refactor(cli): rename and move root validation

internal/cli/root.go

@@ -5,10 +5,10 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"os/exec"
 
 	"github.com/urfave/cli/v3"
 
+	"github.com/89luca89/distrobox/internal/rootful"
 	"github.com/89luca89/distrobox/pkg/config"
 	"github.com/89luca89/distrobox/pkg/containermanager"
 	"github.com/89luca89/distrobox/pkg/containermanager/providers"
@@ -55,19 +55,6 @@ func printInvalidContainerManager(p *ui.Printer, containerManagerType string) {
 	p.Println("The available choices are: 'autodetect', 'podman', 'podman-launcher', 'docker'")
 }
 
-func validateSudo(ctx context.Context) error {
-	cmd := exec.CommandContext(ctx, "sudo", "-v")
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-
-	if err := cmd.Run(); err != nil {
-		return fmt.Errorf("failed to validate sudo: %w", err)
-	}
-
-	return nil
-}
-
 func subcommands(cfg *config.Values) []*cli.Command {
 	return []*cli.Command{
 		composeCommand(
@@ -152,7 +139,7 @@ func withRoot(_ *config.Values, cmd *cli.Command) *cli.Command {
 			}
 		}
 		if c.Bool("root") {
-			if err := validateSudo(ctx); err != nil {
+			if err := rootful.Validate(ctx); err != nil {
 				return nil, fmt.Errorf("cannot run in root mode: %w", err)
 			}
 		}

internal/rootful/rootful.go

@@ -0,0 +1,34 @@
+// Package rootful provides utilities for running operations that require
+// root privileges via sudo.
+package rootful
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"sync"
+)
+
+//nolint:gochecknoglobals // singleton: process-wide memoization is the intent
+var (
+	validateOnce sync.Once
+	errValidate  error
+)
+
+// Validate ensures that sudo is available and the user can elevate.
+// It runs `sudo -v` at most once per process: the first call performs the
+// check and caches the result; subsequent calls return the cached result
+// without re-running the command.
+func Validate(ctx context.Context) error {
+	validateOnce.Do(func() {
+		cmd := exec.CommandContext(ctx, "sudo", "-v")
+		cmd.Stdin = os.Stdin
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			errValidate = fmt.Errorf("failed to validate sudo: %w", err)
+		}
+	})
+	return errValidate
+}