Re: Failure during build of Python 3.8 via cygport

[Mark Geisert <mark@maxrnd.com>]

Hi Corinna,

Corinna Vinschen via Cygwin-developers wrote:
> On Dec 14 02:42, Mark Geisert wrote:
[...]
>> Debugging Python's os.uname showed Cygwin's uname() being called with a
>> 'struct uname' as defined in /usr/include/sys/utsname.h, which is fine.  But
>> it's the "old" pre-335 uname() interface being called, not the "new" 335+
>> interface uname_x().  Note that the famous 'mkimport' script, used when
>> building the Cygwin DLL, has an arg "--replace=uname=uname_x" which I
>> believe is supposed to equate the two names so the code in uname_x() is
>> called whether the interface is uname_x() or uname().  That's not happening.
[...]
>> 'nm' shows that both uname and uname_x exist in libcygwin.a and also
>> cygdll.a. And a newly-created Cygwin DLL has both functions, with different
>> addresses.
>> That's wrong, isn't it?
> 
> No, it isn't.  The old uname entry point is still required for old
> applications built prior to API version 335.  If you build a new
> application it will actually call uname_x when it tries to call uname
> since that's how the libcygwin.a layer translates it.
> 
> It's a bit unfortunate that uname_x is exported by libcygwin.a
> as well (in theory it should only export uname, pointing to uname_x
> in the DLL), but this is how it always was, as you can see in
> the 32 bit build with symbols only available there, e. g. aclcheck:
> 
>    $ nm libcygwin.a | grep aclcheck
>    00000000 I __imp___aclcheck
>    00000000 I __imp___aclcheck32
>    00000000 I __imp__aclcheck
>    00000000 T __aclcheck
> 	   U __imp___aclcheck
>    00000000 T __aclcheck32
> 	   U __imp___aclcheck32
>    00000000 T _aclcheck
> 	   U __imp___aclcheck32
> 
> In retrospect, uname_x should be named _uname_x or so, with a leading
> underscore, so as not to pollute the namespace, but either way, that
> isn;t your problem.

OK, I see.

> The problem here might be that you get the old uname function if
> you dlopen the cygwin dll and dlsym(hdl, "uname").  Is that the
> case in python?

Yes it is.

> If so, I have a simple, dirty workaround below.  Can you check if that's
> the problem, please?

A new Cygwin DLL built with your patch does correct this 'uname' issue when 
building Python.  Wonderful!
Thank you very much!

..mark