termstatus: use errWriter if terminal commands fail

internal/terminal/terminal_posix.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"os"
 )
 
 const (
@@ -18,22 +17,22 @@ const (
 
 // PosixClearCurrentLine removes all characters from the current line and resets the
 // cursor position to the first column.
-func PosixClearCurrentLine(wr io.Writer, _ uintptr) {
+func PosixClearCurrentLine(wr io.Writer, _ uintptr) error {
 	// clear current line
 	_, err := wr.Write([]byte(PosixControlMoveCursorHome + PosixControlClearLine))
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
-		return
+		return fmt.Errorf("write failed: %w", err)
 	}
+	return nil
 }
 
 // PosixMoveCursorUp moves the cursor to the line n lines above the current one.
-func PosixMoveCursorUp(wr io.Writer, _ uintptr, n int) {
+func PosixMoveCursorUp(wr io.Writer, _ uintptr, n int) error {
 	data := []byte(PosixControlMoveCursorHome)
 	data = append(data, bytes.Repeat([]byte(PosixControlMoveCursorUp), n)...)
 	_, err := wr.Write(data)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
-		return
+		return fmt.Errorf("write failed: %w", err)
 	}
+	return nil
 }

internal/terminal/terminal_unix.go

@@ -12,12 +12,12 @@ import (
 
 // ClearCurrentLine removes all characters from the current line and resets the
 // cursor position to the first column.
-func ClearCurrentLine(_ uintptr) func(io.Writer, uintptr) {
+func ClearCurrentLine(_ uintptr) func(io.Writer, uintptr) error {
 	return PosixClearCurrentLine
 }
 
 // MoveCursorUp moves the cursor to the line n lines above the current one.
-func MoveCursorUp(_ uintptr) func(io.Writer, uintptr, int) {
+func MoveCursorUp(_ uintptr) func(io.Writer, uintptr, int) error {
 	return PosixMoveCursorUp
 }
 

internal/terminal/terminal_windows.go

@@ -15,7 +15,7 @@ import (
 
 // clearCurrentLine removes all characters from the current line and resets the
 // cursor position to the first column.
-func ClearCurrentLine(fd uintptr) func(io.Writer, uintptr) {
+func ClearCurrentLine(fd uintptr) func(io.Writer, uintptr) error {
 	// easy case, the terminal is cmd or psh, without redirection
 	if isWindowsTerminal(fd) {
 		return windowsClearCurrentLine
@@ -26,7 +26,7 @@ func ClearCurrentLine(fd uintptr) func(io.Writer, uintptr) {
 }
 
 // moveCursorUp moves the cursor to the line n lines above the current one.
-func MoveCursorUp(fd uintptr) func(io.Writer, uintptr, int) {
+func MoveCursorUp(fd uintptr) func(io.Writer, uintptr, int) error {
 	// easy case, the terminal is cmd or psh, without redirection
 	if isWindowsTerminal(fd) {
 		return windowsMoveCursorUp
@@ -45,7 +45,7 @@ var (
 
 // windowsClearCurrentLine removes all characters from the current line and
 // resets the cursor position to the first column.
-func windowsClearCurrentLine(_ io.Writer, fd uintptr) {
+func windowsClearCurrentLine(_ io.Writer, fd uintptr) error {
 	var info windows.ConsoleScreenBufferInfo
 	windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info)
 
@@ -58,10 +58,11 @@ func windowsClearCurrentLine(_ io.Writer, fd uintptr) {
 	count = uint32(info.Size.X)
 	procFillConsoleOutputAttribute.Call(fd, uintptr(info.Attributes), uintptr(count), *(*uintptr)(unsafe.Pointer(&cursor)), uintptr(unsafe.Pointer(&w)))
 	procFillConsoleOutputCharacter.Call(fd, uintptr(' '), uintptr(count), *(*uintptr)(unsafe.Pointer(&cursor)), uintptr(unsafe.Pointer(&w)))
+	return nil
 }
 
 // windowsMoveCursorUp moves the cursor to the line n lines above the current one.
-func windowsMoveCursorUp(_ io.Writer, fd uintptr, n int) {
+func windowsMoveCursorUp(_ io.Writer, fd uintptr, n int) error {
 	var info windows.ConsoleScreenBufferInfo
 	windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info)
 
@@ -70,6 +71,7 @@ func windowsMoveCursorUp(_ io.Writer, fd uintptr, n int) {
 		X: 0,
 		Y: info.CursorPosition.Y - int16(n),
 	})
+	return nil
 }
 
 // isWindowsTerminal return true if the file descriptor is a windows terminal (cmd, psh).

internal/ui/termstatus/status.go

@@ -37,8 +37,8 @@ type Terminal struct {
 	// yield a default value immediately
 	closed chan struct{}
 
-	clearCurrentLine func(io.Writer, uintptr)
-	moveCursorUp     func(io.Writer, uintptr, int)
+	clearCurrentLine func(io.Writer, uintptr) error
+	moveCursorUp     func(io.Writer, uintptr, int) error
 }
 
 type message struct {
@@ -214,7 +214,10 @@ func (t *Terminal) run(ctx context.Context) {
 				// ignore all messages, do nothing, we are in the background process group
 				continue
 			}
-			t.clearCurrentLine(t.wr, t.fd)
+			if err := t.clearCurrentLine(t.wr, t.fd); err != nil {
+				_, _ = fmt.Fprintf(t.errWriter, "write failed: %v\n", err)
+				continue
+			}
 
 			var dst io.Writer
 			if msg.err {
@@ -256,7 +259,9 @@ func (t *Terminal) writeStatus(status []string) {
 	t.lastStatusLen = statusLen
 
 	for _, line := range status {
-		t.clearCurrentLine(t.wr, t.fd)
+		if err := t.clearCurrentLine(t.wr, t.fd); err != nil {
+			_, _ = fmt.Fprintf(t.errWriter, "write failed: %v\n", err)
+		}
 
 		_, err := t.wr.Write([]byte(line))
 		if err != nil {
@@ -265,7 +270,9 @@ func (t *Terminal) writeStatus(status []string) {
 	}
 
 	if len(status) > 0 {
-		t.moveCursorUp(t.wr, t.fd, len(status)-1)
+		if err := t.moveCursorUp(t.wr, t.fd, len(status)-1); err != nil {
+			_, _ = fmt.Fprintf(t.errWriter, "write failed: %v\n", err)
+		}
 	}
 }