NSS error reporting (bug 20532)

[Zack Weinberg]

On Thu, Aug 3, 2017 at 12:28 PM, Florian Weimer <fweimer@redhat.com> wrote:
> I'm looking again at bug 20532 and related issues.
>
> The core problem is that the NSS service functions have many different
> ways of reporting result status:

It might be useful to make a list of _external conditions_, as
exhaustive as possible, and reason out what the visible results [at
the level of the documented interface] _should be_ for each one.

For instance, for gethostbyname:

 - address records successfully retrieved - returns nonnull, ideally
h_errno and errno are unmodified
 - configured DNS server returned a NXDOMAIN packet - returns NULL,
h_errno set to HOST_NOT_FOUND, ideally errno unmodified
 - query to configured DNS server times out - h_errno set to TRY_AGAIN?
 - etc

zw