GCM Store: Fix invalid argument errors

google_apis/gcm/engine/gcm_store_impl.cc

 // Copyright 2014 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 "google_apis/gcm/engine/gcm_store_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 160 matching lines @@
   return key.substr(arraysize(kInstanceIDKeyStart) - 1);
 }
 
 // Note: leveldb::Slice keeps a pointer to the data in |s|, which must therefore
 // outlive the slice.
 // For example: MakeSlice(MakeOutgoingKey(x)) is invalid.
 leveldb::Slice MakeSlice(const base::StringPiece& s) {
   return leveldb::Slice(s.begin(), s.size());
 }
 
+bool DatabaseExists(const base::FilePath& path) {
+   // It's not enough to check that the directory exists, since DestroyDB
+   // sometimes leaves behind an empty directory
+   // (https://github.com/google/leveldb/issues/215).
+  return base::DirectoryExists(path) &&
+         base::PathExists(path.Append("CURRENT"));

[Nicolas Zea, 2016/09/29 16:49:57]

is PathExists sufficient? Do we still need DirectoryExists?

[johnme, 2016/09/29 17:08:29]

Done (yeah, I was just trying to be explicit, but it's probably not worth the
extra disk I/O).

+}
+
 }  // namespace
 
 class GCMStoreImpl::Backend
     : public base::RefCountedThreadSafe<GCMStoreImpl::Backend> {
  public:
   Backend(const base::FilePath& path,
           scoped_refptr<base::SequencedTaskRunner> foreground_runner,
           std::unique_ptr<Encryptor> encryptor);
 
   // Blocking implementations of GCMStoreImpl methods.
@@ skipping 89 matching lines @@
 LoadStatus GCMStoreImpl::Backend::OpenStoreAndLoadData(StoreOpenMode open_mode,
                                                        LoadResult* result) {
   LoadStatus load_status;
   if (db_.get()) {
     LOG(ERROR) << "Attempting to reload open database.";
     return RELOADING_OPEN_STORE;
   }
 
   // Checks if the store exists or not. Calling DB::Open with create_if_missing
   // not set will still create a new directory if the store does not exist.
-  if (open_mode == DO_NOT_CREATE && !base::DirectoryExists(path_)) {
+  if (open_mode == DO_NOT_CREATE && !DatabaseExists(path_)) {
     DVLOG(2) << "Database " << path_.value() << " does not exist";
     return STORE_DOES_NOT_EXIST;
   }
 
   leveldb::Options options;
   options.create_if_missing = open_mode == CREATE_IF_MISSING;
   options.reuse_logs = leveldb_env::kDefaultLogReuseOptionValue;
   options.paranoid_checks = true;
   leveldb::DB* db;
   leveldb::Status status =
@@ skipping 1173 matching lines @@
            removed_message_counts.begin();
        iter != removed_message_counts.end(); ++iter) {
     DCHECK_NE(app_message_counts_.count(iter->first), 0U);
     app_message_counts_[iter->first] -= iter->second;
     DCHECK_GE(app_message_counts_[iter->first], 0);
   }
   callback.Run(true);
 }
 
 }  // namespace gcm