Create some util funcs that are common between start and exec

and it'll really help my start/create PR when I need to rebase  :-)

Signed-off-by: Doug Davis <dug@us.ibm.com>

exec.go

@@ -9,7 +9,6 @@ import (
 	"path"
 	"strconv"
 	"strings"
-	"syscall"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
@@ -71,39 +70,19 @@ func execProcess(context *cli.Context) (int, error) {
 	if err != nil {
 		return -1, err
 	}
+
 	var (
 		detach = context.Bool("detach")
 		rootfs = container.Config().Rootfs
 	)
-	rootuid, err := container.Config().HostUID()
+
-	if err != nil {
-		return -1, err
-	}
 	p, err := getProcess(context, path.Dir(rootfs))
 	if err != nil {
 		return -1, err
 	}
-	process := newProcess(*p)
+
-	tty, err := setupIO(process, rootuid, context.String("console"), p.Terminal, detach)
+	return runProcess(container, p, nil, context.String("console"), context.String("pid-file"), detach)
-	if err != nil {
+
-		return -1, err
-	}
-	if err := container.Start(process); err != nil {
-		return -1, err
-	}
-	if pidFile := context.String("pid-file"); pidFile != "" {
-		if err := createPidFile(pidFile, process); err != nil {
-			process.Signal(syscall.SIGKILL)
-			process.Wait()
-			return -1, err
-		}
-	}
-	if detach {
-		return 0, nil
-	}
-	handler := newSignalHandler(tty)
-	defer handler.Close()
-	return handler.forward(process)
 }
 
 func getProcess(context *cli.Context, bundle string) (*specs.Process, error) {

start.go

@@ -3,10 +3,8 @@
 package main
 
 import (
-	"fmt"
 	"os"
 	"runtime"
-	"syscall"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
@@ -88,61 +86,23 @@ func startContainer(context *cli.Context, spec *specs.LinuxSpec) (int, error) {
 	if id == "" {
 		return -1, errEmptyID
 	}
-	config, err := createLibcontainerConfig(id, spec)
+	container, err := createContainer(context, id, spec)
-	if err != nil {
-		return -1, err
-	}
-	if _, err := os.Stat(config.Rootfs); err != nil {
-		if os.IsNotExist(err) {
-			return -1, fmt.Errorf("rootfs (%q) does not exist", config.Rootfs)
-		}
-		return -1, err
-	}
-	rootuid, err := config.HostUID()
-	if err != nil {
-		return -1, err
-	}
-	factory, err := loadFactory(context)
-	if err != nil {
-		return -1, err
-	}
-	container, err := factory.Create(id, config)
 	if err != nil {
 		return -1, err
 	}
+
 	// ensure that the container is always removed if we were the process
 	// that created it.
 	detach := context.Bool("detach")
 	if !detach {
 		defer destroy(container)
 	}
-	process := newProcess(spec.Process)
+
 	// Support on-demand socket activation by passing file descriptors into the container init process.
+	listenFDs := []*os.File{}
 	if os.Getenv("LISTEN_FDS") != "" {
-		listenFds := activation.Files(false)
+		listenFDs = activation.Files(false)
-		if len(listenFds) > 0 {
-			process.Env = append(process.Env, fmt.Sprintf("LISTEN_FDS=%d", len(listenFds)), "LISTEN_PID=1")
-			process.ExtraFiles = append(process.ExtraFiles, listenFds...)
-		}
 	}
-	tty, err := setupIO(process, rootuid, context.String("console"), spec.Process.Terminal, detach)
+
-	if err != nil {
+	return runProcess(container, &spec.Process, listenFDs, context.String("console"), context.String("pid-file"), detach)
-		return -1, err
-	}
-	if err := container.Start(process); err != nil {
-		return -1, err
-	}
-	if pidFile := context.String("pid-file"); pidFile != "" {
-		if err := createPidFile(pidFile, process); err != nil {
-			process.Signal(syscall.SIGKILL)
-			process.Wait()
-			return -1, err
-		}
-	}
-	if detach {
-		return 0, nil
-	}
-	handler := newSignalHandler(tty)
-	defer handler.Close()
-	return handler.forward(process)
 }

utils.go

@@ -265,3 +265,64 @@ func createPidFile(path string, process *libcontainer.Process) error {
 	_, err = fmt.Fprintf(f, "%d", pid)
 	return err
 }
+
+func createContainer(context *cli.Context, id string, spec *specs.LinuxSpec) (libcontainer.Container, error) {
+	config, err := createLibcontainerConfig(id, spec)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, err := os.Stat(config.Rootfs); err != nil {
+		if os.IsNotExist(err) {
+			return nil, fmt.Errorf("rootfs (%q) does not exist", config.Rootfs)
+		}
+		return nil, err
+	}
+
+	factory, err := loadFactory(context)
+	if err != nil {
+		return nil, err
+	}
+	return factory.Create(id, config)
+}
+
+// runProcess will create a new process in the specified container
+// by executing the process specified in the 'config'.
+func runProcess(container libcontainer.Container, config *specs.Process, listenFDs []*os.File, console string, pidFile string, detach bool) (int, error) {
+	process := newProcess(*config)
+
+	// Add extra file descriptors if needed
+	if len(listenFDs) > 0 {
+		process.Env = append(process.Env, fmt.Sprintf("LISTEN_FDS=%d", len(listenFDs)), "LISTEN_PID=1")
+		process.ExtraFiles = append(process.ExtraFiles, listenFDs...)
+	}
+
+	rootuid, err := container.Config().HostUID()
+	if err != nil {
+		return -1, err
+	}
+
+	tty, err := setupIO(process, rootuid, console, config.Terminal, detach)
+	if err != nil {
+		return -1, err
+	}
+
+	if err := container.Start(process); err != nil {
+		return -1, err
+	}
+
+	if pidFile != "" {
+		if err := createPidFile(pidFile, process); err != nil {
+			process.Signal(syscall.SIGKILL)
+			process.Wait()
+			return -1, err
+		}
+	}
+	if detach {
+		return 0, nil
+	}
+	handler := newSignalHandler(tty)
+	defer handler.Close()
+
+	return handler.forward(process)
+}