer conn.handlersLck.RUnlock()
handlers, ok := conn.handlers[path]
if ok {
return handlers, ok
}
// If handlers weren't found for this exact path, look for a matching subtree
// registration
handlers = make(map[string]exportedObj)
path = path[:strings.LastIndex(string(path), "/")]
for len(path) > 0 {
var subtreeHandlers map[string]exportedObj
subtreeHandlers, ok = conn.handlers[path]
if ok {
for iface, handler := range subtreeHandlers {
// Only include this handler if it registered for the subtree
if handler.includeSubtree {
handlers[iface] = handler
}
}
break
}
path = path[:strings.LastIndex(string(path), "/")]
}
return handlers, ok
}
// handleCall handles the given method call (i.e. looks if it's one of the
// pre-implemented ones and searches for a corresponding handler if not).
func (conn *Conn) handleCall(msg *Message) {
name := msg.Headers[FieldMember].value.(string)
path := msg.Headers[FieldPath].value.(ObjectPath)
ifaceName, hasIface := msg.Headers[FieldInterface].value.(string)
sender, hasSender := msg.Headers[FieldSender].value.(string)
serial := msg.serial
if ifaceName == "org.freedesktop.DBus.Peer" {
switch name {
case "Ping":
conn.sendReply(sender, serial)
case "GetMachineId":
conn.sendReply(sender, serial, conn.uuid)
default:
conn.sendError(errmsgUnknownMethod, sender, serial)
}
return
} else if ifaceName == "org.freedesktop.DBus.Introspectable" && name == "Introspect" {
if _, ok := conn.handlers[path]; !ok {
subpath := make(map[string]struct{})
var xml bytes.Buffer
xml.WriteString("<node>")
for h, _ := range conn.handlers {
p := string(path)
if p != "/" {
p += "/"
}
if strings.HasPrefix(string(h), p) {
node_name := strings.Split(string(h[len(p):]), "/")[0]
subpath[node_name] = struct{}{}
}
}
for s, _ := range subpath {
xml.WriteString("\n\t<node name=\"" + s + "\"/>")
}
xml.WriteString("\n</node>")
conn.sendReply(sender, serial, xml.String())
return
}
}
if len(name) == 0 {
conn.sendError(errmsgUnknownMethod, sender, serial)
}
// Find the exported handler (if any) for this path
handlers, ok := conn.searchHandlers(path)
if !ok {
conn.sendError(errmsgNoObject, sender, serial)
return
}
var m reflect.Value
var exists bool
if hasIface {
iface := handlers[ifaceName]
m, exists = iface.Method(name)
} else {
for _, v := range handlers {
m, exists = v.Method(name)
if exists {
break
}
}
}
if !exists {
conn.sendError(errmsgUnknownMethod, sender, serial)
return
}
t := m.Type()
vs := msg.Body
pointers := make([]interface{}, t.NumIn())
decode := make([]interface{}, 0, len(vs))
for i := 0; i < t.NumIn(); i++ {
tp := t.In(i)
val := reflect.New(tp)
pointers[i] = val.Interface()
if tp == reflect.TypeOf((*Sender)(nil)).Elem() {
val.Elem().SetString(sender)
} else if tp == reflect.TypeOf((*Message)(nil)).Elem() {
val.Elem().Set(reflect.ValueOf(*msg))
} else {
decode = append(decode, pointers[i])
}
}
if len(decode) != len(vs) {
conn.sendError(errmsgInvalidArg, sender, serial)
return
}
if err := Store(vs, decode...); err != nil {
conn.sendError(errmsgInvalidArg, sender, serial)
return
}
// Extract parameters
params := make([]reflect.Value, len(pointers))
for i := 0; i < len(pointers); i++ {
params[i] = reflect.ValueOf(pointers[i]).Elem()
}
// Call method
ret := m.Call(params)
if em := ret[t.NumOut()-1].Interface().(*Error); em != nil {
conn.sendError(*em, sender, serial)
return
}
if msg.Flags&FlagNoReplyExpected == 0 {
reply := new(Message)
reply.Type = TypeMethodReply
reply.serial = conn.getSerial()
reply.Headers = make(map[HeaderField]Variant)
if hasSender {
reply.Headers[FieldDestination] = msg.Headers[FieldSender]
}
reply.Headers[FieldReplySerial] = MakeVariant(msg.serial)
reply.Body = make([]interface{}, len(ret)-1)
for i := 0; i < len(ret)-1; i++ {
reply.Body[i] = ret[i].Interface()
}
if len(ret) != 1 {
reply.Headers[FieldSignature] = MakeVariant(SignatureOf(reply.Body...))
}
conn.outLck.RLock()
if !conn.closed {
conn.out <- reply
}
conn.outLck.RUnlock()
}
}
// Emit emits the given signal on the message bus. The name parameter must be
// formatted as "interface.member", e.g., "org.freedesktop.DBus.NameLost".
func (conn *Conn) Emit(path ObjectPath, name string, values ...interface{}) error {
if !path.IsValid() {
return errors.New("dbus: invalid object path")
}
i := strings.LastIndex(name, ".")
if i == -1 {
return errors.New("dbus: invalid method name")
}
iface := name[:i]
member := name[i+1:]
if !isValidMember(member) {
return errors.New("dbus: invalid method name")
}
if !isValidInterface(iface) {
return errors.New("dbus: invalid interface name")
}
msg := new(Message)
msg.Type = TypeSignal
msg.serial = conn.getSerial()
msg.Headers = make(map[HeaderField]Variant)
msg.Headers[FieldInterface] = MakeVariant(iface)
msg.Headers[FieldMember] = MakeVariant(member)
msg.Headers[FieldPath] = MakeVariant(path)
msg.Body = values
if len(values) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(values...))
}
conn.outLck.RLock()
defer conn.outLck.RUnlock()
if conn.closed {
return ErrClosed
}
conn.out <- msg
return nil
}
// Export registers the given value to be exported as an object on the
// message bus.
//
// If a method call on the given path and interface is received, an exported
// method with the same name is called with v as the receiver if the
// parameters match and the last return value is of type *Error. If this
// *Error is not nil, it is sent back to the caller as an error.
// Otherwise, a method reply is sent with the other return values as its body.
//
// Any parameters with the special type Sender are set to the sender of the
// dbus message when the method is called. Parameters of this type do not
// contribute to the dbus signature of the method (i.e. the method is exposed
// as if the parameters of type Sender were not there).
//
// Similarly, any parameters with the type Message are set to the raw message
// received on the bus. Again, parameters of this type do not contribute to the
// dbus signature of the method.
//
// Every method call is executed in a new goroutine, so the method may be called
// in multiple goroutines at once.
//
// Method calls on the interface org.freedesktop.DBus.Peer will be automatically
// handled for every object.
//
// Passing nil as the first parameter will cause conn to cease handling calls on
// the given combination of path and interface.
//
// Export returns an error if path is not a valid path name.
func (conn *Conn) Export(v interface{}, path ObjectPath, iface string) error {
return conn.ExportWithMap(v, nil, path, iface)
}
// ExportWithMap works exactly like Export but provides the ability to remap
// method names (e.g. export a lower-case method).
//
// The keys in the map are the real method names (exported on the struct), and
// the values are the method names to be exported on DBus.
func (conn *Conn) ExportWithMap(v interface{}, mapping map[string]string, path ObjectPath, iface string) error {
return conn.export(getMethods(v, mapping), path, iface, false)
}
// ExportSubtree works exactly like Export but registers the given value for
// an entire subtree rather under the root path provided.
//
// In order to make this useful, one parameter in each of the value's exported
// methods should be a Message, in which case it will contain the raw message
// (allowing one to get access to the path that caused the method to be called).
//
// Note that more specific export paths take precedence over less specific. For
// example, a method call using the ObjectPath /foo/bar/baz will call a method
// exported on /foo/bar before a method exported on /foo.
func (conn *Conn) ExportSubtree(v interface{}, path ObjectPath, iface string) error {
return conn.ExportSubtreeWithMap(v, nil, path, iface)
}
// ExportSubtreeWithMap works exactly like ExportSubtree but provides the
// ability to remap method names (e.g. export a lower-case method).
//
// The keys in the map are the real method names (exported on the struct), and
// the values are the method names to be exported on DBus.
func (conn *Conn) ExportSubtreeWithMap(v interface{}, mapping map[string]string, path ObjectPath, iface string) error {
return conn.export(getMethods(v, mapping), path, iface, true)
}
// ExportMethodTable like Export registers the given methods as an object
// on the message bus. Unlike Export the it uses a method table to define
// the object instead of a native go object.
//
// The method table is a map from method name to function closure
// representing the method. This allows an object exported on the bus to not
// necessarily be a native go object. It can be useful for generating exposed
// methods on the fly.
//
// Any non-function objects in the method table are ignored.
func (conn *Conn) ExportMethodTable(methods map[string]interface{}, path ObjectPath, iface string) error {
return conn.exportMethodTable(methods, path, iface, false)
}
// Like ExportSubtree, but with the same caveats as ExportMethodTable.
func (conn *Conn) ExportSubtreeMethodTable(methods map[string]interface{}, path ObjectPath, iface string) error {
return conn.exportMethodTable(methods, path, iface, true)
}
func (conn *Conn) exportMethodTable(methods map[string]interface{}, path ObjectPath, iface string, includeSubtree bool) error {
out := make(map[string]reflect.Value)
for name, method := range methods {
rval := reflect.ValueOf(method)
if rval.Kind() != reflect.Func {
continue
}
t := rval.Type()
// only track valid methods must return *Error as last arg
if t.NumOut() == 0 ||
t.Out(t.NumOut()-1) != reflect.TypeOf(&errmsgInvalidArg) {
continue
}
out[name] = rval
}
return conn.export(out, path, iface, includeSubtree)
}
// exportWithMap is the worker function for all exports/registrations.
func (conn *Conn) export(methods map[string]reflect.Value, path ObjectPath, iface string, includeSubtree bool) error {
if !path.IsValid() {
return fmt.Errorf(`dbus: Invalid path name: "%s"`, path)
}
conn.handlersLck.Lock()
defer conn.handlersLck.Unlock()
// Remove a previous export if the interface is nil
if methods == nil {
if _, ok := conn.handlers[path]; ok {
delete(conn.handlers[path], iface)
if len(conn.handlers[path]) == 0 {
delete(conn.handlers, path)
}
}
return nil
}
// If this is the first handler for this path, make a new map to hold all
// handlers for this path.
if _, ok := conn.handlers[path]; !ok {
conn.handlers[path] = make(map[string]exportedObj)
}
// Finally, save this handler
conn.handlers[path][iface] = exportedObj{
methods: methods,
includeSubtree: includeSubtree,
}
return nil
}
// ReleaseName calls org.freedesktop.DBus.ReleaseName and awaits a response.
func (conn *Conn) ReleaseName(name string) (ReleaseNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.ReleaseName", 0, name).Store(&r)
if err != nil {
return 0, err
}
return ReleaseNameReply(r), nil
}
// RequestName calls org.freedesktop.DBus.RequestName and awaits a response.
func (conn *Conn) RequestName(name string, flags RequestNameFlags) (RequestNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.RequestName", 0, name, flags).Store(&r)
if err != nil {
return 0, err
}
return RequestNameReply(r), nil
}
// ReleaseNameReply is the reply to a ReleaseName call.
type ReleaseNameReply uint32
const (
ReleaseNameReplyReleased ReleaseNameReply = 1 + iota
ReleaseNameReplyNonExistent
ReleaseNameReplyNotOwner
)
// RequestNameFlags represents the possible flags for a RequestName call.
type RequestNameFlags uint32
const (
NameFlagAllowReplacement RequestNameFlags = 1 << iota
NameFlagReplaceExisting
NameFlagDoNotQueue
)
// RequestNameReply is the reply to a RequestName call.
type RequestNameReply uint32
const (
RequestNameReplyPrimaryOwner RequestNameReply = 1 + iota
RequestNameReplyInQueue
RequestNameReplyExists
RequestNameReplyAlreadyOwner
)