[cros] RlzValueStore made protected by a cross-process lock and not persisted over browser lifetime…

base/files/important_file_writer.cc

 // Copyright (c) 2011 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 "base/files/important_file_writer.h"
 
 #include <stdio.h>
 
 #include <string>
 
@@ skipping 24 matching lines @@
 };
 
 void LogFailure(const FilePath& path, TempFileFailure failure_code,
                 const std::string& message) {
   UMA_HISTOGRAM_ENUMERATION("ImportantFile.TempFileFailures", failure_code,
                             TEMP_FILE_FAILURE_MAX);
   DPLOG(WARNING) << "temp file failure: " << path.value().c_str()
                  << " : " << message;
 }
 
-void WriteToDiskTask(const FilePath& path, const std::string& data) {
+}  // namespace
+
+// static
+bool ImportantFileWriter::WriteFileAtomically(const FilePath& path,
+                                              const std::string& data) {
   // Write the data to a temp file then rename to avoid data loss if we crash
   // while writing the file. Ensure that the temp file is on the same volume
   // as target file, so it can be moved in one step, and that the temp file
   // is securely created.
   FilePath tmp_file_path;
   if (!file_util::CreateTemporaryFileInDir(path.DirName(), &tmp_file_path)) {
     LogFailure(path, FAILED_CREATING, "could not create temporary file");
-    return;
+    return false;
   }
 
   int flags = PLATFORM_FILE_OPEN | PLATFORM_FILE_WRITE;
   PlatformFile tmp_file =
       CreatePlatformFile(tmp_file_path, flags, NULL, NULL);
   if (tmp_file == kInvalidPlatformFileValue) {
     LogFailure(path, FAILED_OPENING, "could not open temporary file");
-    return;
+    return false;
   }
 
   // If this happens in the wild something really bad is going on.
   CHECK_LE(data.length(), static_cast<size_t>(kint32max));
   int bytes_written = WritePlatformFile(
       tmp_file, 0, data.data(), static_cast<int>(data.length()));
   FlushPlatformFile(tmp_file);  // Ignore return value.
 
   if (!ClosePlatformFile(tmp_file)) {
     LogFailure(path, FAILED_CLOSING, "failed to close temporary file");
     file_util::Delete(tmp_file_path, false);
-    return;
+    return false;
   }
 
   if (bytes_written < static_cast<int>(data.length())) {
     LogFailure(path, FAILED_WRITING, "error writing, bytes_written=" +
                IntToString(bytes_written));
     file_util::Delete(tmp_file_path, false);
-    return;
+    return false;
   }
 
   if (!file_util::ReplaceFile(tmp_file_path, path)) {
     LogFailure(path, FAILED_RENAMING, "could not rename temporary file");
     file_util::Delete(tmp_file_path, false);
-    return;
+    return false;
   }
+
+  return true;
 }
 
-}  // namespace
-
 ImportantFileWriter::ImportantFileWriter(
     const FilePath& path, base::SequencedTaskRunner* task_runner)
         : path_(path),
           task_runner_(task_runner),
           serializer_(NULL),
           commit_interval_(TimeDelta::FromMilliseconds(
               kDefaultCommitIntervalMs)) {
   DCHECK(CalledOnValidThread());
   DCHECK(task_runner_.get());
 }
@@ skipping 13 matching lines @@
 void ImportantFileWriter::WriteNow(const std::string& data) {
   DCHECK(CalledOnValidThread());
   if (data.length() > static_cast<size_t>(kint32max)) {
     NOTREACHED();
     return;
   }
 
   if (HasPendingWrite())
     timer_.Stop();
 
-  if (!task_runner_->PostTask(FROM_HERE,
-          MakeCriticalClosure(Bind(&WriteToDiskTask, path_, data)))) {
+  if (!task_runner_->PostTask(
+          FROM_HERE,
+          MakeCriticalClosure(
+              Bind(IgnoreResult(&ImportantFileWriter::WriteFileAtomically),
+                   path_, data)))) {
     // Posting the task to background message loop is not expected
     // to fail, but if it does, avoid losing data and just hit the disk
     // on the current thread.
     NOTREACHED();
 
-    WriteToDiskTask(path_, data);
+    WriteFileAtomically(path_, data);
   }
 }
 
 void ImportantFileWriter::ScheduleWrite(DataSerializer* serializer) {
   DCHECK(CalledOnValidThread());
 
   DCHECK(serializer);
   serializer_ = serializer;
 
   if (!timer_.IsRunning()) {
     timer_.Start(FROM_HERE, commit_interval_, this,
                  &ImportantFileWriter::DoScheduledWrite);
   }
 }
 
 void ImportantFileWriter::DoScheduledWrite() {
   DCHECK(serializer_);
   std::string data;
   if (serializer_->SerializeData(&data)) {
     WriteNow(data);
   } else {
     DLOG(WARNING) << "failed to serialize data to be saved in "
                   << path_.value().c_str();
   }
   serializer_ = NULL;
 }
 
 }  // namespace base