Index: src/pager.c
==================================================================
--- src/pager.c
+++ src/pager.c
@@ -16,11 +16,11 @@
 ** is separate from the database file.  The pager also implements file
 ** locking to prevent two processes from writing the same database
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.157 2004/08/18 16:05:19 drh Exp $
+** @(#) $Id: pager.c,v 1.158 2004/08/18 19:09:44 drh Exp $
 */
 #include "os.h"         /* Must be first to enable large file support */
 #include "sqliteInt.h"
 #include "pager.h"
 #include <assert.h>
@@ -1014,10 +1014,18 @@
     pPg->needSync = 0;
     pPg->dirty = 0;
   }
   return rc;
 }
+
+/*
+** Truncate the main file of the given pager to the number of pages
+** indicated.
+*/
+static int pager_truncate(Pager *pPager, int nPage){
+  return sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(off_t)nPage);
+}
 
 /*
 ** Playback the journal and thus restore the database file to
 ** the state it was in before we started making changes.  
 **
@@ -1133,11 +1141,11 @@
     /* If this is the first header read from the journal, truncate the
     ** database file back to it's original size.
     */
     if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
       assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg );
-      rc = sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(off_t)mxPg);
+      rc = pager_truncate(pPager, mxPg);
       if( rc!=SQLITE_OK ){
         goto end_playback;
       }
       pPager->dbSize = mxPg;
     }
@@ -1233,11 +1241,11 @@
   }
   
 
   /* Truncate the database back to its original size.
   */
-  rc = sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(off_t)pPager->stmtSize);
+  rc = pager_truncate(pPager, pPager->stmtSize);
   pPager->dbSize = pPager->stmtSize;
 
   /* Figure out how many records are in the statement journal.
   */
   assert( pPager->stmtInUse && pPager->journalOpen );
@@ -1671,11 +1679,11 @@
   }
   rc = syncJournal(pPager);
   if( rc!=SQLITE_OK ){
     return rc;
   }
-  rc = sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(off_t)nPage);
+  rc = pager_truncate(pPager, nPage);
   if( rc==SQLITE_OK ){
     pPager->dbSize = nPage;
   }
   return rc;
 }
@@ -2858,15 +2866,17 @@
       pager_playback(pPager);
     }
     return pager_errcode(pPager);
   }
   if( pPager->state==PAGER_RESERVED ){
-    int rc2;
+    int rc2, rc3;
     rc = pager_reload_cache(pPager);
-    rc2 = pager_unwritelock(pPager);
+    rc2 = pager_truncate(pPager, pPager->origDbSize);
+    rc3 = pager_unwritelock(pPager);
     if( rc==SQLITE_OK ){
       rc = rc2;
+      if( rc3 ) rc = rc3;
     }
   }else{
     rc = pager_playback(pPager);
   }
   if( rc!=SQLITE_OK ){

ADDED   test/pager3.test
Index: test/pager3.test
==================================================================
--- test/pager3.test
+++ test/pager3.test
@@ -0,0 +1,68 @@
+# 2001 September 15
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this script is page cache subsystem.
+#
+# $Id: pager3.test,v 1.1 2004/08/18 19:09:44 drh Exp $
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# This test makes sure the database file is truncated back to the correct
+# length on a rollback.
+#
+# After some preliminary setup, a transaction is start at NOTE (1).
+# The create table on the following line allocates an additional page
+# at the end of the database file.  But that page is not written because
+# the database still has a RESERVED lock, not an EXCLUSIVE lock.  The
+# new page is held in memory and the size of the file is unchanged.
+# The insert at NOTE (2) begins adding additional pages.  Then it hits
+# a constraint error and aborts.  The abort causes sqlite3OsTruncate()
+# to be called to restore the file to the same length as it was after
+# the create table.  But the create table results had not yet been
+# written so the file is actually lengthened by this truncate.  Finally,
+# the rollback at NOTE (3) is called to undo all the changes since the
+# begin.  This rollback should truncate the database again.
+# 
+# This test was added because the second truncate at NOTE (3) was not
+# occurring on early versions of SQLite 3.0.
+#
+do_test pager3-1.1 {
+  execsql {
+    create table t1(a unique, b);
+    insert into t1 values(1, 'abcdefghijklmnopqrstuvwxyz');
+    insert into t1 values(2, 'abcdefghijklmnopqrstuvwxyz');
+    update t1 set b=b||a||b;
+    update t1 set b=b||a||b;
+    update t1 set b=b||a||b;
+    update t1 set b=b||a||b;
+    update t1 set b=b||a||b;
+    update t1 set b=b||a||b;
+    create temp table t2 as select * from t1;
+    begin;                  ------- NOTE (1)
+    create table t3(x);
+  }
+  catchsql {
+    insert into t1 select 4-a, b from t2;  ----- NOTE (2)
+  }
+  execsql {
+    rollback;  ------- NOTE (3)
+  }
+  db close
+  sqlite3 db test.db
+  execsql {
+    pragma integrity_check;
+  }
+} ok
+
+
+finish_test