1 files changed, 22 insertions, 5 deletions

diff --git a/src/wal.c b/src/wal.c
index 54274640e..5924a6375 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -1521,6 +1521,7 @@ static int walCheckpoint(
   u32 iDbpage = 0;                /* Next database page to write */
   u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
   u32 mxSafeFrame;                /* Max frame that can be backfilled */
+  u32 mxPage;                     /* Max database page to write */
   int i;                          /* Loop counter */
   volatile WalCkptInfo *pInfo;    /* The checkpoint status information */
 
@@ -1545,6 +1546,7 @@ static int walCheckpoint(
   ** cannot be backfilled from the WAL.
   */
   mxSafeFrame = pWal->hdr.mxFrame;
+  mxPage = pWal->hdr.nPage;
   pInfo = walCkptInfo(pWal);
   for(i=1; i<WAL_NREADER; i++){
     u32 y = pInfo->aReadMark[i];
@@ -1565,6 +1567,7 @@ static int walCheckpoint(
   if( pInfo->nBackfill<mxSafeFrame
    && (rc = walLockExclusive(pWal, WAL_READ_LOCK(0), 1))==SQLITE_OK
   ){
+    i64 nSize;                    /* Current size of database file */
     u32 nBackfill = pInfo->nBackfill;
 
     /* Sync the WAL to disk */
@@ -1572,11 +1575,22 @@ static int walCheckpoint(
       rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
     }
 
+    /* If the database file may grow as a result of this checkpoint, hint
+    ** about the eventual size of the db file to the VFS layer. 
+    */
+    if( rc==SQLITE_OK ){
+      i64 nReq = ((i64)mxPage * szPage);
+      rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
+      if( rc==SQLITE_OK && nSize<nReq ){
+        sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
+      }
+    }
+
     /* Iterate through the contents of the WAL, copying data to the db file. */
     while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
       i64 iOffset;
       assert( walFramePgno(pWal, iFrame)==iDbpage );
-      if( iFrame<=nBackfill || iFrame>mxSafeFrame ) continue;
+      if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ) continue;
       iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
       /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
       rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
@@ -2031,6 +2045,7 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
 ** read-lock.
 */
 void sqlite3WalEndReadTransaction(Wal *pWal){
+  sqlite3WalEndWriteTransaction(pWal);
   if( pWal->readLock>=0 ){
     walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
     pWal->readLock = -1;
@@ -2153,11 +2168,13 @@ int sqlite3WalRead(
 
 
 /* 
-** Set *pPgno to the size of the database file (or zero, if unknown).
+** Return the size of the database in pages (or zero, if unknown).
 */
-void sqlite3WalDbsize(Wal *pWal, Pgno *pPgno){
-  assert( pWal->readLock>=0 || pWal->lockError );
-  *pPgno = pWal->hdr.nPage;
+Pgno sqlite3WalDbsize(Wal *pWal){
+  if( pWal && pWal->readLock>=0 ){
+    return pWal->hdr.nPage;
+  }
+  return 0;
 }