From 6d89ecc3171be8be317b1d687909bd1dc0cfed4f Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 5 May 2020 15:26:12 +0530
Subject: [PATCH v17] Fix the MSVC build for versions 2015 and later.

Visual Studio 2015 and later versions should still be able to do the same
as Visual Studio 2012, but the declaration of locale_name is missing in
_locale_t, causing the code compilation to fail, hence this falls back
instead on to enumerating all system locales by using EnumSystemLocalesEx
to find the required locale name.  If the input argument is in Unix-style
then we can get ISO Locale name directly by using GetLocaleInfoEx() with
LCType as LOCALE_SNAME.

In passing, change the documentation references to the now obsolete links.

Note that this problem occurs only with NLS enabled builds.

Author: Juan José Santamaría Flecha, Davinder Singh and Amit Kapila
Reviewed-by: Ranier Vilela and Amit Kapila
Backpatch-through: 9.5
Discussion: https://postgr.es/m/CAHzhFSFoJEWezR96um4-rg5W6m2Rj9Ud2CNZvV4NWc9tXV7aXQ@mail.gmail.com
---
 src/backend/utils/adt/pg_locale.c | 197 ++++++++++++++++++++++++++++++++++----
 1 file changed, 177 insertions(+), 20 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 2562eb5..a995238 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -234,6 +234,7 @@ pg_perm_setlocale(int category, const char *locale)
 			result = IsoLocaleName(locale);
 			if (result == NULL)
 				result = (char *) locale;
+			elog(DEBUG3, "IsoLocaleName() executed; locale: \"%s\"", result);
 #endif							/* WIN32 */
 			break;
 #endif							/* LC_MESSAGES */
@@ -971,25 +972,172 @@ cache_locale_time(void)
  * string.  Furthermore, msvcr110.dll changed the undocumented _locale_t
  * content to carry locale names instead of locale identifiers.
  *
- * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol.
- * IsoLocaleName() always fails in a MinGW-built postgres.exe, so only
- * Unix-style values of the lc_messages GUC can elicit localized messages.  In
- * particular, every lc_messages setting that initdb can select automatically
- * will yield only C-locale messages.  XXX This could be fixed by running the
- * fully-qualified locale name through a lookup table.
+ * Visual Studio 2015 should still be able to do the same as Visual Studio
+ * 2012, but the declaration of locale_name is missing in _locale_t, causing
+ * this code compilation to fail, hence this falls back instead on to
+ * enumerating all system locales by using EnumSystemLocalesEx to find the
+ * required locale name.  If the input argument is in Unix-style then we can
+ * get ISO Locale name directly by using GetLocaleInfoEx() with LCType as
+ * LOCALE_SNAME.
+ *
+ * MinGW headers declare _create_locale(), but msvcrt.dll lacks that symbol in
+ * releases before Windows 8. IsoLocaleName() always fails in a MinGW-built
+ * postgres.exe, so only Unix-style values of the lc_messages GUC can elicit
+ * localized messages. In particular, every lc_messages setting that initdb
+ * can select automatically will yield only C-locale messages. XXX This could
+ * be fixed by running the fully-qualified locale name through a lookup table.
  *
  * This function returns a pointer to a static buffer bearing the converted
  * name or NULL if conversion fails.
  *
- * [1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373763.aspx
- * [2] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373814.aspx
+ * [1] https://docs.microsoft.com/en-us/windows/win32/intl/locale-identifiers
+ * [2] https://docs.microsoft.com/en-us/windows/win32/intl/locale-names
  */
+
+#if _MSC_VER >= 1900
+/*
+ * Callback function for EnumSystemLocalesEx() in get_iso_localename().
+ *
+ * This function enumerates all system locales, searching for one that matches
+ * an input with the format: <Language>[_<Country>], e.g.
+ * English[_United States]
+ *
+ * The input is a three wchar_t array as an LPARAM. The first element is the
+ * locale_name we want to match, the second element is an allocated buffer
+ * where the Unix-style locale is copied if a match is found, and the third
+ * element is the search status, 1 if a match was found, 0 otherwise.
+ */
+static BOOL CALLBACK
+search_locale_enum(LPWSTR pStr, DWORD dwFlags, LPARAM lparam)
+{
+	wchar_t		test_locale[LOCALE_NAME_MAX_LENGTH];
+	wchar_t   **argv;
+
+	(void) (dwFlags);
+
+	argv = (wchar_t **) lparam;
+	*argv[2] = (wchar_t) 0;
+
+	memset(test_locale, 0, sizeof(test_locale));
+
+	/* Get the name of the <Language> in English */
+	if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHLANGUAGENAME,
+						test_locale, LOCALE_NAME_MAX_LENGTH))
+	{
+		/*
+		 * If the enumerated locale does not have a hyphen ("en") OR  the
+		 * lc_message input does not have an underscore ("English"), we only
+		 * need to compare the <Language> tags.
+		 */
+		if (wcsrchr(pStr, '-') == NULL || wcsrchr(argv[0], '_') == NULL)
+		{
+			if (_wcsicmp(argv[0], test_locale) == 0)
+			{
+				wcscpy(argv[1], pStr);
+				*argv[2] = (wchar_t) 1;
+				return FALSE;
+			}
+		}
+
+		/*
+		 * We have to compare a full <Language>_<Country> tag, so we append
+		 * the underscore and name of the country/region in English, e.g.
+		 * "English_United States".
+		 */
+		else
+		{
+			size_t		len;
+
+			wcscat(test_locale, L"_");
+			len = wcslen(test_locale);
+			if (GetLocaleInfoEx(pStr, LOCALE_SENGLISHCOUNTRYNAME,
+								test_locale + len,
+								LOCALE_NAME_MAX_LENGTH - len))
+			{
+				if (_wcsicmp(argv[0], test_locale) == 0)
+				{
+					wcscpy(argv[1], pStr);
+					*argv[2] = (wchar_t) 1;
+					return FALSE;
+				}
+			}
+		}
+	}
+
+	return TRUE;
+}
+
+/*
+ * This function converts a Windows locale name to an ISO formatted version
+ * for Visual Studio 2015 or greater.
+ *
+ * Returns the size of the ISO locale name, where -1 means that no valid
+ * conversion was found.
+ */
+static size_t
+get_iso_localename(const char *winlocname, char *isolocname)
+{
+	wchar_t		wc_locale_name[LOCALE_NAME_MAX_LENGTH];
+	wchar_t		buffer[LOCALE_NAME_MAX_LENGTH];
+	char	   *period;
+	int			len;
+	int			ret_val;
+
+	/*
+	 * Valid locales have the following syntax:
+	 * <Language>[_<Country>[.<CodePage>]]
+	 *
+	 * GetLocaleInfoEx can only take locale name without code-page and for the
+	 * purpose of this API the code-page doesn't matter.
+	 */
+	period = strchr(winlocname, '.');
+	if (period != NULL)
+		len = period - winlocname;
+	else
+		len = pg_mbstrlen(winlocname);
+
+	memset(wc_locale_name, 0, sizeof(wc_locale_name));
+	memset(buffer, 0, sizeof(buffer));
+	MultiByteToWideChar(CP_ACP, 0, winlocname, len, wc_locale_name,
+						LOCALE_NAME_MAX_LENGTH);
+
+	/*
+	 * If the lc_messages is already an Unix-style string, we have a direct
+	 * match with LOCALE_SNAME, e.g. en-US, en_US.
+	 */
+	ret_val = GetLocaleInfoEx(wc_locale_name, LOCALE_SNAME, (LPWSTR) &buffer,
+							  LOCALE_NAME_MAX_LENGTH);
+	if (!ret_val)
+	{
+		/*
+		 * Search for a locale in the system that matches language and country
+		 * name.
+		 */
+		wchar_t    *argv[3];
+
+		argv[0] = wc_locale_name;
+		argv[1] = buffer;
+		argv[2] = (wchar_t *) &ret_val;
+		EnumSystemLocalesEx(search_locale_enum, LOCALE_WINDOWS, (LPARAM) argv,
+							NULL);
+	}
+
+	if (ret_val)
+	{
+		/* Locale names use only ASCII, any conversion locale suffices. */
+		return wchar2char(isolocname, buffer, sizeof(isolocname),
+						  NULL);
+	}
+
+	return (size_t) -1;
+}
+#endif							/* _MSC_VER >= 1900 */
+
 static char *
 IsoLocaleName(const char *winlocname)
 {
-#ifdef _MSC_VER
-	static char iso_lc_messages[32];
-	_locale_t	loct = NULL;
+#if defined(_MSC_VER)
+	static char iso_lc_messages[LOCALE_NAME_MAX_LENGTH];
 
 	if (pg_strcasecmp("c", winlocname) == 0 ||
 		pg_strcasecmp("posix", winlocname) == 0)
@@ -997,17 +1145,26 @@ IsoLocaleName(const char *winlocname)
 		strcpy(iso_lc_messages, "C");
 		return iso_lc_messages;
 	}
-
-	loct = _create_locale(LC_CTYPE, winlocname);
-	if (loct != NULL)
+	else
 	{
-		size_t		rc;
+		size_t		rc = -1;
 		char	   *hyphen;
 
-		/* Locale names use only ASCII, any conversion locale suffices. */
-		rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
-						sizeof(iso_lc_messages), NULL);
-		_free_locale(loct);
+#if (_MSC_VER >= 1900)			/* Visual Studio 2015 or later */
+		rc = get_iso_localename(winlocname, iso_lc_messages);
+#else
+		_locale_t	loct;
+
+		loct = _create_locale(LC_CTYPE, winlocname);
+		if (loct != NULL)
+		{
+			/* Locale names use only ASCII, any conversion locale suffices. */
+			rc = wchar2char(iso_lc_messages, loct->locinfo->locale_name[LC_CTYPE],
+							sizeof(iso_lc_messages), NULL);
+			_free_locale(loct);
+		}
+#endif							/* Visual Studio 2015 or later */
+
 		if (rc == -1 || rc == sizeof(iso_lc_messages))
 			return NULL;
 
@@ -1029,7 +1186,7 @@ IsoLocaleName(const char *winlocname)
 			*hyphen = '_';
 		return iso_lc_messages;
 	}
-#endif							/* _MSC_VER */
+#endif							/* defined(_MSC_VER) */
 	return NULL;				/* Not supported on this version of msvc/mingw */
 }
 #endif							/* WIN32 && LC_MESSAGES */
-- 
1.8.3.1

