* Gleb Natapov wrote on Mon, Aug 01, 2005 at 04:58:03PM CEST: > On Mon, Aug 01, 2005 at 03:42:17PM +0200, Ralf Wildenhues wrote: > > * Gleb Natapov wrote on Sun, Jul 17, 2005 at 11:39:34AM CEST: > > > > > > I have library (lets say liba.so) that on startup checks available > > > hardware and loads appropriate plugin (say plugin.so) to drive the > > > hardware. > > > plugin.so uses symbols from liba.so. > > > > > > Everything works OK if liba.so linked with application, but if > > > application is modular by itself and use module (say module.so) that > > > is linked with liba.so then dlopen of plugin.so from liba.so fails with > > > unresolved symbols. > > > > > > How can I solve this issue? > > > > If you use Libtool/libltdl for portable modules (which you do not seem > > to do), look at Libtool branch-2-0 or CVS HEAD, which allows ltdlopen'ing > > from libraries. Make sure to read the corresponding documentation > > pertaining to libltdl, make use of `-module' and `-export-dynamic'. > > > The project I saw this problem with actually use libtool (not 2.0 > though). And both flags are used.
OK. Well, for portable use of modules from within a library you should use either branch-2-0 or HEAD. > After investigation of the problem I found that liba.so tries to load > plugin.so from library constructor. Even if liba.so is dlopen with > RTLD_GLOBAL flag set, plugin.so can't resolve symbols from liba.so Just so we don't misunderstand each other: what exactly do you mean by library constructor? Are you overwriting DT_INIT? (If so, you are a far way from portable shared libraries.) > Let me explain this one more time. > > Program 'prog' calls dlopen(liba.so, RTLD_GLOBAL), in constructor liba.so > calls dlopen(plugin.so) and this call fails with unresolved symbols > from liba.so. > > If we add function init_a() to liba.so and move dlopen(plugin.so) from > constructor to the function and we call this function from 'prog' after > dlopen (liba.so, RTLD_GLOBAL) then everything works as expected. Best would be if you showed short reproducible code. Not that I know whether I could help you then. Regards, Ralf _______________________________________________ http://lists.gnu.org/mailman/listinfo/libtool
