diff --git a/manifest b/manifest
index a2b8e3a1f8..7547dff413 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sassert()\sstatements\sto\sos_unix.c\swhich\sfire\sif\sthere\sis\sa\sread\sor\nwrite\sfor\sthe\slocking\sregion\sof\sa\sdatabase\sfile.\s(CVS\s6270)
-D 2009-02-09T17:34:07
+C Fix\sa\sproblem\sin\sbackup.c\scausing\sOsTruncate()\sto\sbe\scalled\swith\san\sargument\slarger\sthan\sthe\scurrent\sfile-size.\s(CVS\s6271)
+D 2009-02-09T18:55:46
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in c7a5a30fb6852bd7839b1024e1661da8549878ee
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -101,7 +101,7 @@ F src/alter.c 0ec29744c36c6e976596ce38c16289ebc5dc94db
 F src/analyze.c c86fd6a1425b22b3a46ce72ad403e4280026364f
 F src/attach.c 81d37d1948f409146a7b22b96998fd90649d1fd3
 F src/auth.c c8b2ab5c8bad4bd90ed7c294694f48269162c627
-F src/backup.c 9563f47385f491579135fd7924d70c76c2eba740
+F src/backup.c 7aff2b795c4a001716c40fff7e3928750e2f6b8f
 F src/bitvec.c 44f7059ac1f874d364b34af31b9617e52223ba75
 F src/btmutex.c 63c5cc4ad5715690767ffcb741e185d7bc35ec1a
 F src/btree.c 71f30e74389aa7ae51421592dfaf69511152677c
@@ -233,7 +233,7 @@ F test/autoinc.test ab549b48b389cabd92967b86c379ec8b31fa6c16
 F test/autovacuum.test 61260e25744189ff766f61ca3df23c1eeec0060e
 F test/autovacuum_ioerr2.test 598b0663074d3673a9c1bc9a16e80971313bafe6
 F test/avtrans.test 1e901d8102706b63534dbd2bdd4d8f16c4082650
-F test/backup.test 12d7ad0545f47175e27445267d0810a277679ef2
+F test/backup.test e1ccee089c190f480afe32f7795690399c644dea
 F test/backup2.test 392318e059b83e87e5e4175f08be181a6ddce468
 F test/backup_ioerr.test a9b8084e488154341719833783ac9db321e14284
 F test/backup_malloc.test 1e063c6d75143d0d6e0ae77971dd690070369387
@@ -701,7 +701,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81
 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
-P e20bf384668bcde7c2f2152ca88e28cf65a02679
-R 3a3cb4e439892d819d6a33e750f5e099
-U drh
-Z 7b54fb55986a7fded747f515afad0223
+P 93e792ffa88ba2e8422d041f36b70d9b2e220da2
+R f4d030cfc7856238ca71232918484f1a
+U danielk1977
+Z e7286071c615582b1903f957fbdb0fad
diff --git a/manifest.uuid b/manifest.uuid
index 210287e1c1..0146e6bb8e 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-93e792ffa88ba2e8422d041f36b70d9b2e220da2
\ No newline at end of file
+b34bde80c7e2028baf7ba2ff26e587a63a170f3d
\ No newline at end of file
diff --git a/src/backup.c b/src/backup.c
index 31d14a0aec..cda0263a3d 100644
--- a/src/backup.c
+++ b/src/backup.c
@@ -12,7 +12,7 @@
 ** This file contains the implementation of the sqlite3_backup_XXX() 
 ** API functions and the related features.
 **
-** $Id: backup.c,v 1.8 2009/02/06 05:59:44 danielk1977 Exp $
+** $Id: backup.c,v 1.9 2009/02/09 18:55:46 danielk1977 Exp $
 */
 #include "sqliteInt.h"
 #include "btreeInt.h"
@@ -254,6 +254,23 @@ static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
   return rc;
 }
 
+/*
+** If pFile is currently larger than iSize bytes, then truncate it to
+** exactly iSize bytes. If pFile is not larger than iSize bytes, then
+** this function is a no-op.
+**
+** Return SQLITE_OK if everything is successful, or an SQLite error 
+** code if an error occurs.
+*/
+static int backupTruncateFile(sqlite3_file *pFile, i64 iSize){
+  i64 iCurrent;
+  int rc = sqlite3OsFileSize(pFile, &iCurrent);
+  if( rc==SQLITE_OK && iCurrent>iSize ){
+    rc = sqlite3OsTruncate(pFile, iSize);
+  }
+  return rc;
+}
+
 /*
 ** Copy nPage pages from the source b-tree to the destination.
 */
@@ -330,8 +347,6 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
       const int nSrcPagesize = sqlite3BtreeGetPageSize(p->pSrc);
       const int nDestPagesize = sqlite3BtreeGetPageSize(p->pDest);
       int nDestTruncate;
-      sqlite3_file *pFile = 0;
-      i64 iSize;
   
       /* Update the schema version field in the destination database. This
       ** is to make sure that the schema-version really does change in
@@ -373,11 +388,13 @@ int sqlite3_backup_step(sqlite3_backup *p, int nPage){
         **     pending-byte page in the source database may need to be
         **     copied into the destination database.
         */
-        iSize = (i64)nSrcPagesize * (i64)nSrcPage;
-        pFile = sqlite3PagerFile(pDestPager);
+        const i64 iSize = (i64)nSrcPagesize * (i64)nSrcPage;
+        sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
+
         assert( pFile );
+        assert( (i64)nDestTruncate*(i64)nDestPagesize >= iSize );
         if( SQLITE_OK==(rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1))
-         && SQLITE_OK==(rc = sqlite3OsTruncate(pFile, iSize))
+         && SQLITE_OK==(rc = backupTruncateFile(pFile, iSize))
          && SQLITE_OK==(rc = sqlite3PagerSync(pDestPager))
         ){
           i64 iOff;
diff --git a/test/backup.test b/test/backup.test
index 3db2a499d5..c1978b9ef1 100644
--- a/test/backup.test
+++ b/test/backup.test
@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing the sqlite3_backup_XXX API.
 #
-# $Id: backup.test,v 1.4 2009/02/06 05:59:45 danielk1977 Exp $
+# $Id: backup.test,v 1.5 2009/02/09 18:55:46 danielk1977 Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -263,7 +263,7 @@ foreach nPagePerStep {1 200} {
 #   * Target database page-size is smaller than the source.
 #
 set iTest 1
-foreach nSrcRow {10 100} {
+foreach nSrcPg {10 64 65 66 100} {
 foreach nDestRow {10 100} {
 foreach nDestPgsz {512 1024 2048 4096} {
 
@@ -274,18 +274,24 @@ foreach nDestPgsz {512 1024 2048 4096} {
 
   # Set up the content of the two databases.
   #
-  foreach {db nRow} [list db $nSrcRow db2 $nDestRow] {
+  execsql { PRAGMA page_size = 1024 }
+  execsql "PRAGMA page_size = $nDestPgsz" db2
+  foreach db {db db2} {
     execsql {
       BEGIN; 
       CREATE TABLE t1(a, b);
       CREATE INDEX i1 ON t1(a, b);
+      COMMIT;
     } $db
-    for {set ii 0} {$ii < $nSrcRow} {incr ii} {
-      execsql { INSERT INTO t1 VALUES($ii, randstr(1000,1000)) } $db
-    }
-    execsql COMMIT $db
   }
-    
+  while {[file size test.db]/1024 < $nSrcPg} {
+    execsql { INSERT INTO t1 VALUES($ii, randstr(200,200)) }
+  }
+
+  for {set ii 0} {$ii < $nDestRow} {incr ii} {
+    execsql { INSERT INTO t1 VALUES($ii, randstr(1000,1000)) } db2
+  }
+
   # Backup the source database.
   do_test backup-3.$iTest.1 {
     sqlite3_backup B db main db2 main