strtol() and friends may set EINVAL if no conversion was performed, but
they are not required to do so. In practice they don't. We need to check
for it.
https://bugzilla.redhat.com/show_bug.cgi?id=870577
There is no point in clearing the bits of a "struct stat" when the very
next statement just calls stat or fstat to fill in that same memory.
[zj: two more places]
Michal Schmidt