On Fri, Aug 2, 2013 at 8:55 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > Isn't it possible to have a valid uid of (unsigned int)-1? I know that > at least some sites use that for "nobody". Why not just require passing > in the correct UID? POSIX requires valid UIDs to be non-nengative. POSIX does not require uid_t to be signed or unsigned. POSIX does make use of (uid_t)-1 as a sentinel (e.g., in setreuid(2)). (uid_t)-1 is special. Do not use it. As an aside, note that on Solaris 10 and less uid_t was signed, so UIDs 2^31..2^32-2 were unusable. Interop with S10 and less requires that you not use such UIDs. Ditto gid_t and GIDs. Also note that in Solaris 11 uid_t is unsigned BUT the range of UIDs 2^31..2^32-2 is still reserved (for automatic, on-demand, non-persistent allocation for ID mapping purposes). Interop with S11 requires that you not use such UIDs. Ditto gid_t and GIDs. Nico -- -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
