transaction: Add support for using raw binary pointers conversation handler

This requires the allocating function to provide a binary pointer that
will be free'd by the conversation handlers finalizers.

This is for a more advanced usage scenario where the binary conversion
may be handled manually.

utils.go

@@ -2,6 +2,8 @@
 package pam
 
 /*
+#include <stdlib.h>
+
 #ifdef __SANITIZE_ADDRESS__
 #include <sanitizer/lsan_interface.h>
 #endif
@@ -20,6 +22,7 @@ import (
 	"os"
 	"runtime"
 	"time"
+	"unsafe"
 )
 
 func maybeDoLeakCheck() {
@@ -29,3 +32,11 @@ func maybeDoLeakCheck() {
 		C.maybe_do_leak_check()
 	}
 }
+
+func allocateCBytes(bytes []byte) BinaryPointer {
+	return BinaryPointer(C.CBytes(bytes))
+}
+
+func binaryPointerCBytesFinalizer(ptr BinaryPointer) {
+	C.free(unsafe.Pointer(ptr))
+}