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Re: [PATCH 64bit] ssize_t
On Feb 20 18:16, Ralf Corsepius wrote:
> On 02/20/2013 05:06 PM, Corinna Vinschen wrote:
> >Unfortunately we're not living in an ideal world. That said, I'm
> >willing to go with the obvious as I outlined above. Since size_t is
> >*likely* defined as int if int == long, and defined as long if int <
> >long, this should match most cases. Oh, and then there are the
> >potential LLP64 systems which define sizeof size_t == sizeof long long.
> >An additional elif would catch that:
> ># if defined (__SIZEOF_INT__) && __SIZEOF_SIZE_T__ == __SIZEOF_INT__
> >typedef int ssize_t;
> ># elif defined (__SIZEOF_LONG__) && __SIZEOF_SIZE_T__ == __SIZEOF_LONG__
> >typedef long ssize_t
> ># else
> >typedef long long ssize_t;
> ># endif
> Sorry, I think, I did not communicate my point accurately.
> Let me try again:
> GCC doesn't apply a size-based logic to define size_t, but applies
> hard-coded predefined types for size_t, likely based on historic
> per-target conventions.
> I.e. any type-size based logic will sometimes fail:
> E.g. for targets with sizeof(size_t) == sizeof(int) == sizeof(long).
> on some targets GCC uses "typedef unsigned int size_t" and on other
> targets GCC uses "typedef unsigned long size_t".
> Now, if you choose "typedef int ssize_t" on targets, which use
> "typedef long size_t", GCC will raise warnings related to fprintfs.
How is that different from what newlib did before, except that typedef
int ssize_t; is very certainly wrong on most 64 bit platforms. I don't
remember any complaints or patches on this list related to this
What we have is a bad default which needs overriding via machine
dependent files. The suggestion here is to define ssize_t a bit more
correct in most cases. Given your above assessment, there appears to be
no 100% correct way anyway, even when using _WORDSIZE as Chris suggests.
Only exact target knowledge would do that.
So, from my POV, what we can do in sys/_types.h is to provide a sane
default. If this still doesn't match, add a target dependent file.