IO::Buffer#|

static VALUE
io_buffer_or(VALUE self, VALUE mask)
{
    struct rb_io_buffer_view *buffer = get_io_buffer_view(self);

    struct rb_io_buffer_view *mask_buffer = get_io_buffer_view(mask);

    const void *base;
    size_t size;
    io_buffer_get_bytes_for_reading(buffer, &base, &size);

    const void *mask_base;
    size_t mask_size;
    io_buffer_get_bytes_for_reading(mask_buffer, &mask_base, &mask_size);

    io_buffer_check_mask_size(mask_size);

    VALUE output = rb_io_buffer_new(NULL, size, io_flags_for_size(size));
    struct rb_io_buffer_view *output_buffer = get_io_buffer_view(output);

    memory_or(output_buffer->base, base, size, mask_base, mask_size);

    return output;
}