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, 6 insertions, 2 deletions

diff --git a/src/libcharon/plugins/ipseckey/ipseckey_cred.c b/src/libcharon/plugins/ipseckey/ipseckey_cred.c
index ff50d8a17..b3ac2b328 100644
--- a/src/libcharon/plugins/ipseckey/ipseckey_cred.c
+++ b/src/libcharon/plugins/ipseckey/ipseckey_cred.c
@@ -62,13 +62,16 @@ typedef struct {
 } cert_enumerator_t;
 
 METHOD(enumerator_t, cert_enumerator_enumerate, bool,
-	cert_enumerator_t *this, certificate_t **cert)
+	cert_enumerator_t *this, va_list args)
 {
+	certificate_t **cert;
 	ipseckey_t *cur_ipseckey;
 	public_key_t *public;
 	rr_t *cur_rr;
 	chunk_t key;
 
+	VA_ARGS_VGET(args, cert);
+
 	/* Get the next supported IPSECKEY using the inner enumerator. */
 	while (this->inner->enumerate(this->inner, &cur_rr))
 	{
@@ -211,7 +214,8 @@ METHOD(credential_set_t, create_cert_enumerator, enumerator_t*,
 
 	INIT(e,
 		.public = {
-			.enumerate = (void*)_cert_enumerator_enumerate,
+			.enumerate = enumerator_enumerate_default,
+			.venumerate = _cert_enumerator_enumerate,
 			.destroy = _cert_enumerator_destroy,
 		},
 		.inner = rrset->create_rr_enumerator(rrset),