Eryk Sun added the comment: ctypes defines arrays as a pointer FFI type because they degenerate as pointers in C calls. But it's generally wrong to set a pointer FFI type for an array in the `elements` of a struct's FFI type. An integer array in a struct that's 16 bytes or less should be packed in one or two general-purpose registers (rdi, rsi, rdx, rcx, r8, r9).
For the example 16-byte struct, classify_argument() in ffi64.c expects to classify two 8-byte words. But the struct's FFI type only has one element, which we've incorrectly defined as a pointer element. Thus the second word is left at the default classification X86_64_NO_CLASS. Back in ffi_call() it expects two classified words, so it aborts when it sees X86_64_NO_CLASS. I think we can special-case small arrays in PyCStructUnionType_update_stgdict when assigning the `elements` of the FFI type of a struct or union. If we have an array that's 32 bytes or less, unpack it as individual FFI elements, e.g. a c_ushort * 8 array would be stored as 8 ffi_type_uint16 elements in the struct's FFI type. ---------- nosy: +eryksun _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22273> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
