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// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Integration with the systemd D-Bus API. See http://www.freedesktop.org/wiki/Software/systemd/dbus/
package dbus
import (
"fmt"
"os"
"strconv"
"strings"
"sync"
"github.com/godbus/dbus"
)
const (
alpha = `abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`
num = `0123456789`
alphanum = alpha + num
signalBuffer = 100
)
// needsEscape checks whether a byte in a potential dbus ObjectPath needs to be escaped
func needsEscape(i int, b byte) bool {
// Escape everything that is not a-z-A-Z-0-9
// Also escape 0-9 if it's the first character
return strings.IndexByte(alphanum, b) == -1 ||
(i == 0 && strings.IndexByte(num, b) != -1)
}
// PathBusEscape sanitizes a constituent string of a dbus ObjectPath using the
// rules that systemd uses for serializing special characters.
func PathBusEscape(path string) string {
// Special case the empty string
if len(path) == 0 {
return "_"
}
n := []byte{}
for i := 0; i < len(path); i++ {
c := path[i]
if needsEscape(i, c) {
e := fmt.Sprintf("_%x", c)
n = append(n, []byte(e)...)
} else {
n = append(n, c)
}
}
return string(n)
}
// Conn is a connection to systemd's dbus endpoint.
type Conn struct {
// sysconn/sysobj are only used to call dbus methods
sysconn *dbus.Conn
sysobj *dbus.Object
// sigconn/sigobj are only used to receive dbus signals
sigconn *dbus.Conn
sigobj *dbus.Object
jobListener struct {
jobs map[dbus.ObjectPath]chan<- string
sync.Mutex
}
subscriber struct {
updateCh chan<- *SubStateUpdate
errCh chan<- error
sync.Mutex
ignore map[dbus.ObjectPath]int64
cleanIgnore int64
}
}
// New establishes a connection to the system bus and authenticates.
// Callers should call Close() when done with the connection.
func New() (*Conn, error) {
return newConnection(dbus.SystemBusPrivate)
}
// NewUserConnection establishes a connection to the session bus and
// authenticates. This can be used to connect to systemd user instances.
// Callers should call Close() when done with the connection.
func NewUserConnection() (*Conn, error) {
return newConnection(dbus.SessionBusPrivate)
}
// Close closes an established connection
func (c *Conn) Close() {
c.sysconn.Close()
c.sigconn.Close()
}
func newConnection(createBus func() (*dbus.Conn, error)) (*Conn, error) {
sysconn, err := dbusConnection(createBus)
if err != nil {
return nil, err
}
sigconn, err := dbusConnection(createBus)
if err != nil {
sysconn.Close()
return nil, err
}
c := &Conn{
sysconn: sysconn,
sysobj: systemdObject(sysconn),
sigconn: sigconn,
sigobj: systemdObject(sigconn),
}
c.subscriber.ignore = make(map[dbus.ObjectPath]int64)
c.jobListener.jobs = make(map[dbus.ObjectPath]chan<- string)
// Setup the listeners on jobs so that we can get completions
c.sigconn.BusObject().Call("org.freedesktop.DBus.AddMatch", 0,
"type='signal', interface='org.freedesktop.systemd1.Manager', member='JobRemoved'")
c.dispatch()
return c, nil
}
func dbusConnection(createBus func() (*dbus.Conn, error)) (*dbus.Conn, error) {
conn, err := createBus()
if err != nil {
return nil, err
}
// Only use EXTERNAL method, and hardcode the uid (not username)
// to avoid a username lookup (which requires a dynamically linked
// libc)
methods := []dbus.Auth{dbus.AuthExternal(strconv.Itoa(os.Getuid()))}
err = conn.Auth(methods)
if err != nil {
conn.Close()
return nil, err
}
err = conn.Hello()
if err != nil {
conn.Close()
return nil, err
}
return conn, nil
}
func systemdObject(conn *dbus.Conn) *dbus.Object {
return conn.Object("org.freedesktop.systemd1", dbus.ObjectPath("/org/freedesktop/systemd1"))
}