Check column list length in XMLTABLE/JSON_TABLE alias

We weren't checking the length of the column list in the alias clause of
an XMLTABLE or JSON_TABLE function (a "tablefunc" RTE), and it was
possible to make the server crash by passing an overly long one.  Fix it
by throwing an error in that case, like the other places that deal with
alias lists.

In passing, modify the equivalent test used for join RTEs to look like
the other ones, which was different for no apparent reason.

This bug came in when XMLTABLE was born in version 10; backpatch to all
stable versions.

Reported-by: Wang Ke <krking@zju.edu.cn>
Discussion: https://postgr.es/m/17480-1c9d73565bb28e90@postgresql.org

Author: alvherre

src/backend/parser/parse_clause.c

@@ -1444,21 +1444,6 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 									&res_colnames, &res_colvars,
 									res_nscolumns + res_colindex);
 
-		/*
-		 * Check alias (AS clause), if any.
-		 */
-		if (j->alias)
-		{
-			if (j->alias->colnames != NIL)
-			{
-				if (list_length(j->alias->colnames) > list_length(res_colnames))
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("column alias list for \"%s\" has too many entries",
-									j->alias->aliasname)));
-			}
-		}
-
 		/*
 		 * Now build an RTE and nsitem for the result of the join.
 		 * res_nscolumns isn't totally done yet, but that's OK because

src/backend/parser/parse_relation.c

@@ -1989,11 +1989,13 @@ addRangeTableEntryForTableFunc(ParseState *pstate,
 							   bool inFromCl)
 {
 	RangeTblEntry *rte = makeNode(RangeTblEntry);
-	char	   *refname = alias ? alias->aliasname :
-	pstrdup(tf->functype == TFT_XMLTABLE ? "xmltable" : "json_table");
+	char	   *refname;
 	Alias	   *eref;
 	int			numaliases;
 
+	refname = alias ? alias->aliasname :
+		pstrdup(tf->functype == TFT_XMLTABLE ? "xmltable" : "json_table");
+
 	Assert(pstate != NULL);
 
 	rte->rtekind = RTE_TABLEFUNC;
@@ -2013,6 +2015,13 @@ addRangeTableEntryForTableFunc(ParseState *pstate,
 		eref->colnames = list_concat(eref->colnames,
 									 list_copy_tail(tf->colnames, numaliases));
 
+	if (numaliases > list_length(tf->colnames))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+				 errmsg("%s function has %d columns available but %d columns specified",
+						tf->functype == TFT_XMLTABLE ? "XMLTABLE" : "JSON_TABLE",
+						list_length(tf->colnames), numaliases)));
+
 	rte->eref = eref;
 
 	/*
@@ -2192,6 +2201,12 @@ addRangeTableEntryForJoin(ParseState *pstate,
 		eref->colnames = list_concat(eref->colnames,
 									 list_copy_tail(colnames, numaliases));
 
+	if (numaliases > list_length(colnames))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+				 errmsg("join expression \"%s\" has %d columns available but %d columns specified",
+						eref->aliasname, list_length(colnames), numaliases)));
+
 	rte->eref = eref;
 
 	/*

src/test/regress/expected/int2.out

@@ -45,6 +45,10 @@ SELECT * FROM INT2_TBL;
  -32767
 (5 rows)
 
+SELECT * FROM INT2_TBL AS f(a, b);
+ERROR:  table "f" has 1 columns available but 2 columns specified
+SELECT * FROM (TABLE int2_tbl) AS s (a, b);
+ERROR:  table "s" has 1 columns available but 2 columns specified
 SELECT i.* FROM INT2_TBL i WHERE i.f1 <> int2 '0';
    f1   
 --------

src/test/regress/expected/join.out

@@ -5872,6 +5872,9 @@ select * from
  3 | 3
 (6 rows)
 
+-- check the number of columns specified
+SELECT * FROM (int8_tbl i cross join int4_tbl j) ss(a,b,c,d);
+ERROR:  join expression "ss" has 3 columns available but 4 columns specified
 -- check we don't try to do a unique-ified semijoin with LATERAL
 explain (verbose, costs off)
 select * from

src/test/regress/expected/jsonb_sqljson.out

@@ -1031,6 +1031,8 @@ SELECT * FROM JSON_TABLE(NULL, '$' COLUMNS ());
 ERROR:  syntax error at or near ")"
 LINE 1: SELECT * FROM JSON_TABLE(NULL, '$' COLUMNS ());
                                                     ^
+SELECT * FROM JSON_TABLE (NULL::jsonb, '$' COLUMNS (v1 timestamp)) AS f (v1, v2);
+ERROR:  JSON_TABLE function has 1 columns available but 2 columns specified
 -- NULL => empty table
 SELECT * FROM JSON_TABLE(NULL::jsonb, '$' COLUMNS (foo int)) bar;
  foo 

src/test/regress/expected/with.out

@@ -1794,6 +1794,11 @@ DROP TABLE y;
 --
 -- error cases
 --
+WITH x(n, b) AS (SELECT 1)
+SELECT * FROM x;
+ERROR:  WITH query "x" has 1 columns available but 2 columns specified
+LINE 1: WITH x(n, b) AS (SELECT 1)
+             ^
 -- INTERSECT
 WITH RECURSIVE x(n) AS (SELECT 1 INTERSECT SELECT n+1 FROM x)
 	SELECT * FROM x;

src/test/regress/expected/xml.out

@@ -1145,6 +1145,9 @@ EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
          Table Function Call: XMLTABLE(('/ROWS/ROW'::text) PASSING (xmldata.data) COLUMNS id integer PATH ('@id'::text), _id FOR ORDINALITY, country_name text PATH ('COUNTRY_NAME/text()'::text) NOT NULL, country_id text PATH ('COUNTRY_ID'::text), region_id integer PATH ('REGION_ID'::text), size double precision PATH ('SIZE'::text), unit text PATH ('SIZE/@unit'::text), premier_name text DEFAULT ('not specified'::text) PATH ('PREMIER_NAME'::text))
 (7 rows)
 
+-- errors
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
+ERROR:  XMLTABLE function has 1 columns available but 2 columns specified
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'

src/test/regress/sql/int2.sql

@@ -17,6 +17,10 @@ INSERT INTO INT2_TBL(f1) VALUES ('');
 
 SELECT * FROM INT2_TBL;
 
+SELECT * FROM INT2_TBL AS f(a, b);
+
+SELECT * FROM (TABLE int2_tbl) AS s (a, b);
+
 SELECT i.* FROM INT2_TBL i WHERE i.f1 <> int2 '0';
 
 SELECT i.* FROM INT2_TBL i WHERE i.f1 <> int4 '0';

src/test/regress/sql/join.sql

@@ -1985,6 +1985,9 @@ select * from
    (select q1.v)
   ) as q2;
 
+-- check the number of columns specified
+SELECT * FROM (int8_tbl i cross join int4_tbl j) ss(a,b,c,d);
+
 -- check we don't try to do a unique-ified semijoin with LATERAL
 explain (verbose, costs off)
 select * from

src/test/regress/sql/jsonb_sqljson.sql

@@ -328,6 +328,8 @@ SELECT JSON_TABLE('[]', '$');
 -- Should fail (no columns)
 SELECT * FROM JSON_TABLE(NULL, '$' COLUMNS ());
 
+SELECT * FROM JSON_TABLE (NULL::jsonb, '$' COLUMNS (v1 timestamp)) AS f (v1, v2);
+
 -- NULL => empty table
 SELECT * FROM JSON_TABLE(NULL::jsonb, '$' COLUMNS (foo int)) bar;
 

src/test/regress/sql/with.sql

@@ -803,6 +803,9 @@ DROP TABLE y;
 -- error cases
 --
 
+WITH x(n, b) AS (SELECT 1)
+SELECT * FROM x;
+
 -- INTERSECT
 WITH RECURSIVE x(n) AS (SELECT 1 INTERSECT SELECT n+1 FROM x)
 	SELECT * FROM x;

src/test/regress/sql/xml.sql

@@ -384,6 +384,9 @@ SELECT * FROM xmltableview1;
 EXPLAIN (COSTS OFF) SELECT * FROM xmltableview1;
 EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
 
+-- errors
+SELECT * FROM XMLTABLE (ROW () PASSING null COLUMNS v1 timestamp) AS f (v1, v2);
+
 -- XMLNAMESPACES tests
 SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       '/zz:rows/zz:row'