Re: modulename_LTX_ prefix not removed from preloaded symbols?

[Gary V. Vaughan]

Kevin P. Fleming wrote:
> I've just converted an application to use libtool and ltdl for opening 
> its plugin modules; part of that conversion required prefixing the 
> public-visible symbols in the modules with "modulename_LTX_", which ltdl 
> strips when lt_dlsym is called. That all worked fine.
>
> However, one of the reasons for making this change to libtool was so 
> that the application could support being statically linked. I have 
> modified the makefiles to use -dlopen and -dlpreopen where required, and 
> now I get a static binary built with all the plugins linked in. So far 
> so good... however, after figuring out a way to get at the 
> preloaded_symbols list (see my message to this list from yesterday), I 
> find out that the symbols in this list _do not have the prefix removed_! 
> In spite of that, presym_sym (the "symbol finder" for preloaded modules) 
> has no concept of the symbol prefix and makes no attempt to remove it 
> before checking the symbol list. I now have to construct the prefix in 
> my code so I can add it to the symbol, but only when I found the module 
> in the preloaded symbols list.
>
> Is this how this is supposed to work? It doesn't seem logical to me, at 
> this point I could have built the infrastructure to do this myself 
> (given that I don't have to support much portability beyond Linux) and 
> not had to deal with this. Maybe I'm just missing something, but I don't 
> see why the preloaded-symbols case shouldn't act _exactly_ like the 
> shared-library-loaded-symbols case.

You're not supposed to call the loaders directly, just use lt_dlsym, and it 
will add the prefix for you:

  3866        /* this is a libtool module */
  3867        if (handle->loader->sym_prefix)
  3868          {
  3869            strcpy(sym, handle->loader->sym_prefix);
  3870            strcat(sym, handle->info.name);
  3871          }
  3872        else
  3873          {
  3874            strcpy(sym, handle->info.name);
  3875          }
  3876
  3877        strcat(sym, "_LTX_");
  3878        strcat(sym, symbol);
  3879
  3880        /* try "modulename_LTX_symbol" */
  3881        address = handle->loader->find_sym (data, handle->module, sym);

Cheers,
        Gary.
--
  ())_.  Gary V. Vaughan    gary@(lilith.warpmail.net|gnu.org)
  ( '/   Research Scientist http://www.oranda.demon.co.uk       ,_())____
  / )=   GNU Hacker         http://www.gnu.org/software/libtool  \'      `&
`(_~)_   Tech' Author       http://sources.redhat.com/autobook   =`---d__/