Re: [PATCH 3/3] libc: Replace one letter member names in __tzrule_struct

On Fri, Oct 2, 2020 at 3:36 AM Torbjorn SVENSSON <[email protected]>
wrote:

> Hello!
>
> Thanks for the feedback Jeff.
>
> Regarding the alternative to using "__" prefix for the members; would it
> be better to move line 105-123 from newlib/libc/include/time.h to
> newlib/libc/time/local.h, thus not exposing it in the API?
>

Yes.  It was one of the alternatives I mentioned (hiding the struct from
users of time.h).  The struct is hidden in glibc and should have been
hidden likewise in newlib.

The lines in question are:
> typedef struct __tzrule_struct
> {
>   char ch;
>   int m;
>   int n;
>   int d;
>   int s;
>   time_t change;
>   long offset; /* Match type of _timezone. */
> } __tzrule_type;
>
> typedef struct __tzinfo_struct
> {
>   int __tznorth;
>   int __tzyear;
>   __tzrule_type __tzrule[2];
> } __tzinfo_type;
>
> __tzinfo_type *__gettzinfo (void);
>
>
>
> Would this change be easier to get accepted? If this approach is better, I
> guess the single letter member names can be kept too…
> While I took another look at the change, I also noticed that the struct
> definition (not usage) is also present in these files:
> newlib/libc/sys/linux/include/time.h
> newlib/libc/sys/phoenix/include/time.h
>
> I’m not sure in what situations those files are used and when the time.h
> file that I modified is used, but I guess they should be in sync regardless.
>
> Thanks
> Torbjörn
>
> From: Jeff Johnston <[email protected]>
> Sent: den 2 oktober 2020 01:21
> To: Torbjorn SVENSSON <[email protected]>
> Cc: Newlib <[email protected]>
> Subject: Re: [PATCH 3/3] libc: Replace one letter member names in
> __tzrule_struct
>
> Hello, while I fully agree there is an issue (the struct was due to my
> initial check-in in 2005 based on glibc), the change will break API and
> thus technically requires a major release bump of newlib.  I would prefer
> to wait for something else
> to require a major bump before making such a change.  In such a case, I
> also believe that the patch should either use double-underscores for the
> field names (e.g. __month) or hide the struct from regular users of time.h.
>
> -- Jeff J.
>
> On Thu, Oct 1, 2020 at 10:19 AM Torbjörn SVENSSON via Newlib <mailto:
> [email protected]> wrote:
> As discussed in GCC bug 97088
> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
> prototypes of library functions should use reserved names, or no name
> at all.
>
> This patch replaces 'm', 'n', 'd' and 's' members in
> 'struct __tzrule_struct' to avoid possible clashes with user code in
> case someone uses before including Newlib's time.h (or uses some
> other conflicting definition)
>
> Signed-off-by: Torbjörn SVENSSON <mailto:[email protected]>
> ---
>  newlib/libc/include/time.h       |  8 ++++----
>  newlib/libc/time/tzcalc_limits.c | 14 +++++++-------
>  newlib/libc/time/tzset_r.c       | 22 +++++++++++-----------
>  3 files changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/newlib/libc/include/time.h b/newlib/libc/include/time.h
> index 3031590b4..6a540537f 100644
> --- a/newlib/libc/include/time.h
> +++ b/newlib/libc/include/time.h
> @@ -105,10 +105,10 @@ void      _tzset_r        (struct _reent *);
>  typedef struct __tzrule_struct
>  {
>    char ch;
> -  int m;
> -  int n;
> -  int d;
> -  int s;
> +  int month; /* Month of year if ch=M */
> +  int week; /* Week of month if ch=M */
> +  int day; /* Day of week if ch=M, day of year if ch=J or ch=D */
> +  int secs; /* Time of day in seconds */
>    time_t change;
>    long offset; /* Match type of _timezone. */
>  } __tzrule_type;
> diff --git a/newlib/libc/time/tzcalc_limits.c
> b/newlib/libc/time/tzcalc_limits.c
> index e0ea6549c..b2163ed3d 100644
> --- a/newlib/libc/time/tzcalc_limits.c
> +++ b/newlib/libc/time/tzcalc_limits.c
> @@ -34,13 +34,13 @@ __tzcalc_limits (int year)
>        if (tz->__tzrule[i].ch == 'J')
>         {
>           /* The Julian day n (1 <= n <= 365). */
> -         days = year_days + tz->__tzrule[i].d +
> -           (isleap(year) && tz->__tzrule[i].d >= 60);
> +         days = year_days + tz->__tzrule[i].day +
> +           (isleap(year) && tz->__tzrule[i].day >= 60);
>           /* Convert to yday */
>           --days;
>         }
>        else if (tz->__tzrule[i].ch == 'D')
> -       days = year_days + tz->__tzrule[i].d;
> +       days = year_days + tz->__tzrule[i].day;
>        else
>         {
>           const int yleap = isleap(year);
> @@ -49,15 +49,15 @@ __tzcalc_limits (int year)
>
>           days = year_days;
>
> -         for (j = 1; j < tz->__tzrule[i].m; ++j)
> +         for (j = 1; j < tz->__tzrule[i].month; ++j)
>             days += ip[j-1];
>
>           m_wday = (EPOCH_WDAY + days) % DAYSPERWEEK;
>
> -         wday_diff = tz->__tzrule[i].d - m_wday;
> +         wday_diff = tz->__tzrule[i].day - m_wday;
>           if (wday_diff < 0)
>             wday_diff += DAYSPERWEEK;
> -         m_day = (tz->__tzrule[i].n - 1) * DAYSPERWEEK + wday_diff;
> +         m_day = (tz->__tzrule[i].week - 1) * DAYSPERWEEK + wday_diff;
>
>           while (m_day >= ip[j-1])
>             m_day -= DAYSPERWEEK;
> @@ -67,7 +67,7 @@ __tzcalc_limits (int year)
>
>        /* store the change-over time in GMT form by adding offset */
>        tz->__tzrule[i].change = days * SECSPERDAY +
> -      tz->__tzrule[i].s + tz->__tzrule[i].offset;
> +      tz->__tzrule[i].secs + tz->__tzrule[i].offset;
>      }
>
>    tz->__tznorth = (tz->__tzrule[0].change < tz->__tzrule[1].change);
> diff --git a/newlib/libc/time/tzset_r.c b/newlib/libc/time/tzset_r.c
> index 9e0cf834b..7117b51e6 100644
> --- a/newlib/libc/time/tzset_r.c
> +++ b/newlib/libc/time/tzset_r.c
> @@ -115,9 +115,9 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
>             return;
>
>           tz->__tzrule[i].ch = 'M';
> -         tz->__tzrule[i].m = m;
> -         tz->__tzrule[i].n = w;
> -         tz->__tzrule[i].d = d;
> +         tz->__tzrule[i].month = m;
> +         tz->__tzrule[i].week = w;
> +         tz->__tzrule[i].day = d;
>
>           tzenv += n;
>         }
> @@ -142,22 +142,22 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
>               if (i == 0)
>                 {
>                   tz->__tzrule[0].ch = 'M';
> -                 tz->__tzrule[0].m = 3;
> -                 tz->__tzrule[0].n = 2;
> -                 tz->__tzrule[0].d = 0;
> +                 tz->__tzrule[0].month = 3;
> +                 tz->__tzrule[0].week = 2;
> +                 tz->__tzrule[0].day = 0;
>                 }
>               else
>                 {
>                   tz->__tzrule[1].ch = 'M';
> -                 tz->__tzrule[1].m = 11;
> -                 tz->__tzrule[1].n = 1;
> -                 tz->__tzrule[1].d = 0;
> +                 tz->__tzrule[1].month = 11;
> +                 tz->__tzrule[1].week = 1;
> +                 tz->__tzrule[1].day = 0;
>                 }
>             }
>           else
>             {
>               tz->__tzrule[i].ch = ch;
> -             tz->__tzrule[i].d = d;
> +             tz->__tzrule[i].day = d;
>             }
>
>           tzenv = end;
> @@ -172,7 +172,7 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
>        if (*tzenv == '/')
>         sscanf (tzenv, "/%hu%n:%hu%n:%hu%n", &hh, &n, &mm, &n, &ss, &n);
>
> -      tz->__tzrule[i].s = ss + SECSPERMIN * mm + SECSPERHOUR  * hh;
> +      tz->__tzrule[i].secs = ss + SECSPERMIN * mm + SECSPERHOUR  * hh;
>
>        tzenv += n;
>      }
> --
> 2.18.0
>