Prevent assertion failure in contrib/pg_freespacemap.

Applying pg_freespacemap() to a relation lacking storage (such as a
view) caused an assertion failure, although there was no ill effect
in non-assert builds.  Add an error check for that case.

Bug: #18866
Reported-by: Robins Tharakan <tharakan@gmail.com>
Author: Tender Wang <tndrwang@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Discussion: https://postgr.es/m/18866-d68926d0f1c72d44@postgresql.org
Backpatch-through: 13

diff --git a/contrib/pg_freespacemap/pg_freespacemap.c b/contrib/pg_freespacemap/pg_freespacemap.c
index b82cab2d97ef4deed9736211398efba47986ad68..c9b794806bab9ffa369e1c4cf7660a996c35639c 100644 (file)
--- a/contrib/pg_freespacemap/pg_freespacemap.c
+++ b/contrib/pg_freespacemap/pg_freespacemap.c
@@ -11,6 +11,7 @@
 #include "access/relation.h"
 #include "funcapi.h"
 #include "storage/freespace.h"
+#include "utils/rel.h"
 
 PG_MODULE_MAGIC;
 
@@ -30,6 +31,12 @@ pg_freespace(PG_FUNCTION_ARGS)
 
        rel = relation_open(relid, AccessShareLock);
 
+       if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+               ereport(ERROR,
+                               (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                                errmsg("relation \"%s\" does not have storage",
+                                               RelationGetRelationName(rel))));
+
        if (blkno < 0 || blkno > MaxBlockNumber)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),