On Fri, Oct 4, 2019 at 9:20 PM Ian Pilcher <arequipeno@xxxxxxxxx> wrote:
>
> I am writing a Python extension that calls strerror_r. Unfortunately,
> the Python extension build system requires that Python.h be the first
> header file included; it also sets the _GNU_SOURCE feature test macro
> *and* includes string.h.
>
> If I define _GNU_SOURCE before including Python.h, I receive a warning
> about the macro being redefined. AFAICT, gcc does not provide a way to
> suppress this warning.
>
> My tests show that I am getting the GNU version of strerror_r, but I
> hate relying on the internal structure of the Python header files (even
> more that I hate warnings).
>
> So I'm trying to come up with a compile-time check, to ensure that
> strerror_r has the desired signature (i.e. it returns a char *, not an
> int). Here's what I've got:
>
I did this:
PyObject* _strerror()
{
char buf[1024] = {0};
// this is a compile time assertion to ensure the GNU version of
// strerror_r is used.
if (0)
{
// ensures the strerror_r() returns a pointer
int ret = *strerror_r(errno, buf, sizeof(buf));
return PyString_FromString(buf + ret);
}
// now for the real implementation
return PyString_FromString(strerror_r(errno, buf, sizeof(buf)));
}
I don’t mind unhelpful error messages as long as it is commented.
