Re: [V2 patch] Enhance comments in nsswitch.h

[DJ Delorie <dj@redhat.com>]

Florian Weimer <fweimer@redhat.com> writes:
>> +   We define several types of pointers to try help identify the data:
>> +   - ptr-to-malloc'd: Pointer to data which needs freeing.
>> +   - ptr-to-persistent: Pointer to persistent object.
>> +   - ptr-to-unloadable: Pointer to unloadlable object.  */
>
> What is a pointer to an unloadable object?  A DSO handle?  Or is it a
> heap pointer that is never freed?

The intention is, if/when we allow for nsswitch.conf to be reloaded, we
need to understand which internal data *is* reloaded, and which *isn't*.

So ptr-to-unloadable means those malloc'd objects that can be free'd
when we reload nsswitch.conf.

> Is ptr-to-persistent to a static object?

Just to something that doesn't change once created.  The problem is, if
we load a DSO and some thread is using it via nss, and we reload
nsswitch.conf, we can't unload the DSO, because it might be in use.  So
ptr-to-persistent means it points to something that, once created, won't
go away.  Since the DSO doesn't change, any data mapping names to DSO
functions also won't need to change, etc.