Enable macros in 1.8 to find the next highest "h" extension in a context, like in 1.4.

This change restores functionality that was present in 1.4, when AEL macros
were implemented with the Macro dialplan application.  Macros are fraught with
functionality issues, because they consume a large portion of the underlying
application stack.  This limits the ability of AEL users to call many layers
of subroutines, an issue which Gosub does not have (originally tested to
100,000 levels deep).  Therefore, starting in 1.6.0, AEL macros were
implemented with Gosub.

However, there were some implicit behaviors of Macro, which were not replicated
at the same time as with the transition to Gosub, one of which is documented in
the related issue.  In particular, the "h" extension is designed to execute not
in the Macro context, but in the topmost calling context.  Due to legacy issues
with a misapplied bugfix many years ago, when a macro exited in 1.4, it looks
in all calling contexts, bubbling up from the deepest level until it finds an
"h" extension.

Since AEL hides the complexity of the underlying dialplan logic from the AEL
programmer, it's reasonable to assume that this behavior should not change in
the transition from Asterisk 1.4 LTS to Asterisk 1.8 LTS, lest we break
working AEL configurations in the transition to Asterisk 1.8 LTS.  This fix
is the result, which implements a search for the "h" extension in all calling
Gosub contexts.

Fixes ASTERISK-19336

Patch: 20120308__ael_bugfix_for_trunk__2.diff (License #5003) by Tilghman Lesher
	(with slight modifications for 1.8)

Tested by: Johan Wilfer

Review: https://reviewboard.asterisk.org/r/1776/
........

Merged revisions 358810 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 358811 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@358812 65c4cc65-6c06-0410-ace0-fbb531ad65f3

6 files changed, 295 insertions, 15 deletions

diff --git a/apps/app_stack.c b/apps/app_stack.c
index 827bb508a..28bd3cfb4 100644
--- a/apps/app_stack.c
+++ b/apps/app_stack.c
@@ -165,6 +165,24 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 			<ref type="application">Return</ref>
 		</see-also>
 	</function>
+	<function name="STACK_PEEK" language="en_US">
+		<synopsis>
+			View info about the location which called Gosub
+		</synopsis>
+		<syntax>
+			<parameter name="n" required="true" />
+			<parameter name="which" required="true" />
+			<parameter name="suppress" required="false" />
+		</syntax>
+		<description>
+			<para>Read the calling <literal>c</literal>ontext, <literal>e</literal>xtension,
+			<literal>p</literal>riority, or <literal>l</literal>abel, as specified by
+			<replaceable>which</replaceable>, by going up <replaceable>n</replaceable> frames
+			in the Gosub stack.  If <replaceable>suppress</replaceable> is true, then if the
+			number of available stack frames is exceeded, then no error message will be
+			printed.</para>
+		</description>
+	</function>
 	<agi name="gosub" language="en_US">
 		<synopsis>
 			Cause the channel to execute the specified dialplan subroutine.
@@ -285,12 +303,14 @@ static void gosub_free(void *data)
 
 static int pop_exec(struct ast_channel *chan, const char *data)
 {
-	struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
+	struct ast_datastore *stack_store;
 	struct gosub_stack_frame *oldframe;
 	AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 
-	if (!stack_store) {
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
 		ast_log(LOG_WARNING, "%s called with no gosub stack allocated.\n", app_pop);
+		ast_channel_unlock(chan);
 		return 0;
 	}
 
@@ -304,19 +324,22 @@ static int pop_exec(struct ast_channel *chan, const char *data)
 	} else {
 		ast_debug(1, "%s called with an empty gosub stack\n", app_pop);
 	}
+	ast_channel_unlock(chan);
 	return 0;
 }
 
 static int return_exec(struct ast_channel *chan, const char *data)
 {
-	struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
+	struct ast_datastore *stack_store;
 	struct gosub_stack_frame *oldframe;
 	AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 	const char *retval = data;
 	int res = 0;
 
-	if (!stack_store) {
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
 		ast_log(LOG_ERROR, "Return without Gosub: stack is unallocated\n");
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
@@ -327,6 +350,7 @@ static int return_exec(struct ast_channel *chan, const char *data)
 
 	if (!oldframe) {
 		ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
+		ast_channel_unlock(chan);
 		return -1;
 	} else if (oldframe->is_agi) {
 		/* Exit from AGI */
@@ -338,12 +362,13 @@ static int return_exec(struct ast_channel *chan, const char *data)
 
 	/* Set a return value, if any */
 	pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
+	ast_channel_unlock(chan);
 	return res;
 }
 
 static int gosub_exec(struct ast_channel *chan, const char *data)
 {
-	struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
+	struct ast_datastore *stack_store;
 	AST_LIST_HEAD(,gosub_stack_frame) *oldlist;
 	struct gosub_stack_frame *newframe, *lastframe;
 	char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
@@ -357,11 +382,13 @@ static int gosub_exec(struct ast_channel *chan, const char *data)
 		return -1;
 	}
 
-	if (!stack_store) {
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
 		ast_debug(1, "Channel %s has no datastore, so we're allocating one.\n", ast_channel_name(chan));
 		stack_store = ast_datastore_alloc(&stack_info, NULL);
 		if (!stack_store) {
 			ast_log(LOG_ERROR, "Unable to allocate new datastore.  Gosub will fail.\n");
+			ast_channel_unlock(chan);
 			return -1;
 		}
 
@@ -369,6 +396,7 @@ static int gosub_exec(struct ast_channel *chan, const char *data)
 		if (!oldlist) {
 			ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Gosub will fail.\n");
 			ast_datastore_free(stack_store);
+			ast_channel_unlock(chan);
 			return -1;
 		}
 
@@ -405,12 +433,14 @@ static int gosub_exec(struct ast_channel *chan, const char *data)
 	newframe = gosub_allocate_frame(ast_channel_context(chan), ast_channel_exten(chan), ast_channel_priority(chan) + 1, max_argc);
 
 	if (!newframe) {
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
 	if (ast_parseable_goto(chan, label)) {
 		ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
 		ast_free(newframe);
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
@@ -423,6 +453,7 @@ static int gosub_exec(struct ast_channel *chan, const char *data)
 		ast_channel_exten_set(chan, newframe->extension);
 		ast_channel_priority_set(chan, newframe->priority - 1);
 		ast_free(newframe);
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
@@ -440,6 +471,7 @@ static int gosub_exec(struct ast_channel *chan, const char *data)
 	AST_LIST_LOCK(oldlist);
 	AST_LIST_INSERT_HEAD(oldlist, newframe, entries);
 	AST_LIST_UNLOCK(oldlist);
+	ast_channel_unlock(chan);
 
 	return 0;
 }
@@ -483,44 +515,49 @@ static int gosubif_exec(struct ast_channel *chan, const char *data)
 
 static int local_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
 {
-	struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
+	struct ast_datastore *stack_store;
 	AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 	struct gosub_stack_frame *frame;
 	struct ast_var_t *variables;
 
-	if (!stack_store)
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
+		ast_channel_unlock(chan);
 		return -1;
+	}
 
 	oldlist = stack_store->data;
 	AST_LIST_LOCK(oldlist);
 	if (!(frame = AST_LIST_FIRST(oldlist))) {
 		/* Not within a Gosub routine */
 		AST_LIST_UNLOCK(oldlist);
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
 	AST_LIST_TRAVERSE(&frame->varshead, variables, entries) {
 		if (!strcmp(data, ast_var_name(variables))) {
 			const char *tmp;
-			ast_channel_lock(chan);
 			tmp = pbx_builtin_getvar_helper(chan, data);
 			ast_copy_string(buf, S_OR(tmp, ""), len);
-			ast_channel_unlock(chan);
 			break;
 		}
 	}
 	AST_LIST_UNLOCK(oldlist);
+	ast_channel_unlock(chan);
 	return 0;
 }
 
 static int local_write(struct ast_channel *chan, const char *cmd, char *var, const char *value)
 {
-	struct ast_datastore *stack_store = ast_channel_datastore_find(chan, &stack_info, NULL);
+	struct ast_datastore *stack_store;
 	AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
 	struct gosub_stack_frame *frame;
 
-	if (!stack_store) {
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
 		ast_log(LOG_ERROR, "Tried to set LOCAL(%s), but we aren't within a Gosub routine\n", var);
+		ast_channel_unlock(chan);
 		return -1;
 	}
 
@@ -528,10 +565,12 @@ static int local_write(struct ast_channel *chan, const char *cmd, char *var, con
 	AST_LIST_LOCK(oldlist);
 	frame = AST_LIST_FIRST(oldlist);
 
-	if (frame)
+	if (frame) {
 		frame_set_var(chan, frame, var, value);
+	}
 
 	AST_LIST_UNLOCK(oldlist);
+	ast_channel_unlock(chan);
 
 	return 0;
 }
@@ -576,6 +615,89 @@ static struct ast_custom_function peek_function = {
 	.read = peek_read,
 };
 
+static int stackpeek_read(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **str, ssize_t len)
+{
+	struct ast_datastore *stack_store;
+	AST_LIST_HEAD(, gosub_stack_frame) *oldlist;
+	struct gosub_stack_frame *frame;
+	int n;
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(n);
+		AST_APP_ARG(which);
+		AST_APP_ARG(suppress);
+	);
+
+	if (!chan) {
+		ast_log(LOG_ERROR, "STACK_PEEK must be called on an active channel\n");
+		return -1;
+	}
+
+	data = ast_strdupa(data);
+	AST_STANDARD_APP_ARGS(args, data);
+
+	n = atoi(args.n);
+	if (n <= 0) {
+		ast_log(LOG_ERROR, "STACK_PEEK must be called with a positive peek value\n");
+		return -1;
+	}
+
+	ast_channel_lock(chan);
+	if (!(stack_store = ast_channel_datastore_find(chan, &stack_info, NULL))) {
+		if (!ast_true(args.suppress)) {
+			ast_log(LOG_ERROR, "STACK_PEEK called on a channel without a gosub stack\n");
+		}
+		ast_channel_unlock(chan);
+		return -1;
+	}
+
+	oldlist = stack_store->data;
+
+	AST_LIST_LOCK(oldlist);
+	AST_LIST_TRAVERSE(oldlist, frame, entries) {
+		if (--n == 0) {
+			break;
+		}
+	}
+
+	if (!frame) {
+		/* Too deep */
+		if (!ast_true(args.suppress)) {
+			ast_log(LOG_ERROR, "Stack peek of '%s' is more stack frames than I have\n", args.n);
+		}
+		ast_channel_unlock(chan);
+		return -1;
+	}
+
+	args.which = ast_skip_blanks(args.which);
+
+	switch (args.which[0]) {
+	case 'l': /* label */
+		ast_str_set(str, len, "%s,%s,%d", frame->context, frame->extension, frame->priority - 1);
+		break;
+	case 'c': /* context */
+		ast_str_set(str, len, "%s", frame->context);
+		break;
+	case 'e': /* extension */
+		ast_str_set(str, len, "%s", frame->extension);
+		break;
+	case 'p': /* priority */
+		ast_str_set(str, len, "%d", frame->priority - 1);
+		break;
+	default:
+		ast_log(LOG_ERROR, "Unknown argument '%s' to STACK_PEEK\n", args.which);
+	}
+
+	AST_LIST_UNLOCK(oldlist);
+	ast_channel_unlock(chan);
+
+	return 0;
+}
+
+static struct ast_custom_function stackpeek_function = {
+	.name = "STACK_PEEK",
+	.read2 = stackpeek_read,
+};
+
 static int handle_gosub(struct ast_channel *chan, AGI *agi, int argc, const char * const *argv)
 {
 	int old_priority, priority;
@@ -687,6 +809,7 @@ static int unload_module(void)
 	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;
 }
@@ -701,12 +824,14 @@ static int load_module(void)
 	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);
 
 	return 0;
 }
 
-AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Dialplan subroutines (Gosub, Return, etc)",
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT | AST_MODFLAG_LOAD_ORDER, "Dialplan subroutines (Gosub, Return, etc)",
 		.load = load_module,
 		.unload = unload_module,
+		.load_pri = AST_MODPRI_APP_DEPEND,
 		.nonoptreq = "res_agi",
 		);
diff --git a/funcs/func_dialplan.c b/funcs/func_dialplan.c
index 0c2e8c707..d06ddba9a 100644
--- a/funcs/func_dialplan.c
+++ b/funcs/func_dialplan.c
@@ -185,4 +185,8 @@ static int load_module(void)
 	return res;
 }
 
-AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan Context/Extension/Priority Checking Functions");
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Dialplan Context/Extension/Priority Checking Functions",
+	.load = load_module,
+	.unload = unload_module,
+	.load_pri = AST_MODPRI_APP_DEPEND,
+	);
diff --git a/res/ael/pval.c b/res/ael/pval.c
index 6fe21b5ca..8dd1f7cf6 100644
--- a/res/ael/pval.c
+++ b/res/ael/pval.c
@@ -4423,6 +4423,20 @@ static void fix_gotos_in_extensions(struct ael_extension *exten)
 	}
 }
 
+static int context_used(struct ael_extension *exten_list, struct ast_context *context)
+{
+	struct ael_extension *exten;
+	/* Check the simple elements first */
+	if (ast_walk_context_extensions(context, NULL) || ast_walk_context_includes(context, NULL) || ast_walk_context_ignorepats(context, NULL) || ast_walk_context_switches(context, NULL)) {
+		return 1;
+	}
+	for (exten = exten_list; exten; exten = exten->next_exten) {
+		if (exten->context == context) {
+			return 1;
+		}
+	}
+	return 0;
+}
 
 int ast_compile_ael2(struct ast_context **local_contexts, struct ast_hashtab *local_table, struct pval *root)
 {
@@ -4604,6 +4618,71 @@ int ast_compile_ael2(struct ast_context **local_contexts, struct ast_hashtab *lo
 			
 		}
 	}
+
+	/* Create default "h" bubble context */
+	if (ast_custom_function_find("DIALPLAN_EXISTS") && ast_custom_function_find("STACK_PEEK")) {
+		int i;
+		const char *h_context = "ael-builtin-h-bubble";
+		struct ael_priority *np;
+		struct {
+			int priority;
+			const char *app;
+			const char *arg;
+		} steps[] = {
+			/* Start high, to avoid conflict with existing h extensions */
+			{ 1, "Goto", "9991" },
+			/* Save the context, because after the StackPop, it disappears */
+			{ 9991, "Set", "~~parentcxt~~=${STACK_PEEK(1,c,1)}" },
+			/* If we're not in a Gosub frame, exit */
+			{ 9992, "GotoIf", "$[\"${~~parentcxt~~}\"=\"\"]?9996" },
+			/* Check for an "h" extension in that context */
+			{ 9993, "GotoIf", "${DIALPLAN_EXISTS(${~~parentcxt~~},h,1)}?9994:9996" },
+			/* Pop off the stack frame to prevent an infinite loop */
+			{ 9994, "StackPop", "" },
+			/* Finally, go there. */
+			{ 9995, "Goto", "${~~parentcxt~~},h,1" },
+			/* Just an empty priority for jumping out early */
+			{ 9996, "NoOp", "" }
+		};
+		context = ast_context_find_or_create(local_contexts, local_table, h_context, registrar);
+		if (context_used(exten_list, context)) {
+			int found = 0;
+			while (!found) {
+				/* Pick a new context name that is not used. */
+				char h_context_template[] = "/tmp/ael-builtin-h-bubble-XXXXXX";
+				int fd = mkstemp(h_context_template);
+				unlink(h_context_template);
+				close(fd);
+				context = ast_context_find_or_create(local_contexts, local_table, h_context_template + 5, registrar);
+				found = !context_used(exten_list, context);
+			}
+			h_context = ast_get_context_name(context);
+		}
+		exten = new_exten();
+		exten->context = context;
+		exten->name = strdup("h");
+
+		for (i = 0; i < ARRAY_LEN(steps); i++) {
+			np = new_prio();
+			np->type = AEL_APPCALL;
+			np->priority_num = steps[i].priority;
+			np->app = strdup(steps[i].app);
+			np->appargs = strdup(steps[i].arg);
+			linkprio(exten, np, NULL);
+		}
+		attach_exten(&exten_list, exten);
+
+		/* Include the default "h" bubble context in each macro context */
+		for (exten = exten_list; exten; exten = exten->next_exten) {
+			/* All macros contain a "~~s~~" extension, and it's the first created.  If
+			 * we perchance get a non-macro context, it's no big deal; the logic is
+			 * designed to exit out smoothly if not called from within a Gosub. */
+			if (!strcmp(exten->name, "~~s~~")) {
+				ast_context_add_include2(exten->context, h_context, registrar);
+			}
+		}
+	}
+
 	/* moved these from being done after a macro or extension were processed,
 	   to after all processing is done, for the sake of fixing gotos to labels inside cases... */
 	/* I guess this would be considered 2nd pass of compiler now... */
diff --git a/tests/test_gosub.c b/tests/test_gosub.c
index e65ebbcbb..36573faf2 100644
--- a/tests/test_gosub.c
+++ b/tests/test_gosub.c
@@ -51,12 +51,24 @@ AST_TEST_DEFINE(test_gosub)
 		const char *args;
 		const char *expected_value;
 	} testplan[] = {
+		{ NULL, "${STACK_PEEK(1,e,1)}", "" },         /* Stack is empty */
 		{ "Gosub", "tests_test_gosub_virtual_context,s,1" },
+		{ NULL, "${PRIORITY}", "1" },
 		{ NULL, "${EXTEN}", "s" },
+		{ NULL, "${STACK_PEEK(1,e,1)}", "" },         /* No extension originally */
 		{ "Gosub", "test,dne,1", (const char *) -1 }, /* This is the only invocation that should fail. */
+		{ NULL, "${PRIORITY}", "1" },
 		{ NULL, "${EXTEN}", "s" },
 		{ "Gosub", "tests_test_gosub_virtual_context,s,1(5,5,5,5,5)" },
+		{ NULL, "${PRIORITY}", "1" },
 		{ NULL, "$[0${ARG1} + 0${ARG5}]", "10" },
+		{ NULL, "${STACK_PEEK(1,e)}", "s" },
+		{ NULL, "${STACK_PEEK(1,c)}", "tests_test_gosub_virtual_context" },
+		{ NULL, "${STACK_PEEK(1,p)}", "1" },
+		{ NULL, "${STACK_PEEK(1,l)}", "tests_test_gosub_virtual_context,s,1" },
+		{ "StackPop", "" },
+		{ NULL, "${STACK_PEEK(1,e,1)}", "" },         /* Only 1 frame deep, my caller is top-level */
+		{ "Gosub", "tests_test_gosub_virtual_context,s,1(5,5,5,5,5)" },
 		{ "Gosub", "tests_test_gosub_virtual_context,s,1(4,4,4,4)" },
 		{ NULL, "$[0${ARG1} + 0${ARG5}]", "4" },
 		{ NULL, "$[0${ARG1} + 0${ARG4}]", "8" },
diff --git a/utils/ael_main.c b/utils/ael_main.c
index d3a23382a..fff28b738 100644
--- a/utils/ael_main.c
+++ b/utils/ael_main.c
@@ -425,6 +425,36 @@ void ast_context_destroy(void)
 		printf("Executed ast_context_destroy();\n");
 }
 
+const char *ast_get_context_name(struct ast_context *con);
+const char *ast_get_context_name(struct ast_context *con)
+{
+	return con ? con->name : NULL;
+}
+
+struct ast_exten *ast_walk_context_extensions(struct ast_context *con, struct ast_exten *exten);
+struct ast_exten *ast_walk_context_extensions(struct ast_context *con, struct ast_exten *exten)
+{
+	return NULL;
+}
+
+struct ast_include *ast_walk_context_includes(struct ast_context *con, struct ast_include *inc);
+struct ast_include *ast_walk_context_includes(struct ast_context *con, struct ast_include *inc)
+{
+	return NULL;
+}
+
+struct ast_ignorepat *ast_walk_context_ignorepats(struct ast_context *con, struct ast_ignorepat *ip);
+struct ast_ignorepat *ast_walk_context_ignorepats(struct ast_context *con, struct ast_ignorepat *ip)
+{
+	return NULL;
+}
+
+struct ast_sw *ast_walk_context_switches(struct ast_context *con, struct ast_sw *sw);
+struct ast_sw *ast_walk_context_switches(struct ast_context *con, struct ast_sw *sw)
+{
+	return NULL;
+}
+
 void filter_leading_space_from_exprs(char *str)
 {
 	/*  Mainly for aesthetics */
diff --git a/utils/conf2ael.c b/utils/conf2ael.c
index 020dbe3af..f0ac38fad 100644
--- a/utils/conf2ael.c
+++ b/utils/conf2ael.c
@@ -668,6 +668,36 @@ void ast_merge_contexts_and_delete(struct ast_context **extcontexts, struct ast_
 	localized_merge_contexts_and_delete(extcontexts, exttable, registrar);
 }
 
+const char *ast_get_context_name(struct ast_context *con);
+const char *ast_get_context_name(struct ast_context *con)
+{
+	return con ? con->name : NULL;
+}
+
+struct ast_exten *ast_walk_context_extensions(struct ast_context *con, struct ast_exten *exten);
+struct ast_exten *ast_walk_context_extensions(struct ast_context *con, struct ast_exten *exten)
+{
+	return NULL;
+}
+
+struct ast_include *ast_walk_context_includes(struct ast_context *con, struct ast_include *inc);
+struct ast_include *ast_walk_context_includes(struct ast_context *con, struct ast_include *inc)
+{
+	return NULL;
+}
+
+struct ast_ignorepat *ast_walk_context_ignorepats(struct ast_context *con, struct ast_ignorepat *ip);
+struct ast_ignorepat *ast_walk_context_ignorepats(struct ast_context *con, struct ast_ignorepat *ip)
+{
+	return NULL;
+}
+
+struct ast_sw *ast_walk_context_switches(struct ast_context *con, struct ast_sw *sw);
+struct ast_sw *ast_walk_context_switches(struct ast_context *con, struct ast_sw *sw)
+{
+	return NULL;
+}
+
 struct ast_exten *pbx_find_extension(struct ast_channel *chan,
 									 struct ast_context *bypass,
 									 struct pbx_find_info *q,