Re: [PATCH] PR ada/54040: [x32] Incorrect timeval and timespec

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Nov 18, 2013 at 5:57 AM, Arnaud Charlet <charlet@adacore.com> wrote:
>> >> struct timespec {
>> >>         __kernel_time_t tv_sec;                 /* seconds */
>> >>         long            tv_nsec;                /* nanoseconds */
>> >> };
>>
>> This is wrong for x32 where tv_nsec is long long, not
>> long.  There are a couple places where long should be
>> long long for x32.
>
> Well yes, but the type is *not* time_t, it's conceptually a different type.
>
>> Glibc gets them right properly:
>
> But that's for timeval, not timespec.

Glibc has

struct timespec
  {
    __time_t tv_sec;            /* Seconds.  */
    __syscall_slong_t tv_nsec;  /* Nanoseconds.  */
  };

__syscall_slong_t is long long for x32.

>> All for Linux architectures, __suseconds_t and
>> __suseconds_t are the same as time_t, including
>> x32.  If not, we can't use array for timeval.
>
> Well this PR is about x32 being different from all other linux ports. There's
> no guarantee that we won't have exactly the same issue on future ports where
> __suseconds_t is *not* the same as time_t.

Ada was using long for time_t and

type timeval is array (1 .. 2) of C.long

It assumes that the type of tv_nsec is the same as tv_sec.

> Also there's the issue of s-osinte-solaris-posix.ads which is broken with
> your change right now.
>
> The short term solution would be to apply this change:
>
> --- s-osinte-solaris-posix.ads  (revision 298928)
> +++ s-osinte-solaris-posix.ads  (working copy)
> @@ -513,7 +513,7 @@
>
>     type timespec is record
>        tv_sec  : time_t;
> -      tv_nsec : long;
> +      tv_nsec : time_t;
>     end record;
>     pragma Convention (C, timespec);
>
> But I'd rather settle on which type is appropriate for the tv_nsec
> field before making this change.
>

__syscall_slong_t is a Linux specific type.  We
can add tv_nsec_t, which should be the same
as time_t for all the current targets.

-- 
H.J.