Fix up and make sv_strftime_ints() public

This enhanced function now allows you to specify if you want the system
to consider the possibility of daylight savings time being in effect.
Formerly, it was never considered.  As a result, the function is good
enough to be made public.

embed.fnc

@@ -3413,16 +3413,14 @@ Adm	|bool	|sv_streq	|NULLOK SV *sv1 			\
 Adp	|bool	|sv_streq_flags |NULLOK SV *sv1 			\
 				|NULLOK SV *sv2 			\
 				|const U32 flags
-EXpx	|SV *	|sv_strftime_ints					\
+Adp	|SV *	|sv_strftime_ints					\
 				|NN SV *fmt				\
 				|int sec				\
 				|int min				\
 				|int hour				\
 				|int mday				\
 				|int mon				\
 				|int year				\
-				|int wday				\
-				|int yday				\
 				|int isdst
 Adp	|SV *	|sv_strftime_tm |NN SV *fmt				\
 				|NN const struct tm *mytm
@@ -4423,8 +4421,6 @@ S	|void	|ints_to_tm	|NN struct tm *my_tm			\
 				|int mday				\
 				|int mon				\
 				|int year				\
-				|int wday				\
-				|int yday				\
 				|int isdst
 S	|bool	|is_locale_utf8 |NN const char *locale
 S	|HV *	|my_localeconv	|const int item

embed.h

@@ -748,6 +748,7 @@
 # define sv_setuv(a,b)                          Perl_sv_setuv(aTHX_ a,b)
 # define sv_setuv_mg(a,b)                       Perl_sv_setuv_mg(aTHX_ a,b)
 # define sv_streq_flags(a,b,c)                  Perl_sv_streq_flags(aTHX_ a,b,c)
+# define sv_strftime_ints(a,b,c,d,e,f,g,h)      Perl_sv_strftime_ints(aTHX_ a,b,c,d,e,f,g,h)
 # define sv_strftime_tm(a,b)                    Perl_sv_strftime_tm(aTHX_ a,b)
 # define sv_string_from_errnum(a,b)             Perl_sv_string_from_errnum(aTHX_ a,b)
 # define sv_tainted(a)                          Perl_sv_tainted(aTHX_ a)
@@ -1315,7 +1316,7 @@
 #   endif /* defined(PERL_IN_HV_C) */
 #   if defined(PERL_IN_LOCALE_C)
 #     define get_locale_string_utf8ness_i(a,b,c,d) S_get_locale_string_utf8ness_i(aTHX_ a,b,c,d)
-#     define ints_to_tm(a,b,c,d,e,f,g,h,i,j,k)  S_ints_to_tm(aTHX_ a,b,c,d,e,f,g,h,i,j,k)
+#     define ints_to_tm(a,b,c,d,e,f,g,h,i)      S_ints_to_tm(aTHX_ a,b,c,d,e,f,g,h,i)
 #     define is_locale_utf8(a)                  S_is_locale_utf8(aTHX_ a)
 #     define my_localeconv(a)                   S_my_localeconv(aTHX_ a)
 #     define populate_hash_from_C_localeconv(a,b,c,d,e) S_populate_hash_from_C_localeconv(aTHX_ a,b,c,d,e)
@@ -1764,7 +1765,6 @@
 #   define skipspace_flags(a,b)                 Perl_skipspace_flags(aTHX_ a,b)
 #   define sv_magicext_mglob(a)                 Perl_sv_magicext_mglob(aTHX_ a)
 #   define sv_only_taint_gmagic                 Perl_sv_only_taint_gmagic
-#   define sv_strftime_ints(a,b,c,d,e,f,g,h,i,j) Perl_sv_strftime_ints(aTHX_ a,b,c,d,e,f,g,h,i,j)
 #   define utf16_to_utf8_base(a,b,c,d,e,f)      Perl_utf16_to_utf8_base(aTHX_ a,b,c,d,e,f)
 #   define utf8_to_utf16_base(a,b,c,d,e,f)      Perl_utf8_to_utf16_base(aTHX_ a,b,c,d,e,f)
 #   define validate_proto(a,b,c,d)              Perl_validate_proto(aTHX_ a,b,c,d)

ext/POSIX/POSIX.xs

@@ -3582,8 +3582,7 @@ strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1)
 	int		isdst
     CODE:
 	{
-            SV *sv = sv_strftime_ints(fmt, sec, min, hour, mday, mon, year,
-                                      wday, yday, isdst);
+            SV *sv = sv_strftime_ints(fmt, sec, min, hour, mday, mon, year, 0);
 	    if (sv) {
                 sv = sv_2mortal(sv);
             }

ext/POSIX/lib/POSIX.pm

@@ -4,7 +4,7 @@ use warnings;
 
 our ($AUTOLOAD, %SIGRT);
 
-our $VERSION = '2.20';
+our $VERSION = '2.21';
 
 require XSLoader;
 

locale.c

@@ -7504,7 +7504,7 @@ S_emulate_langinfo(pTHX_ const PERL_INTMAX_T item,
         /* The year was deliberately chosen so that January 1 is on the
         * first day of the week.  Since we're only getting one thing at a
         * time, it all works */
-        ints_to_tm(&mytm, locale, 30, 30, hour, mday, mon, 2011, 0, 0, 0);
+        ints_to_tm(&mytm, locale, 30, 30, hour, mday, mon, 2011, 0);
         bool succeeded;
         if (utf8ness) {
             succeeded = strftime8(format,
@@ -7648,7 +7648,7 @@ S_emulate_langinfo(pTHX_ const PERL_INTMAX_T item,
             /* Do the strftime.  Once we have determined the UTF8ness (if
             * we want it), assume the rest will be the same, and use
             * strftime_tm(), which doesn't recalculate UTF8ness */
-            ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, 0, 0, 0);
+            ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, 0);
             if (utf8ness && is_utf8 != UTF8NESS_NO && is_utf8 != UTF8NESS_YES) {
                 succeeded = strftime8(fmts[j],
                                       alt_dig_sv,
@@ -8075,16 +8075,25 @@ S_maybe_override_codeset(pTHX_ const char * codeset,
 /*
 =for apidoc_section $time
 =for apidoc      sv_strftime_tm
+=for apidoc_item sv_strftime_ints
 =for apidoc_item my_strftime
 
 These implement the libc strftime().
 
 On failure, they return NULL, and set C<errno> to C<EINVAL>.
 
-C<sv_strftime_tm> is preferred, as it transparently handles the UTF-8ness of
-the current locale, the input C<fmt>, and the returned result.  Only if the
-current C<LC_TIME> locale is a UTF-8 one (and S<C<use bytes>> is not in effect)
-will the result be marked as UTF-8.
+C<sv_strftime_tm> and C<sv_strftime_ints> are preferred, as they transparently
+handle the UTF-8ness of the current locale, the input C<fmt>, and the returned
+result.  Only if the current C<LC_TIME> locale is a UTF-8 one (and S<C<use
+bytes>> is not in effect) will the result be marked as UTF-8.
+
+C<my_strftime> is kept for backwards compatibility.  Knowing if its result
+should be considered UTF-8 or not requires significant extra logic.
+
+Note that all three functions are always executed in the underlying
+C<LC_TIME> locale of the program, giving results based on that locale.
+
+The functions differ as follows:
 
 C<sv_strftime_tm> takes a pointer to a filled-in S<C<struct tm>> parameter.  It
 ignores the values of the C<wday> and C<yday> fields in it.  The other fields
@@ -8093,22 +8102,37 @@ that purpose.
 
 The caller assumes ownership of the returned SV with a reference count of 1.
 
-C<my_strftime> is kept for backwards compatibility.  Knowing if its result
-should be considered UTF-8 or not requires significant extra logic.
+C<sv_strftime_ints> takes a bunch of integer parameters that together
+completely define a given time.  It calculates the S<C<struct tm>> to pass to
+libc strftime(), and calls that function.  Setting C<isdst> to 0 causes the
+date to be calculated as if there is no daylight savings time in effect; any
+other value causes the possibility of daylight savings time to be considered.
+A positive value is a hint to the function that daylight savings is likely to
+be in effect for the passed-in time.
 
-The return value is a pointer to the formatted result (which MUST be arranged
-to be FREED BY THE CALLER).  This allows this function to increase the buffer
-size as needed, so that the caller doesn't have to worry about that, unlike
-libc C<strftime()>.
+The caller assumes ownership of the returned SV with a reference count of 1.
 
-The C<wday>, C<yday>, and C<isdst> parameters are ignored by C<my_strftime>.
-Daylight savings time is never considered to exist, and the values returned for
-the other two fields (if C<fmt> even calls for them) are calculated from the
-other parameters, without need for referencing these.
+C<my_strftime> is like C<sv_strftime_ints> except that:
 
-Note that both functions are always executed in the underlying
-C<LC_TIME> locale of the program, giving results based on that locale.
+=over
 
+=item The C<fmt> parameter and the return are S<C<char *>> instead of
+S<C<SV *>>.
+
+This means the UTF-8ness of the result is unspecified.  The result MUST be
+arranged to be FREED BY THE CALLER).
+
+=item It has extra parameters C<yday>, C<wday> and C<is_dst>.
+
+These are completely ignored, and exist only for historical reasons.
+
+Daylight savings time is never considered to be in effect, and C<yday> and
+C<wday> are calculated from the other arguments.
+
+=back
+
+Note that all three functions are always executed in the underlying C<LC_TIME>
+locale of the program, giving results based on that locale.
 =cut
  */
 
@@ -8118,6 +8142,9 @@ Perl_my_strftime(pTHX_ const char *fmt, int sec, int min, int hour,
                        int isdst)
 {   /* Documented above */
     PERL_ARGS_ASSERT_MY_STRFTIME;
+    PERL_UNUSED_ARG(wday);
+    PERL_UNUSED_ARG(yday);
+    PERL_UNUSED_ARG(isdst);
 
 #ifdef USE_LOCALE_TIME
     const char * locale = querylocale_c(LC_TIME);
@@ -8126,8 +8153,7 @@ Perl_my_strftime(pTHX_ const char *fmt, int sec, int min, int hour,
 #endif
 
     struct tm  mytm;
-    ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, wday, yday,
-               isdst);
+    ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, 0);
     if (! strftime_tm(fmt, PL_scratch_langinfo, locale, &mytm)) {
         return NULL;
     }
@@ -8137,8 +8163,7 @@ Perl_my_strftime(pTHX_ const char *fmt, int sec, int min, int hour,
 
 SV *
 Perl_sv_strftime_ints(pTHX_ SV * fmt, int sec, int min, int hour,
-                            int mday, int mon, int year, int wday,
-                            int yday, int isdst)
+                            int mday, int mon, int year, int isdst)
 {   /* Documented above */
     PERL_ARGS_ASSERT_SV_STRFTIME_INTS;
 
@@ -8149,8 +8174,7 @@ Perl_sv_strftime_ints(pTHX_ SV * fmt, int sec, int min, int hour,
 #endif
 
     struct tm  mytm;
-    ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, wday, yday,
-               isdst);
+    ints_to_tm(&mytm, locale, sec, min, hour, mday, mon, year, isdst);
     return sv_strftime_common(fmt, locale, &mytm);
 }
 
@@ -8212,10 +8236,14 @@ STATIC void
 S_ints_to_tm(pTHX_ struct tm * mytm,
                    const char * locale,
                    int sec, int min, int hour, int mday, int mon, int year,
-                   int wday, int yday, int isdst)
+                   int isdst)
 {
     /* Create a struct tm structure from the input time-related integer
-     * variables for 'locale' */
+     * variables for 'locale'.  Unlike mini_mktime(), this populates the
+     * tm_gmtoff and tm_zone fields of the structure if the platform has those;
+     * and unlike mktime(), it allows you to specify to not consider the
+     * possibility of there being daylight savings time.  This is done by
+     * calling with 'isdst' set to 0 */
 
     /* Override with the passed-in values */
     Zero(mytm, 1, struct tm);
@@ -8225,34 +8253,86 @@ S_ints_to_tm(pTHX_ struct tm * mytm,
     mytm->tm_mday = mday;
     mytm->tm_mon = mon;
     mytm->tm_year = year;
-    mytm->tm_wday = wday;
-    mytm->tm_yday = yday;
-    mytm->tm_isdst = isdst;
 
-    /* Long-standing behavior is to ignore the effects of locale (in
-     * particular, daylight savings time) on the input, so we use mini_mktime.
-     * See GH #22062. */
+    struct tm * which_tm = mytm;
+    struct tm aux_tm;
+
+#ifndef HAS_MKTIME
+
     mini_mktime(mytm);
 
-    /* But some of those effect are deemed desirable, so use libc to get the
-     * values for tm_gmtoff and tm_zone on platforms that have them [perl
-     * #18238] */
-#if  defined(HAS_MKTIME)                                      \
- && (defined(HAS_TM_TM_GMTOFF) || defined(HAS_TM_TM_ZONE))
+#else
 
-    const char * orig_TIME_locale = toggle_locale_c(LC_TIME, locale);
-    struct tm aux_tm = *mytm;
-    MKTIME_LOCK;
-    mktime(&aux_tm);
-    MKTIME_UNLOCK;
-    restore_toggled_locale_c(LC_TIME, orig_TIME_locale);
+    /* On platforms that have either of these two fields, we have to run the
+     * libc mktime() in order to set them, as mini_mktime() doesn't deal with
+     * them.  [perl #18238] */
+#  if defined(HAS_TM_TM_GMTOFF) || defined(HAS_TM_TM_ZONE)
+#    define ALWAYS_RUN_MKTIME
+#  endif
+
+    /* When isdst is 0, it means to consider daylight savings time as never
+     * being in effect.  Many libc implementations of mktime() do not allow
+     * this; they always consider the possibility of dst.  But mini_mktime()
+     * never considers dst, so use it under this condition. */
+    if (isdst == 0) {
+        mini_mktime(mytm);
+
+#  if defined(ALWAYS_RUN_MKTIME)
+
+        /* Here will have to run libc mktime() in order to get the values of
+         * some fields that mini_mktime doesn't populate.  We don't want
+         * mktime's side effect of looking for dst, so we have to have a
+         * separate tm structure from which we copy just those fields into the
+         * returned structure.  Initialize its values.  mytm should now be a
+         * normalized version of the input. */
+        StructCopy(mytm, &aux_tm, struct tm);
+        aux_tm.tm_isdst = isdst;
+        which_tm = &aux_tm;
+    }
+
+#  else
+
+    /* When we don't always need libc mktime(), we call it only when we didn't
+     * call mini_mktime() */
+    else
 
-#  ifdef HAS_TM_TM_GMTOFF
-    mytm->tm_gmtoff = aux_tm.tm_gmtoff;
 #  endif
-#  ifdef HAS_TM_TM_ZONE
-    mytm->tm_zone = aux_tm.tm_zone;
+
+    {   /* Here, we need to run libc mktime(), either because we want to take
+         * dst into consideration, or because it calculates one or two fields
+         * that we need that mini_mktime() doesn't handle.
+         *
+         * Unlike mini_mktime(), it does consider the locale, so have to switch
+         * to the correct one. */
+        const char * orig_TIME_locale = toggle_locale_c(LC_TIME, locale);
+        MKTIME_LOCK;
+
+        /* which_tm points to an auxiliary copy if we ran mini_mktime().
+         * Otherwise it points to the passed-in one which now gets populated
+         * directly. */
+        (void) mktime(which_tm);
+
+        MKTIME_UNLOCK;
+        restore_toggled_locale_c(LC_TIME, orig_TIME_locale);
+    }
+
+#  if defined(HAS_TM_TM_GMTOFF) || defined(HAS_TM_TM_ZONE)
+
+    /* And use the saved libc values for tm_gmtoff and tm_zone if we used an
+     * auxiliary struct to get them */
+    if (which_tm != mytm) {
+
+#    ifdef HAS_TM_TM_GMTOFF
+        mytm->tm_gmtoff = aux_tm.tm_gmtoff;
+#    endif
+#    ifdef HAS_TM_TM_ZONE
+        mytm->tm_zone = aux_tm.tm_zone;
+#    endif
+
+    }
+
 #  endif
+#  undef ALWAYS_RUN_MKTIME
 #endif
 
     return;

pod/perldelta.pod

@@ -348,7 +348,12 @@ well.
 
 =item *
 
-XXX
+The L<perlapi/C<sv_strftime_ints>> function is introduced.  This is an
+enhanced version of L<perlapi/C<my_strftime>>, which is retained for
+backwards compatibility.  Both are to call L<strftime(3)> when you have
+the year, month, hour, etc.  The new function handles UTF8ness for you,
+and allows you to specify if you want the possibility of daylight
+savings time to be considered.  C<my_strftime> never considers DST.
 
 =back