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.)

1 files changed, 17 insertions, 1 deletions

diff --git a/contrib/tsearch2/rank.c b/contrib/tsearch2/rank.c
index 7bd5e1adf01..f5de5c7746f 100644
--- a/contrib/tsearch2/rank.c
+++ b/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),