fix(iostreams): Translation of ANSI escape on Windows for stderr (#2209)

Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>
Approved-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>

Author: craciunoiuc

iostreams/iostreams.go

@@ -52,7 +52,7 @@ type FileWriter interface {
 	Fd() uintptr
 }
 
-type fileReader interface {
+type FileReader interface {
 	io.ReadCloser
 	Fd() uintptr
 }
@@ -69,9 +69,9 @@ type Terminal interface {
 type IOStreams struct {
 	term Terminal
 
-	In     fileReader
+	In     FileReader
 	Out    FileWriter
-	ErrOut io.Writer
+	ErrOut FileWriter
 
 	terminalTheme string
 
@@ -158,7 +158,7 @@ func (s *IOStreams) SetOut(out FileWriter) {
 	s.Out = out
 }
 
-func (s *IOStreams) SetIn(in fileReader) {
+func (s *IOStreams) SetIn(in FileReader) {
 	s.In = in
 }
 
@@ -429,10 +429,21 @@ func System() *IOStreams {
 		}
 	}
 
+	var stderr FileWriter = os.Stderr
+	// On Windows with no virtual terminal processing support, translate ANSI escape
+	// sequences to console syscalls.
+	if colorableStderr := colorable.NewColorable(os.Stderr); colorableStderr != os.Stderr {
+		// Ensure that the file descriptor of the original stderr is preserved.
+		stderr = &fdWriter{
+			fd:     os.Stderr.Fd(),
+			Writer: colorableStderr,
+		}
+	}
+
 	io := &IOStreams{
 		In:           os.Stdin,
 		Out:          stdout,
-		ErrOut:       colorable.NewColorable(os.Stderr),
+		ErrOut:       stderr,
 		pagerCommand: os.Getenv("PAGER"),
 		term:         &terminal,
 	}

tui/processtree/processtree.go

@@ -148,7 +148,7 @@ func NewProcessTree(ctx context.Context, opts []ProcessTreeOption, tree ...*Proc
 		}
 
 		ios.Out = iostreams.NewNoTTYWriter(item, iostreams.G(ctx).Out.Fd())
-		ios.ErrOut = item
+		ios.ErrOut = iostreams.NewNoTTYWriter(item, iostreams.G(ctx).ErrOut.Fd())
 		ios.In = iostreams.G(ctx).In
 		ictx = iostreams.WithIOStreams(ictx, ios)
 
@@ -189,7 +189,7 @@ func (pti *ProcessTreeItem) Write(p []byte) (int, error) {
 	return len(p), nil
 }
 
-func (pti *ProcessTreeItem) Fd() int {
+func (pti *ProcessTreeItem) Fd() uintptr {
 	return 0
 }