interfaces/mount: add OptsToFlags for converting arguments to syscall…

interfaces/mount/entry.go

@@ -26,6 +26,7 @@ import (
 	"io"
 	"strconv"
 	"strings"
+	"syscall"
 )
 
 // Entry describes an /etc/fstab-like mount entry.
@@ -190,3 +191,60 @@ func SaveFSTab(writer io.Writer, entries []Entry) error {
 	_, err := buf.WriteTo(writer)
 	return err
 }
+
+// OptsToFlags converts mount options strings to a mount flag.
+func OptsToFlags(opts []string) (flags int, err error) {
+	for _, opt := range opts {
+		switch opt {
+		case "ro":
+			flags |= syscall.MS_RDONLY
+		case "nosuid":
+			flags |= syscall.MS_NOSUID
+		case "nodev":
+			flags |= syscall.MS_NODEV
+		case "noexec":
+			flags |= syscall.MS_NOEXEC
+		case "sync":
+			flags |= syscall.MS_SYNCHRONOUS
+		case "remount":
+			flags |= syscall.MS_REMOUNT
+		case "mand":
+			flags |= syscall.MS_MANDLOCK
+		case "dirsync":
+			flags |= syscall.MS_DIRSYNC
+		case "noatime":
+			flags |= syscall.MS_NOATIME
+		case "nodiratime":
+			flags |= syscall.MS_NODIRATIME
+		case "bind":
+			flags |= syscall.MS_BIND
+		case "rbind":
+			flags |= syscall.MS_BIND | syscall.MS_REC
+		case "move":
+			flags |= syscall.MS_MOVE
+		case "silent":
+			flags |= syscall.MS_SILENT
+		case "acl":
+			flags |= syscall.MS_POSIXACL
+		case "private":
+			flags |= syscall.MS_PRIVATE
+		case "rprivate":
+			flags |= syscall.MS_PRIVATE | syscall.MS_REC
+		case "slave":
+			flags |= syscall.MS_SLAVE
+		case "rslave":
+			flags |= syscall.MS_SLAVE | syscall.MS_REC
+		case "shared":
+			flags |= syscall.MS_SHARED
+		case "rshared":
+			flags |= syscall.MS_SHARED | syscall.MS_REC
+		case "relatime":
+			flags |= syscall.MS_RELATIME
+		case "strictatime":
+			flags |= syscall.MS_STRICTATIME
+		default:
+			return 0, fmt.Errorf("unsupported mount option: %q", opt)
+		}
+	}
+	return flags, nil
+}

interfaces/mount/entry_test.go

@@ -22,6 +22,7 @@ package mount_test
 import (
 	"bytes"
 	"strings"
+	"syscall"
 
 	. "gopkg.in/check.v1"
 
@@ -197,3 +198,15 @@ func (s *entrySuite) TestSaveFSTab2(c *C) {
 		"name-1 dir-1 type-1 options-1 1 1\n" +
 		"name-2 dir-2 type-2 options-2 2 2\n"))
 }
+
+// Test (string) options -> (int) flag conversion code.
+func (s *entrySuite) TestOptsToFlags(c *C) {
+	flags, err := mount.OptsToFlags(nil)
+	c.Assert(err, IsNil)
+	c.Assert(flags, Equals, 0)
+	flags, err = mount.OptsToFlags([]string{"ro", "nodev", "nosuid"})
+	c.Assert(err, IsNil)
+	c.Assert(flags, Equals, syscall.MS_RDONLY|syscall.MS_NODEV|syscall.MS_NOSUID)
+	_, err = mount.OptsToFlags([]string{"bogus"})
+	c.Assert(err, ErrorMatches, `unsupported mount option: "bogus"`)
+}