Abstract out diff implementations for importing

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

libcontainer/nsinit/command.go

@@ -0,0 +1,34 @@
+package nsinit
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+type CommandFactory interface {
+	Create(container *libcontainer.Container, console, logFile string, syncFd uintptr, args []string) *exec.Cmd
+}
+
+type DefaultCommandFactory struct{}
+
+// Create will return an exec.Cmd with the Cloneflags set to the proper namespaces
+// defined on the container's configuration and use the current binary as the init with the
+// args provided
+func (c *DefaultCommandFactory) Create(container *libcontainer.Container, console, logFile string, pipe uintptr, args []string) *exec.Cmd {
+	// get our binary name so we can always reexec ourself
+	name := os.Args[0]
+	command := exec.Command(name, append([]string{
+		"-console", console,
+		"-pipe", fmt.Sprint(pipe),
+		"-log", logFile,
+		"init"}, args...)...)
+
+	command.SysProcAttr = &syscall.SysProcAttr{
+		Cloneflags: uintptr(GetNamespaceFlags(container.Namespaces)),
+	}
+	command.Env = container.Env
+	return command
+}