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Re: [PATCH 64bit] ssize_t

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

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.


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