Add a defense to prevent core dumps if 8.2 version of rank_cd() is used with

the 8.1 SQL function definition for it.  Per report from Rajesh Kumar Mallah,
such a DBA error doesn't seem at all improbable, and the cost of checking for
it is not very high compared to the cost of running this function.  (It would
have been better to change the C name of the function so it wouldn't be called
by the old SQL definition, but it's too late for that now in the 8.2 branch.)

contrib/tsearch2/rank.c

@@ -728,12 +728,28 @@ calc_rank_cd(float4 *arrdata, tsvector * txt, QUERYTYPE * query, int method)
 Datum
 rank_cd(PG_FUNCTION_ARGS)
 {
-	ArrayType  *win = (ArrayType *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+	ArrayType  *win;
 	tsvector   *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
 	QUERYTYPE  *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(2));
 	int			method = DEF_NORM_METHOD;
 	float4		res;
 
+	/*
+	 * Pre-8.2, rank_cd took just a plain int as its first argument.
+	 * It was a mistake to keep the same C function name while changing the
+	 * signature, but it's too late to fix that.  Instead, do a runtime test
+	 * to make sure the expected datatype has been passed.  This is needed
+	 * to prevent core dumps if tsearch2 function definitions from an old
+	 * database are loaded into an 8.2 server.
+	 */
+	if (get_fn_expr_argtype(fcinfo->flinfo, 0) != FLOAT4ARRAYOID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+				 errmsg("rank_cd() now takes real[] as its first argument, not integer")));
+
+	/* now safe to dereference the first arg */
+	win = (ArrayType *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+
 	if (ARR_NDIM(win) != 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),

src/include/catalog/pg_type.h

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_type.h,v 1.173 2006/12/21 16:05:15 petere Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_type.h,v 1.174 2006/12/28 01:09:01 tgl Exp $
  *
  * NOTES
  *	  the genbki.sh script reads this file and generates .bki
@@ -422,6 +422,7 @@ DATA(insert OID = 1018 (  _lseg		 PGNSP PGUID -1 f b t \054 0 601 array_in array
 DATA(insert OID = 1019 (  _path		 PGNSP PGUID -1 f b t \054 0 602 array_in array_out array_recv array_send - d x f 0 -1 0 _null_ _null_ ));
 DATA(insert OID = 1020 (  _box		 PGNSP PGUID -1 f b t \073 0 603 array_in array_out array_recv array_send - d x f 0 -1 0 _null_ _null_ ));
 DATA(insert OID = 1021 (  _float4	 PGNSP PGUID -1 f b t \054 0 700 array_in array_out array_recv array_send - i x f 0 -1 0 _null_ _null_ ));
+#define FLOAT4ARRAYOID 1021
 DATA(insert OID = 1022 (  _float8	 PGNSP PGUID -1 f b t \054 0 701 array_in array_out array_recv array_send - d x f 0 -1 0 _null_ _null_ ));
 DATA(insert OID = 1023 (  _abstime	 PGNSP PGUID -1 f b t \054 0 702 array_in array_out array_recv array_send - i x f 0 -1 0 _null_ _null_ ));
 DATA(insert OID = 1024 (  _reltime	 PGNSP PGUID -1 f b t \054 0 703 array_in array_out array_recv array_send - i x f 0 -1 0 _null_ _null_ ));