time/tst-strftime2.c: Make the file easier to maintain

Express the years as full Gregorian years (e.g., 1988 instead of 88)
and months with natural numbers (1-12 rather than 0-11).

Compare actual dates rather than indexes when selecting the era name.

Declare the local variable era as a string character pointer rather
than an array of chars where the actual string is copied which might
lead to potential buffer overflows in future.

Co-authored-by: Rafal Luzynski <digitalfreak@lingonborough.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

ChangeLog:

	* time/tst-strftime2.c (date_t): Explicitly define the type.
	(dates): Use natural month and year numbers to express a date.
	(is_before): New function to compare dates.
	(mkreftable): Minor improvements to simplify maintenance.
	(do_test): Reflect the changes in dates array.

2 files changed, 82 insertions, 40 deletions

diff --git a/ChangeLog b/ChangeLog
index 50a00bb40f..55e501e32e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2019-04-02  TAMUKI Shoichi  <tamuki@linet.gr.jp>
+	    Rafal Luzynski  <digitalfreak@lingonborough.com>
+
+	* time/tst-strftime2.c (date_t): Explicitly define the type.
+	(dates): Use natural month and year numbers to express a date.
+	(is_before): New function to compare dates.
+	(mkreftable): Minor improvements to simplify maintenance.
+	(do_test): Reflect the changes in dates array.
+
 2019-04-01  Carlos O'Donell  <carlos@redhat.com>
 
 	* localedata/locales/ja_JP: Add comments to era entries.
diff --git a/time/tst-strftime2.c b/time/tst-strftime2.c
index 3dca2a997f..be15c773a4 100644
--- a/time/tst-strftime2.c
+++ b/time/tst-strftime2.c
@@ -19,69 +19,102 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <array_length.h>
+#include <stdbool.h>
+#include <support/check.h>
+#include <stdlib.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 *locales[] =
+{
+  "ja_JP.UTF-8", "lo_LA.UTF-8", "th_TH.UTF-8"
+};
+
+/* Must match locale index into locales array.  */
+enum
+{
+  ja_JP, lo_LA, th_TH
+};
 
 static const char *formats[] = { "%EY", "%_EY", "%-EY" };
 
-static const struct
+typedef 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 }
-  };
+} date_t;
+
+static const date_t dates[] =
+{
+  {  1,  4, 1988 },
+  {  7,  1, 1989 },
+  {  8,  1, 1989 },
+  {  1,  4, 1990 },
+  {  1,  4, 1997 },
+  {  1,  4, 1998 }
+};
 
 static char ref[array_length (locales)][array_length (formats)]
 	       [array_length (dates)][100];
 
+static bool
+is_before (const int i, const int d, const int m, const int y)
+{
+  if (dates[i].y < y)
+    return true;
+  else if (dates[i].y > y)
+    return false;
+  else if (dates[i].m < m)
+    return true;
+  else if (dates[i].m > m)
+    return false;
+  else
+    return dates[i].d < d;
+}
+
 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 };
+  int i, j, k, yr;
+  const char *era, *sfx;
+  /* Japanese era year to be checked.  */
+  static const int yrj[] =
+  {
+    63, 64, 1, 2, 9, 10
+  };
+  /* Buddhist calendar year to be checked.  */
+  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)
+	  if (i == ja_JP)
 	    {
-	      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]);
+	      era = (is_before (k, 8, 1, 1989)) ? "\u662d\u548c"
+						: "\u5e73\u6210";
+	      yr = yrj[k], sfx = "\u5e74";
 	    }
+	  else if (i == lo_LA)
+	    era = "\u0e9e.\u0eaa. ", yr = yrb[k], sfx = "";
+	  else if (i == th_TH)
+	    era = "\u0e1e.\u0e28. ", yr = yrb[k], sfx = "";
 	  else
-	    {
-	      sprintf (era, "\xe0\xb8\x9e\x2e\xe0\xb8\xa8\x2e ");
-	      sprintf (ref[i][j][k], "%s%d", era, yrb[k]);
-	    }
+	    FAIL_EXIT1 ("Invalid table index!");
+	  if (yr == 1)
+	    sprintf (ref[i][j][k], "%s\u5143%s", era, sfx);
+	  else if (j == 0)
+	    sprintf (ref[i][j][k], "%s%02d%s", era, abs (yr), sfx);
+	  else if (j == 1)
+	    sprintf (ref[i][j][k], "%s%2d%s", era, abs (yr), sfx);
+	  else if (j == 2)
+	    sprintf (ref[i][j][k], "%s%d%s", era, abs (yr), sfx);
+	  else
+	    FAIL_EXIT1 ("Invalid table index!");
 	}
 }
 
@@ -107,8 +140,8 @@ do_test (void)
 	  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;
+	      ttm.tm_mon  = dates[k].m - 1;
+	      ttm.tm_year = dates[k].y - 1900;
 	      strftime (date, sizeof (date), "%F", &ttm);
 	      r = strftime (buf, sizeof (buf), formats[j], &ttm);
 	      e = strlen (ref[i][j][k]);