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[PATCH v2] Improve the width of alternate representation for year in strftime [BZ #23758]


The Japanese era name is scheduled to be changed on May 1, 2019.
Prior to this, change the alternate representation for year in
strftime to pad the number with zero to keep it constant width, so
that prevent the trouble we saw in the past from becoming obvious
again from the year after the era name changes onward.

Since only one Japanese era name is used by each emperor's reign, it
is rare that the year ends in one digit or lasts more than three
digits.  In addition, the width of month, day, hour, minute, and
second is 2, so adjust the width of year the same as them, and then
the whole display balance is improved.  Therefore, it would be
reasonable to change the width padding with zero of %Ey default to 2.

Currently in glibc, besides ja_JP locale, the locales using the
conversion specifier above are lo_LA (Laos) and th_TH (Thailand).  In
these locales, they use the Buddhist era.  The Buddhist era is a value
obtained by adding 543 to the Christian era, so it is not affected by
this change of the conversion specifier %Ey.

Furthermore, for the output string of the conversion specifier %EY,
an optional flag is given to the conversion specifier so that it can
be also used the current non-padding format, and the padding format
can be controlled.  To achieve this, when an optional flag is given to
the conversion specifier %EY, the %Ey included in the combined
conversion specifier is interpreted as if decorated with the
appropriate flag.

ChangeLog:

	[BZ #23758]
	* time/Makefile (tests): Add tst-strftime2.
	* time/strftime_l.c (__strftime_internal): Add argument
	yr_spec to override padding for %Ey.
	Change the width padding with zero of %Ey default to 2.
	If an optional flag ('_' or '-') is specified to %EY, the %Ey
	in subformat is interpreted as if decorated with the
	appropriate flag.
	* time/tst-strftime2.c: New file.
---
 Changes since v1:
 - change to be handled by not rewriting the format string
 - slightly modify the commit message

 time/Makefile        |   2 +-
 time/strftime_l.c    |  28 ++++++-----
 time/tst-strftime2.c | 134 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 152 insertions(+), 12 deletions(-)
 create mode 100644 time/tst-strftime2.c

diff --git a/time/Makefile b/time/Makefile
index ec3e39dcea..6dc2acceaa 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -43,7 +43,7 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
 	   tst-getdate tst-mktime tst-mktime2 tst-ftime_l tst-strftime \
 	   tst-mktime3 tst-strptime2 bug-asctime bug-asctime_r bug-mktime1 \
 	   tst-strptime3 bug-getdate1 tst-strptime-whitespace tst-ftime \
-	   tst-tzname tst-y2039
+	   tst-tzname tst-y2039 tst-strftime2
 
 include ../Rules
 
diff --git a/time/strftime_l.c b/time/strftime_l.c
index c71f9f47a9..8797341ea5 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -434,7 +434,7 @@ static CHAR_T const month_name[][10] =
 #endif
 
 static size_t __strftime_internal (CHAR_T *, size_t, const CHAR_T *,
-				   const struct tm *, bool *
+				   const struct tm *, int *, bool *
 				   ut_argument_spec
 				   LOCALE_PARAM) __THROW;
 
@@ -456,8 +456,9 @@ my_strftime (CHAR_T *s, size_t maxsize, const CHAR_T *format,
   tmcopy = *tp;
   tp = &tmcopy;
 #endif
+  int yr_spec = 0;		/* Override padding for %Ey.  */
   bool tzset_called = false;
-  return __strftime_internal (s, maxsize, format, tp, &tzset_called
+  return __strftime_internal (s, maxsize, format, tp, &yr_spec, &tzset_called
 			      ut_argument LOCALE_ARG);
 }
 #ifdef _LIBC
@@ -466,7 +467,7 @@ libc_hidden_def (my_strftime)
 
 static size_t
 __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
-		     const struct tm *tp, bool *tzset_called
+		     const struct tm *tp, int *yr_spec, bool *tzset_called
 		     ut_argument_spec LOCALE_PARAM)
 {
 #if defined _LIBC && defined USE_IN_EXTENDED_LOCALE_MODEL
@@ -820,7 +821,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	  if (modifier == L_('O'))
 	    goto bad_format;
 #ifdef _NL_CURRENT
-	  if (! (modifier == 'E'
+	  if (! (modifier == L_('E')
 		 && (*(subfmt =
 		       (const CHAR_T *) _NL_CURRENT (LC_TIME,
 						     NLW(ERA_D_T_FMT)))
@@ -838,11 +839,12 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	  {
 	    CHAR_T *old_start = p;
 	    size_t len = __strftime_internal (NULL, (size_t) -1, subfmt,
-					      tp, tzset_called ut_argument
-					      LOCALE_ARG);
+					      tp, yr_spec, tzset_called
+					      ut_argument LOCALE_ARG);
 	    add (len, __strftime_internal (p, maxsize - i, subfmt,
-					   tp, tzset_called ut_argument
-					   LOCALE_ARG));
+					   tp, yr_spec, tzset_called
+					   ut_argument LOCALE_ARG));
+	    *yr_spec = 0;
 
 	    if (to_uppcase)
 	      while (old_start < p)
@@ -917,7 +919,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 #ifdef _NL_CURRENT
 	  if (! (modifier == L_('E')
 		 && (*(subfmt =
-		       (const CHAR_T *)_NL_CURRENT (LC_TIME, NLW(ERA_D_FMT)))
+		       (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(ERA_D_FMT)))
 		     != L_('\0'))))
 	    subfmt = (const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(D_FMT));
 	  goto subformat;
@@ -1262,7 +1264,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	  DO_NUMBER (1, tp->tm_wday);
 
 	case L_('Y'):
-	  if (modifier == 'E')
+	  if (modifier == L_('E'))
 	    {
 #if HAVE_STRUCT_ERA_ENTRY
 	      struct era_entry *era = _nl_get_era_entry (tp HELPER_LOCALE_ARG);
@@ -1273,6 +1275,8 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 # else
 		  subfmt = era->era_format;
 # endif
+		  if (pad != 0)
+		    *yr_spec = pad;
 		  goto subformat;
 		}
 #else
@@ -1294,7 +1298,9 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	      if (era)
 		{
 		  int delta = tp->tm_year - era->start_date[0];
-		  DO_NUMBER (1, (era->offset
+		  if (*yr_spec != 0)
+		    pad = *yr_spec;
+		  DO_NUMBER (2, (era->offset
 				 + delta * era->absolute_direction));
 		}
 #else
diff --git a/time/tst-strftime2.c b/time/tst-strftime2.c
new file mode 100644
index 0000000000..3e7ddfe9ea
--- /dev/null
+++ b/time/tst-strftime2.c
@@ -0,0 +1,134 @@
+/* Verify the behavior of strftime on alternate representation for year.
+
+   Copyright (C) 2013-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <locale.h>
+#include <time.h>
+#include <stdio.h>
+#include <string.h>
+
+static const char *locales[] = { "ja_JP.UTF-8", "lo_LA.UTF-8", "th_TH.UTF-8" };
+#define nlocales (sizeof (locales) / sizeof (locales[0]))
+
+static const char *formats[] = { "%EY", "%_EY", "%-EY" };
+#define nformats (sizeof (formats) / sizeof (formats[0]))
+
+static const struct
+{
+  const int d, m, y;
+} dates[] =
+  {
+    { 1, 3, 88 },
+    { 7, 0, 89 },
+    { 8, 0, 89 },
+    { 1, 3, 90 },
+    { 1, 3, 97 },
+    { 1, 3, 98 }
+  };
+#define ndates (sizeof (dates) / sizeof (dates[0]))
+
+static char ref[nlocales][nformats][ndates][100];
+
+static void
+mkreftable (void)
+{
+  int i, j, k;
+  char era[10];
+  static const int yrj[] = { 63, 64, 1, 2, 9, 10 };
+  static const int yrb[] = { 2531, 2532, 2532, 2533, 2540, 2541 };
+
+  for (i = 0; i < nlocales; i++)
+    for (j = 0; j < nformats; j++)
+      for (k = 0; k < ndates; k++)
+	{
+	  if (i == 0)
+	    {
+	      sprintf (era, "%s", (k < 2) ? "\xe6\x98\xad\xe5\x92\x8c"
+					  : "\xe5\xb9\xb3\xe6\x88\x90");
+	      if (yrj[k] == 1)
+		sprintf (ref[i][j][k], "%s\xe5\x85\x83\xe5\xb9\xb4", era);
+	      else
+		{
+		  if (j == 0)
+		    sprintf (ref[i][j][k], "%s%02d\xe5\xb9\xb4", era, yrj[k]);
+		  else if (j == 1)
+		    sprintf (ref[i][j][k], "%s%2d\xe5\xb9\xb4", era, yrj[k]);
+		  else
+		    sprintf (ref[i][j][k], "%s%d\xe5\xb9\xb4", era, yrj[k]);
+		}
+	    }
+	  else if (i == 1)
+	    {
+	      sprintf (era, "\xe0\xba\x9e\x2e\xe0\xba\xaa\x2e ");
+	      sprintf (ref[i][j][k], "%s%d", era, yrb[k]);
+	    }
+	  else
+	    {
+	      sprintf (era, "\xe0\xb8\x9e\x2e\xe0\xb8\xa8\x2e ");
+	      sprintf (ref[i][j][k], "%s%d", era, yrb[k]);
+	    }
+	}
+}
+
+static int
+do_test (void)
+{
+  int i, j, k, result = 0;
+  struct tm ttm;
+  char date[11], buf[100];
+  size_t r, e;
+
+  mkreftable ();
+  for (i = 0; i < nlocales; i++)
+    {
+      if (setlocale (LC_ALL, locales[i]) == NULL)
+	{
+	  printf ("locale %s does not exist, skipping...\n", locales[i]);
+	  continue;
+	}
+      printf ("[%s]\n", locales[i]);
+      for (j = 0; j < nformats; j++)
+	{
+	  for (k = 0; k < ndates; k++)
+	    {
+	      ttm.tm_mday = dates[k].d;
+	      ttm.tm_mon  = dates[k].m;
+	      ttm.tm_year = dates[k].y;
+	      strftime (date, sizeof (date), "%F", &ttm);
+	      r = strftime (buf, sizeof (buf), formats[j], &ttm);
+	      e = strlen (ref[i][j][k]);
+	      printf ("%s\t\"%s\"\t\"%s\"", date, formats[j], buf);
+	      if (strcmp (buf, ref[i][j][k]) != 0)
+		{
+		  printf ("\tshould be \"%s\"", ref[i][j][k]);
+		  if (r != e)
+		    printf ("\tgot: %zu, expected: %zu", r, e);
+		  result = 1;
+		}
+	      else
+		printf ("\tOK");
+	      putchar ('\n');
+	    }
+	  putchar ('\n');
+	}
+    }
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
-- 
2.12.2


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