pbx_lua: fix regression with global sym export and context clash by pbx_config.

ASTERISK-23818 (lua contexts being overwritten by contexts of the same name in
pbx_config) surfaced because pbx_lua, having the AST_MODFLAG_GLOBAL_SYMBOLS
set, was always force loaded before pbx_config.  Since I couldn't find any
reason for pbx_lua to export it's symbols to the rest of Asterisk, I simply
changed the flag to AST_MODFLAG_DEFAULT.  Problem solved.  What I didn't
realize was that the symbols need to be exported not because Asterisk needs
them but because any external Lua modules like luasql.mysql need the base
Lua language APIs exported (ASTERISK-17279).

Back to ASTERISK-23818...  It looks like there's an issue in pbx.c where
context_merge was only merging includes, switches and ignore patterns if
the context was already existing AND has extensions, or if the context was
brand new.  If pbx_lua is loaded before pbx_config, the context will exist
BUT pbx_lua, being implemented as a switch, will never place extensions in
it, just the switch statement.  The result is that when pbx_config loads,
it never merges the switch statement created by pbx_lua into the final
context.

This patch sets pbx_lua's modflag back to AST_MODFLAG_GLOBAL_SYMBOLS and adds
an "else if" in context_merge that catches the case where an existing context
has includes, switchs or ingore patterns but no actual extensions.

ASTERISK-23818 #close
Reported by: Dennis Guse
Reported by: Timo Teräs
Tested by: George Joseph
Review: https://reviewboard.asterisk.org/r/3891/


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@420146 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/pbx.c

@@ -7868,6 +7868,11 @@ static void context_merge(struct ast_context **extcontexts, struct ast_hashtab *
 			ast_hashtab_end_traversal(prio_iter);
 		}
 		ast_hashtab_end_traversal(exten_iter);
+	} else if (new) {
+		/* If the context existed but had no extensions, we still want to merge
+		 * the includes, switches and ignore patterns.
+		 */
+		context_merge_incls_swits_igps_other_registrars(new, context, registrar);
 	}
 
 	if (!insert_count && !new && (strcmp(context->registrar, registrar) != 0 ||

pbx/pbx_lua.c

@@ -1562,7 +1562,7 @@ static int load_module(void)
 	return AST_MODULE_LOAD_SUCCESS;
 }
 
-AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Lua PBX Switch",
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "Lua PBX Switch",
 		.load = load_module,
 		.unload = unload_module,
 		.reload = reload,