Refactor mounts into pkg to make changes easier

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

libcontainer/mount/nodes/nodes.go

@@ -0,0 +1,49 @@
+// +build linux
+
+package nodes
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/pkg/system"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+// Default list of device nodes to copy
+var DefaultNodes = []string{
+	"null",
+	"zero",
+	"full",
+	"random",
+	"urandom",
+	"tty",
+}
+
+// CopyN copies the device node from the host into the rootfs
+func CopyN(rootfs string, nodesToCopy []string) error {
+	oldMask := system.Umask(0000)
+	defer system.Umask(oldMask)
+
+	for _, node := range nodesToCopy {
+		if err := Copy(rootfs, node); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func Copy(rootfs, node string) error {
+	stat, err := os.Stat(filepath.Join("/dev", node))
+	if err != nil {
+		return err
+	}
+	var (
+		dest = filepath.Join(rootfs, "dev", node)
+		st   = stat.Sys().(*syscall.Stat_t)
+	)
+	if err := system.Mknod(dest, st.Mode, int(st.Rdev)); err != nil && !os.IsExist(err) {
+		return fmt.Errorf("copy %s %s", node, err)
+	}
+	return nil
+}