persist: Tighten reads; empty every buffer before reading into it
persist: Tighten reads; empty every buffer before reading into it

This is done to prevent bugs from creeping in while reading this weak
file format. Ideally, it should not be necessary.

Signed-off-by: Ramkumar Ramachandra <5c355d1d38066ed0c5de420d67c1b5ed0687c4bd@gmail.com>

artagnon/phoenixfs,artagnon/phoenixfs,artagnon/phoenixfs