v1-0005-Add-global_lc_ctype-to-hold-locale_t-for-datctype.patch

From 60e659df02c33b14ee232c578d8dfdbfe1fb6dc6 Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Fri, 6 Jun 2025 14:13:16 -0700
Subject: [PATCH v1 5/8] Add global_lc_ctype to hold locale_t for datctype.

Callers of locale-aware ctype operations should use the "_l" variants
of the functions and pass global_lc_ctype for the locale. Doing so
avoids depending on setlocale().
---
 src/backend/utils/adt/pg_locale_libc.c | 32 ++++++++++++++++++++++++--
 src/backend/utils/init/postinit.c      |  2 ++
 src/include/utils/pg_locale.h          |  7 ++++++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale_libc.c b/src/backend/utils/adt/pg_locale_libc.c
index 199857e22db..a45fb4df38c 100644
--- a/src/backend/utils/adt/pg_locale_libc.c
+++ b/src/backend/utils/adt/pg_locale_libc.c
@@ -85,6 +85,12 @@ static size_t strupper_libc_mb(char *dest, size_t destsize,
 							   const char *src, ssize_t srclen,
 							   pg_locale_t locale);
 
+/*
+ * Represents datctype in a global variable, so that we don't need to rely on
+ * setlocale().
+ */
+locale_t	global_lc_ctype = NULL;
+
 static const struct collate_methods collate_methods_libc = {
 	.strncoll = strncoll_libc,
 	.strnxfrm = strnxfrm_libc,
@@ -417,6 +423,28 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen,
 	return result_size;
 }
 
+void
+init_global_lc_ctype(const char *ctype)
+{
+	locale_t	loc;
+
+	errno = 0;
+#ifndef WIN32
+	loc = newlocale(LC_CTYPE_MASK, ctype, NULL);
+#else
+	loc = _create_locale(LC_ALL, ctype);
+#endif
+
+	if (!loc)
+		ereport(FATAL,
+				(errmsg("database locale is incompatible with operating system"),
+				 errdetail("The database was initialized with LC_CTYPE \"%s\", "
+						   " which is not recognized by setlocale().", ctype),
+				 errhint("Recreate the database with another locale or install the missing locale.")));
+
+	global_lc_ctype = loc;
+}
+
 pg_locale_t
 create_pg_locale_libc(Oid collid, MemoryContext context)
 {
@@ -912,7 +940,7 @@ wchar2char(char *to, const wchar_t *from, size_t tolen, pg_locale_t locale)
 	if (locale == (pg_locale_t) 0)
 	{
 		/* Use wcstombs directly for the default locale */
-		result = wcstombs(to, from, tolen);
+		result = wcstombs_l(to, from, tolen, global_lc_ctype);
 	}
 	else
 	{
@@ -972,7 +1000,7 @@ char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen,
 		if (locale == (pg_locale_t) 0)
 		{
 			/* Use mbstowcs directly for the default locale */
-			result = mbstowcs(to, str, tolen);
+			result = mbstowcs_l(to, str, tolen, global_lc_ctype);
 		}
 		else
 		{
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index c86ceefda94..3eaa1486f6f 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -431,6 +431,8 @@ CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connect
 						   " which is not recognized by setlocale().", ctype),
 				 errhint("Recreate the database with another locale or install the missing locale.")));
 
+	init_global_lc_ctype(ctype);
+
 	if (strcmp(ctype, "C") == 0 ||
 		strcmp(ctype, "POSIX") == 0)
 		database_ctype_is_c = true;
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 7b8cbf58d2c..7fdf420dd7a 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -32,6 +32,12 @@ extern PGDLLIMPORT char *localized_full_days[];
 extern PGDLLIMPORT char *localized_abbrev_months[];
 extern PGDLLIMPORT char *localized_full_months[];
 
+/*
+ * Represents datctype in a global variable, so that we don't need to rely on
+ * setlocale().
+ */
+extern PGDLLIMPORT locale_t global_lc_ctype;
+
 /* is the databases's LC_CTYPE the C locale? */
 extern PGDLLIMPORT bool database_ctype_is_c;
 
@@ -121,6 +127,7 @@ struct pg_locale_struct
 	}			info;
 };
 
+extern void init_global_lc_ctype(const char *ctype);
 extern void init_database_collation(void);
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
-- 
2.43.0