Define the Settings interface for a CrashReportDatabase and provide a Mac implementation.

client/settings_mac.h

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_CLIENT_SETTINGS_MAC_H_
+#define CRASHPAD_CLIENT_SETTINGS_MAC_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/files/file_path.h"
+#include "client/settings.h"
+#include "util/file/file_io.h"
+
+namespace crashpad {
+namespace internal {
+
+//! \brief An implementation of the Settings interface, which stores the values
+//!     in a property list (plist) file.
+class SettingsMac : public Settings {
+ public:
+  explicit SettingsMac(const base::FilePath& file_path);
+  ~SettingsMac() override;
+
+  bool Initialize();
+
+  // Settings:
+  bool GetClientID(std::string* client_id) override;
+  bool GetUploadsEnabled(bool* enabled) override;
+  bool SetUploadsEnabled(bool enabled) override;
+  bool GetLastUploadAttemptTime(time_t* time) override;
+  bool SetLastUploadAttemptTime(time_t time) override;
+
+ private:
+  // Deserializes the plist from |fd|, which must be opened for reading and
+  // have at least a shared file lock. Returns nil if an error occurred, with
+  // an error logged.
+  NSMutableDictionary* ReadPlist(FileHandle fd);
+
+  // Serializes the |plist| to the |fd|, which must be opened for writing and
+  // have the exclusive file lock. Returns true on success and false on failure.
+  bool WritePlist(FileHandle fd, NSDictionary* plist);
+
+  // Reads the settings file and returns the value associated with |key|, or nil
+  // if it is not set. The value must be of type |value_class| or it is an
+  // error. If an error occurs, it is logged and this returns nil.
+  id GetSetting(NSString* key, Class value_class);

[Mark Mentovai, 2015/03/09 14:01:23]

This can be templatized so that it returns the correct type instead of id.

+
+  // Sets the |value| for |key| and writes the plist file. Returns true on
+  // success and false on failure, with an error logged.
+  bool SetSetting(NSString* key, NSObject* value);
+
+  // Generates a client ID and writes it as the sole value in a plist to |fd|.
+  bool GenerateClientID(FileHandle fd);
+
+  // Performs error recovery by reopening the file with an exclusive lock and
+  // reading it. If the operation fails, the settings plist is recreated with
+  // a new client ID, and the new plist is returned.
+  NSMutableDictionary* RecoverPlist();
+
+  const char* file_path() { return file_path_.value().c_str(); };
+
+  base::FilePath file_path_;
+
+  DISALLOW_COPY_AND_ASSIGN(SettingsMac);
+};
+
+}  // namespace internal
+}  // namespace crashpad
+
+#endif  // CRASHPAD_CLIENT_SETTINGS_MAC_H_