Re: [PLUGIN] dlopen and RTLD_NOW

[Richard Guenther <richard.guenther@gmail.com>]

On Mon, Sep 5, 2011 at 9:50 AM, Romain Geissler
<romain.geissler@gmail.com> wrote:
> Hi
>
> Is there any particular reason to load plugin with the RTLD_NOW option?
> This option force .so symbol resolution to be completely made at load time,
> but this could be done only when a symbol is needed (RTLD_NOW).
>
> Here is the dlopen line in plugin.c:
> dl_handle = dlopen (plugin->full_name, RTLD_NOW | RTLD_GLOBAL);
>
> My issue is, I want to load the same plugin.so in both cc1 and cc1plus, but
> in the C++ case, I may need to reference some cc1plus specific symbols. I can
> check whether cc1 or cc1plus loaded the plugin and thus use custom C++
> symbols only when present. With RTLD_NOW, the plugin fails to load in cc1 as
> symbol resolution is forced at load time.
>
> If RTLD_NOW is removed, dlopen falls back to the RTLD_LAZY mode which fits
> my need. Moreover, if one can force the complete symbol resolution at load time
> by defining the environment LD_BIND_NOW variable.
>
> So, is RTLD_NOW use justified ?

Not really, neither RTLD_GLOBAL.

Richard.

> Romain Geissler
>