Add Markus Kuhn's function to normalize the charset to IANA registered

encodings. Imported version 2002-03-11 from
http://www.cl.cam.ac.uk/~mgk25/ucs/norm_charmap.c

svn path=/trunk/; revision=3970

1 files changed, 144 insertions, 0 deletions

diff --git a/norm_charmap.c b/norm_charmap.c
new file mode 100644
index 00000000..30204871
--- /dev/null
+++ b/norm_charmap.c
@@ -0,0 +1,144 @@
+/*
+ * The Single Unix Specification function nl_langinfo(CODESET)
+ * returns the name of the encoding used by the currently selected
+ * locale:
+ *
+ *   http://www.opengroup.org/onlinepubs/7908799/xsh/langinfo.h.html
+ *
+ * Unfortunately the encoding names are not yet standardized.
+ * This function knows about the encoding names used on many
+ * different systems and converts them where possible into
+ * the corresponding MIME charset name registered in
+ *
+ *   http://www.iana.org/assignments/character-sets
+ *
+ * Please extend it as needed and suggest improvements to the author.
+ *
+ * Markus.Kuhn@cl.cam.ac.uk -- 2002-03-11
+ * Permission to use, copy, modify, and distribute this software
+ * for any purpose and without fee is hereby granted. The author
+ * disclaims all warranties with regard to this software.
+ *
+ * Latest version:
+ *
+ *   http://www.cl.cam.ac.uk/~mgk25/ucs/norm_charmap.c
+ */
+
+#include <string.h>
+
+#ifdef TEST
+#include <stdio.h>
+#include <locale.h>
+#include <langinfo.h>
+#endif
+
+#define digit(x) ((x) >= '0' && (x) <= '9')
+
+static char buf[16];
+
+char *norm_charmap(char *name)
+{
+  char *p;
+  
+  if (!name)
+    return name;
+  
+  /* Many need no remapping, but they are listed here so you
+   * can see what output to expect, and modify for your needs
+   * as necessary. */
+  if (!strcmp(name, "UTF-8"))
+    return "UTF-8";
+  if (!strcmp(name, "EUC-JP"))
+    return "EUC-JP";
+  if (!strcmp(name, "EUC-KR"))
+    return "EUC-KR";
+  if (!strcmp(name, "EUC-TW"))
+    return "EUC-TW";
+  if (!strcmp(name, "KOI8-R"))
+    return "KOI8-R";
+  if (!strcmp(name, "KOI8-U"))
+    return "KOI8-U";
+  if (!strcmp(name, "GBK"))
+    return "GBK";
+  if (!strcmp(name, "GB2312"))
+    return "GB2312";
+  if (!strcmp(name, "GB18030"))
+    return "GB18030";
+  if (!strcmp(name, "VSCII"))
+    return "VSCII";
+  
+  /* ASCII comes in many names */
+  if (!strcmp(name, "ASCII") ||
+      !strcmp(name, "US-ASCII") ||
+      !strcmp(name, "ANSI_X3.4-1968") ||
+      !strcmp(name, "646") ||
+      !strcmp(name, "ISO646") ||
+      !strcmp(name, "ISO_646.IRV"))
+    return "US-ASCII";
+
+  /* ISO 8859 will be converted to "ISO-8859-x" */
+  if ((p = strstr(name, "8859-"))) {
+    memcpy(buf, "ISO-8859-\0\0", 12);
+    p += 5;
+    if (digit(*p)) {
+      buf[9] = *p++;
+      if (digit(*p)) buf[10] = *p++;
+      return buf;
+    }
+  }
+
+  /* Windows code pages will be converted to "WINDOWS-12xx" */
+  if ((p = strstr(name, "CP12"))) {
+    memcpy(buf, "WINDOWS-12\0\0", 13);
+    p += 4;
+    if (digit(*p)) {
+      buf[10] = *p++;
+      if (digit(*p)) buf[11] = *p++;
+      return buf;
+    }
+  }
+
+  /* TIS-620 comes in at least the following two forms */
+  if (!strcmp(name, "TIS-620") ||
+      !strcmp(name, "TIS620.2533"))
+    return "ISO-8859-11";
+
+  /* For some, uppercase/lowercase might differ */
+  if (!strcmp(name, "Big5") || !strcmp(name, "BIG5"))
+    return "Big5";
+  if (!strcmp(name, "Big5HKSCS") || !strcmp(name, "BIG5HKSCS"))
+    return "Big5HKSCS";
+
+  /* I don't know of any implementation of nl_langinfo(CODESET) out
+   * there that returns anything else (and I'm not even certain all of
+   * the above occur in the wild), but just in case, as a fallback,
+   * return the unmodified name. */
+#ifdef TEST
+  printf("**** Unknown encoding name '%s'!\n", name);
+#endif
+  return name;
+}
+
+/* For a demo, compile with
+ *
+ *   gcc -W -Wall -o norm_charmap -D TEST norm_charmap.c
+ *
+ * and then test it on all available locales with
+ *
+ *   for i in `locale -a` ; do printf "$i: " ; LC_ALL=$i ./norm_charmap ; done
+ */
+
+#ifdef TEST
+int main(int argc, char **argv)
+{
+  char *s;
+  if (argc > 1)
+    s = argv[1];
+  else {
+    setlocale(LC_CTYPE, "");
+    s = nl_langinfo(CODESET);
+  }
+  printf("%s -> %s\n", s, norm_charmap(s));
+  return 0;
+}
+#endif