title: How can you create a buffer of the same size as a file?
body: <p>I would like to avoid making a set size buffer because of things like a file being too big, or small enough that there is empty space in the buffer. An <code>ArenaAllocator</code> sounds promising since you can allocate more space as needed. Is there a &quot;proper&quot; way to do this, i.e. load a .json file passed as a command line argument into a buffer?</p>