Move wchar2char() and char2wchar() from tsearch into /mb to be easier to

use for other modules;  also move pnstrdup().

Clean up code slightly.

src/backend/utils/mb/mbutils.c

@@ -4,7 +4,7 @@
  * (currently mule internal code (mic) is used)
  * Tatsuo Ishii
  *
- * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.71 2008/05/27 12:24:42 mha Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.72 2008/06/18 18:42:54 momjian Exp $
  */
 #include "postgres.h"
 
@@ -555,6 +555,134 @@ perform_default_encoding_conversion(const char *src, int len, bool is_client_to_
 	return result;
 }
 
+
+
+#ifdef USE_WIDE_UPPER_LOWER
+
+/*
+ * wchar2char --- convert wide characters to multibyte format
+ *
+ * This has the same API as the standard wcstombs() function; in particular,
+ * tolen is the maximum number of bytes to store at *to, and *from must be
+ * zero-terminated.  The output will be zero-terminated iff there is room.
+ */
+size_t
+wchar2char(char *to, const wchar_t *from, size_t tolen)
+{
+	size_t result;
+	
+	if (tolen == 0)
+		return 0;
+
+#ifdef WIN32
+	/*
+	 * On Windows, the "Unicode" locales assume UTF16 not UTF8 encoding,
+	 * and for some reason mbstowcs and wcstombs won't do this for us,
+	 * so we use MultiByteToWideChar().
+	 */
+	if (GetDatabaseEncoding() == PG_UTF8)
+	{
+		result = WideCharToMultiByte(CP_UTF8, 0, from, -1, to, tolen,
+								NULL, NULL);
+		/* A zero return is failure */
+		if (result <= 0)
+			result = -1;
+		else
+		{
+			Assert(result <= tolen);
+			/* Microsoft counts the zero terminator in the result */
+			result--;
+		}
+	}
+	else
+#endif   /* WIN32 */
+		result = wcstombs(to, from, tolen);
+	return result;
+}
+
+/*
+ * char2wchar --- convert multibyte characters to wide characters
+ *
+ * This has almost the API of mbstowcs(), except that *from need not be
+ * null-terminated; instead, the number of input bytes is specified as
+ * fromlen.  Also, we ereport() rather than returning -1 for invalid
+ * input encoding.	tolen is the maximum number of wchar_t's to store at *to.
+ * The output will be zero-terminated iff there is room.
+ */
+size_t
+char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen)
+{
+	size_t		result;
+
+	if (tolen == 0)
+		return 0;
+
+#ifdef WIN32
+	/* See WIN32 "Unicode" comment above */
+	if (GetDatabaseEncoding() == PG_UTF8)
+	{
+		/* Win32 API does not work for zero-length input */
+		if (fromlen == 0)
+			result = 0;
+		else
+		{
+			result = MultiByteToWideChar(CP_UTF8, 0, from, fromlen, to, tolen - 1);
+			/* A zero return is failure */
+			if (result == 0)
+				result = -1;
+		}
+
+		if (result != -1)
+		{
+			Assert(result < tolen);
+			/* Append trailing null wchar (MultiByteToWideChar() does not) */
+			to[result] = 0;
+		}
+	}
+	else
+#endif   /* WIN32 */
+	{
+		if (lc_ctype_is_c())
+		{
+			/*
+			 * pg_mb2wchar_with_len always adds trailing '\0', so 'to' should be
+			 * allocated with sufficient space
+			 */
+			result = pg_mb2wchar_with_len(from, (pg_wchar *) to, fromlen);
+		}
+		else
+		{
+			/* mbstowcs requires ending '\0' */
+			char	   *str = pnstrdup(from, fromlen);
+
+			result = mbstowcs(to, str, tolen);
+			pfree(str);
+		}
+	}
+
+	if (result == -1)
+	{
+		/*
+		 * Invalid multibyte character encountered.  We try to give a useful
+		 * error message by letting pg_verifymbstr check the string.  But it's
+		 * possible that the string is OK to us, and not OK to mbstowcs ---
+		 * this suggests that the LC_CTYPE locale is different from the
+		 * database encoding.  Give a generic error message if verifymbstr
+		 * can't find anything wrong.
+		 */
+		pg_verifymbstr(from, fromlen, false);	/* might not return */
+		/* but if it does ... */
+		ereport(ERROR,
+				(errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
+				 errmsg("invalid multibyte character for locale"),
+				 errhint("The server's LC_CTYPE locale is probably incompatible with the database encoding.")));
+	}	
+
+	return result;
+}
+
+#endif
+
 /* convert a multibyte string to a wchar */
 int
 pg_mb2wchar(const char *from, pg_wchar *to)