small cleanups to module.h and loader.c to start playing with

new-style modules using static symbols.

Everything will still work as before, but new-style modules
can now be defined by putting a '#define STATIC_MODULE' somewhere
before including module.h, then declaring STATIC_MODULE the
various methods (load, unload, key...) that the module is
supposed to supply, and adding a 'STD_MOD(MOD_1, reload_fn, NULL, NULL)'
macro call at the end.
A module compiled in this way will be loaded RTLD_NOW|RTLD_LOCAL
so symbol pollution is reduced, and symbols are resolved immediately.
Removing just the '#define STATIC_MODULE' will restore the old
behaviour.

In order for a module to be loaded RTLD_NOW|RTLD_LOCAL, it must not
export any symbol[1], and all the modules it depends on (e.g. res_*)
must be loaded already.

[1] Mechanisms are in place, and will be enabled later, to still
allow such modules to 'export' symbols and resolving the dependencies
irrespective of the load order.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@17790 65c4cc65-6c06-0410-ace0-fbb531ad65f3

2 files changed, 45 insertions, 33 deletions

diff --git a/include/asterisk/module.h b/include/asterisk/module.h
index b00ec488d..5e1b6e094 100644
--- a/include/asterisk/module.h
+++ b/include/asterisk/module.h
@@ -34,12 +34,12 @@
 extern "C" {
 #endif
 
-#ifndef STATIC_MODULE
-#define STATIC_MODULE	/* empty - symbols are global */
-#else
+#ifdef STATIC_MODULE	/* symbols are static */
+#define _HAVE_STATIC_MODULE
 #undef STATIC_MODULE
 #define STATIC_MODULE	static /* symbols are static */
-#endif
+#else	/* !STATIC_MODULE, symbols are global */
+#define STATIC_MODULE	/* empty - symbols are global */
 
 /*! \note Every module should provide these functions */
 /*! 
@@ -53,7 +53,7 @@ extern "C" {
  * If the module is not loaded successfully, Asterisk will call its
  * unload_module() function.
  */
-STATIC_MODULE int load_module(void);
+int load_module(void);
 
 /*! 
  * \brief Cleanup all module structures, sockets, etc.
@@ -64,7 +64,7 @@ STATIC_MODULE int load_module(void);
  *
  * \return Zero on success, or non-zero on error.
  */
-STATIC_MODULE int unload_module(void);
+int unload_module(void);
 
 /*! 
  * \brief Provides a usecount.
@@ -76,13 +76,13 @@ STATIC_MODULE int unload_module(void);
  *
  * \return The module's usecount.
  */
-STATIC_MODULE int usecount(void);			/* How many channels provided by this module are in use? */
+int usecount(void);		/* How many channels provided by this module are in use? */
 
 /*! \brief Provides a description of the module.
  *
  * \return a short description of your module
  */
-STATIC_MODULE char *description(void);		/* Description of this module */
+char *description(void);		/* Description of this module */
 
 /*! 
  * \brief Returns the ASTERISK_GPL_KEY
@@ -99,7 +99,7 @@ STATIC_MODULE char *description(void);		/* Description of this module */
  *
  * \return ASTERISK_GPL_KEY
  */
-STATIC_MODULE char *key(void);		/* Return the below mentioned key, unmodified */
+char *key(void);		/* Return the below mentioned key, unmodified */
 
 /*! 
  * \brief Reload stuff.
@@ -109,7 +109,8 @@ STATIC_MODULE char *key(void);		/* Return the below mentioned key, unmodified */
  *
  * \return The return value is not used.
  */
-STATIC_MODULE int reload(void);		/* reload configs */
+int reload(void);		/* reload configs */
+#endif	/* !STATIC_MODULE case */
 
 /*! \brief The text the key() function should return. */
 #define ASTERISK_GPL_KEY \
@@ -506,6 +507,15 @@ struct symbol_entry {
 #define	MOD_FIELD(f)    . ## f = f
 #define	METHOD_BASE(_base, _name)       . ## _name = _base ## _name
 
+/*
+ * Each 'registerable' entity has a pointer in the
+ * struct ast_registry, which points to an array of objects of
+ * the same type. The ast_*_register() function will be able to
+ * derive the size of these entries.
+ */
+struct ast_registry {
+	struct ast_cli_entry *clis;
+};
 
 struct module_symbols {
         int (*load_module)(void);
@@ -520,22 +530,27 @@ struct module_symbols {
 		MOD_1,	/* old style, but symbols here */
 		MOD_2,	/* new style, exported symbols */
 	} type;
+	struct ast_registry *reg;
 	struct symbol_entry *exported_symbols;
 	struct symbol_entry *required_symbols;
 };
 
-#define STD_MOD(t, exp, req)				\
+#ifndef _HAVE_STATIC_MODULE
+#define STD_MOD(t, reload_fn, exp, req)
+#else
+#define STD_MOD(t, reload_fn, exp, req)			\
 struct module_symbols mod_data = {			\
         .load_module = load_module,			\
         .unload_module = unload_module,			\
         .description = description,			\
         .key = key,					\
-        .reload = reload,				\
+        .reload = reload_fn,				\
         .usecount = usecount,				\
 	.type = t,					\
 	.exported_symbols = exp,			\
 	.required_symbols = req				\
 };
+#endif /* _HAVE_STATIC_MODULE */
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }
diff --git a/loader.c b/loader.c
index d467528a5..08dca973a 100644
--- a/loader.c
+++ b/loader.c
@@ -683,26 +683,20 @@ static struct module * __load_resource(const char *resource_name,
 	int res;
 	struct module *cur;
 	struct module_symbols *m, *m1;
-	int flags=RTLD_NOW;
+	int flags = RTLD_NOW;
 	unsigned char *key;
 	char tmp[80];
 
-	if (strncasecmp(resource_name, "res_", 4)) {
-#ifdef RTLD_GLOBAL
-		if (cfg) {
-			char *val;
-			if ((val = ast_variable_retrieve(cfg, "global", resource_name))
-					&& ast_true(val))
-				flags |= RTLD_GLOBAL;
-		}
+#ifndef RTLD_GLOBAL
+#define RTLD_GLOBAL	0	/* so it is a No-op */
 #endif
+	if (strncasecmp(resource_name, "res_", 4) && cfg) {
+		char *val = ast_variable_retrieve(cfg, "global", resource_name);
+		if (val && ast_true(val))
+			flags |= RTLD_GLOBAL;
 	} else {
 		/* Resource modules are always loaded global and lazy */
-#ifdef RTLD_GLOBAL
 		flags = (RTLD_GLOBAL | RTLD_LAZY);
-#else
-		flags = RTLD_LAZY;
-#endif
 	}
 	
 	if (AST_LIST_LOCK(&module_list))
@@ -722,16 +716,19 @@ static struct module * __load_resource(const char *resource_name,
 		ast_copy_string(fn, resource_name, sizeof(fn));
 	else
 		snprintf(fn, sizeof(fn), "%s/%s", ast_config_AST_MODULE_DIR, resource_name);
-#if 0
-	/* XXX test, open in a sane way */
+
+	/* open in a sane way */
 	cur->lib = dlopen(fn, RTLD_NOW | RTLD_LOCAL);
 	if (cur->lib == NULL) {
-		ast_log(LOG_WARNING, "test %s\n", dlerror());
-	} else
+		ast_log(LOG_WARNING, "cannot load %s %s\n", fn, dlerror());
+	} else if ( (m1 = find_symbol(cur, "mod_data", 0)) == NULL || m1->type == MOD_0) {
+		/* old-style module, close and reload with standard flags */
 		dlclose(cur->lib);
-#endif
+		cur->lib = NULL;
+	}
+	if (cur->lib == NULL)	/* try reopen with the old style */
+		cur->lib = dlopen(fn, flags);
 
-	cur->lib = dlopen(fn, flags);
 	if (!cur->lib) {
 		ast_log(LOG_WARNING, "%s\n", dlerror());
 		free(cur);
@@ -740,10 +737,10 @@ static struct module * __load_resource(const char *resource_name,
 	}
 	m1 = find_symbol(cur, "mod_data", 0);
 	if (m1 != NULL) {	/* new style module */
+		ast_log(LOG_WARNING, "new style %s (%d) loaded RTLD_LOCAL\n",
+			resource_name, m1->type);
 		errors = check_exported(cur);
 		*m = *m1;
-		if (m->type == MOD_2)
-			ast_log(LOG_WARNING, "new style %s, should unload and reload with RTLD_LOCAL\n", resource_name);
 	} else {
 		m->type = MOD_0;
 		m->load_module = find_symbol(cur, "load_module", 1);