Re: [gpsd-dev] [PATCH v3 1/1] gps2udp: reset errno after successful getaddrinfo call

[Ferry Huberts]

On 03/01/14 16:00, Mike Frysinger wrote:
> On Friday 03 January 2014 09:29:29 Ferry Huberts wrote:
> > On 03/01/14 15:18, Mike Frysinger wrote:
> > > On Friday 03 January 2014 08:33:47 Ferry Huberts wrote:
> > > > It may return errno==2 ("No such file or directory") when the file
> > > > /etc/gai.conf is not present.
> > > >
> > > > The observed effect was that the port number conversion considered
> > > > a perfectly valid port number as invalid.
> > >
> > > you still haven't really explained why this is the way to go.  functions
> > > do not "return errno".  they return real values, and any code calling
> > > those functions need to first check the return value *before* ever
> > > looking at errno.
> >
> > Which is exactly what happens here: the code bails out if the function
> > call is not successful.
>
> what code is bailing where ?


please do read the code:

>     if ((ret = getaddrinfo(host, service, &hints, &result))) {
>         return NL_NOHOST;
>     }

returns from the function (with return value NL_NOHOST) when the 
getaddrinfo call is not successful (returns a non-zero value).

see also man getaddrinfo



> > The function call may set errno even though it succeeds.
>
> that is not a bug

exactly, which is why we must reset errno, because otherwise other 
functions are affected.

--
Ferry Huberts