Add the SQLITE_FCNTL_OVERWRITE file-control. Used by SQLite to indicate to the OS layer that the current transaction will overwrite the entire file.

FossilOrigin-Name: 1da87fcdacfa7d277c3ee98e410a9ea8b529c368

1 files changed, 9 insertions, 0 deletions

diff --git a/src/backup.c b/src/backup.c
index 70a782665..411a9b8d6 100644
--- a/src/backup.c
+++ b/src/backup.c
@@ -669,10 +669,18 @@ void sqlite3BackupRestart(sqlite3_backup *pBackup){
 */
 int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
   int rc;
+  sqlite3_file *pFd;              /* File descriptor for database pTo */
   sqlite3_backup b;
   sqlite3BtreeEnter(pTo);
   sqlite3BtreeEnter(pFrom);
 
+  assert( sqlite3BtreeIsInTrans(pTo) );
+  pFd = sqlite3PagerFile(sqlite3BtreePager(pTo));
+  if( pFd->pMethods ){
+    i64 nByte = sqlite3BtreeGetPageSize(pFrom)*(i64)sqlite3BtreeLastPage(pFrom);
+    sqlite3OsFileControl(pFd, SQLITE_FCNTL_OVERWRITE, &nByte);
+  }
+
   /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
   ** to 0. This is used by the implementations of sqlite3_backup_step()
   ** and sqlite3_backup_finish() to detect that they are being called
@@ -698,6 +706,7 @@ int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
     pTo->pBt->pageSizeFixed = 0;
   }
 
+  assert( sqlite3BtreeIsInTrans(pTo)==0 );
   sqlite3BtreeLeave(pFrom);
   sqlite3BtreeLeave(pTo);
   return rc;