ffi: fix semantics of ptr-out-d.

Since the callee allocates the buffer for a ptr-out-d, the FFI
mechanism should not also be allocating a buffer to receive
the object. The buffer pointer will just be overwritten by the
callee with its own dynamic pointer. We should pass a null
pointer which the callee fills in (making a ptr-out-d not
suitable as a by-value parameter).

Initially, ptr-out-d was envisioned for return values only
and for use in callbacks, which is why I neglected this
aspect.

* ffi.c (ffi_ptr_out_null_put): New static function.
(ffi_type_compile): Use ffi_ptr_out_null_put for the
ffi_ptr_out_d case, so caller places a null pointer, then
frees the pointer that the callee places there.

0 files changed, 0 insertions, 0 deletions