1 files changed, 72 insertions, 0 deletions
diff --git a/lib/hard-locale.c b/lib/hard-locale.c
new file mode 100644
index 0000000..49bc6ca
--- /dev/null
+++ b/lib/hard-locale.c
@@ -0,0 +1,72 @@
+/* hard-locale.c -- Determine whether a locale is hard.
+
+   Copyright (C) 1997-1999, 2002-2004, 2006-2007, 2009-2018 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "hard-locale.h"
+
+#include <locale.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef __GLIBC__
+# define GLIBC_VERSION __GLIBC__
+#elif defined __UCLIBC__
+# define GLIBC_VERSION 2
+#else
+# define GLIBC_VERSION 0
+#endif
+
+/* Return true if the current CATEGORY locale is hard, i.e. if you
+   can't get away with assuming traditional C or POSIX behavior.  */
+bool
+hard_locale (int category)
+{
+  bool hard = true;
+  char const *p = setlocale (category, NULL);
+
+  if (p)
+    {
+      if (2 <= GLIBC_VERSION)
+        {
+          if (strcmp (p, "C") == 0 || strcmp (p, "POSIX") == 0)
+            hard = false;
+        }
+      else
+        {
+          char *locale = strdup (p);
+          if (locale)
+            {
+              /* Temporarily set the locale to the "C" and "POSIX" locales
+                 to find their names, so that we can determine whether one
+                 or the other is the caller's locale.  */
+              if (((p = setlocale (category, "C"))
+                   && strcmp (p, locale) == 0)
+                  || ((p = setlocale (category, "POSIX"))
+                      && strcmp (p, locale) == 0))
+                hard = false;
+
+              /* Restore the caller's locale.  */
+              setlocale (category, locale);
+              free (locale);
+            }
+        }
+    }
+
+  return hard;
+}