fstatfs() on the open file to verify that no intruder has mounted
something on portions of /proc. This will catch, for instance,
"mount_null /tmp /proc/1378". We already do 5 syscalls per
process, so one more won't hurt :) ... and safety is better than
performance when ps is otherwise broken.
- Also added a few close()'s at early returns, to avoid chewing up fd's.
fallback method is used, as the results could be untrustworthy if an
intruder is present. It is highly likely that NetBSD-1.5 will have
an improved kvm interface for reading process information, at which
point this code can be garbage-collected. Also added a word to the
man page -x option description while I was here.
thorpej