fix: hoist signal handling from prompt confirmation

Signed-off-by: Alano Terblanche <18033717+Benehiko@users.noreply.github.com>

Author: Benehiko

cli/command/utils.go

@@ -9,11 +9,9 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"os/signal"
 	"path/filepath"
 	"runtime"
 	"strings"
-	"syscall"
 
 	"github.com/docker/cli/cli/streams"
 	"github.com/docker/docker/api/types/filters"
@@ -103,11 +101,6 @@ func PromptForConfirmation(ctx context.Context, ins io.Reader, outs io.Writer, m
 
 	result := make(chan bool)
 
-	// Catch the termination signal and exit the prompt gracefully.
-	// The caller is responsible for properly handling the termination.
-	notifyCtx, notifyCancel := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
-	defer notifyCancel()
-
 	go func() {
 		var res bool
 		scanner := bufio.NewScanner(ins)
@@ -121,8 +114,7 @@ func PromptForConfirmation(ctx context.Context, ins io.Reader, outs io.Writer, m
 	}()
 
 	select {
-	case <-notifyCtx.Done():
-		// print a newline on termination
+	case <-ctx.Done():
 		_, _ = fmt.Fprintln(outs, "")
 		return false, ErrPromptTerminated
 	case r := <-result:

cli/command/utils_test.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/signal"
 	"path/filepath"
 	"strings"
 	"syscall"
@@ -135,6 +136,9 @@ func TestPromptForConfirmation(t *testing.T) {
 		}, promptResult{false, nil}},
 	} {
 		t.Run("case="+tc.desc, func(t *testing.T) {
+			notifyCtx, notifyCancel := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
+			t.Cleanup(notifyCancel)
+
 			buf.Reset()
 			promptReader, promptWriter = io.Pipe()
 
@@ -145,7 +149,7 @@ func TestPromptForConfirmation(t *testing.T) {
 
 			result := make(chan promptResult, 1)
 			go func() {
-				r, err := command.PromptForConfirmation(ctx, promptReader, promptOut, "")
+				r, err := command.PromptForConfirmation(notifyCtx, promptReader, promptOut, "")
 				result <- promptResult{r, err}
 			}()
 

cmd/docker/docker.go

@@ -28,7 +28,12 @@ import (
 )
 
 func main() {
-	ctx := context.Background()
+	baseCtx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	ctx, cancelNotify := signal.NotifyContext(baseCtx, platformsignals.TerminationSignals...)
+	defer cancelNotify()
+
 	dockerCli, err := command.NewDockerCli(command.WithBaseContext(ctx))
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
@@ -223,7 +228,7 @@ func setValidateArgs(dockerCli command.Cli, cmd *cobra.Command) {
 	})
 }
 
-func tryPluginRun(dockerCli command.Cli, cmd *cobra.Command, subcommand string, envs []string) error {
+func tryPluginRun(ctx context.Context, dockerCli command.Cli, cmd *cobra.Command, subcommand string, envs []string) error {
 	plugincmd, err := pluginmanager.PluginRunCommand(dockerCli, subcommand, cmd)
 	if err != nil {
 		return err
@@ -241,11 +246,15 @@ func tryPluginRun(dockerCli command.Cli, cmd *cobra.Command, subcommand string,
 
 	// Background signal handling logic: block on the signals channel, and
 	// notify the plugin via the PluginServer (or signal) as appropriate.
-	const exitLimit = 3
-	signals := make(chan os.Signal, exitLimit)
-	signal.Notify(signals, platformsignals.TerminationSignals...)
+	const exitLimit = 2
+
 	go func() {
 		retries := 0
+		<-ctx.Done()
+
+		signals := make(chan os.Signal, exitLimit)
+		signal.Notify(signals, platformsignals.TerminationSignals...)
+
 		for range signals {
 			// If stdin is a TTY, the kernel will forward
 			// signals to the subprocess because the shared
@@ -333,7 +342,7 @@ func runDocker(ctx context.Context, dockerCli *command.DockerCli) error {
 		ccmd, _, err := cmd.Find(args)
 		subCommand = ccmd
 		if err != nil || pluginmanager.IsPluginCommand(ccmd) {
-			err := tryPluginRun(dockerCli, cmd, args[0], envs)
+			err := tryPluginRun(ctx, dockerCli, cmd, args[0], envs)
 			if err == nil {
 				if dockerCli.HooksEnabled() && dockerCli.Out().IsTerminal() && ccmd != nil {
 					_ = pluginmanager.RunPluginHooks(dockerCli, cmd, ccmd, args[0], args)

internal/test/cmd.go

@@ -3,7 +3,6 @@ package test
 import (
 	"context"
 	"os"
-	"syscall"
 	"testing"
 	"time"
 
@@ -32,8 +31,11 @@ func TerminatePrompt(ctx context.Context, t *testing.T, cmd *cobra.Command, cli
 	assert.NilError(t, err)
 	cli.SetIn(streams.NewIn(r))
 
+	notifyCtx, notifyCancel := context.WithCancel(ctx)
+	t.Cleanup(notifyCancel)
+
 	go func() {
-		errChan <- cmd.ExecuteContext(ctx)
+		errChan <- cmd.ExecuteContext(notifyCtx)
 	}()
 
 	writeCtx, writeCancel := context.WithTimeout(ctx, 100*time.Millisecond)
@@ -66,7 +68,7 @@ func TerminatePrompt(ctx context.Context, t *testing.T, cmd *cobra.Command, cli
 
 	// sigint and sigterm are caught by the prompt
 	// this allows us to gracefully exit the prompt with a 0 exit code
-	syscall.Kill(syscall.Getpid(), syscall.SIGINT)
+	notifyCancel()
 
 	select {
 	case <-errCtx.Done():