Add 'flog' service implementation.

services/flog/flog_directory.cc

+// Copyright 2016 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 <ctime>
+#include <iomanip>
+#include <sstream>
+
+#include "base/logging.h"
+#include "mojo/public/cpp/application/connect.h"
+#include "services/flog/flog_directory.h"
+
+namespace mojo {
+namespace flog {
+
+FlogDirectory::FlogDirectory(Shell* shell) {
+  ConnectToService(shell, "mojo:files", GetProxy(&files_));
+  files_->OpenFileSystem("app_persistent_cache", GetProxy(&file_system_),
+                         [this](files::Error error) {
+                           files_.reset();
+                           if (error != files::Error::OK) {
+                             DCHECK(false) << "Failed to open file system: "
+                                           << error;
+                             delete this;
+                           }
+                         });
+}
+
+FlogDirectory::~FlogDirectory() {}
+
+void FlogDirectory::GetExistingFiles(GetExistingFilesCallback callback) {
+  file_system_->Read([this, callback](files::Error error,
+                                      Array<files::DirectoryEntryPtr> entries) {
+    std::map<uint32_t, std::string> labels_by_id;
+    for (const files::DirectoryEntryPtr& entry : entries) {
+      if (entry->type == files::FileType::REGULAR_FILE) {
+        uint32_t id;
+        std::string label;
+        if (ParseLogFileName(entry->name, &id, &label)) {
+          labels_by_id.insert(std::pair<uint32_t, std::string>(id, label));
+        }
+      }
+    }
+
+    callback(std::move(labels_by_id));
+  });
+}
+
+files::FilePtr FlogDirectory::GetFile(uint32_t id,
+                                      const std::string& label,
+                                      bool create) {
+  files::FilePtr file;
+  file_system_->OpenFile(
+      LogFileName(id, label), GetProxy(&file),
+      files::kOpenFlagRead |
+          (create ? (files::kOpenFlagWrite | files::kOpenFlagCreate) : 0),
+      [this](files::Error error) {
+        if (error != files::Error::OK) {
+          DCHECK(false) << "Failed to OpenFile" << error;
+          // TODO: Fail.
+          return;
+        }
+      });
+  file_system_.WaitForIncomingResponse();
+  return file.Pass();
+}
+
+std::string FlogDirectory::LogFileName(uint32_t id, const std::string& label) {
+  // Format is "<id>_<label>.flog" where <id> is the kLogIdWidth-digit,
+  // zero-padded info.id_ and <label> is the label.
+  std::ostringstream file_name_stream;
+  file_name_stream << std::setfill('0') << std::setw(kLogIdWidth) << id << "_"
+                   << label << ".flog";
+  return file_name_stream.str();
+}
+
+bool FlogDirectory::ParseLogFileName(const std::string& name,
+                                     uint32_t* id_out,
+                                     std::string* label_out) {
+  DCHECK(id_out != nullptr);
+  DCHECK(label_out != nullptr);
+
+  if (name.size() < kLogIdWidth + 2) {
+    return false;
+  }
+
+  for (size_t i = 0; i < kLogIdWidth; i++) {
+    if (!isdigit(name[i])) {
+      return false;
+    }
+  }
+
+  if (name[kLogIdWidth] != '_') {
+    return false;
+  }
+
+  size_t after_label = name.find_first_of('.', kLogIdWidth + 1);
+  if (after_label == std::string::npos) {
+    return false;
+  }
+
+  *id_out = std::stoul(name);
+  *label_out = name.substr(kLogIdWidth + 1, after_label - (kLogIdWidth + 1));
+
+  return true;
+}
+
+}  // namespace flog
+}  // namespace mojo