Fix missed lock acquisition while inlining new-style SQL functions.

When starting to use a query parsetree loaded from the catalogs,
we must begin by applying AcquireRewriteLocks(), to obtain the same
relation locks that the parser would have gotten if the query were
entered interactively, and to do some other cleanup such as dealing
with later-dropped columns.  New-style SQL functions are just as
subject to this rule as other stored parsetrees; however, of the
places dealing with such functions, only init_sql_fcache had gotten
the memo.  In particular, if we successfully inlined a new-style
set-returning SQL function that contained any relation references,
we'd either get an assertion failure or attempt to use those
relation(s) sans locks.

I also added AcquireRewriteLocks calls to fmgr_sql_validator and
print_function_sqlbody.  Desultory experiments didn't demonstrate any
failures in those, but I suspect that I just didn't try hard enough.
Certainly we don't expect nearby code paths to operate without locks.

On the same logic of it-ought-to-have-the-same-effects-as-the-old-code,
call pg_rewrite_query() in fmgr_sql_validator, too.  It's possible
that neither code path there needs to bother with rewriting, but
doing the analysis to prove that is beyond my goals for today.

Per bug #17161 from Alexander Lakhin.

Discussion: https://postgr.es/m/17161-048a1cdff8422800@postgresql.org

src/backend/catalog/pg_proc.c

@@ -35,6 +35,7 @@
 #include "parser/analyze.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_type.h"
+#include "rewrite/rewriteHandler.h"
 #include "tcop/pquery.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
@@ -891,12 +892,30 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
 		if (!isnull)
 		{
 			Node	   *n;
+			List	   *stored_query_list;
 
 			n = stringToNode(TextDatumGetCString(tmp));
 			if (IsA(n, List))
-				querytree_list = castNode(List, n);
+				stored_query_list = linitial(castNode(List, n));
 			else
-				querytree_list = list_make1(list_make1(n));
+				stored_query_list = list_make1(n);
+
+			querytree_list = NIL;
+			foreach(lc, stored_query_list)
+			{
+				Query	   *parsetree = lfirst_node(Query, lc);
+				List	   *querytree_sublist;
+
+				/*
+				 * Typically, we'd have acquired locks already while parsing
+				 * the body of the CREATE FUNCTION command.  However, a
+				 * validator function cannot assume that it's only called in
+				 * that context.
+				 */
+				AcquireRewriteLocks(parsetree, true, false);
+				querytree_sublist = pg_rewrite_query(parsetree);
+				querytree_list = lappend(querytree_list, querytree_sublist);
+			}
 		}
 		else
 		{

src/backend/optimizer/util/clauses.c

@@ -43,6 +43,7 @@
 #include "parser/parse_agg.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_func.h"
+#include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteManip.h"
 #include "tcop/tcopprot.h"
 #include "utils/acl.h"
@@ -4423,6 +4424,12 @@ inline_function(Oid funcid, Oid result_type, Oid result_collid,
 		if (list_length(querytree_list) != 1)
 			goto fail;
 		querytree = linitial(querytree_list);
+
+		/*
+		 * Because we'll insist below that the querytree have an empty rtable
+		 * and no sublinks, it cannot have any relation references that need
+		 * to be locked or rewritten.  So we can omit those steps.
+		 */
 	}
 	else
 	{
@@ -4975,6 +4982,8 @@ inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
 			goto fail;
 		querytree = linitial(querytree_list);
 
+		/* Acquire necessary locks, then apply rewriter. */
+		AcquireRewriteLocks(querytree, true, false);
 		querytree_list = pg_rewrite_query(querytree);
 		if (list_length(querytree_list) != 1)
 			goto fail;

src/backend/utils/adt/ruleutils.c

@@ -2973,7 +2973,7 @@ pg_get_functiondef(PG_FUNCTION_ARGS)
 	}
 
 	/* And finally the function definition ... */
-	tmp = SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
+	(void) SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
 	if (proc->prolang == SQLlanguageId && !isnull)
 	{
 		print_function_sqlbody(&buf, proctup);
@@ -3439,7 +3439,10 @@ print_function_sqlbody(StringInfo buf, HeapTuple proctup)
 		{
 			Query	   *query = lfirst_node(Query, lc);
 
-			get_query_def(query, buf, list_make1(&dpns), NULL, PRETTYFLAG_INDENT, WRAP_COLUMN_DEFAULT, 1);
+			/* It seems advisable to get at least AccessShareLock on rels */
+			AcquireRewriteLocks(query, false, false);
+			get_query_def(query, buf, list_make1(&dpns), NULL,
+						  PRETTYFLAG_INDENT, WRAP_COLUMN_DEFAULT, 1);
 			appendStringInfoChar(buf, ';');
 			appendStringInfoChar(buf, '\n');
 		}
@@ -3448,7 +3451,12 @@ print_function_sqlbody(StringInfo buf, HeapTuple proctup)
 	}
 	else
 	{
-		get_query_def(castNode(Query, n), buf, list_make1(&dpns), NULL, 0, WRAP_COLUMN_DEFAULT, 0);
+		Query	   *query = castNode(Query, n);
+
+		/* It seems advisable to get at least AccessShareLock on rels */
+		AcquireRewriteLocks(query, false, false);
+		get_query_def(query, buf, list_make1(&dpns), NULL,
+					  0, WRAP_COLUMN_DEFAULT, 0);
 	}
 }
 
@@ -3467,7 +3475,7 @@ pg_get_function_sqlbody(PG_FUNCTION_ARGS)
 	if (!HeapTupleIsValid(proctup))
 		PG_RETURN_NULL();
 
-	SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
+	(void) SysCacheGetAttr(PROCOID, proctup, Anum_pg_proc_prosqlbody, &isnull);
 	if (isnull)
 	{
 		ReleaseSysCache(proctup);

src/test/regress/expected/create_function_3.out

@@ -543,11 +543,13 @@ ERROR:  cannot change routine kind
 DETAIL:  "functest1" is a function.
 DROP FUNCTION functest1(a int);
 -- inlining of set-returning functions
+CREATE TABLE functest3 (a int);
+INSERT INTO functest3 VALUES (1), (2), (3);
 CREATE FUNCTION functest_sri1() RETURNS SETOF int
 LANGUAGE SQL
 STABLE
 AS '
-    VALUES (1), (2), (3);
+    SELECT * FROM functest3;
 ';
 SELECT * FROM functest_sri1();
  functest_sri1 
@@ -559,16 +561,16 @@ SELECT * FROM functest_sri1();
 
 EXPLAIN (verbose, costs off) SELECT * FROM functest_sri1();
               QUERY PLAN              
-------------------------------
- Values Scan on "*VALUES*"
-   Output: "*VALUES*".column1
+--------------------------------------
+ Seq Scan on temp_func_test.functest3
+   Output: functest3.a
 (2 rows)
 
 CREATE FUNCTION functest_sri2() RETURNS SETOF int
 LANGUAGE SQL
 STABLE
 BEGIN ATOMIC
-    VALUES (1), (2), (3);
+    SELECT * FROM functest3;
 END;
 SELECT * FROM functest_sri2();
  functest_sri2 
@@ -580,11 +582,13 @@ SELECT * FROM functest_sri2();
 
 EXPLAIN (verbose, costs off) SELECT * FROM functest_sri2();
               QUERY PLAN              
-------------------------------
- Values Scan on "*VALUES*"
-   Output: "*VALUES*".column1
+--------------------------------------
+ Seq Scan on temp_func_test.functest3
+   Output: functest3.a
 (2 rows)
 
+DROP TABLE functest3 CASCADE;
+NOTICE:  drop cascades to function functest_sri2()
 -- Check behavior of VOID-returning SQL functions
 CREATE FUNCTION voidtest1(a int) RETURNS VOID LANGUAGE SQL AS
 $$ SELECT a + 1 $$;
@@ -643,7 +647,7 @@ SELECT * FROM voidtest5(3);
 
 -- Cleanup
 DROP SCHEMA temp_func_test CASCADE;
-NOTICE:  drop cascades to 30 other objects
+NOTICE:  drop cascades to 29 other objects
 DETAIL:  drop cascades to function functest_a_1(text,date)
 drop cascades to function functest_a_2(text[])
 drop cascades to function functest_a_3()
@@ -668,7 +672,6 @@ drop cascades to function functest_s_13()
 drop cascades to function functest_s_15(integer)
 drop cascades to function functest_b_2(bigint)
 drop cascades to function functest_sri1()
-drop cascades to function functest_sri2()
 drop cascades to function voidtest1(integer)
 drop cascades to function voidtest2(integer,integer)
 drop cascades to function voidtest3(integer)

src/test/regress/sql/create_function_3.sql

@@ -319,11 +319,14 @@ DROP FUNCTION functest1(a int);
 
 -- inlining of set-returning functions
 
+CREATE TABLE functest3 (a int);
+INSERT INTO functest3 VALUES (1), (2), (3);
+
 CREATE FUNCTION functest_sri1() RETURNS SETOF int
 LANGUAGE SQL
 STABLE
 AS '
-    VALUES (1), (2), (3);
+    SELECT * FROM functest3;
 ';
 
 SELECT * FROM functest_sri1();
@@ -333,12 +336,14 @@ CREATE FUNCTION functest_sri2() RETURNS SETOF int
 LANGUAGE SQL
 STABLE
 BEGIN ATOMIC
-    VALUES (1), (2), (3);
+    SELECT * FROM functest3;
 END;
 
 SELECT * FROM functest_sri2();
 EXPLAIN (verbose, costs off) SELECT * FROM functest_sri2();
 
+DROP TABLE functest3 CASCADE;
+
 
 -- Check behavior of VOID-returning SQL functions