locale.c: Fix some unused code for potential future use

This code extends the heuristics used to determine if a locale is UTF-8
or not on older platforms.  It has been #ifdef'd out because it only
added a little value on dromedary.  Now the previous commit has added
new heuristics, and tests on dromedary show that this adds nothing to
that.  But I'm leaving it in the source in case it might ever prove
useful.  In order to test it, I compiled it and found some problems with
the earlier version that this now fixes.

1 files changed, 46 insertions, 33 deletions

diff --git a/locale.c b/locale.c
index 291e178f5a..20edb19f5d 100644
--- a/locale.c
+++ b/locale.c
@@ -1335,63 +1335,68 @@ Perl__is_cur_LC_category_utf8(pTHX_ int category)
 #if 0 && defined(USE_LOCALE_MESSAGES) && defined(HAS_SYS_ERRLIST)
 
 /* This code is ifdefd out because it was found to not be necessary in testing
- * on our dromedary test machine, which has over 700 locales.  There, looking
- * at just the currency symbol gave essentially the same results as doing this
- * extra work.  Executing this also caused segfaults in miniperl.  I left it in
- * so as to avoid rewriting it if real-world experience indicates that
- * dromedary is an outlier.  Essentially, instead of returning abpve if we
+ * on our dromedary test machine, which has over 700 locales.  There, this
+ * added no value to looking at the currency symbol and the time strings.  I
+ * left it in so as to avoid rewriting it if real-world experience indicates
+ * that dromedary is an outlier.  Essentially, instead of returning abpve if we
  * haven't found illegal utf8, we continue on and examine all the strerror()
  * messages on the platform for utf8ness.  If all are ASCII, we still don't
  * know the answer; but otherwise we have a pretty good indication of the
- * utf8ness.  The reason this doesn't necessarily help much is that the
- * messages may not have been translated into the locale.  The currency symbol
- * is much more likely to have been translated.  The code below would need to
- * be altered somewhat to just be a continuation of testing the currency
- * symbol. */
+ * utf8ness.  The reason this doesn't help much is that the messages may not
+ * have been translated into the locale.  The currency symbol and time strings
+ * are much more likely to have been translated.  */
+    {
         int e;
-        unsigned int failures = 0, non_ascii = 0;
+        bool is_utf8 = FALSE;
+        bool non_ascii = FALSE;
         char *save_messages_locale = NULL;
+        const char * errmsg = NULL;
 
-        /* Like above for LC_CTYPE, we set LC_MESSAGES to the locale of the
-         * desired category, if it isn't that locale already */
+        /* Like above, we set LC_MESSAGES to the locale of the desired
+         * category, if it isn't that locale already */
 
         if (category != LC_MESSAGES) {
 
-            save_messages_locale = stdize_locale(savepv(setlocale(LC_MESSAGES,
-                                                                  NULL)));
+            save_messages_locale = setlocale(LC_MESSAGES, NULL);
             if (! save_messages_locale) {
+                DEBUG_L(PerlIO_printf(Perl_debug_log,
+                            "Could not find current locale for LC_MESSAGES\n"));
                 goto cant_use_messages;
             }
+            save_messages_locale = stdize_locale(savepv(save_messages_locale));
 
             if (strEQ(save_messages_locale, save_input_locale)) {
-                Safefree(save_input_locale);
+                Safefree(save_messages_locale);
+                save_messages_locale = NULL;
             }
             else if (! setlocale(LC_MESSAGES, save_input_locale)) {
+                DEBUG_L(PerlIO_printf(Perl_debug_log,
+                            "Could not change LC_MESSAGES locale to %s\n",
+                                                        save_input_locale));
                 Safefree(save_messages_locale);
                 goto cant_use_messages;
             }
         }
 
         /* Here the current LC_MESSAGES is set to the locale of the category
-         * whose information is desired.  Look through all the messages */
+         * whose information is desired.  Look through all the messages.  We
+         * can't use Strerror() here because it may expand to code that
+         * segfaults in miniperl */
 
-        for (e = 0;
-#ifdef HAS_SYS_ERRLIST
-             e <= sys_nerr
-#endif
-             ; e++)
-        {
-            const U8* const errmsg = (U8 *) Strerror(e) ;
-            if (!errmsg)
-                break;
-            if (! is_utf8_string(errmsg, 0)) {
-                failures++;
+        for (e = 0; e <= sys_nerr; e++) {
+            errno = 0;
+            errmsg = sys_errlist[e];
+            if (errno || !errmsg) {
                 break;
             }
-            else if (! is_ascii_string(errmsg, 0)) {
-                non_ascii++;
+            errmsg = savepv(errmsg);
+            if (! is_ascii_string((U8 *) errmsg, 0)) {
+                non_ascii = TRUE;
+                is_utf8 = is_utf8_string((U8 *) errmsg, 0);
+                break;
             }
         }
+        Safefree(errmsg);
 
         /* And, if we changed it, restore LC_MESSAGES to its original locale */
         if (save_messages_locale) {
@@ -1399,10 +1404,18 @@ Perl__is_cur_LC_category_utf8(pTHX_ int category)
             Safefree(save_messages_locale);
         }
 
-        /* Any non-UTF-8 message means not a UTF-8 locale; if all are valid,
-         * any non-ascii means it is one; otherwise we assume it isn't */
-        return (failures) ? FALSE : non_ascii;
+        if (non_ascii) {
+
+            /* Any non-UTF-8 message means not a UTF-8 locale; if all are valid,
+             * any non-ascii means it is one; otherwise we assume it isn't */
+            DEBUG_L(PerlIO_printf(Perl_debug_log, "\t?error messages for %s are UTF-8=%d\n",
+                                save_input_locale,
+                                is_utf8));
+            Safefree(save_input_locale);
+            return is_utf8;
+        }
 
+        DEBUG_L(PerlIO_printf(Perl_debug_log, "All error messages for %s contain only ASCII; can't use for determining if UTF-8 locale\n", save_input_locale));
     }
   cant_use_messages: