From 07fca603b56e39c50478b44070fdfb38313cd51c Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Wed, 13 Nov 2013 13:44:46 +0200
Subject: [PATCH] Fix bug in GIN posting tree root creation.
The root page is filled with as many items as fit, and the rest are inserted
using normal insertions. However, I fumbled the variable names, and the code
actually memcpy'd all the items on the page, overflowing the buffer. While
at it, rename the variable to make the distinction more clear.
Reported by Teodor Sigaev. This bug was introduced by my recent
refactorings, so no backpatching required.
---
src/backend/access/gin/gindatapage.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/src/backend/access/gin/gindatapage.c b/src/backend/access/gin/gindatapage.c
index 049db38a2bf..c9506cc0de1 100644
--- a/src/backend/access/gin/gindatapage.c
+++ b/src/backend/access/gin/gindatapage.c
@@ -623,10 +623,10 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
BlockNumber blkno;
Buffer buffer;
Page page;
- int itemsCount;
+ int nrootitems;
/* Calculate how many TIDs will fit on first page. */
- itemsCount = Min(nitems, GinMaxLeafDataItems);
+ nrootitems = Min(nitems, GinMaxLeafDataItems);
/*
* Create the root page.
@@ -638,8 +638,8 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
START_CRIT_SECTION();
GinInitBuffer(buffer, GIN_DATA | GIN_LEAF);
- memcpy(GinDataPageGetData(page), items, sizeof(ItemPointerData) * nitems);
- GinPageGetOpaque(page)->maxoff = nitems;
+ memcpy(GinDataPageGetData(page), items, sizeof(ItemPointerData) * nrootitems);
+ GinPageGetOpaque(page)->maxoff = nrootitems;
MarkBufferDirty(buffer);
@@ -651,7 +651,7 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
data.node = index->rd_node;
data.blkno = blkno;
- data.nitem = nitems;
+ data.nitem = nrootitems;
rdata[0].buffer = InvalidBuffer;
rdata[0].data = (char *) &data;
@@ -660,7 +660,7 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
rdata[1].buffer = InvalidBuffer;
rdata[1].data = (char *) items;
- rdata[1].len = sizeof(ItemPointerData) * itemsCount;
+ rdata[1].len = sizeof(ItemPointerData) * nrootitems;
rdata[1].next = NULL;
recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_CREATE_PTREE, rdata);
@@ -678,7 +678,7 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
/*
* Add any remaining TIDs to the newly-created posting tree.
*/
- if (itemsCount < nitems)
+ if (nitems > nrootitems)
{
GinPostingTreeScan *gdi;
@@ -686,8 +686,8 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
gdi->btree.isBuild = (buildStats != NULL);
ginInsertItemPointers(gdi,
- items + itemsCount,
- nitems - itemsCount,
+ items + nrootitems,
+ nitems - nrootitems,
buildStats);
pfree(gdi);
--
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