Check that input is a tty before using it

The current UI library will crash, if trying to read
input from something that is not a terminal (a TTY).

Signed-off-by: Anders F Björklund <[email protected]>

Author: afbjorklund

cmd/limactl/clone.go

@@ -121,7 +121,7 @@ func cloneOrRenameAction(cmd *cobra.Command, args []string) error {
 	}
 
 	if tty && !flags.Changed("start") {
-		start, err = askWhetherToStart()
+		start, err = askWhetherToStart(cmd)
 		if err != nil {
 			return err
 		}

cmd/limactl/edit.go

@@ -153,7 +153,7 @@ func editAction(cmd *cobra.Command, args []string) error {
 	}
 
 	if tty && !flags.Changed("start") {
-		start, err = askWhetherToStart()
+		start, err = askWhetherToStart(cmd)
 		if err != nil {
 			return err
 		}
@@ -180,9 +180,13 @@ func editAction(cmd *cobra.Command, args []string) error {
 	return instance.Start(ctx, inst, false, false)
 }
 
-func askWhetherToStart() (bool, error) {
-	message := "Do you want to start the instance now? "
-	return uiutil.Confirm(message, true)
+func askWhetherToStart(cmd *cobra.Command) (bool, error) {
+	isTTY := uiutil.InputIsTTY(cmd.InOrStdin())
+	if isTTY {
+		message := "Do you want to start the instance now? "
+		return uiutil.Confirm(message, true)
+	}
+	return false, nil
 }
 
 func editBashComplete(cmd *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {

pkg/uiutil/uiutil.go

@@ -41,6 +41,17 @@ func Select(message string, options []string) (int, error) {
 	return ans, nil
 }
 
+// InputIsTTY returns true if reader is coming from stdin, and stdin is a terminal device,
+// not a regular file, stream, or pipe etc.
+func InputIsTTY(reader io.Reader) bool {
+	// This setting is needed so we can write integration tests for the TTY input.
+	// It is probably not useful otherwise.
+	if os.Getenv("_LIMA_INPUT_IS_TTY") != "" {
+		return true
+	}
+	return reader == os.Stdin && (isatty.IsTerminal(os.Stdin.Fd()) || isatty.IsCygwinTerminal(os.Stdin.Fd()))
+}
+
 // OutputIsTTY returns true if writer is going to stdout, and stdout is a terminal device,
 // not a regular file, stream, or pipe etc.
 func OutputIsTTY(writer io.Writer) bool {