Check block number against the correct fork in get_raw_page().

get_raw_page tried to validate the supplied block number against
RelationGetNumberOfBlocks(), which of course is only right when
accessing the main fork.  In most cases, the main fork is longer
than the others, so that the check was too weak (allowing a
lower-level error to be reported, but no real harm to be done).
However, very small tables could have an FSM larger than their heap,
in which case the mistake prevented access to some FSM pages.
Per report from Torsten Foertsch.

In passing, make the bad-block-number error into an ereport not elog
(since it's certainly not an internal error); and fix sloppily
maintained comment for RelationGetNumberOfBlocksInFork.

This has been wrong since we invented relation forks, so back-patch
to all supported branches.

diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c
index 2607576c378d3f6bbcab7c20abe8e258ffa3108c..1548dc2e2574da91cf2abb7bd0502416b0be0431 100644 (file)
--- a/contrib/pageinspect/rawpage.c
+++ b/contrib/pageinspect/rawpage.c
@@ -135,9 +135,11 @@ get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno)
                                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                 errmsg("cannot access temporary tables of other sessions")));
 
-       if (blkno >= RelationGetNumberOfBlocks(rel))
-               elog(ERROR, "block number %u is out of range for relation \"%s\"",
-                        blkno, RelationGetRelationName(rel));
+       if (blkno >= RelationGetNumberOfBlocksInFork(rel, forknum))
+               ereport(ERROR,
+                               (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                                errmsg("block number %u is out of range for relation \"%s\"",
+                                               blkno, RelationGetRelationName(rel))));
 
        /* Initialize buffer to copy to */
        raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ);

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 58b64f6570dc50802eaecddd699406b9ab0d2e9f..aeb814e9efcdc14af69f2f1dbdea90f60bbaa6dc 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1926,8 +1926,8 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 }
 
 /*
- * RelationGetNumberOfBlocks
- *             Determines the current number of pages in the relation.
+ * RelationGetNumberOfBlocksInFork
+ *             Determines the current number of pages in the specified relation fork.
  */
 BlockNumber
 RelationGetNumberOfBlocksInFork(Relation relation, ForkNumber forkNum)