cmd/mbf: enable output colouring

This respects the de facto standards, on top of checking stderr.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/mbf/cache.go

@@ -28,6 +28,8 @@ type cache struct {
 	idle bool
 	// Unset [pkg.CSuppressInit].
 	verboseInit bool
+	// Whether to enable output colours.
+	color bool
 	// Unset [pkg.CExternShallow].
 	deep bool
 	// Loaded artifact of [rosa.QEMU].
@@ -61,6 +63,9 @@ func (cache *cache) open() (err error) {
 	if !cache.deep {
 		cache.attr.Flags |= pkg.CExternShallow
 	}
+	if cache.color {
+		cache.attr.Flags |= pkg.CColourOutput
+	}
 
 	done := make(chan struct{})
 	defer close(done)

cmd/mbf/main.go

@@ -92,6 +92,11 @@ func main() {
 
 	var cm cache
 	defer func() { cm.Close() }()
+	if cm.color = ext.Isatty(syscall.Stderr) &&
+		os.Getenv("NO_COLOR") == "" &&
+		os.Getenv("TERM") != "dumb"; cm.color {
+		log.SetPrefix("\x1b[2mmbf: \x1b[0m")
+	}
 
 	var (
 		flagQuiet bool

internal/rosa/rosa_test.go

@@ -58,11 +58,11 @@ func getCache(t *testing.T) *pkg.Cache {
 			ctx, buildTestCacheCancel = signal.NotifyContext(context.Background(),
 				syscall.SIGINT, syscall.SIGTERM)
 
-			msg := message.New(log.New(os.Stderr, "rosa: ", 0))
+			msg := message.New(log.New(os.Stderr, "\x1b[2mrosa: \x1b[0m", 0))
 			msg.SwapVerbose(true)
 
 			if buildTestCache, err = pkg.Open(ctx, msg, a, &pkg.CacheAttr{
-				Flags: pkg.CSuppressInit,
+				Flags: pkg.CSuppressInit | pkg.CColourOutput,
 			}); err != nil {
 				t.Fatal(err)
 			}