Fixes unchecked results from parsecmd

Before accessing the strings of a parsecmd, we must check the nf (num
fields).  Many devices were not checking, so something like
	echo "" > /net/ether0/stats
Would trigger a PF.

Using lookupcmd() is safe, since it check the nf internally.  But any
naked access to the fields (like with strcmp) requires a check.
6 files changed