Merge pull request #22873 from jstarks/fix_bs_del

Windows: Work around Windows BS/DEL behavior

libcontainerd/client_windows.go

@@ -291,6 +291,9 @@ func (clnt *client) AddProcess(containerID, processFriendlyName string, procToAd
 		return err
 	}
 
+	// TEMP: Work around Windows BS/DEL behavior.
+	iopipe.Stdin = fixStdinBackspaceBehavior(iopipe.Stdin, procToAdd.Terminal)
+
 	// Convert io.ReadClosers to io.Readers
 	if stdout != nil {
 		iopipe.Stdout = openReaderFromPipe(stdout)

libcontainerd/container_windows.go

@@ -102,6 +102,9 @@ func (ctr *container) start() error {
 	}
 	ctr.startedAt = time.Now()
 
+	// TEMP: Work around Windows BS/DEL behavior.
+	iopipe.Stdin = fixStdinBackspaceBehavior(iopipe.Stdin, ctr.ociSpec.Process.Terminal)
+
 	// Convert io.ReadClosers to io.Readers
 	if stdout != nil {
 		iopipe.Stdout = openReaderFromPipe(stdout)

libcontainerd/process_windows.go

@@ -2,6 +2,8 @@ package libcontainerd
 
 import (
 	"io"
+
+	"github.com/docker/docker/pkg/system"
 )
 
 // process keeps the state for both main container process and exec process.
@@ -25,3 +27,33 @@ func openReaderFromPipe(p io.ReadCloser) io.Reader {
 	}()
 	return r
 }
+
+// fixStdinBackspaceBehavior works around a bug in Windows before build 14350
+// where it interpreted DEL as VK_DELETE instead of as VK_BACK. This replaces
+// DEL with BS to work around this.
+func fixStdinBackspaceBehavior(w io.WriteCloser, tty bool) io.WriteCloser {
+	if !tty || system.GetOSVersion().Build >= 14350 {
+		return w
+	}
+	return &delToBsWriter{w}
+}
+
+type delToBsWriter struct {
+	io.WriteCloser
+}
+
+func (w *delToBsWriter) Write(b []byte) (int, error) {
+	const (
+		backspace = 0x8
+		del       = 0x7f
+	)
+	bc := make([]byte, len(b))
+	for i, c := range b {
+		if c == del {
+			bc[i] = backspace
+		} else {
+			bc[i] = c
+		}
+	}
+	return w.WriteCloser.Write(bc)
+}