fix: ensure terminal has required read settings in non-canonical mode (…

…#409)

terminal/runereader_posix.go

@@ -50,6 +50,11 @@ func (rr *RuneReader) SetTermMode() error {
 
 	newState := rr.state.term
 	newState.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG
+	// Because we are clearing canonical mode, we need to ensure VMIN & VTIME are
+	// set to the values we expect. This combination puts things in standard
+	// "blocking read" mode (see termios(3)).
+	newState.Cc[syscall.VMIN] = 1
+	newState.Cc[syscall.VTIME] = 0
 
 	if _, _, err := syscall.Syscall6(syscall.SYS_IOCTL, uintptr(rr.stdio.In.Fd()), ioctlWriteTermios, uintptr(unsafe.Pointer(&newState)), 0, 0, 0); err != 0 {
 		return err