[sql] Prevent recovery against a closed database.

sql/recovery_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sql/recovery.h"
 
 #include <stddef.h>
 #include <string>
 #include <utility>
 
@@ skipping 85 matching lines @@
     ASSERT_TRUE(recovery.get());
     sql::Recovery::Unrecoverable(std::move(recovery));
 
     // TODO(shess): Test that calls to recover.db() start failing.
   }
   EXPECT_FALSE(db().is_open());
   ASSERT_TRUE(Reopen());
   EXPECT_TRUE(db().is_open());
   ASSERT_EQ("", GetSchema(&db()));
 
+  // Attempting to recover a previously-recovered handle fails early.
+  {
+    scoped_ptr<sql::Recovery> recovery = sql::Recovery::Begin(&db(), db_path());
+    ASSERT_TRUE(recovery.get());
+    recovery.reset();
+
+    recovery = sql::Recovery::Begin(&db(), db_path());
+    ASSERT_FALSE(recovery.get());

[Ryan Hamilton, 2016/02/02 05:00:06]

Presumably, this test failed or crashed with the old code?

+  }
+  ASSERT_TRUE(Reopen());
+
   // Recreate the database.
   ASSERT_TRUE(db().Execute(kCreateSql));
   ASSERT_TRUE(db().Execute(kInsertSql));
   ASSERT_EQ("CREATE TABLE x (t TEXT)", GetSchema(&db()));
 
   // Recovered() replaces the original with the "recovered" version.
   {
     scoped_ptr<sql::Recovery> recovery = sql::Recovery::Begin(&db(), db_path());
     ASSERT_TRUE(recovery.get());
 
@@ skipping 585 matching lines @@
   scoped_ptr<sql::Recovery> recovery = sql::Recovery::Begin(&db(), db_path());
   ASSERT_TRUE(recovery.get());
 
   // In the current implementation, the PRAGMA successfully runs with no result
   // rows.  Running with a single result of |0| is also acceptable.
   sql::Statement s(recovery->db()->GetUniqueStatement("PRAGMA mmap_size"));
   EXPECT_TRUE(!s.Step() || !s.ColumnInt64(0));
 }
 
 }  // namespace