Modules

Define properly modules.

Modules should only use the queue to communicate information to the lkt_state.

The lkt_state should use the reg to get function pointers and other properties from the modules. This reg will include macros to get function pointers and call the function with the given arguments. The reg will notify when a function is not available, and won't segfault. By doing so:

• Some modules (player, repo) won't be necessary to launch lektord. The server can be launched even if some functionalities are not here.
• Simplify the modules information in the lektor.ini file.
• It will be possible to unload and load modules on the fly.
• Events from the lkt_state queue can be differed to when the module is loaded.

inc/lektor/reg.h

-#pragma once
+#if ! defined(__REG_H__)
 
 struct lkt_state;
 
@@ -9,18 +9,28 @@ struct module_reg {
     void (*func)(void);
 };
 
-extern struct module_reg *reg;
-
 #define REG_BEGIN(reg)          struct module_reg reg[] = {
 #define REG_ADD(__f)            { .name = #__f,  .func = (void(*)(void)) __f    },
 #define REG_ADD_NAMED(__n, __f) { .name = __n,   .func = (void(*)(void)) __f    },
 #define REG_END()               { .name = NULL,  .func = NULL                   } };
 
+#if ! defined(_STATIC_MODULES)
+#define REG_EXPORT(__reg)       struct module_reg *__reg__ = __reg;
+#else
+#define REG_EXPORT(__reg)
+#endif
+
 /* If handle is NULL, file is unused and the reg is red. Otherwise,
    we use dlfcn to search for the symbol which is returned. If *handle
    is NULL, it will be created by opening the file. */
 void *reg_pick(const char *file, void **handle, const char *symbol);
 
+/* Get the reg from a .so file. This reg must be exported by the
+   shared library with REG_EXPORT. Note that this reg is named `__reg__`,
+   thus no symbol must be named `__reg__` in the .so file.
+   Returns 0 on success, something else on error. */
+int reg_from_file(const char *file, struct module_reg *ret);
+
 /* Set the ref for this .a / .so file */
 void reg_set(struct module_reg *);
 
@@ -28,3 +38,5 @@ void reg_set(struct module_reg *);
    type is done, it is up to the user to check if the structure passed as a
    `void*` is the right structure. */
 int load_module_by_name(struct lkt_state *srv, const char *name, void *mod);
+
+#endif