Re: [PATCH] sysctl: add support for poll()

[ebiederm@xmission.com (Eric W. Biederman)]

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> Host names are dynamic, can change during system runtime by dhcp or
>> similar setups, or just get changed by the user.
>
> I don't actually see what this has to do with utsname. uname historically
> defined nodename as "name within an implementation-defined communications
> network" and actually tended to be the UUCP name. Modern SuS says "`the
> name of the node of the communications network to which this node is
> attached, if any"

>
> The latter unfortunately makes no sense anyway and is a fine example of
> standards body cluelessness as name mapping on IP networks is not one
> name per host, and also because the standard doesn't require the fields
> in the struct are long enough to hold a DNS name!
>
> (Indeed in its usual head up backside manner its technically valid to
> define
>
> 	char nodename[1];
>
> and have only \0 as a valid reply)

However we have conveniently defined sethostname and gethostname to use
the same state in the kernel, as uname.  I believe at least one of these
interfaces that map to the same storage in linux has a usable size
guaranteed by all of the implementations.

Eric