Refactor tty code into its own package

tools/tty/tty_bsd.go

@@ -0,0 +1,26 @@
+//go:build darwin || freebsd || openbsd || netbsd || dragonfly
+// +build darwin freebsd openbsd netbsd dragonfly
+
+package tty
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+func Tcgetattr(fd uintptr, argp *unix.Termios) error {
+	return unix.IoctlSetTermios(int(fd), unix.TIOCGETA, argp)
+}
+
+func Tcsetattr(fd, opt uintptr, argp *unix.Termios) error {
+	switch opt {
+	case TCSANOW:
+		opt = unix.TIOCSETA
+	case TCSADRAIN:
+		opt = unix.TIOCSETAW
+	case TCSAFLUSH:
+		opt = unix.TIOCSETAF
+	default:
+		return unix.EINVAL
+	}
+	return unix.IoctlSetTermios(int(fd), uint(opt), argp)
+}