Improvements to the way that truncation is implemented in sqlite_dbpage().

FossilOrigin-Name: ac4bb2e4ecf0bdb0d8ac12b1ccb42d51af02f519a038cfc79faab5c216971056

1 files changed, 25 insertions, 11 deletions

diff --git a/src/dbpage.c b/src/dbpage.c
index 74f345570..e435dcfec 100644
--- a/src/dbpage.c
+++ b/src/dbpage.c
@@ -317,6 +317,24 @@ static int dbpageRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
   return SQLITE_OK;
 }
 
+/* 
+** Open write transactions. Since we do not know in advance which database
+** files will be written by the sqlite_dbpage virtual table, start a write
+** transaction on them all.
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise.
+*/
+static int dbpageBeginTrans(DbpageTable *pTab){
+  sqlite3 *db = pTab->db;
+  int rc = SQLITE_OK;
+  int i;
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ) rc = sqlite3BtreeBeginTrans(pBt, 1, 0);
+  }
+  return rc;
+}
+
 static int dbpageUpdate(
   sqlite3_vtab *pVtab,
   int argc,
@@ -384,6 +402,12 @@ static int dbpageUpdate(
       goto update_fail;
     }
   }
+
+  if( dbpageBeginTrans(pTab)!=SQLITE_OK ){
+    zErr = "failed to open transaction";
+    goto update_fail;
+  }
+
   pPager = sqlite3BtreePager(pBt);
   rc = sqlite3PagerGet(pPager, pgno, (DbPage**)&pDbPage, 0);
   if( rc==SQLITE_OK ){
@@ -405,18 +429,8 @@ update_fail:
   return SQLITE_ERROR;
 }
 
-/* Since we do not know in advance which database files will be
-** written by the sqlite_dbpage virtual table, start a write transaction
-** on them all.
-*/
 static int dbpageBegin(sqlite3_vtab *pVtab){
   DbpageTable *pTab = (DbpageTable *)pVtab;
-  sqlite3 *db = pTab->db;
-  int i;
-  for(i=0; i<db->nDb; i++){
-    Btree *pBt = db->aDb[i].pBt;
-    if( pBt ) (void)sqlite3BtreeBeginTrans(pBt, 1, 0);
-  }
   pTab->pgnoTrunc = 0;
   return SQLITE_OK;
 }
@@ -474,7 +488,7 @@ int sqlite3DbpageRegister(sqlite3 *db){
     0,                            /* xRename */
     0,                            /* xSavepoint */
     0,                            /* xRelease */
-    dbpageRollbackTo,             /* xRollbackTo */
+    0/*dbpageRollbackTo*/,             /* xRollbackTo */
     0,                            /* xShadowName */
     0                             /* xIntegrity */
   };