Re: libldap and libldap_r in the same process

[Howard Chu <hyc@symas.com>]

Jan Engelhardt wrote:
> A given (threaded) program makes use of libldap_r. It now also wants to
> make use of, say, libcurl. On certain systems, libcurl happens to be
> linked against libldap (not _r).
>
> Eventually, both libldap and libldap_r end up in the process image of my
> program, and a symbol like "ldap_init" may point to the function of
> either library file. The threaded program may end up unexpectedly been
> given the non-threaded functions, depending on how the runtime linker
> loaded said libraries and binds the symbols. (I am seeing crashes in a
> large program's initialization because of this.)
>
>
> There is a 7-year old post indicating libldap should get locking/
> be replaced by libldap_r.
> http://www.openldap.org/lists/openldap-devel/200909/msg00018.html
> To date, openldap still consists of the two libraries.
> What are the preferred options to go forward here?
>
> * Killing non-threaded libldap in openldap for real
> If not,
> * Should curl have used -lldap_r instead of -lldap?

Is curl already multithreaded? On Ubuntu curl is built with libldap_r already. 
If curl is a threaded program then yes, it should use libldap_r.

> * Should Linux distributions make libldap and libldap_r be the same thing?

I'm wary of doing that, but I suppose thread support on Linux today is a lot 
more stable than it was 7-15 years ago.

> * Should libldap and libldap_r be augmented by ELF symbol versions?
> * All of the above? :)


--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/