1 files changed, 72 insertions, 54 deletions

diff --git a/src/attach.c b/src/attach.c
index fa38e8415..151b52e7a 100644
--- a/src/attach.c
+++ b/src/attach.c
@@ -55,6 +55,10 @@ static int resolveAttachExpr(NameContext *pName, Expr *pExpr)
 **
 ** If the optional "KEY z" syntax is omitted, an SQL NULL is passed as the
 ** third argument.
+**
+** If the db->init.reopenMemdb flags is set, then instead of attaching a
+** new database, close the database on db->init.iDb and reopen it as an
+** empty MemDB.
 */
 static void attachFunc(
   sqlite3_context *context,
@@ -75,65 +79,79 @@ static void attachFunc(
   sqlite3_vfs *pVfs;
 
   UNUSED_PARAMETER(NotUsed);
-
   zFile = (const char *)sqlite3_value_text(argv[0]);
   zName = (const char *)sqlite3_value_text(argv[1]);
   if( zFile==0 ) zFile = "";
   if( zName==0 ) zName = "";
 
-  /* Check for the following errors:
-  **
-  **     * Too many attached databases,
-  **     * Transaction currently open
-  **     * Specified database name already being used.
-  */
-  if( db->nDb>=db->aLimit[SQLITE_LIMIT_ATTACHED]+2 ){
-    zErrDyn = sqlite3MPrintf(db, "too many attached databases - max %d", 
-      db->aLimit[SQLITE_LIMIT_ATTACHED]
-    );
-    goto attach_error;
-  }
-  for(i=0; i<db->nDb; i++){
-    char *z = db->aDb[i].zDbSName;
-    assert( z && zName );
-    if( sqlite3StrICmp(z, zName)==0 ){
-      zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
+  if( db->init.reopenMemdb ){
+    /* This is not a real ATTACH.  Instead, this routine is being called
+    ** from sqlite3_deserialize() to close database db->init.iDb and
+    ** reopen it as a MemDB */
+    pVfs = sqlite3_vfs_find("memdb");
+    if( pVfs==0 ) return;
+    pNew = &db->aDb[db->init.iDb];
+    sqlite3BtreeClose(pNew->pBt);
+    pNew->pBt = 0;
+    pNew->pSchema = 0;
+    rc = sqlite3BtreeOpen(pVfs, "x", db, &pNew->pBt, 0, SQLITE_OPEN_MAIN_DB);
+  }else{
+    /* This is a real ATTACH */
+  
+    /* Check for the following errors:
+    **
+    **     * Too many attached databases,
+    **     * Transaction currently open
+    **     * Specified database name already being used.
+    */
+    if( db->nDb>=db->aLimit[SQLITE_LIMIT_ATTACHED]+2 ){
+      zErrDyn = sqlite3MPrintf(db, "too many attached databases - max %d", 
+        db->aLimit[SQLITE_LIMIT_ATTACHED]
+      );
       goto attach_error;
     }
+    for(i=0; i<db->nDb; i++){
+      char *z = db->aDb[i].zDbSName;
+      assert( z && zName );
+      if( sqlite3StrICmp(z, zName)==0 ){
+        zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
+        goto attach_error;
+      }
+    }
+  
+    /* Allocate the new entry in the db->aDb[] array and initialize the schema
+    ** hash tables.
+    */
+    if( db->aDb==db->aDbStatic ){
+      aNew = sqlite3DbMallocRawNN(db, sizeof(db->aDb[0])*3 );
+      if( aNew==0 ) return;
+      memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
+    }else{
+      aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
+      if( aNew==0 ) return;
+    }
+    db->aDb = aNew;
+    pNew = &db->aDb[db->nDb];
+    memset(pNew, 0, sizeof(*pNew));
+  
+    /* Open the database file. If the btree is successfully opened, use
+    ** it to obtain the database schema. At this point the schema may
+    ** or may not be initialized.
+    */
+    flags = db->openFlags;
+    rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
+    if( rc!=SQLITE_OK ){
+      if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
+      sqlite3_result_error(context, zErr, -1);
+      sqlite3_free(zErr);
+      return;
+    }
+    assert( pVfs );
+    flags |= SQLITE_OPEN_MAIN_DB;
+    rc = sqlite3BtreeOpen(pVfs, zPath, db, &pNew->pBt, 0, flags);
+    sqlite3_free( zPath );
+    db->nDb++;
   }
-
-  /* Allocate the new entry in the db->aDb[] array and initialize the schema
-  ** hash tables.
-  */
-  if( db->aDb==db->aDbStatic ){
-    aNew = sqlite3DbMallocRawNN(db, sizeof(db->aDb[0])*3 );
-    if( aNew==0 ) return;
-    memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
-  }else{
-    aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
-    if( aNew==0 ) return;
-  }
-  db->aDb = aNew;
-  pNew = &db->aDb[db->nDb];
-  memset(pNew, 0, sizeof(*pNew));
-
-  /* Open the database file. If the btree is successfully opened, use
-  ** it to obtain the database schema. At this point the schema may
-  ** or may not be initialized.
-  */
-  flags = db->openFlags;
-  rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
-  if( rc!=SQLITE_OK ){
-    if( rc==SQLITE_NOMEM ) sqlite3OomFault(db);
-    sqlite3_result_error(context, zErr, -1);
-    sqlite3_free(zErr);
-    return;
-  }
-  assert( pVfs );
-  flags |= SQLITE_OPEN_MAIN_DB;
-  rc = sqlite3BtreeOpen(pVfs, zPath, db, &pNew->pBt, 0, flags);
-  sqlite3_free( zPath );
-  db->nDb++;
   db->skipBtreeMutex = 0;
   if( rc==SQLITE_CONSTRAINT ){
     rc = SQLITE_ERROR;
@@ -160,7 +178,7 @@ static void attachFunc(
     sqlite3BtreeLeave(pNew->pBt);
   }
   pNew->safety_level = SQLITE_DEFAULT_SYNCHRONOUS+1;
-  pNew->zDbSName = sqlite3DbStrDup(db, zName);
+  if( !db->init.reopenMemdb ) pNew->zDbSName = sqlite3DbStrDup(db, zName);
   if( rc==SQLITE_OK && pNew->zDbSName==0 ){
     rc = SQLITE_NOMEM_BKPT;
   }
@@ -200,8 +218,8 @@ static void attachFunc(
 
   /* If the file was opened successfully, read the schema for the new database.
   ** If this fails, or if opening the file failed, then close the file and 
-  ** remove the entry from the db->aDb[] array. i.e. put everything back the way
-  ** we found it.
+  ** remove the entry from the db->aDb[] array. i.e. put everything back the
+  ** way we found it.
   */
   if( rc==SQLITE_OK ){
     sqlite3BtreeEnterAll(db);