pkg/mount: use strings.Cut

In some places, using strings.Cut (available since Go 1.18) instead of
strings.SplitN allows for simpler more readable code.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

pkg/mount/flags.go

@@ -97,14 +97,14 @@ func MergeTmpfsOptions(options []string) ([]string, error) {
 			}
 			continue
 		}
-		opt := strings.SplitN(option, "=", 2)
-		if len(opt) != 2 || !validFlags[opt[0]] {
+		opt, _, ok := strings.Cut(option, "=")
+		if !ok || !validFlags[opt] {
 			return nil, fmt.Errorf("invalid tmpfs option %q", opt)
 		}
-		if !dataCollisions[opt[0]] {
+		if !dataCollisions[opt] {
 			// We prepend the option and add to collision map
 			newOptions = append([]string{option}, newOptions...)
-			dataCollisions[opt[0]] = true
+			dataCollisions[opt] = true
 		}
 	}
 
@@ -140,8 +140,8 @@ func ParseOptions(options string) (int, string) {
 func ParseTmpfsOptions(options string) (int, string, error) {
 	flags, data := ParseOptions(options)
 	for _, o := range strings.Split(data, ",") {
-		opt := strings.SplitN(o, "=", 2)
-		if !validFlags[opt[0]] {
+		opt, _, _ := strings.Cut(o, "=")
+		if !validFlags[opt] {
 			return 0, "", fmt.Errorf("invalid tmpfs option %q", opt)
 		}
 	}

pkg/mount/mounter_freebsd.go

@@ -40,13 +40,9 @@ func mount(device, target, mType string, flag uintptr, data string) error {
 				isNullFS = true
 				continue
 			}
-			opt := strings.SplitN(x, "=", 2)
-			options = append(options, opt[0])
-			if len(opt) == 2 {
-				options = append(options, opt[1])
-			} else {
-				options = append(options, "")
-			}
+			name, val, _ := strings.Cut(x, "=")
+			options = append(options, name)
+			options = append(options, val)
 		}
 	}
 

pkg/mount/mounter_linux_test.go

@@ -209,7 +209,8 @@ func validateMount(t *testing.T, mnt string, opts, optional, vfs string) {
 
 // clean strips off any value param after the colon
 func clean(v string) string {
-	return strings.SplitN(v, ":", 2)[0]
+	ret, _, _ := strings.Cut(v, ":")
+	return ret
 }
 
 // has returns true if key is a member of m