pass display number to use for xpra instance to oz-init

oz-daemon/daemon.go

@@ -16,6 +16,7 @@ type daemonState struct {
 	profiles oz.Profiles
 	sandboxes []*Sandbox
 	nextSboxId int
+	nextDisplay int
 	memBackend *logging.ChannelMemoryBackend
 	backends []logging.Backend
 }
@@ -47,6 +48,7 @@ func initialize() *daemonState {
 	d.profiles = ps
 	oz.ReapChildProcs(d.log, d.handleChildExit)
 	d.nextSboxId = 1
+	d.nextDisplay = 100
 	return d
 }
 

oz-daemon/launch.go

@@ -17,6 +17,7 @@ const initPath = "/usr/local/bin/oz-init"
 type Sandbox struct {
 	daemon *daemonState
 	id int
+	display int
 	profile *oz.Profile
 	init *exec.Cmd
 	fs *fs.Filesystem
@@ -36,7 +37,7 @@ func findSandbox(id int) *Sandbox {
 */
 const initCloneFlags = syscall.CLONE_NEWNS | syscall.CLONE_NEWIPC | syscall.CLONE_NEWPID | syscall.CLONE_NEWUTS
 
-func createInitCommand(addr, name, chroot string, uid uint32) *exec.Cmd {
+func createInitCommand(addr, name, chroot string, uid uint32, display int) *exec.Cmd {
 	cmd := exec.Command(initPath)
 	cmd.Dir = "/"
 	cmd.SysProcAttr = &syscall.SysProcAttr{
@@ -48,6 +49,9 @@ func createInitCommand(addr, name, chroot string, uid uint32) *exec.Cmd {
 		"INIT_PROFILE="+name,
 		fmt.Sprintf("INIT_UID=%d", uid),
 	}
+	if display > 0 {
+		cmd.Env = append(cmd.Env, fmt.Sprintf("INIT_DISPLAY=%d", display))
+	}
 	return cmd
 }
 
@@ -64,7 +68,13 @@ func (d *daemonState) launch(p *oz.Profile, uid uint32) (*Sandbox, error) {
 	if err != nil {
 		return nil, err
 	}
-	cmd := createInitCommand(addr, p.Name, fs.Root(), uid)
+	display := 0
+	if p.XServer.Enabled {
+		display = d.nextDisplay
+		d.nextDisplay += 1
+	}
+
+	cmd := createInitCommand(addr, p.Name, fs.Root(), uid, display)
 	pp,err := cmd.StderrPipe()
 	if err != nil {
 		fs.Cleanup()
@@ -78,6 +88,7 @@ func (d *daemonState) launch(p *oz.Profile, uid uint32) (*Sandbox, error) {
 	sbox := &Sandbox{
 		daemon: d,
 		id: d.nextSboxId,
+		display: display,
 		profile: p,
 		init: cmd,
 		fs: fs,

oz-init/init.go

@@ -25,8 +25,6 @@ type initState struct {
 	fs *fs.Filesystem
 }
 
-//var log = createLogger()
-
 // By convention oz-init writes log messages to stderr with a single character
 // prefix indicating the logging level.  These messages are read one line at a time
 // over a pipe by oz-daemon and translated into appropriate log events.
@@ -61,6 +59,10 @@ func Main() {
 			Name: "uid",
 			EnvVar: "INIT_UID",
 		},
+		cli.IntFlag{
+			Name: "display",
+			EnvVar: "INIT_DISPLAY",
+		},
 	}
 	app.Run(os.Args)
 }
@@ -71,6 +73,8 @@ func runInit(c *cli.Context) {
 	address := c.String("address")
 	profile := c.String("profile")
 	uid := uint32(c.Int("uid"))
+	disp := c.Int("display")
+
 	if address == "" {
 		st.log.Error("Error: missing required 'address' argument")
 		os.Exit(1)
@@ -101,7 +105,11 @@ func runInit(c *cli.Context) {
 	}
 	st.fs = fs
 	if p.XServer.Enabled {
-		st.startXpraServer(&p.XServer, fs)
+		if disp == 0 {
+			st.log.Error("Cannot start xpra because no display number was passed to oz-init")
+			os.Exit(1)
+		}
+		st.startXpraServer(&p.XServer, fs, disp)
 	}
 
 	oz.ReapChildProcs(st.log, st.handleChildExit)
@@ -116,7 +124,7 @@ func runInit(c *cli.Context) {
 	st.log.Info("oz-init exiting...")
 }
 
-func (is *initState) startXpraServer (config *oz.XServerConf,  fs *fs.Filesystem) {
+func (is *initState) startXpraServer (config *oz.XServerConf,  fs *fs.Filesystem, display int) {
 	workdir := fs.Xpra()
 	if workdir == "" {
 		is.log.Warning("Xpra work directory not set")
@@ -129,7 +137,7 @@ func (is *initState) startXpraServer (config *oz.XServerConf,  fs *fs.Filesystem
 		return
 	}
 	defer f.Close()
-	xpra := xpra.NewServer(config, 123, workdir)
+	xpra := xpra.NewServer(config, uint64(display), workdir)
 	xpra.Process.Stdout = f
 	xpra.Process.Stderr = f
 	xpra.Process.Env = []string{