app_stack.c

	saved_in_subroutine = ast_test_flag(ast_channel_flags(chan), AST_FLAG_SUBROUTINE_EXEC);

	ast_debug(4, "%s Original location: %s,%s,%d\n", ast_channel_name(chan),
		saved_context, saved_exten, saved_priority);

	ast_channel_unlock(chan);
	res = gosub_exec(chan, sub_args);
	ast_debug(4, "%s exited with status %d\n", app_gosub, res);
	ast_channel_lock(chan);
	if (!res) {
		struct ast_datastore *stack_store;

		/* Mark the return location as special. */
		stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
		if (!stack_store) {
			/* Should never happen! */
			ast_log(LOG_ERROR, "No %s stack!\n", app_gosub);
			res = -1;
		} else {
			struct gosub_stack_list *oldlist;
			struct gosub_stack_frame *cur;

			oldlist = stack_store->data;
			cur = AST_LIST_FIRST(oldlist);
			cur->is_special = 1;
		}
	}
	if (!res) {
		int found = 0;	/* set if we find at least one match */

		/*
		 * Run gosub body autoloop.
		 *
		 * Note that this loop is inverted from the normal execution
		 * loop because we just executed the Gosub application as the
		 * first extension of the autoloop.
		 */
		do {
			/* Check for hangup. */
			if (ast_check_hangup(chan)) {
				if (ast_channel_softhangup_internal_flag(chan) & AST_SOFTHANGUP_ASYNCGOTO) {
					ast_log(LOG_ERROR, "%s An async goto just messed up our execution location.\n",
						ast_channel_name(chan));
					break;
				}
				if (!ignore_hangup) {
					break;
				}
			}

			/* Next dialplan priority. */
			ast_channel_priority_set(chan, ast_channel_priority(chan) + 1);

			ast_channel_unlock(chan);
			res = ast_spawn_extension(chan, ast_channel_context(chan),
				ast_channel_exten(chan), ast_channel_priority(chan),
				S_COR(ast_channel_caller(chan)->id.number.valid,
					ast_channel_caller(chan)->id.number.str, NULL),
				&found, 1);
			ast_channel_lock(chan);
		} while (!res);
		if (found && res) {
			/* Something bad happened, or a hangup has been requested. */
			ast_debug(1, "Spawn extension (%s,%s,%d) exited with %d on '%s'\n",
				ast_channel_context(chan), ast_channel_exten(chan),
				ast_channel_priority(chan), res, ast_channel_name(chan));
			ast_verb(2, "Spawn extension (%s, %s, %d) exited non-zero on '%s'\n",
				ast_channel_context(chan), ast_channel_exten(chan),
				ast_channel_priority(chan), ast_channel_name(chan));
		}

		/* Did the routine return? */
		if (ast_channel_priority(chan) == saved_priority
			&& !strcmp(ast_channel_context(chan), saved_context)
			&& !strcmp(ast_channel_exten(chan), saved_exten)) {
			ast_verb(3, "%s Internal %s(%s) complete GOSUB_RETVAL=%s\n",
				ast_channel_name(chan), app_gosub, sub_args,
				S_OR(pbx_builtin_getvar_helper(chan, "GOSUB_RETVAL"), ""));
		} else {
			ast_log(LOG_NOTICE, "%s Abnormal '%s(%s)' exit.  Popping routine return locations.\n",
				ast_channel_name(chan), app_gosub, sub_args);
			balance_stack(chan);
			pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", "");
		}

		/* We executed the requested subroutine to the best of our ability. */
		res = 0;
	}

	ast_debug(4, "%s Ending location: %s,%s,%d\n", ast_channel_name(chan),
		ast_channel_context(chan), ast_channel_exten(chan),
		ast_channel_priority(chan));

	/* Restore dialplan location */
	if (!(ast_channel_softhangup_internal_flag(chan) & AST_SOFTHANGUP_ASYNCGOTO)) {
		ast_channel_context_set(chan, saved_context);
		ast_channel_exten_set(chan, saved_exten);
		ast_channel_priority_set(chan, saved_priority);
	}

	/* Restore autoloop flag */
	ast_set2_flag(ast_channel_flags(chan), saved_autoloopflag, AST_FLAG_IN_AUTOLOOP);

	/* Restore subroutine flag */
	ast_set2_flag(ast_channel_flags(chan), saved_in_subroutine, AST_FLAG_SUBROUTINE_EXEC);

	/* Restore non-hangup softhangup flags. */
	if (saved_hangup_flags) {
		ast_softhangup_nolock(chan, saved_hangup_flags);
	}

	ast_channel_unlock(chan);

	return res;
}

static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, const char * const *argv)
{
	int res;
	int priority;
	int old_autoloopflag;
	int old_in_subroutine;
	int old_priority;
	const char *old_context;
	const char *old_extension;
	char *gosub_args;

	if (argc < 4 || argc > 5) {
		return RESULT_SHOWUSAGE;
	}

	ast_debug(1, "Gosub called with %d arguments: 0:%s 1:%s 2:%s 3:%s 4:%s\n", argc, argv[0], argv[1], argv[2], argv[3], argc == 5 ? argv[4] : "");

	if (sscanf(argv[3], "%30d", &priority) != 1 || priority < 1) {
		/* Lookup the priority label */
		priority = ast_findlabel_extension(chan, argv[1], argv[2], argv[3],
			S_COR(ast_channel_caller(chan)->id.number.valid, ast_channel_caller(chan)->id.number.str, NULL));
		if (priority < 0) {
			ast_log(LOG_ERROR, "Priority '%s' not found in '%s@%s'\n", argv[3], argv[2], argv[1]);
			ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
			return RESULT_FAILURE;
		}
	} else if (!ast_exists_extension(chan, argv[1], argv[2], priority,
		S_COR(ast_channel_caller(chan)->id.number.valid, ast_channel_caller(chan)->id.number.str, NULL))) {
		ast_agi_send(agi->fd, chan, "200 result=-1 Gosub label not found\n");
		return RESULT_FAILURE;
	}

	if (argc == 5) {
		if (ast_asprintf(&gosub_args, "%s,%s,%d(%s)", argv[1], argv[2], priority, argv[4]) < 0) {
			gosub_args = NULL;
		}
	} else {
		if (ast_asprintf(&gosub_args, "%s,%s,%d", argv[1], argv[2], priority) < 0) {
			gosub_args = NULL;
		}
	}
	if (!gosub_args) {
		ast_agi_send(agi->fd, chan, "503 result=-2 Memory allocation failure\n");
		return RESULT_FAILURE;
	}

	ast_channel_lock(chan);

	ast_verb(3, "%s AGI %s(%s) start\n", ast_channel_name(chan), app_gosub, gosub_args);

	/* Save autoloop flag */
	old_autoloopflag = ast_test_flag(ast_channel_flags(chan), AST_FLAG_IN_AUTOLOOP);
	ast_set_flag(ast_channel_flags(chan), AST_FLAG_IN_AUTOLOOP);

	/* Save subroutine flag */
	old_in_subroutine = ast_test_flag(ast_channel_flags(chan), AST_FLAG_SUBROUTINE_EXEC);

	/* Save previous location, since we're going to change it */
	old_context = ast_strdupa(ast_channel_context(chan));
	old_extension = ast_strdupa(ast_channel_exten(chan));
	old_priority = ast_channel_priority(chan);

	ast_debug(4, "%s Original location: %s,%s,%d\n", ast_channel_name(chan),
		old_context, old_extension, old_priority);
	ast_channel_unlock(chan);

	res = gosub_exec(chan, gosub_args);
	if (!res) {
		struct ast_datastore *stack_store;

		/* Mark the return location as special. */
		ast_channel_lock(chan);
		stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
		if (!stack_store) {
			/* Should never happen! */
			ast_log(LOG_ERROR, "No %s stack!\n", app_gosub);
			res = -1;
		} else {
			struct gosub_stack_list *oldlist;
			struct gosub_stack_frame *cur;

			oldlist = stack_store->data;
			cur = AST_LIST_FIRST(oldlist);
			cur->is_special = 1;
		}
		ast_channel_unlock(chan);
	}
	if (!res) {
		struct ast_pbx *pbx;
		struct ast_pbx_args args;
		int abnormal_exit;

		memset(&args, 0, sizeof(args));
		args.no_hangup_chan = 1;

		ast_channel_lock(chan);

		/* Next dialplan priority. */
		ast_channel_priority_set(chan, ast_channel_priority(chan) + 1);

		/* Suppress warning about PBX already existing */
		pbx = ast_channel_pbx(chan);
		ast_channel_pbx_set(chan, NULL);
		ast_channel_unlock(chan);

		ast_agi_send(agi->fd, chan, "100 result=0 Trying...\n");
		ast_pbx_run_args(chan, &args);

		ast_channel_lock(chan);
		ast_free(ast_channel_pbx(chan));
		ast_channel_pbx_set(chan, pbx);

		/* Did the routine return? */
		if (ast_channel_priority(chan) == old_priority
			&& !strcmp(ast_channel_context(chan), old_context)
			&& !strcmp(ast_channel_exten(chan), old_extension)) {
			ast_verb(3, "%s AGI %s(%s) complete GOSUB_RETVAL=%s\n",
				ast_channel_name(chan), app_gosub, gosub_args,
				S_OR(pbx_builtin_getvar_helper(chan, "GOSUB_RETVAL"), ""));
			abnormal_exit = 0;
		} else {
			ast_log(LOG_NOTICE, "%s Abnormal AGI %s(%s) exit.  Popping routine return locations.\n",
				ast_channel_name(chan), app_gosub, gosub_args);
			balance_stack(chan);
			pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", "");
			abnormal_exit = 1;
		}
		ast_channel_unlock(chan);

		ast_agi_send(agi->fd, chan, "200 result=0 Gosub complete%s\n",
			abnormal_exit ? " (abnormal exit)" : "");
	} else {
		ast_agi_send(agi->fd, chan, "200 result=%d Gosub failed\n", res);
	}

	ast_free(gosub_args);

	ast_channel_lock(chan);
	ast_debug(4, "%s Ending location: %s,%s,%d\n", ast_channel_name(chan),
		ast_channel_context(chan), ast_channel_exten(chan),
		ast_channel_priority(chan));

	/* Restore previous location */
	ast_channel_context_set(chan, old_context);
	ast_channel_exten_set(chan, old_extension);
	ast_channel_priority_set(chan, old_priority);

	/* Restore autoloop flag */
	ast_set2_flag(ast_channel_flags(chan), old_autoloopflag, AST_FLAG_IN_AUTOLOOP);

	/* Restore subroutine flag */
	ast_set2_flag(ast_channel_flags(chan), old_in_subroutine, AST_FLAG_SUBROUTINE_EXEC);
	ast_channel_unlock(chan);

	return RESULT_SUCCESS;
}

static struct agi_command gosub_agi_command =
	{ { "gosub", NULL }, handle_gosub, NULL, NULL, 0 };

static int unload_module(void)
{
	ast_install_stack_functions(NULL);

	ast_agi_unregister(&gosub_agi_command);

	ast_unregister_application(app_return);
	ast_unregister_application(app_pop);
	ast_unregister_application(app_gosubif);
	ast_unregister_application(app_gosub);
	ast_custom_function_unregister(&local_function);
	ast_custom_function_unregister(&peek_function);
	ast_custom_function_unregister(&stackpeek_function);

	return 0;
}

static int load_module(void)
{
	/* Setup the stack application callback functions. */
	static struct ast_app_stack_funcs funcs = {
		.run_sub = gosub_run,
		.expand_sub_args = expand_gosub_args,
	};

	ast_agi_register(ast_module_info->self, &gosub_agi_command);

	ast_register_application_xml(app_pop, pop_exec);
	ast_register_application_xml(app_return, return_exec);
	ast_register_application_xml(app_gosubif, gosubif_exec);
	ast_register_application_xml(app_gosub, gosub_exec);
	ast_custom_function_register(&local_function);
	ast_custom_function_register(&peek_function);
	ast_custom_function_register(&stackpeek_function);

	funcs.module = ast_module_info->self,
	ast_install_stack_functions(&funcs);

	return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT | AST_MODFLAG_LOAD_ORDER, "Dialplan subroutines (Gosub, Return, etc)",
	.support_level = AST_MODULE_SUPPORT_CORE,
	.load = load_module,
	.unload = unload_module,
	.load_pri = AST_MODPRI_APP_DEPEND,
	.optional_modules = "res_agi",
);