Google OAuth Device Flow support for FNL

services/authentication/accounts_db_manager.cc

+// Copyright 2015 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 "services/authentication/accounts_db_manager.h"
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/strings/string_tokenizer.h"
+#include "mojo/public/cpp/bindings/array.h"
+#include "mojo/public/cpp/bindings/type_converter.h"
+#include "mojo/services/files/interfaces/files.mojom.h"
+
+namespace authentication {
+
+const char* kAccountsDbFileName = "accounts_db.txt";
+AccountsDbManager::AccountsDbManager()
+    : directory_(nullptr), contents_(nullptr) {}
+
+AccountsDbManager::AccountsDbManager(mojo::files::FilesPtr files) {
+  // TODO: Move to a file system with secure privileges as the accounts db needs
+  // to persist across multiple invocations and apps, and the temporary root
+  // solution here is just a short term path.
+  mojo::files::Error error = mojo::files::Error::INTERNAL;
+  files->OpenFileSystem(nullptr, GetProxy(&directory_), Capture(&error));
+  files.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    LOG(FATAL) << "Unable to initialize accounts DB";
+  }
+}
+
+AccountsDbManager::~AccountsDbManager() {}
+
+bool AccountsDbManager::UpdateAccount(const mojo::String& username,
+                                      const mojo::String& new_account_data) {
+  if (username.is_null() || new_account_data.is_null()) {
+    return false;
+  }
+
+  std::string buffer;
+  std::string new_contents(AccountsDbManager::contents_);

[jln (very slow on Chromium), 2015/12/08 22:27:29]

No need for AccountsDbManager:: qualifier.

[ukode, 2015/12/16 19:24:12]

Done.

+  mojo::String existing_user_data;
+  AccountsDbManager::GetAccountDataForUser(username, existing_user_data);
+
+  if (existing_user_data.is_null()) {  // new account to be added

[jln (very slow on Chromium), 2015/12/08 22:27:29]

I don't quite understand what's happening here yet, but it looks like something
that should be done in a separate utility function, possibly in the anonymous
namespace, no?

[ukode, 2015/12/16 19:24:12]

This is very specific to account db functionality. Refactored this into a
separate helper method. Issue here is mojo::String is missing some append
capabilities. So I need to format the updated db contents first and then use
that to update the current DB contents. This method does two things (also
clarified in comments above):

1. Updates the user credential if it already exists. (Using File Write mode)
2. Or else adds a new record to the Db file. (Using File Append mode)

+    if (!AccountsDbManager::contents_.empty()) {
+      buffer += "\n";
+    }
+    buffer += new_account_data.get();
+    new_contents += buffer;
+  } else {
+    // Parse the existing account data and replace the token
+    base::StringTokenizer lines(AccountsDbManager::contents_, "\n");
+    std::string user_data;
+    while (lines.GetNext()) {
+      user_data = lines.token();
+      if (user_data.find(username) != std::string::npos) {
+        buffer += new_account_data.get();  // replace with new contents
+      } else {
+        buffer += user_data;  // carry forward the existing user data
+      }
+      buffer += "\n";
+    }
+    if (!buffer.empty()) {
+      buffer.pop_back();
+    }
+    new_contents.assign(buffer.c_str(), buffer.size());

[jln (very slow on Chromium), 2015/12/08 22:27:29]

Why are new_contents and buffer both needed. It looks like you could do with
just one or am I mistaken?

[ukode, 2015/12/16 19:24:13]

Fixed it as part of refactoring.

+  }
+
+  // Open accounts db file
+  mojo::files::FilePtr file;
+  mojo::files::Error error = mojo::files::Error::INTERNAL;
+  if (existing_user_data.is_null()) {
+    // Append to existing File
+    directory_->OpenFile(kAccountsDbFileName, GetProxy(&file),
+                         mojo::files::kOpenFlagWrite |
+                             mojo::files::kOpenFlagCreate |
+                             mojo::files::kOpenFlagAppend,
+                         Capture(&error));
+  } else {
+    // Rewrite the file contents with updated info
+    directory_->OpenFile(
+        kAccountsDbFileName, GetProxy(&file),
+        mojo::files::kOpenFlagWrite | mojo::files::kOpenFlagCreate,
+        Capture(&error));
+  }
+  directory_.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return false;

[jln (very slow on Chromium), 2015/12/08 22:27:29]

Looks like the opened file is not getting closed here or in the next "return
false". Need to check how scoping is typically done in Mojo.

[ukode, 2015/12/16 19:24:12]

Good catch. Fixed it.

+  }
+
+  // Write to it.
+  std::vector<uint8_t> bytes_to_write(buffer.begin(), buffer.end());
+  bytes_to_write.push_back('\0');
+  error = mojo::files::Error::INTERNAL;
+  uint32_t num_bytes_written = 0;
+  file->Write(mojo::Array<uint8_t>::From(bytes_to_write), 0,
+              mojo::files::Whence::FROM_CURRENT,
+              Capture(&error, &num_bytes_written));
+  file.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return false;
+  }
+
+  // Close the accounts db file
+  error = mojo::files::Error::INTERNAL;
+  file->Close(Capture(&error));
+  file.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return false;
+  }
+
+  // Update the existing contents with new data
+  AccountsDbManager::contents_.assign(new_contents.c_str(),
+                                      new_contents.size());
+  return true;
+}
+
+void AccountsDbManager::GetAccountDataForUser(const mojo::String& username,
+                                              mojo::String& user_data) {
+  if (username.is_null()) {
+    return;
+  }
+
+  if (AccountsDbManager::contents_.empty()) {
+    mojo::Array<uint8_t> all_accounts_data(
+        AccountsDbManager::FetchAllAccounts());
+    if (!all_accounts_data.size()) {
+      return;
+    }
+  }
+
+  base::StringTokenizer lines(AccountsDbManager::contents_, "\n");
+  std::string entry;
+  while (lines.GetNext()) {
+    entry = lines.token();
+    if (entry.find(username) != std::string::npos) {
+      user_data.Swap(&entry);
+      return;
+    }
+  }
+}
+
+mojo::Array<uint8_t> AccountsDbManager::FetchAllAccounts() {
+  const size_t kMaxReadSize = 1 * 1024 * 1024;
+
+  // Open accounts db file
+  mojo::files::FilePtr file;
+  mojo::files::Error error = mojo::files::Error::INTERNAL;
+  directory_->OpenFile(kAccountsDbFileName, GetProxy(&file),
+                       mojo::files::kOpenFlagRead, Capture(&error));
+  directory_.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return mojo::Array<uint8_t>();
+  }
+
+  // Read from it.
+  mojo::Array<uint8_t> bytes_read;
+  error = mojo::files::Error::INTERNAL;
+  file->Read(kMaxReadSize - 1, 0, mojo::files::Whence::FROM_START,
+             Capture(&error, &bytes_read));
+
+  file.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return mojo::Array<uint8_t>();
+  }
+
+  // Close the accounts db file
+  error = mojo::files::Error::INTERNAL;
+  file->Close(Capture(&error));
+  file.WaitForIncomingResponse();
+  if (mojo::files::Error::OK != error) {
+    return mojo::Array<uint8_t>();
+  }
+
+  const std::vector<uint8_t> vec = bytes_read.storage();

[jln (very slow on Chromium), 2015/12/08 22:27:29]

I'm surprised if Mojo doesn't offer a better way to do this.

[ukode, 2015/12/16 19:24:12]

+vtl/mitch - do you have any other suggestion here?

+  AccountsDbManager::contents_.assign((char*)vec.data(), vec.size());
+
+  return bytes_read.Pass();
+}
+
+}  // namespace authentication