18.5 User Module Loaders

While writing the module loading code for GNU M4 1.5, I found that libltdl did not provide a way for loading modules in exactly the way I required: As good as the preloading feature of libltdl may be, and as useful as it is for simplifying debugging, it doesn't have all the functionality of full dynamic module loading when the host platform is limited to static linking. After all, you can only ever load modules that were specified at link time, so for access to user supplied modules the whole application must be relinked to preload these new modules before lt_dlopen will be able to make use of the additional module code.

In this situation, it would be useful to be able to automate this process. That is, if a libltdl using process is unable to lt_dlopen a module in any other fashion, but can find a suitable static archive in the module search path, it should relink itself along with the static archive (using libtool to preload the module), and then exec the new executable. Assuming all of this is successful, the attempt to lt_dlopen can be tried again -- if the `suitable' static archive was chosen correctly it should now be possible to access the preloaded code.