Add has_largeobject_privilege function.

This function checks whether a user has specific privileges on a large object,
identified by OID. The user can be provided by name, OID,
or default to the current user. If the specified large object doesn't exist,
the function returns NULL. It raises an error for a non-existent user name.
This behavior is basically consistent with other privilege inquiry functions
like has_table_privilege.

Bump catalog version.

Author: Yugo Nagata
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/20240702163444.ab586f6075e502eb84f11b1a@sranhm.sraoss.co.jp

src/backend/utils/adt/acl.c

@@ -26,6 +26,7 @@
 #include "catalog/pg_foreign_data_wrapper.h"
 #include "catalog/pg_foreign_server.h"
 #include "catalog/pg_language.h"
+#include "catalog/pg_largeobject.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_tablespace.h"
@@ -39,6 +40,7 @@
 #include "lib/bloomfilter.h"
 #include "lib/qunique.h"
 #include "miscadmin.h"
+#include "storage/large_object.h"
 #include "utils/acl.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
@@ -46,6 +48,7 @@
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
+#include "utils/snapmgr.h"
 #include "utils/syscache.h"
 #include "utils/varlena.h"
 
@@ -124,6 +127,7 @@ static AclMode convert_tablespace_priv_string(text *priv_type_text);
 static Oid	convert_type_name(text *typename);
 static AclMode convert_type_priv_string(text *priv_type_text);
 static AclMode convert_parameter_priv_string(text *priv_text);
+static AclMode convert_largeobject_priv_string(text *priv_text);
 static AclMode convert_role_priv_string(text *priv_type_text);
 static AclResult pg_role_aclcheck(Oid role_oid, Oid roleid, AclMode mode);
 
@@ -4663,6 +4667,142 @@ convert_parameter_priv_string(text *priv_text)
 	return convert_any_priv_string(priv_text, parameter_priv_map);
 }
 
+/*
+ * has_largeobject_privilege variants
+ *		These are all named "has_largeobject_privilege" at the SQL level.
+ *		They take various combinations of large object OID with
+ *		user name, user OID, or implicit user = current_user.
+ *
+ *		The result is a boolean value: true if user has the indicated
+ *		privilege, false if not, or NULL if object doesn't exist.
+ */
+
+/*
+ * has_lo_priv_byid
+ *
+ *		Helper function to check user privileges on a large object given the
+ *		role by Oid, large object by Oid, and privileges as AclMode.
+ */
+static bool
+has_lo_priv_byid(Oid roleid, Oid lobjId, AclMode priv, bool *is_missing)
+{
+	Snapshot	snapshot = NULL;
+	AclResult	aclresult;
+
+	if (priv & ACL_UPDATE)
+		snapshot = NULL;
+	else
+		snapshot = GetActiveSnapshot();
+
+	if (!LargeObjectExistsWithSnapshot(lobjId, snapshot))
+	{
+		Assert(is_missing != NULL);
+		*is_missing = true;
+		return false;
+	}
+
+	if (lo_compat_privileges)
+		return true;
+
+	aclresult = pg_largeobject_aclcheck_snapshot(lobjId,
+												 roleid,
+												 priv,
+												 snapshot);
+	return aclresult == ACLCHECK_OK;
+}
+
+/*
+ * has_largeobject_privilege_name_id
+ *		Check user privileges on a large object given
+ *		name username, large object oid, and text priv name.
+ */
+Datum
+has_largeobject_privilege_name_id(PG_FUNCTION_ARGS)
+{
+	Name		username = PG_GETARG_NAME(0);
+	Oid			roleid = get_role_oid_or_public(NameStr(*username));
+	Oid			lobjId = PG_GETARG_OID(1);
+	text	   *priv_type_text = PG_GETARG_TEXT_PP(2);
+	AclMode		mode;
+	bool		is_missing = false;
+	bool		result;
+
+	mode = convert_largeobject_priv_string(priv_type_text);
+	result = has_lo_priv_byid(roleid, lobjId, mode, &is_missing);
+
+	if (is_missing)
+		PG_RETURN_NULL();
+
+	PG_RETURN_BOOL(result);
+}
+
+/*
+ * has_largeobject_privilege_id
+ *		Check user privileges on a large object given
+ *		large object oid, and text priv name.
+ *		current_user is assumed
+ */
+Datum
+has_largeobject_privilege_id(PG_FUNCTION_ARGS)
+{
+	Oid			lobjId = PG_GETARG_OID(0);
+	Oid			roleid = GetUserId();
+	text	   *priv_type_text = PG_GETARG_TEXT_PP(1);
+	AclMode		mode;
+	bool		is_missing = false;
+	bool		result;
+
+	mode = convert_largeobject_priv_string(priv_type_text);
+	result = has_lo_priv_byid(roleid, lobjId, mode, &is_missing);
+
+	if (is_missing)
+		PG_RETURN_NULL();
+
+	PG_RETURN_BOOL(result);
+}
+
+/*
+ * has_largeobject_privilege_id_id
+ *		Check user privileges on a large object given
+ *		roleid, large object oid, and text priv name.
+ */
+Datum
+has_largeobject_privilege_id_id(PG_FUNCTION_ARGS)
+{
+	Oid			roleid = PG_GETARG_OID(0);
+	Oid			lobjId = PG_GETARG_OID(1);
+	text	   *priv_type_text = PG_GETARG_TEXT_PP(2);
+	AclMode		mode;
+	bool		is_missing = false;
+	bool		result;
+
+	mode = convert_largeobject_priv_string(priv_type_text);
+	result = has_lo_priv_byid(roleid, lobjId, mode, &is_missing);
+
+	if (is_missing)
+		PG_RETURN_NULL();
+
+	PG_RETURN_BOOL(result);
+}
+
+/*
+ * convert_largeobject_priv_string
+ *		Convert text string to AclMode value.
+ */
+static AclMode
+convert_largeobject_priv_string(text *priv_type_text)
+{
+	static const priv_map largeobject_priv_map[] = {
+		{"SELECT", ACL_SELECT},
+		{"SELECT WITH GRANT OPTION", ACL_GRANT_OPTION_FOR(ACL_SELECT)},
+		{"UPDATE", ACL_UPDATE},
+		{"UPDATE WITH GRANT OPTION", ACL_GRANT_OPTION_FOR(ACL_UPDATE)},
+		{NULL, 0}
+	};
+
+	return convert_any_priv_string(priv_type_text, largeobject_priv_map);
+}
+
 /*
  * pg_has_role variants
  *		These are all named "pg_has_role" at the SQL level.