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

[Ferry Huberts]

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.
The function call may set errno even though it succeeds.

How about if I rephrase like:
It may set errno to 2 ("No such file or directory") when the file
/etc/gai.conf is not present, even though it succeeds.


> i.e. any code that does:
>         socket_t foo = netlib_connectsock(...);
>         if (errno) {
>                 ... do error stuff ...
>         }
> is completely broken.  resetting errno is the wrong way to fix this.

I did not write that code, I only fixed it.


--
Ferry Huberts