Only ever used as struct FF_Handle *, not seeing why this void is here.
error: 'FastFileOpen' violates the C++ One Definition Rule [-Werror=odr]
--- a/src/fastfile.cpp
+++ b/src/fastfile.cpp
@@ -217,3 +217,3 @@
 
-void *
+struct FF_Handle *
 FastFileOpen(char *name)
@@ -254,3 +254,3 @@
 		    i->len = next_off - i->off;
-		  return (void*)i;
+		  return i;
 		}