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, 3 insertions, 6 deletions

diff --git a/src/libcharon/kernel/kernel_interface.c b/src/libcharon/kernel/kernel_interface.c
index ea5af9eb8..3d736b25b 100644
--- a/src/libcharon/kernel/kernel_interface.c
+++ b/src/libcharon/kernel/kernel_interface.c
@@ -632,21 +632,18 @@ METHOD(kernel_interface_t, enable_udp_decap, bool,
 METHOD(kernel_interface_t, is_interface_usable, bool,
 	private_kernel_interface_t *this, const char *iface)
 {
-	status_t expected;
-
 	if (!this->ifaces_filter)
 	{
 		return TRUE;
 	}
-	expected = this->ifaces_exclude ? NOT_FOUND : SUCCESS;
-	return this->ifaces_filter->find_first(this->ifaces_filter, (void*)streq,
-										   NULL, iface) == expected;
+	return this->ifaces_filter->find_first(this->ifaces_filter,
+					linked_list_match_str, NULL, iface) != this->ifaces_exclude;
 }
 
 METHOD(kernel_interface_t, all_interfaces_usable, bool,
 	private_kernel_interface_t *this)
 {
-	return this->ifaces_filter == NULL;
+	return !this->ifaces_filter;
 }
 
 METHOD(kernel_interface_t, get_address_by_ts, status_t,