From: "Kaz Kylheku (libffi)" <382-725-6798@kylheku.com>
To: Cheng Jin <jincheng@ca.ibm.com>
Cc: libffi-discuss@sourceware.org
Subject: Re: Incorrect data detected in the nested float struct with x86/libffi on Linux/64bit
Date: Wed, 09 Jun 2021 16:48:37 -0700 [thread overview]
Message-ID: <dc1d82f0f6d2ca17d31448e20a5fb9fb@mail.kylheku.com> (raw)
In-Reply-To: <OF5D0877D1.6ACE238D-ON002586EF.0055990B-852586EF.005BA901@ibm.com>
On 2021-06-09 09:41, Cheng Jin via Libffi-discuss wrote:
> Hi,
Hi Cheng Jin,
A small matter on a tangent.
>
> cls_struct_fields1[0] = &ffi_type_float;
> cls_struct_fields1[1] = &cls_struct_type2;
> cls_struct_fields1[2] = NULL;
Indeed, the array describing the element types of a structure must be
null terminated, so this is required.
> cls_struct_type1.size = 0;
> cls_struct_type1.alignment = 0;
> cls_struct_type1.type = FFI_TYPE_STRUCT;
> cls_struct_type1.elements = cls_struct_fields1;
Note that here, the size of the object is not indicated. That's why
the extra null pointer is required to infer the size.
>
> dbl_arg_types[0] = &ffi_type_float;
> dbl_arg_types[1] = &cls_struct_type1;
> dbl_arg_types[2] = NULL;
But, for the argument array of a ffi_cif, no null termination is
required.
> ffi_prep_cif(&cif_temp, FFI_DEFAULT_ABI, 2, retType, dbl_arg_types);
No requirement for a null terminator is documented or appears in
examples. The 2 argument indicates the number of elements.
There is no harm in it; just pointing it out.
When I looked at your code, I went scrambling through documentation
to see if I was missing a required null terminator. :)
Cheers ...
next prev parent reply other threads:[~2021-06-09 23:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 16:41 Cheng Jin
2021-06-09 16:50 ` Anthony Green
2021-06-09 17:53 ` Cheng Jin
2021-06-15 18:02 ` Jakub Jelinek
2021-06-15 19:02 ` Jakub Jelinek
2021-06-15 19:29 ` Anthony Green
2021-06-09 23:48 ` Kaz Kylheku (libffi) [this message]
2021-06-10 0:21 ` Cheng Jin
2021-06-10 2:05 ` Kaz Kylheku (libffi)
2021-06-10 2:39 ` Cheng Jin
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