v4-0003-Handle-the-und-locale-in-ICU-versions-54-and-olde.patch

From 0ae14118d593d73ea441648fc3c8df067253f627 Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Tue, 14 Mar 2023 22:28:21 -0700
Subject: [PATCH v4 3/3] Handle the "und" locale in ICU versions 54 and older.

The "und" locale is an alternative spelling of the root locale, but it
was not recognized until ICU 55. To maintain common behavior across
all supported ICU versions, check for "und" and replace with "root"
before opening.

Previously, the lack of support for "und" was dangerous, because
versions 54 and older fall back to the environment when a locale is
not found. If the user specified "und" for the language (which is
expected and documented), it could not only resolve to the wrong
collator, but it could unexpectedly change (which could lead to
corrupt indexes).

This effectively reverts commit d72900bded, which worked around the
problem for the built-in "unicode" collation, and is no longer
necessary.
---
 src/backend/utils/adt/pg_locale.c             | 30 +++++++++++++++++++
 src/bin/initdb/initdb.c                       |  2 +-
 src/include/catalog/catversion.h              |  2 +-
 .../regress/expected/collate.icu.utf8.out     |  7 +++++
 src/test/regress/sql/collate.icu.utf8.sql     |  2 ++
 5 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 04d1fa72a8..4dee0f40cb 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1420,12 +1420,35 @@ lc_ctype_is_c(Oid collation)
 
 struct pg_locale_struct default_locale;
 
+#ifdef USE_ICU
+
 static UCollator *
 pg_ucol_open(const char *locale_str)
 {
 	UCollator  *collator;
 	UErrorCode	status;
 
+	/*
+	 * In ICU versions 55 and earlier, "und" is not a recognized spelling of
+	 * the root locale. If the first component of the locale is "und", replace
+	 * with "root" before opening.
+	 */
+#if U_ICU_VERSION_MAJOR_NUM < 55
+	char *fixed_str = NULL;
+
+	if (strncasecmp(locale_str, "und", strlen("und")) == 0 &&
+		!isalnum(locale_str[strlen("und")]))
+	{
+		const char *remainder = locale_str + strlen("und");
+
+		fixed_str = palloc(strlen("root") + strlen(remainder) + 1);
+		strcpy(fixed_str, "root");
+		strcat(fixed_str, remainder);
+
+		locale_str = fixed_str;
+	}
+#endif
+
 	status = U_ZERO_ERROR;
 	collator = ucol_open(locale_str, &status);
 	if (U_FAILURE(status))
@@ -1437,9 +1460,16 @@ pg_ucol_open(const char *locale_str)
 	icu_set_collation_attributes(collator, locale_str);
 #endif
 
+#if U_ICU_VERSION_MAJOR_NUM < 55
+	if (fixed_str != NULL)
+		pfree(fixed_str);
+#endif
+
 	return collator;
 }
 
+#endif
+
 void
 make_icu_collator(const char *iculocstr,
 				  const char *icurules,
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 68d430ed63..d48b7b6060 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1498,7 +1498,7 @@ setup_collation(FILE *cmdfd)
 	 * that they win if libc defines a locale with the same name.
 	 */
 	PG_CMD_PRINTF("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, colliculocale)"
-				  "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'unicode', 'pg_catalog'::regnamespace, %u, '%c', true, -1, '');\n\n",
+				  "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'unicode', 'pg_catalog'::regnamespace, %u, '%c', true, -1, 'und');\n\n",
 				  BOOTSTRAP_SUPERUSERID, COLLPROVIDER_ICU);
 
 	PG_CMD_PRINTF("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 309aed3703..b2eed22d46 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202303141
+#define CATALOG_VERSION_NO	202303151
 
 #endif
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 6225b575ce..f135200c99 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1312,6 +1312,13 @@ SELECT 'aBcD' COLLATE lt_insensitive = 'AbCd' COLLATE lt_insensitive;
  t
 (1 row)
 
+CREATE COLLATION lt_upperfirst (provider = icu, locale = 'und-u-kf-upper');
+SELECT 'Z' COLLATE lt_upperfirst < 'z' COLLATE lt_upperfirst;
+ ?column? 
+----------
+ t
+(1 row)
+
 CREATE TABLE test1cs (x text COLLATE case_sensitive);
 CREATE TABLE test2cs (x text COLLATE case_sensitive);
 CREATE TABLE test3cs (x text COLLATE case_sensitive);
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 64cbfd0a5b..8105ebc8ae 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -521,6 +521,8 @@ SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_inse
 -- test language tags
 CREATE COLLATION lt_insensitive (provider = icu, locale = 'en-u-ks-level1', deterministic = false);
 SELECT 'aBcD' COLLATE lt_insensitive = 'AbCd' COLLATE lt_insensitive;
+CREATE COLLATION lt_upperfirst (provider = icu, locale = 'und-u-kf-upper');
+SELECT 'Z' COLLATE lt_upperfirst < 'z' COLLATE lt_upperfirst;
 
 CREATE TABLE test1cs (x text COLLATE case_sensitive);
 CREATE TABLE test2cs (x text COLLATE case_sensitive);
-- 
2.34.1