fix: cli prompt termination exit code

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

cli/command/utils.go

@@ -8,9 +8,11 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/signal"
 	"path/filepath"
 	"runtime"
 	"strings"
+	"syscall"
 
 	"github.com/docker/cli/cli/streams"
 	"github.com/docker/docker/api/types/filters"
@@ -90,9 +92,23 @@ func PromptForConfirmation(ins io.Reader, outs io.Writer, message string) bool {
 		ins = streams.NewIn(os.Stdin)
 	}
 
-	reader := bufio.NewReader(ins)
-	answer, _, _ := reader.ReadLine()
-	return strings.ToLower(string(answer)) == "y"
+	result := make(chan bool, 1)
+	go func() {
+		reader := bufio.NewReader(ins)
+		answer, _, _ := reader.ReadLine()
+		result <- strings.ToLower(string(answer)) == "y"
+	}()
+
+	go func() {
+		// We catch the signal to avoid the prompt
+		// from exiting as an error
+		c := make(chan os.Signal, 1)
+		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
+		<-c
+		result <- false
+	}()
+
+	return <-result
 }
 
 // PruneFilters returns consolidated prune filters obtained from config.json and cli

cli/command/utils_test.go

@@ -1,9 +1,14 @@
 package command
 
 import (
+	"bufio"
+	"bytes"
 	"os"
 	"path/filepath"
+	"strings"
+	"syscall"
 	"testing"
+	"time"
 
 	"github.com/pkg/errors"
 	"gotest.tools/v3/assert"
@@ -68,3 +73,24 @@ func TestValidateOutputPath(t *testing.T) {
 		})
 	}
 }
+
+func TestPromptForConfirmation(t *testing.T) {
+	buf := new(bytes.Buffer)
+	w := bufio.NewWriter(buf)
+	result := make(chan bool)
+	go func() {
+		result <- PromptForConfirmation(os.Stdin, w, "")
+	}()
+
+	time.Sleep(100 * time.Millisecond)
+
+	syscall.Kill(syscall.Getpid(), syscall.SIGINT)
+	select {
+	case r := <-result:
+		assert.Check(t, !r)
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("PromptForConfirmation did not return after SIGINT")
+	}
+	assert.NilError(t, w.Flush())
+	assert.Equal(t, strings.TrimSpace(buf.String()), "Are you sure you want to proceed? [y/N]")
+}

cli/command/volume/prune_test.go

@@ -5,7 +5,9 @@ import (
 	"io"
 	"runtime"
 	"strings"
+	"syscall"
 	"testing"
+	"time"
 
 	"github.com/docker/cli/cli/streams"
 	"github.com/docker/cli/internal/test"
@@ -183,3 +185,32 @@ func simplePruneFunc(filters.Args) (types.VolumesPruneReport, error) {
 		SpaceReclaimed: 2000,
 	}, nil
 }
+
+func TestVolumePrunePromptTerminate(t *testing.T) {
+	cli := test.NewFakeCli(&fakeClient{
+		volumePruneFunc: func(filter filters.Args) (types.VolumesPruneReport, error) {
+			return types.VolumesPruneReport{}, errors.New("should not be called")
+		},
+	})
+
+	cmd := NewPruneCommand(cli)
+
+	errChan := make(chan error)
+	go func() {
+		errChan <- cmd.Execute()
+	}()
+
+	// wait for the prompt to be displayed
+	time.Sleep(100 * time.Millisecond)
+
+	syscall.Kill(syscall.Getpid(), syscall.SIGINT)
+	// sigint and sigterm are caught by the prompt
+	// this allows us to gracefully exit the prompt with a 0 exit code
+	select {
+	case err := <-errChan:
+		assert.NilError(t, err)
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("Prune Volume did not return after SIGINT")
+	}
+	golden.Assert(t, cli.OutBuffer().String(), "volume-prune-terminate.golden")
+}