locale: Remove private union from struct __locale_data

This avoids an alias violation later.  This commit also fixes
an incorrect double-checked locking idiom in _nl_init_era_entries.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

3 files changed, 45 insertions, 54 deletions

diff --git a/time/alt_digit.c b/time/alt_digit.c
index 7ed9b6b..331cb39 100644
--- a/time/alt_digit.c
+++ b/time/alt_digit.c
@@ -30,19 +30,18 @@ __libc_rwlock_define (extern, __libc_setlocale_lock attribute_hidden)
 #define CURRENT_WSTR(item) \
   ((wchar_t *) current->values[_NL_ITEM_INDEX (item)].wstr)
 
-static void
+static struct lc_time_data *
 _nl_init_alt_digit (struct __locale_data *current)
 {
-  struct lc_time_data *data;
+  struct lc_time_data *data = current->private;
 
-  if (current->private.time == NULL)
+  if (data == NULL)
     {
-      current->private.time = malloc (sizeof *current->private.time);
-      if (current->private.time == NULL)
-	return;
-      memset (current->private.time, 0, sizeof *current->private.time);
+      data = calloc (sizeof *data, 1);
+      if (data == NULL)
+	return NULL;
+      current->private = data;
     }
-  data = current->private.time;
 
   if (! data->alt_digits_initialized)
     {
@@ -65,6 +64,7 @@ _nl_init_alt_digit (struct __locale_data *current)
 	}
     }
 
+  return data;
 }
 
 const char *
@@ -77,13 +77,11 @@ _nl_get_alt_digit (unsigned int number, struct __locale_data *current)
 
   __libc_rwlock_wrlock (__libc_setlocale_lock);
 
-  if (current->private.time == NULL
-      || ! current->private.time->alt_digits_initialized)
-    _nl_init_alt_digit (current);
+  struct lc_time_data *data = _nl_init_alt_digit (current);
 
-  result = ((current->private.time != NULL
-	     && current->private.time->alt_digits != NULL)
-	    ? current->private.time->alt_digits[number]
+  result = ((data != NULL
+	     && data->alt_digits != NULL)
+	    ? data->alt_digits[number]
 	    : NULL);
 
   __libc_rwlock_unlock (__libc_setlocale_lock);
@@ -96,21 +94,20 @@ const wchar_t *
 _nl_get_walt_digit (unsigned int number, struct __locale_data *current)
 {
   const wchar_t *result = NULL;
-  struct lc_time_data *data;
 
   if (number >= 100 || CURRENT_WSTR (_NL_WALT_DIGITS)[0] == L'\0')
     return NULL;
 
   __libc_rwlock_wrlock (__libc_setlocale_lock);
 
-  if (current->private.time == NULL)
+  struct lc_time_data *data = current->private;
+  if (data == NULL)
     {
-      current->private.time = malloc (sizeof *current->private.time);
-      if (current->private.time == NULL)
+      data = calloc (sizeof *data, 1);
+      if (data == NULL)
 	goto out;
-      memset (current->private.time, 0, sizeof *current->private.time);
+      current->private = data;
     }
-  data = current->private.time;
 
   if (! data->walt_digits_initialized)
     {
@@ -156,12 +153,8 @@ _nl_parse_alt_digit (const char **strp, struct __locale_data *current)
 
   __libc_rwlock_wrlock (__libc_setlocale_lock);
 
-  if (current->private.time == NULL
-      || ! current->private.time->alt_digits_initialized)
-    _nl_init_alt_digit (current);
-
-  if (current->private.time != NULL
-      && current->private.time->alt_digits != NULL)
+  struct lc_time_data *data = _nl_init_alt_digit (current);
+  if (data != NULL && data->alt_digits != NULL)
     /* Matching is not unambiguous.  The alternative digits could be like
        I, II, III, ... and the first one is a substring of the second
        and third.  Therefore we must keep on searching until we found
@@ -169,7 +162,7 @@ _nl_parse_alt_digit (const char **strp, struct __locale_data *current)
        the standard.  */
     for (cnt = 0; cnt < 100; ++cnt)
       {
-	const char *const dig = current->private.time->alt_digits[cnt];
+	const char *const dig = data->alt_digits[cnt];
 	size_t len = strlen (dig);
 
 	if (len > maxlen && strncmp (dig, str, len) == 0)
diff --git a/time/era.c b/time/era.c
index d4b538c..7f18071 100644
--- a/time/era.c
+++ b/time/era.c
@@ -35,7 +35,7 @@ __libc_rwlock_define (extern, __libc_setlocale_lock attribute_hidden)
 
 /* Look up the era information in CURRENT's locale strings and
    cache it in CURRENT->private.  */
-static void
+static struct lc_time_data *
 _nl_init_era_entries (struct __locale_data *current)
 {
   size_t cnt;
@@ -43,18 +43,22 @@ _nl_init_era_entries (struct __locale_data *current)
 
   /* Avoid touching CURRENT if there is no data at all, for _nl_C_LC_TIME.  */
   if (CURRENT_WORD (_NL_TIME_ERA_NUM_ENTRIES) == 0)
-    return;
+    return NULL;
+
+  data = current->private;
+  if (data != NULL && atomic_load_acquire (&data->era_initialized))
+    return data;
 
   __libc_rwlock_wrlock (__libc_setlocale_lock);
 
-  if (current->private.time == NULL)
+  data = current->private;
+  if (data == NULL)
     {
-      current->private.time = malloc (sizeof *current->private.time);
-      if (current->private.time == NULL)
+      data = calloc (sizeof *data, 1);
+      if (data == NULL)
 	goto out;
-      memset (current->private.time, 0, sizeof *current->private.time);
+      current->private = data;
     }
-  data = current->private.time;
 
   if (! data->era_initialized)
     {
@@ -130,33 +134,30 @@ _nl_init_era_entries (struct __locale_data *current)
 	    }
 	}
 
-      data->era_initialized = 1;
+      atomic_store_release (&data->era_initialized, 1);
     }
 
  out:
   __libc_rwlock_unlock (__libc_setlocale_lock);
+  return data;
 }
 
 struct era_entry *
 _nl_get_era_entry (const struct tm *tp, struct __locale_data *current)
 {
-  if (current->private.time == NULL || !current->private.time->era_initialized)
-    _nl_init_era_entries (current);
+  struct lc_time_data *data = _nl_init_era_entries (current);
 
-  if (current->private.time != NULL)
+  if (data != NULL)
     {
       /* Now compare date with the available eras.  */
       const int32_t tdate[3] = { tp->tm_year, tp->tm_mon, tp->tm_mday };
       size_t cnt;
-      for (cnt = 0; cnt < current->private.time->num_eras; ++cnt)
-	if ((ERA_DATE_CMP (current->private.time->eras[cnt].start_date, tdate)
-	     && ERA_DATE_CMP (tdate,
-			      current->private.time->eras[cnt].stop_date))
-	    || (ERA_DATE_CMP (current->private.time->eras[cnt].stop_date,
-			      tdate)
-		&& ERA_DATE_CMP (tdate,
-				 current->private.time->eras[cnt].start_date)))
-	  return &current->private.time->eras[cnt];
+      for (cnt = 0; cnt < data->num_eras; ++cnt)
+	if ((ERA_DATE_CMP (data->eras[cnt].start_date, tdate)
+	     && ERA_DATE_CMP (tdate, data->eras[cnt].stop_date))
+	    || (ERA_DATE_CMP (data->eras[cnt].stop_date, tdate)
+		&& ERA_DATE_CMP (tdate, data->eras[cnt].start_date)))
+	  return &data->eras[cnt];
     }
 
   return NULL;
@@ -166,9 +167,6 @@ _nl_get_era_entry (const struct tm *tp, struct __locale_data *current)
 struct era_entry *
 _nl_select_era_entry (int cnt, struct __locale_data *current)
 {
-  if (current->private.time == NULL || !current->private.time->era_initialized)
-    _nl_init_era_entries (current);
-
-  return (current->private.time == NULL
-	  ? NULL : &current->private.time->eras[cnt]);
+  struct lc_time_data *data = _nl_init_era_entries (current);
+  return data == NULL ? NULL : &data->eras[cnt];
 }
diff --git a/time/lc-time-cleanup.c b/time/lc-time-cleanup.c
index f844e04..bcf6d2f 100644
--- a/time/lc-time-cleanup.c
+++ b/time/lc-time-cleanup.c
@@ -22,10 +22,10 @@
 void
 _nl_cleanup_time (struct __locale_data *locale)
 {
-  struct lc_time_data *const data = locale->private.time;
+  struct lc_time_data *const data = locale->private;
   if (data != NULL)
     {
-      locale->private.time = NULL;
+      locale->private = NULL;
 
       free (data->eras);
       free (data->alt_digits);