How to load a plugin from another plugin?

Question

Hi,
I'm trying to load a plugin, which is not located in the plugin-paths of After Effects from another plugin. It seems to load the aex(dll) and execute the main function fine, but afterwards it crashes immediately and I have no idea why.
This is how my pluginLoader-PlugIn looks like:
1. I created a commandHook to be able to trigger the pluginLoad from the Edit Menu
2. for the actual load of the dll I use the following commands:
          AEGP_SuiteHandler    suites(basic_suite);
        std::string dllName = "C:/PATH/TO/plugin.aex";
        // defining type and order of the arguments of the entry function
        typedef A_Err (*args_type)(SPBasicSuite *pica_basicP, A_long major_versionL, A_long minor_versionL, A_long aegp_plugin_id, AEGP_GlobalRefcon *global_refconP);
        args_type pluginEntryMethod = NULL;
        // loading the dll(aex) and the entry function
        # ifdef _WIN32
        HMODULE hDLL = LoadLibrary(dllName.c_str());
        if (hDLL != NULL)
            pluginEntryMethod = (args_type) GetProcAddress(hDLL, "EntryPointFunc");
        else
            return err;
        # else
        void *pLib = ::dlopen(szMyLib, RTLD_LAZY);
        if (pLib != NULL) {
            pluginEntryMethod = (args_type)::dlsym(pLib, "EntryPointFunc");
        else
            return err;
        # endif
        if (pluginEntryMethod != NULL)
            // hardcoding the plugin version
            A_long mavL = 0L;
            A_long mivL = 1L;
            AEGP_PluginID plId;
            // to get a valid plugin-id I use this command
            suites.UtilitySuite3()->AEGP_RegisterWithAEGP(*globalRefcon, "nameOfPlugin", &plId);
            // I create copy of the refcon and the suite
            AEGP_GlobalRefcon newRefcon(*globalRefcon);
            SPBasicSuite newSuite(*basic_suite);
            pluginEntryMethod(&newSuite, mavL, mivL, plId, &newRefcon);
        # ifdef _WIN32
            FreeLibrary(hDLL);
        # else
            dlclose(pLib);
        # endif
If I run After Effects with the debugger, the EntryFunction of the new plugin runs through without errors. But Then it crashes and stops at random positions: sometimes in the IdleHook of the newly loaded Plugin, sometimes in the MenuHook.
Does anyone have an idea, what I am doing wrong?
btw: when I copy the second plugin in the default Afx-Plugin-Folder it loads fine and seems to work correct.
Thanks for your help!
Martin

Answer 1

Okay, unfortunately it had nothing to do with static or dynamic linking of the dependencies.
I was able to boil it down to the following problem but I'm still stuck on how to solve the situation:
The problem has to do with an invalid AEGP_GlobalRefcon of the Plugin I load:
the plugin loader:
// the load of the inner plugin..
AEGP_GlobalRefcon newRefcon; // generating a new refcon
suites.UtilitySuite5()->AEGP_RegisterWithAEGP(newRefcon, pluginName.c_str(), &plId); // gathering a plugin id
pluginEntryMethod(basic_suite, mavL, mivL, plId, &newRefcon) // calling the entry function
the loaded plugin:
A_Err EntryPointFunc(
    struct SPBasicSuite        *pica_basicP,
    A_long                     major_versionL,
    A_long                    minor_versionL,
    AEGP_PluginID            aegp_plugin_id,
    AEGP_GlobalRefcon        *global_refconP)
    *global_refconP = (AEGP_GlobalRefcon) new CustomClass(pica_basicP, aegp_plugin_id); // this is where the refcon gets invalid
    return err;
To gather a valid plugin id, I register the plugin and assign a new AEGP_GlobalRefcon to it, which is for instance at address 0x0001234abcd (plugin-loader line 3)
then I call the entry function(plugin-loader line 4) and the entry function creates a custom class and stores a pointer to its instance in the global_refconP pointer, which changes the address from 0x0001234abcd to 0x0a010b020c3d4.
The crash happens later, when a hook (eg IdleHook) is called, which tries to reinterpret the refconPV-pointer of the plugin (address 0x0001234abcd) to a CustomClass-instance, because the actual instance is stored at 0x0a010b020c3d4.
I reckon, that I can fix this if I either can change the global refcon of the plugin after the enty function has run or if I can get a valid plugin id before calling the entry function and doing the registration with the new refcon I got returned by the entry function of the loaded plugin.
Does anyone know how to achieve one of these two goals?