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, 13 insertions, 4 deletions

diff --git a/src/libstrongswan/crypto/hashers/hash_algorithm_set.c b/src/libstrongswan/crypto/hashers/hash_algorithm_set.c
index 93b67cb13..4087fe1d9 100644
--- a/src/libstrongswan/crypto/hashers/hash_algorithm_set.c
+++ b/src/libstrongswan/crypto/hashers/hash_algorithm_set.c
@@ -71,17 +71,26 @@ METHOD(hash_algorithm_set_t, count, int,
 	return array_count(this->algorithms);
 }
 
-static bool hash_filter(void *data, void **in, hash_algorithm_t *out)
+CALLBACK(hash_filter, bool,
+	void *data, enumerator_t *orig, va_list args)
 {
-	*out = **(hash_algorithm_t**)in;
-	return TRUE;
+	hash_algorithm_t *algo, *out;
+
+	VA_ARGS_VGET(args, out);
+
+	if (orig->enumerate(orig, &algo))
+	{
+		*out = *algo;
+		return TRUE;
+	}
+	return FALSE;
 }
 
 METHOD(hash_algorithm_set_t, create_enumerator, enumerator_t*,
 	private_hash_algorithm_set_t *this)
 {
 	return enumerator_create_filter(array_create_enumerator(this->algorithms),
-									(void*)hash_filter, NULL, NULL);
+									hash_filter, NULL, NULL);
 }
 
 METHOD(hash_algorithm_set_t, destroy, void,