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, 2 deletions

diff --git a/src/manager/xml.c b/src/manager/xml.c
index bf5bbbf05..0aee5f69b 100644
--- a/src/manager/xml.c
+++ b/src/manager/xml.c
@@ -67,8 +67,13 @@ typedef struct {
 } child_enum_t;
 
 METHOD(enumerator_t, child_enumerate, bool,
-	child_enum_t *e, private_xml_t **child, char **name, char **value)
+	child_enum_t *e, va_list args)
 {
+	private_xml_t **child;
+	char **name, **value;
+
+	VA_ARGS_VGET(args, child, name, value);
+
 	while (e->node && e->node->type != XML_ELEMENT_NODE)
 	{
 		e->node = e->node->next;
@@ -120,7 +125,8 @@ METHOD(xml_t, children, enumerator_t*,
 	child_enum_t *ce;
 	INIT(ce,
 		.e = {
-			.enumerate = (void*)_child_enumerate,
+			.enumerate = enumerator_enumerate_default,
+			.venumerate = _child_enumerate,
 			.destroy = _child_destroy,
 		},
 		.child = {