From e969d86f4cbdad1d9aa3a7fc7797fc403f922f7c Mon Sep 17 00:00:00 2001
From: "D. Richard Hipp" <drh@hwaci.com>
Date: Thu, 3 May 2018 16:56:06 +0000
Subject: [PATCH] Fix various error handling conditions on the cell overwrite
 optimization. Fix a test case so that it works with the new optimization.

---
 src/btree.c      | 21 ++++++++++++---------
 test/pager1.test |  2 +-
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/btree.c b/src/btree.c
index 3811c59de7..9dc91fe982 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -8176,7 +8176,9 @@ static int btreeOverwriteContent(
     if( nData<iAmt ){
       /* Mixed read data and zeros at the end.  Make a recursive call
       ** to write the zeros then fall through to write the real data */
-      btreeOverwriteContent(pPage, pDest+nData, pX, iOffset+nData, iAmt-nData);
+      int rc = btreeOverwriteContent(pPage, pDest+nData, pX, iOffset+nData,
+                                 iAmt-nData);
+      if( rc ) return rc;
       iAmt = nData;
     }
     if( memcmp(pDest, ((u8*)pX->pData) + iOffset, iAmt)!=0 ){
@@ -8219,18 +8221,19 @@ static int btreeOverwriteCell(BtCursor *pCur, const BtreePayload *pX){
     rc = btreeGetPage(pBt, ovflPgno, &pPage, 0);
     if( rc ) return rc;
     if( sqlite3PagerPageRefcount(pPage->pDbPage)!=1 ){
-      return SQLITE_CORRUPT_BKPT;
-    }
-    if( iOffset+ovflPageSize<nTotal ){
-      ovflPgno = get4byte(pPage->aData);
+      rc = SQLITE_CORRUPT_BKPT;
     }else{
-      ovflPageSize = nTotal - iOffset;
+      if( iOffset+ovflPageSize<nTotal ){
+        ovflPgno = get4byte(pPage->aData);
+      }else{
+        ovflPageSize = nTotal - iOffset;
+      }
+      rc = btreeOverwriteContent(pPage, pPage->aData+4, pX,
+                                 iOffset, ovflPageSize);
     }
-    rc = btreeOverwriteContent(pPage, pPage->aData+4, pX,
-                               iOffset, ovflPageSize);
+    sqlite3PagerUnref(pPage->pDbPage);
     if( rc ) return rc;
     iOffset += ovflPageSize;
-    sqlite3PagerUnref(pPage->pDbPage);
   }while( iOffset<nTotal );
   return SQLITE_OK;    
 }
diff --git a/test/pager1.test b/test/pager1.test
index 42edc3d16b..1d56fad30b 100644
--- a/test/pager1.test
+++ b/test/pager1.test
@@ -1149,7 +1149,7 @@ do_test pager1-5.5.1 {
     PRAGMA journal_mode = PERSIST;
     CREATE TABLE t3(a, b);
     INSERT INTO t3 SELECT randomblob(1500), randomblob(1500) FROM t1;
-    UPDATE t3 SET b = randomblob(1500);
+    UPDATE t3 SET b = randomblob(1501);
   }
   expr [file size test.db-journal] > 15000
 } {1}
-- 
2.11.4.GIT