Merge branch 'variadic-enumerators'

This adds several changes to enumerator_t and linked_list_t to improve
portability.  In particular to Apple's ARM64 iOS platform, whose calling
convention for variadic and regular functions are different.  This means
that assigning a non-variadic function to a variadic function pointer,
as we did with our enumerator_t::enumerate() implementations and several
callbacks, will result in crashes as the called function will access the
arguments differently than the caller provided them.

To avoid this issue the enumerator_t interface is now fully variadic.
A new mandatory method is added, venumerate(), that takes a va_list with
the arguments provided while enumerating.  enumerate() is replaced with
a generic implementation that prepares a va_list and calls the
enumerator's venumerate() implementation.  As this allows passing the
arguments of one enumerator to another it avoids the five pointer hack
used by enumerator_create_nested() and enumerator_create_cleaner().
To simplify the implementation of venumerate() a helper macro is provided
that assigns values from a given va_list to local variables.

The signature of the callback passed to enumerator_create_filter() has
also changed significantly.  It's now required to enumerate over the
original enumerator in the callback as this avoids the previous in/out
pointer hack. The arguments to the outer enumerator are provided in a
va_list.

Similar changes to avoid such five pointer hacks affect the signatures
of the callbacks for linked_list_t's invoke_function() and find_first()
methods.  For the latter the return type also changed from status_t to
bool, which is important as SUCCESS is defined as 0, so checks for ==
SUCCESS will now fail.

1 files changed, 8 insertions, 4 deletions

diff --git a/src/libcharon/plugins/resolve/resolve_handler.c b/src/libcharon/plugins/resolve/resolve_handler.c
index 9077b51d4..05b865464 100644
--- a/src/libcharon/plugins/resolve/resolve_handler.c
+++ b/src/libcharon/plugins/resolve/resolve_handler.c
@@ -391,10 +391,13 @@ typedef struct {
 	bool v6;
 } attribute_enumerator_t;
 
-static bool attribute_enumerate(attribute_enumerator_t *this,
-								configuration_attribute_type_t *type,
-								chunk_t *data)
+METHOD(enumerator_t, attribute_enumerate, bool,
+	attribute_enumerator_t *this, va_list args)
 {
+	configuration_attribute_type_t *type;
+	chunk_t *data;
+
+	VA_ARGS_VGET(args, type, data);
 	if (this->v4)
 	{
 		*type = INTERNAL_IP4_DNS;
@@ -443,7 +446,8 @@ METHOD(attribute_handler_t, create_attribute_enumerator, enumerator_t*,
 
 	INIT(enumerator,
 		.public = {
-			.enumerate = (void*)attribute_enumerate,
+			.enumerate = enumerator_enumerate_default,
+			.venumerate = _attribute_enumerate,
 			.destroy = (void*)free,
 		},
 		.v4 = has_host_family(vips, AF_INET),