client: Use io.Writer for Stdout/Stderr in InstanceExecArgs

This changes the Stdout and Stderr fields to be of type io.Writer
instead of io.WriteCloser since `Close()` is never called on these
fields.

Fixes #12197

Signed-off-by: Thomas Hipp <[email protected]>

client/interfaces.go

@@ -643,10 +643,10 @@ type InstanceExecArgs struct {
 	Stdin io.ReadCloser
 
 	// Standard output
-	Stdout io.WriteCloser
+	Stdout io.Writer
 
 	// Standard error
-	Stderr io.WriteCloser
+	Stderr io.Writer
 
 	// Control message handler (window resize, signals, ...)
 	Control func(conn *websocket.Conn)

shared/ws/mirror.go

@@ -45,8 +45,8 @@ func MirrorRead(conn *websocket.Conn, rc io.ReadCloser) chan error {
 	return chDone
 }
 
-// MirrorWrite is a uni-directional mirror which replicates a websocket to an io.WriteCloser.
-func MirrorWrite(conn *websocket.Conn, wc io.WriteCloser) chan error {
+// MirrorWrite is a uni-directional mirror which replicates a websocket to an io.Writer.
+func MirrorWrite(conn *websocket.Conn, wc io.Writer) chan error {
 	chDone := make(chan error, 1)
 	if wc == nil {
 		close(chDone)