error in trimdomain(3)

Brooks Davis brooks at one-eyed-alien.net
Mon Oct 3 11:03:47 PDT 2005


On Mon, Oct 03, 2005 at 11:31:24AM +0100, Ceri Davies wrote:
> On Sat, Oct 01, 2005 at 02:35:50AM -0700, Brooks Davis wrote:
> > I discovered today that the trimdomain() implementation in libutil deviates
> > slightly from the manpage.  The manpage says:
> > 
> >      The function trimdomain() removes the current domain name from the passed
> >      fullhost name by writing a NUL character over the first period of the
> >                                                        ^^^^^^^^^^^^
> >      passed name.  The current domain name is determined by calling
> >      gethostname(3) and removing everything up to the first period.
> > 
> > which clearly indicates that trimdomain() should return either the
> > unmodified string or a host name with no domain.  In reality it will
> > remove the domain name even if the result is not a host name.  This
> > means that if the host b.com calls trimdomain with "a.b.com" as the
> > input string, the result is "a.b".
> 
> That's actually what the excerpt above says will happen.
> 
> gethostname returns "b.com", removing everything up to the first period
> yields ".com", and that removed from "a.b.com" gives you "a.b".
> 
> I don't care if it needs to be changed, but that does exactly what it
> says on the tin so far as I can see.

There are two refrences to "first period".  You are correct that the
domain name of b.com is .com, but the refrence I highlighted states that
the only allowable modification to the host name is writing a NUL to
the first period in the string (it's actually messier than this because
trimdomain also supports X11 DISPLAY strings and thus does a memmove and
reterminates if there is a :0 or :0.0 type string after domain.)

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.
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