Re: 329-gary-allow-RTLD_GLOBAL

[Gary V. Vaughan]

Hallo Ralf,

On 22 May 2007, at 13:16, Ralf Wildenhues wrote:
> * Gary V. Vaughan wrote on Tue, May 22, 2007 at 02:11:03PM CEST:
> > I'm wondering how to best warn people who have their project
> > build rely on RTLD_GLOBAL that what they are doing is inherently
> > non-portable.
>
> Erm, relying on RTLD_LOCAL is non-portable.

It is?  You mean that relying on identical symbols from two dlopened
modules to not clash is non-portable?  On what architectures?

> Relying on RTLD_GLOBAL is not; after all, dlpreloading offers similar.

Relying on RTLD_GLOBAL exported symbols to resolve undefined symbols
in subsequently dlopened modules doesn't work on windows, or AIX.  That
seems pretty non-portable to me...

> But also relying on
> allowing undefined symbols in your link is non-portable.  I don't see
> how you can distinguish cases here reliably, in an automatic way.

Except for annoyance to the end-user, I was originally thinking that
we don't need to distinguish.  When the developer's libltdl client
code calls lt_dladvise_global, we could have it emit a warning to
stderr that says: If what you are trying to do won't work without
calling lt_dladvise_global(), then you're code will not be fully
portable.

> > At first I thought about having the call to lt_dladvise_global
> > emit a warning to stderr on first call, but that affects users
> > as well as developers.
> >
> > Now I'm thinking the best we can do is flag it in the release
> > notes, the NEWS file and the manual.
>
> That would be fine.

I'll add it to my TODO.

Cheers,
        Gary
--
  ())_.              Email me: address@hidden
  ( '/           Read my blog: http://blog.azazil.net
  / )=         ...and my book: http://sources.redhat.com/autobook
`(_~)_ Join my AGLOCO Network: http://www.agloco.com/r/BBBS7912

PGP.sig
Description: This is a digitally signed message part