[PATCH 1/3] Change _offset type from int to _off_t

Sebastian Huber sebastian.huber@embedded-brains.de
Mon Nov 26 16:30:00 GMT 2012

On 11/23/2012 02:15 PM, Corinna Vinschen wrote:
> On Nov 23 13:24, Sebastian Huber wrote:
>> On 11/23/2012 11:21 AM, Corinna Vinschen wrote:
>>> On Nov 22 12:24, Sebastian Huber wrote:
>>>> 2012-11-22  Sebastian Huber <sebastian.huber@embedded-brains.de>
>>>> 	* libc/include/sys/reent.h (__sFILE): Change type of _offset
>>>> 	from int to _off_t.
>>>> [...]
>>>> It breaks binary compatibility also on some RTEMS targets, but this is
>>>> not a problem.
>>> It breaks binary compatibility.  Full stop.  And this is a problem.
>> Yes, this is a problem, but not for RTEMS.
>>> If we do that, we must make really sure that this isn't a problem.
>> We can add a new type, which is int by default and for example _off_t on RTEMS.
> But this new type doesn't match your fseeko/ftello implementation
> anymore.

Yes, this is bad.

>>> For instance, on 32 bit Cygwin, _off_t is 32 bit (while off_t ==
>>> _off64_t), so the change from int to _off_t would not break the ABI.
>>> But newlib is not only RTEMS and Cygwin, that's the problem.
>>> However, see the thread starting at
>>> http://sourceware.org/ml/newlib/2012/msg00214.html
>>> In theory you're not supposed to change struct __sFILE, rather you're
>>> supposed to use struct __sFILE64 and the functions defined in the
>>> libc/stdio64 subdir.  This discussion seems to have gone lost.
>> Ok, and how can I do this.  Is this a configure option?  I don't
>> want to use fseeko64() directly.
> Why not?  Cygwin is doing the same.  The application calls fseeko,
> but internally Cygwin calls fseeko64 since the link lib redirects
> the call.  fseeko64 does not exist on the application level.

Ok, the problem is that I am not a Newlib configuration guru.  How do I get 
this behaviour for RTEMS.  Is this a magic configure option or do I have to set 
some pre-processor defines somewhere?

Sebastian Huber, embedded brains GmbH

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