Don't block user interaction while fetching the image size

.github/workflows/ubuntu-tests.yaml

@@ -44,7 +44,7 @@ jobs:
             fish \
             gcc \
             go-md2man \
-            golang \
+            golang-1.20 \
             meson \
             ninja-build \
             openssl \
@@ -54,6 +54,10 @@ jobs:
             systemd \
             udisks2
 
+      - name: Set up PATH for Go 1.20
+        run: |
+          echo "PATH=/usr/lib/go-1.20/bin:$PATH" >> "$GITHUB_ENV"
+
       - name: Checkout Bats
         uses: actions/checkout@v3
         with:

src/cmd/create.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"os"
@@ -28,14 +29,18 @@ import (
 	"github.com/containers/toolbox/pkg/podman"
 	"github.com/containers/toolbox/pkg/shell"
 	"github.com/containers/toolbox/pkg/skopeo"
+	"github.com/containers/toolbox/pkg/term"
 	"github.com/containers/toolbox/pkg/utils"
 	"github.com/docker/go-units"
 	"github.com/godbus/dbus/v5"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
-	"golang.org/x/term"
 )
 
+type promptForDownloadError struct {
+	ImageSize string
+}
+
 const (
 	alpha    = `abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`
 	num      = `0123456789`
@@ -449,10 +454,7 @@ func createContainer(container, image, release, authFile string, showCommandToEn
 	}
 
 	s := spinner.New(spinner.CharSets[9], 500*time.Millisecond)
-
-	stdoutFd := os.Stdout.Fd()
-	stdoutFdInt := int(stdoutFd)
-	if logLevel := logrus.GetLevel(); logLevel < logrus.DebugLevel && term.IsTerminal(stdoutFdInt) {
+	if logLevel := logrus.GetLevel(); logLevel < logrus.DebugLevel && term.IsTerminal(os.Stdout) {
 		s.Prefix = fmt.Sprintf("Creating container %s: ", container)
 		s.Writer = os.Stdout
 		s.Start()
@@ -575,8 +577,8 @@ func getFullyQualifiedImageFromRepoTags(image string) (string, error) {
 	return imageFull, nil
 }
 
-func getImageSizeFromRegistry(imageFull string) (string, error) {
-	image, err := skopeo.Inspect(imageFull)
+func getImageSizeFromRegistry(ctx context.Context, imageFull string) (string, error) {
+	image, err := skopeo.Inspect(ctx, imageFull)
 	if err != nil {
 		return "", err
 	}
@@ -599,6 +601,23 @@ func getImageSizeFromRegistry(imageFull string) (string, error) {
 	return imageSizeHuman, nil
 }
 
+func getImageSizeFromRegistryAsync(ctx context.Context, imageFull string) (<-chan string, <-chan error) {
+	retValCh := make(chan string)
+	errCh := make(chan error)
+
+	go func() {
+		imageSize, err := getImageSizeFromRegistry(ctx, imageFull)
+		if err != nil {
+			errCh <- err
+			return
+		}
+
+		retValCh <- imageSize
+	}()
+
+	return retValCh, errCh
+}
+
 func getServiceSocket(serviceName string, unitName string) (string, error) {
 	logrus.Debugf("Resolving path to the %s socket", serviceName)
 
@@ -711,18 +730,7 @@ func pullImage(image, release, authFile string) (bool, error) {
 	}
 
 	if promptForDownload {
-		fmt.Println("Image required to create toolbox container.")
-
-		var prompt string
-
-		if imageSize, err := getImageSizeFromRegistry(imageFull); err != nil {
-			logrus.Debugf("Getting image size failed: %s", err)
-			prompt = fmt.Sprintf("Download %s? [y/N]:", imageFull)
-		} else {
-			prompt = fmt.Sprintf("Download %s (%s)? [y/N]:", imageFull, imageSize)
-		}
-
-		shouldPullImage = askForConfirmation(prompt)
+		shouldPullImage = showPromptForDownload(imageFull)
 	}
 
 	if !shouldPullImage {
@@ -731,9 +739,7 @@ func pullImage(image, release, authFile string) (bool, error) {
 
 	logrus.Debugf("Pulling image %s", imageFull)
 
-	stdoutFd := os.Stdout.Fd()
-	stdoutFdInt := int(stdoutFd)
-	if logLevel := logrus.GetLevel(); logLevel < logrus.DebugLevel && term.IsTerminal(stdoutFdInt) {
+	if logLevel := logrus.GetLevel(); logLevel < logrus.DebugLevel && term.IsTerminal(os.Stdout) {
 		s := spinner.New(spinner.CharSets[9], 500*time.Millisecond)
 		s.Prefix = fmt.Sprintf("Pulling %s: ", imageFull)
 		s.Writer = os.Stdout
@@ -754,6 +760,214 @@ func pullImage(image, release, authFile string) (bool, error) {
 	return true, nil
 }
 
+func createPromptForDownload(imageFull, imageSize string) string {
+	var prompt string
+	if imageSize == "" {
+		prompt = fmt.Sprintf("Download %s? [y/N]:", imageFull)
+	} else {
+		prompt = fmt.Sprintf("Download %s (%s)? [y/N]:", imageFull, imageSize)
+	}
+
+	return prompt
+}
+
+func showPromptForDownloadFirst(imageFull string) (bool, error) {
+	prompt := createPromptForDownload(imageFull, " ... MB")
+
+	parentCtx := context.Background()
+	askCtx, askCancel := context.WithCancelCause(parentCtx)
+	defer askCancel(errors.New("clean-up"))
+
+	askCh, askErrCh := askForConfirmationAsync(askCtx, prompt, nil)
+
+	imageSizeCtx, imageSizeCancel := context.WithCancelCause(parentCtx)
+	defer imageSizeCancel(errors.New("clean-up"))
+
+	imageSizeCh, imageSizeErrCh := getImageSizeFromRegistryAsync(imageSizeCtx, imageFull)
+
+	var imageSize string
+	var shouldPullImage bool
+
+	select {
+	case val := <-askCh:
+		shouldPullImage = val
+		cause := fmt.Errorf("%w: received confirmation without image size", context.Canceled)
+		imageSizeCancel(cause)
+	case err := <-askErrCh:
+		shouldPullImage = false
+		cause := fmt.Errorf("failed to ask for confirmation without image size: %w", err)
+		imageSizeCancel(cause)
+	case val := <-imageSizeCh:
+		imageSize = val
+		cause := fmt.Errorf("%w: received image size", context.Canceled)
+		askCancel(cause)
+	case err := <-imageSizeErrCh:
+		cause := fmt.Errorf("failed to get image size: %w", err)
+		askCancel(cause)
+	}
+
+	if imageSizeCtx.Err() != nil && askCtx.Err() == nil {
+		cause := context.Cause(imageSizeCtx)
+		logrus.Debugf("Show prompt for download: image size canceled: %s", cause)
+		return shouldPullImage, nil
+	}
+
+	var done bool
+
+	if imageSizeCtx.Err() == nil && askCtx.Err() != nil {
+		select {
+		case val := <-askCh:
+			logrus.Debugf("Show prompt for download: received pending confirmation without image size")
+			shouldPullImage = val
+			done = true
+		case err := <-askErrCh:
+			logrus.Debugf("Show prompt for download: failed to ask for confirmation without image size: %s",
+				err)
+		}
+	} else {
+		panic("code should not be reached")
+	}
+
+	cause := context.Cause(askCtx)
+	logrus.Debugf("Show prompt for download: ask canceled: %s", cause)
+
+	if done {
+		return shouldPullImage, nil
+	}
+
+	return false, &promptForDownloadError{imageSize}
+}
+
+func showPromptForDownloadSecond(imageFull string, errFirst *promptForDownloadError) bool {
+	oldState, err := term.GetState(os.Stdin)
+	if err != nil {
+		logrus.Debugf("Show prompt for download: failed to get terminal state: %s", err)
+		return false
+	}
+
+	defer term.SetState(os.Stdin, oldState)
+
+	lockedState := term.NewStateFrom(oldState,
+		term.WithVMIN(1),
+		term.WithVTIME(0),
+		term.WithoutECHO(),
+		term.WithoutICANON())
+
+	if err := term.SetState(os.Stdin, lockedState); err != nil {
+		logrus.Debugf("Show prompt for download: failed to set terminal state: %s", err)
+		return false
+	}
+
+	parentCtx := context.Background()
+	discardCtx, discardCancel := context.WithCancelCause(parentCtx)
+	defer discardCancel(errors.New("clean-up"))
+
+	discardCh, discardErrCh := discardInputAsync(discardCtx)
+
+	var prompt string
+	if errors.Is(errFirst, context.Canceled) {
+		prompt = createPromptForDownload(imageFull, errFirst.ImageSize)
+	} else {
+		prompt = createPromptForDownload(imageFull, "")
+	}
+
+	fmt.Printf("\r")
+
+	askCtx, askCancel := context.WithCancelCause(parentCtx)
+	defer askCancel(errors.New("clean-up"))
+
+	var askForConfirmationPreFnDone bool
+	askForConfirmationPreFn := func() error {
+		defer discardCancel(errors.New("clean-up"))
+		if askForConfirmationPreFnDone {
+			return nil
+		}
+
+		// Erase to end of line
+		fmt.Printf("\033[K")
+
+		// Save the cursor position.
+		fmt.Printf("\033[s")
+
+		if err := term.SetState(os.Stdin, oldState); err != nil {
+			return fmt.Errorf("failed to restore terminal state: %w", err)
+		}
+
+		cause := errors.New("terminal restored")
+		discardCancel(cause)
+
+		err := <-discardErrCh
+		if !errors.Is(err, context.Canceled) {
+			return fmt.Errorf("failed to discard input: %w", err)
+		}
+
+		logrus.Debugf("Show prompt for download: stopped discarding input: %s", err)
+
+		discardTotal := <-discardCh
+		logrus.Debugf("Show prompt for download: discarded input: %d bytes", discardTotal)
+
+		if discardTotal == 0 {
+			askForConfirmationPreFnDone = true
+			return nil
+		}
+
+		if err := term.SetState(os.Stdin, lockedState); err != nil {
+			return fmt.Errorf("failed to set terminal state: %w", err)
+		}
+
+		discardCtx, discardCancel = context.WithCancelCause(parentCtx)
+		// A deferred call can't be used for this CancelCauseFunc,
+		// because the 'discard' operation needs to continue running
+		// until the next invocation of this function.  It relies on
+		// the guarantee that AskForConfirmationAsync will always call
+		// its askForConfirmationPreFunc as long as the function
+		// returns errContinue.
+
+		discardCh, discardErrCh = discardInputAsync(discardCtx)
+
+		// Restore the cursor position
+		fmt.Printf("\033[u")
+
+		// Erase to end of line
+		fmt.Printf("\033[K")
+
+		fmt.Printf("...\n")
+		return errContinue
+	}
+
+	askCh, askErrCh := askForConfirmationAsync(askCtx, prompt, askForConfirmationPreFn)
+	var shouldPullImage bool
+
+	select {
+	case val := <-askCh:
+		logrus.Debug("Show prompt for download: received confirmation with image size")
+		shouldPullImage = val
+	case err := <-askErrCh:
+		logrus.Debugf("Show prompt for download: failed to ask for confirmation with image size: %s", err)
+		shouldPullImage = false
+	}
+
+	return shouldPullImage
+}
+
+func showPromptForDownload(imageFull string) bool {
+	fmt.Println("Image required to create toolbox container.")
+
+	shouldPullImage, err := showPromptForDownloadFirst(imageFull)
+	if err == nil {
+		return shouldPullImage
+	}
+
+	var errPromptForDownload *promptForDownloadError
+	if !errors.As(err, &errPromptForDownload) {
+		panicMsg := fmt.Sprintf("unexpected %T: %s", err, err)
+		panic(panicMsg)
+	}
+
+	shouldPullImage = showPromptForDownloadSecond(imageFull, errPromptForDownload)
+	return shouldPullImage
+}
+
 // systemdNeedsEscape checks whether a byte in a potential dbus ObjectPath needs to be escaped
 func systemdNeedsEscape(i int, b byte) bool {
 	// Escape everything that is not a-z-A-Z-0-9
@@ -781,3 +995,17 @@ func systemdPathBusEscape(path string) string {
 	}
 	return string(n)
 }
+
+func (err *promptForDownloadError) Error() string {
+	innerErr := err.Unwrap()
+	errMsg := innerErr.Error()
+	return errMsg
+}
+
+func (err *promptForDownloadError) Unwrap() error {
+	if err.ImageSize == "" {
+		return errors.New("failed to get image size")
+	}
+
+	return context.Canceled
+}