fix: Avoid background color query hang (#636)

jedevc · web-flow · commit 472d718e2314 · 2026-04-13T13:14:58.000-04:00
Which seems to happen if stdin/stdout are somehow accidentally not TTYs.

Signed-off-by: Justin Chadwell &lt;justin@unikraft.com&gt;
diff --git a/query.go b/query.go
@@ -54,13 +54,16 @@ func BackgroundColor(in term.File, out term.File) (bg color.Color, err error) {
 	}
 
 	// NOTE: On Unix, one of the given files must be a tty.
+	if !term.IsTerminal(in.Fd()) || !term.IsTerminal(out.Fd()) {
+		return nil, fmt.Errorf("input/output is not a terminal")
+	}
 	for _, f := range []term.File{in, out} {
 		if bg, err = backgroundColor(f, f); err == nil {
 			return bg, nil
 		}
 	}
 
-	return
+	return bg, err
 }
 
 // HasDarkBackground detects whether the terminal has a light or dark

Original file line number	Diff line number	Diff line change
`@@ -54,13 +54,16 @@ func BackgroundColor(in term.File, out term.File) (bg color.Color, err error) {`
`54`	`54`	`}`
`55`	`55`
`56`	`56`	`// NOTE: On Unix, one of the given files must be a tty.`
	`57`	`+ if !term.IsTerminal(in.Fd()) \|\| !term.IsTerminal(out.Fd()) {`
	`58`	`+ return nil, fmt.Errorf("input/output is not a terminal")`
	`59`	`+ }`
`57`	`60`	`for _, f := range []term.File{in, out} {`
`58`	`61`	`if bg, err = backgroundColor(f, f); err == nil {`
`59`	`62`	`return bg, nil`
`60`	`63`	`}`
`61`	`64`	`}`
`62`	`65`
`63`		`- return`
	`66`	`+ return bg, err`
`64`	`67`	`}`
`65`	`68`
`66`	`69`	`// HasDarkBackground detects whether the terminal has a light or dark`