new file mode 100644
--- /dev/null
+++ b/lib/localcharset.c
@@ -0,0 +1,185 @@
+/* Determine a canonical name for the current locale's character encoding.
+
+   Copyright (C) 2000 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU Library General Public License as published
+   by the Free Software Foundation; either version 2, 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA.  */
+
+/* Written by Bruno Haible <haible@clisp.cons.org>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#if HAVE_STDLIB_H
+# include <stdlib.h>
+#endif
+
+#if HAVE_LANGINFO_CODESET
+# include <langinfo.h>
+#else
+# if HAVE_SETLOCALE
+#  include <locale.h>
+# endif
+#endif
+
+char *xmalloc ();
+char *xrealloc ();
+
+/* Pointer to the contents of the charset.alias file, if it has already been
+   read, else NULL.  Its format is:
+   ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
+static char * volatile charset_aliases;
+
+/* Return a pointer to the contents of the charset.alias file.  */
+static const char *
+get_charset_aliases ()
+{
+  char *cp;
+
+  cp = charset_aliases;
+  if (cp == NULL)
+    {
+      FILE *fp;
+
+      fp = fopen (LIBDIR "/" "charset.alias", "r");
+      if (fp == NULL)
+	/* File not found, treat it as empty.  */
+	cp = "";
+      else
+	{
+	  /* Parse the file's contents.  */
+	  int c;
+	  char buf1[50+1];
+	  char buf2[50+1];
+	  char *res_ptr = NULL;
+	  size_t res_size = 0;
+	  size_t l1, l2;
+
+	  for (;;)
+	    {
+	      c = getc (fp);
+	      if (c == EOF)
+		break;
+	      if (c == '\n' || c == ' ' || c == '\t')
+		continue;
+	      if (c == '#')
+		{
+		  /* Skip comment, to end of line.  */
+		  do
+		    c = getc (fp);
+		  while (!(c == EOF || c == '\n'));
+		  if (c == EOF)
+		    break;
+		  continue;
+		}
+	      ungetc (c, fp);
+	      if (fscanf(fp, "%50s %50s", buf1, buf2) < 2)
+		break;
+	      l1 = strlen (buf1);
+	      l2 = strlen (buf2);
+	      if (res_size == 0)
+		{
+		  res_size = l1 + 1 + l2 + 1;
+		  res_ptr = xmalloc (res_size + 1);
+		}
+	      else
+		{
+		  res_size += l1 + 1 + l2 + 1;
+		  res_ptr = xrealloc (res_ptr, res_size + 1);
+		}
+	      strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
+	      strcpy (res_ptr + res_size - (l2 + 1), buf2);
+	    }
+	  fclose (fp);
+	  if (res_size == 0)
+	    cp = "";
+	  else
+	    {
+	      *(res_ptr + res_size) = '\0';
+	      cp = res_ptr;
+	    }
+	}
+
+      charset_aliases = cp;
+    }
+
+  return cp;
+}
+
+/* Determine the current locale's character encoding, and canonicalize it
+   into one of the canonical names listed in config.charset.
+   The result must not be freed; it is statically allocated.
+   If the canonical name cannot be determined, the result is a non-canonical
+   name or NULL.  */
+
+#ifdef STATIC
+STATIC
+#endif
+const char *
+locale_charset ()
+{
+  const char *codeset;
+  const char *aliases;
+
+#if HAVE_LANGINFO_CODESET
+
+  /* Most systems support nl_langinfo (CODESET) nowadays.  */
+  codeset = nl_langinfo (CODESET);
+
+#else
+
+  /* On old systems which lack it, use setlocale and getenv.  */
+  const char *locale = NULL;
+
+# if HAVE_SETLOCALE
+  locale = setlocale (LC_CTYPE, NULL);
+# endif
+  if (locale == NULL)
+    {
+      locale = getenv ("LC_ALL");
+      if (locale == NULL)
+	{
+	  locale = getenv ("LC_CTYPE");
+	  if (locale == NULL)
+	    locale = getenv ("LANG");
+	}
+    }
+
+  /* On some old systems, one used to set locale = "iso8859_1". On others,
+     you set it to "language_COUNTRY.charset". In any case, we resolve it
+     through the charset.alias file.  */
+  codeset = locale;
+
+#endif
+
+  if (codeset != NULL)
+    {
+      /* Resolve alias. */
+      for (aliases = get_charset_aliases ();
+	   *aliases != '\0';
+	   aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
+	if (!strcmp (codeset, aliases))
+	  {
+	    codeset = aliases + strlen (aliases) + 1;
+	    break;
+	  }
+    }
+
+  return codeset;
+}