This patch inconditionally initializes the buffer we get to
nul-terminate it, whenever possible. It's a very simple solution to
catch three overly corner cases:
1) snprintf() returns -1, very much unlikely in practise.
2) msg->len == 0: In such case, I would expect this function is never
called with an empty message, but let's be safe in this case too.
3) If your buffer is empty, it doesn't nul-terminate the buffer.
Change-Id: I97e517f2d98e83894ea707c63489559302ff6bd2
5994198208