v4-0003-Initialize-datctype-in-global-locale_t-variable.patch

From 3b7f43c4ad3b2bd99de95ae9db980d7bc465a8a9 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 v4 3/8] Initialize datctype in global locale_t variable.

Callers of locale-aware ctype operations should use the "_l" variants
of the functions and pass global_libc_ctype for the locale. Doing so
avoids depending on setlocale().

Discussion: https://postgr.es/m/9875f7f9-50f1-4b5d-86fc-ee8b03e8c162@eisentraut.org
---
 src/backend/utils/adt/pg_locale_libc.c | 35 ++++++++++++++++++++++++++
 src/backend/utils/init/postinit.c      |  2 ++
 src/include/utils/pg_locale.h          |  7 ++++++
 3 files changed, 44 insertions(+)

diff --git a/src/backend/utils/adt/pg_locale_libc.c b/src/backend/utils/adt/pg_locale_libc.c
index 8d88b53c375..33a082b6490 100644
--- a/src/backend/utils/adt/pg_locale_libc.c
+++ b/src/backend/utils/adt/pg_locale_libc.c
@@ -81,6 +81,12 @@
  */
 #define		TEXTBUFLEN			1024
 
+/*
+ * Represents datctype locale in a global variable, so that we don't need to
+ * rely on setlocale() anywhere.
+ */
+locale_t	global_libc_ctype = NULL;
+
 extern pg_locale_t create_pg_locale_libc(Oid collid, MemoryContext context);
 
 static int	strncoll_libc(const char *arg1, ssize_t len1,
@@ -665,6 +671,35 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen,
 	return result_size;
 }
 
+/*
+ * Initialize global locale for LC_COLLATE and LC_CTYPE from datcollate and
+ * datctype, respectively.
+ *
+ * NB: should be consistent with make_libc_collator(), except that it must
+ * create the locale even for "C" and "POSIX".
+ */
+void
+init_global_libc_ctype(const char *ctype)
+{
+	locale_t	loc = 0;
+
+	/* Normal case where they're the same */
+	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_libc_ctype = loc;
+}
+
 pg_locale_t
 create_pg_locale_libc(Oid collid, MemoryContext context)
 {
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 464f1196be3..81bde31a791 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -429,6 +429,8 @@ 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_libc_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 6c60f2e2a74..a4ab020685f 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -34,6 +34,12 @@ extern PGDLLIMPORT char *localized_full_days[];
 extern PGDLLIMPORT char *localized_abbrev_months[];
 extern PGDLLIMPORT char *localized_full_months[];
 
+/*
+ * Represents datcollate and datctype locales in a global variable, so that we
+ * don't need to rely on setlocale() anywhere.
+ */
+extern PGDLLIMPORT locale_t global_libc_ctype;
+
 /* is the databases's LC_CTYPE the C locale? */
 extern PGDLLIMPORT bool database_ctype_is_c;
 
@@ -169,6 +175,7 @@ struct pg_locale_struct
 	}			info;
 };
 
+extern void init_global_libc_ctype(const char *ctype);
 extern void init_database_collation(void);
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
-- 
2.43.0