strftime: Pass the additional flags from "%EY" to "%Ey" [BZ #24096]

The full representation of the alternative calendar year (%EY)
typically includes an internal use of "%Ey".  As a GNU extension,
apply any flags on "%EY" (e.g. "%_EY", "%-EY") to the internal "%Ey",
allowing users of "%EY" to control how the year is padded.

Reviewed-by: Rafal Luzynski <digitalfreak@lingonborough.com>
Reviewed-by: Zack Weinberg <zackw@panix.com>

ChangeLog:

	[BZ #24096]
	* manual/time.texi (strftime): Document "%EC" and "%EY".
	* time/Makefile (tests): Add tst-strftime2.
	(LOCALES): Add ja_JP.UTF-8, lo_LA.UTF-8, and th_TH.UTF-8.
	* time/strftime_l.c (__strftime_internal): Add argument yr_spec to
	override padding for "%Ey".
	If an optional flag ('_' or '-') is specified to "%EY", interpret the
	"%Ey" in the subformat as if decorated with that flag.
	* time/tst-strftime2.c: New file.

6 files changed, 171 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 64ed089867..8f3924d742 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,16 @@
 	* time/strftime_l.c (__strftime_internal): Set the default width
 	padding with zero of "%Ey" to 2.
 
+	[BZ #24096]
+	* manual/time.texi (strftime): Document "%EC" and "%EY".
+	* time/Makefile (tests): Add tst-strftime2.
+	(LOCALES): Add ja_JP.UTF-8, lo_LA.UTF-8, and th_TH.UTF-8.
+	* time/strftime_l.c (__strftime_internal): Add argument yr_spec to
+	override padding for "%Ey".
+	If an optional flag ('_' or '-') is specified to "%EY", interpret the
+	"%Ey" in the subformat as if decorated with that flag.
+	* time/tst-strftime2.c: New file.
+
 2019-01-24  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* support/xsigstack.c (MAP_NORESERVE, MAP_STACK): Define if they
diff --git a/NEWS b/NEWS
index aec18367a4..76679f3393 100644
--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,10 @@ Major new features:
   alternative year numbers less than 10).  Zero-padding can be
   overridden with the '_' or '-' flags (which are GNU extensions).
 
+* As a GNU extension, the '_' and '-' flags can now be applied to
+  "%EY" to control how the year number is formatted; they have the
+  same effect that they would on "%Ey".
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.tune tunable namespace has been renamed to glibc.cpu and the
diff --git a/manual/time.texi b/manual/time.texi
index 03a8a0e10f..6d398bfe1f 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1393,6 +1393,10 @@ The preferred calendar time representation for the current locale.
 The century of the year.  This is equivalent to the greatest integer not
 greater than the year divided by 100.
 
+If the @code{E} modifier is specified (@code{%EC}), instead produces
+the name of the period for the year (e.g.@: an era name) in the
+locale's alternative calendar.
+
 This format was first standardized by POSIX.2-1992 and by @w{ISO C99}.
 
 @item %d
@@ -1579,6 +1583,13 @@ can be overridden by an explicit field width or by the @code{_} and
 The year as a decimal number, using the Gregorian calendar.  Years
 before the year @code{1} are numbered @code{0}, @code{-1}, and so on.
 
+If the @code{E} modifier is specified (@code{%EY}), instead produces a
+complete representation of the year according to the locale's
+alternative calendar.  Generally this will be some combination of the
+information produced by @code{%EC} and @code{Ey}.  As a GNU extension,
+the formatting flags @code{_} or @code{-} may be used with this
+conversion specifier; they affect how the year number is printed.
+
 @item %z
 @w{RFC 822}/@w{ISO 8601:1988} style numeric time zone (e.g.,
 @code{-0600} or @code{+0100}), or nothing if no time zone is
diff --git a/time/Makefile b/time/Makefile
index d23ba2dee6..5c6304ece1 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -43,13 +43,14 @@ 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 bug-mktime4
+	   tst-tzname tst-y2039 bug-mktime4 tst-strftime2
 
 include ../Rules
 
 ifeq ($(run-built-tests),yes)
 LOCALES := de_DE.ISO-8859-1 en_US.ISO-8859-1 ja_JP.EUC-JP fr_FR.UTF-8 \
-	   es_ES.UTF-8 pl_PL.UTF-8 ru_RU.UTF-8
+	   es_ES.UTF-8 pl_PL.UTF-8 ru_RU.UTF-8 \
+	   ja_JP.UTF-8 lo_LA.UTF-8 th_TH.UTF-8
 include ../gen-locales.mk
 
 $(objpfx)tst-ftime_l.out: $(gen-locales)
diff --git a/time/strftime_l.c b/time/strftime_l.c
index cbe08e7afb..cb3b8d36f6 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;
 
@@ -457,7 +457,7 @@ my_strftime (CHAR_T *s, size_t maxsize, const CHAR_T *format,
   tp = &tmcopy;
 #endif
   bool tzset_called = false;
-  return __strftime_internal (s, maxsize, format, tp, &tzset_called
+  return __strftime_internal (s, maxsize, format, tp, 0, &tzset_called
 			      ut_argument LOCALE_ARG);
 }
 #ifdef _LIBC
@@ -466,7 +466,7 @@ 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
@@ -838,11 +838,11 @@ __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));
 
 	    if (to_uppcase)
 	      while (old_start < p)
@@ -1273,6 +1273,8 @@ __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
@@ -1294,6 +1296,8 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	      if (era)
 		{
 		  int delta = tp->tm_year - era->start_date[0];
+		  if (yr_spec != 0)
+		    pad = yr_spec;
 		  DO_NUMBER (2, (era->offset
 				 + delta * era->absolute_direction));
 		}
diff --git a/time/tst-strftime2.c b/time/tst-strftime2.c
new file mode 100644
index 0000000000..57d2144c83
--- /dev/null
+++ b/time/tst-strftime2.c
@@ -0,0 +1,132 @@
+/* Verify the behavior of strftime on alternative representation for
+   year.
+
+   Copyright (C) 2019 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 <array_length.h>
+#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" };
+
+static const char *formats[] = { "%EY", "%_EY", "%-EY" };
+
+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 }
+  };
+
+static char ref[3][3][6][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 < array_length (locales); i++)
+    for (j = 0; j < array_length (formats); j++)
+      for (k = 0; k < array_length (dates); 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 < array_length (locales); 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 < array_length (formats); j++)
+	{
+	  for (k = 0; k < array_length (dates); 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;
+}
+
+#include <support/test-driver.c>