Re: [PATCH 64bit] ssize_t

[Ralf Corsepius <ralf dot corsepius at rtems dot org>]

On 02/20/2013 03:14 PM, Corinna Vinschen wrote:
> Hi Yaakov,
>
> On Feb 20 03:23, Yaakov (Cygwin/X) wrote:
> > I just discovered an issue resulting from this commit:
> >
> > 2002-06-27  Jeff Johnston  <jjohnstn@...>
> >
> >          * libc/include/sys/_types.h: Define _ssize_t as int if int is
> >          32-bits, otherwise define it as long.
> >
> > On x86_64-cygwin (as on Linux), int is still 32 bits, but size_t is a
> > 64bit unsigned long and ssize_t should be as large but signed.
> > Possible patch for newlib attached; corresponding patches for
> > cygwin-64bit-branch on cygwin-patches@.
>
> Thanks for the patch.  I'm just wondering if ssize_t shouldn't ideally
> be based on size_t, at least when using GCC.  GCC has a predefined
> __SIZEOF_SIZE_T__ macro.
>
> What I'm thinking of is something like
>
> #ifndef __ssize_t_defined
> # ifdef __SIZEOF_SIZE_T__
> #  if defined (__SIZEOF_INT__) && __SIZEOF_SIZE_T__ == __SIZEOF_INT__
> typedef int ssize_t;
> #  else
> typedef long ssize_t
> #  endif
> # elif defined(__INT_MAX__) && defined(__LONG_MAX__) && __LONG_MAX__ == __INT_MAX__
> typedef int _ssize_t;
> # else
> typedef long _ssize_t;
> # endif
> #endif
>
>
> Does that make sense?

GCC requires exact symmetry of types between ssize_t and size_t.
I.e. checking for sizes of types is not sufficient for [s]size_t.

Ralf