Added FileIo class for reading and writing persisted values to disk, as well as

a mock class to faciliate testing.

PiperOrigin-RevId: 261015096

Author: amablue

database/src/desktop/persistence/file_io.cc

@@ -0,0 +1,58 @@
+// Copyright 2019 Google LLC
+//
+// 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.
+
+#include "database/src/desktop/persistence/file_io.h"
+
+#include <fstream>
+#include <iostream>
+
+#include "third_party/flatbuffers/include/flatbuffers/util.h"
+
+namespace firebase {
+namespace database {
+namespace internal {
+
+FileIoInterface::~FileIoInterface() {}
+
+FileIo::~FileIo() {}
+
+bool FileIo::ClearFile(const char* name) {
+  std::ofstream ofs(name, std::ios::binary);
+  if (!ofs.is_open()) return false;
+  ofs.write(nullptr, 0);
+  return !ofs.bad();
+}
+
+bool FileIo::AppendToFile(const char* name, const char* buffer, size_t size) {
+  std::ofstream ofs(name, std::ios::binary | std::ios::app);
+  if (!ofs.is_open()) return false;
+  ofs.write(buffer, size);
+  return !ofs.bad();
+}
+
+bool FileIo::ReadFromFile(const char* name, std::string* buffer) {
+  bool result = flatbuffers::LoadFile(name, true, buffer);
+  return result;
+}
+
+bool FileIo::SetByte(const char* name, size_t offset, uint8_t byte) {
+  std::fstream ofs(name, std::ios::binary | std::ios::in | std::ios::out);
+  ofs.seekp(offset);
+  ofs.put(byte);
+  return !ofs.bad();
+}
+
+}  // namespace internal
+}  // namespace database
+}  // namespace firebase

database/src/desktop/persistence/file_io.h

@@ -0,0 +1,47 @@
+// Copyright 2019 Google LLC
+//
+// 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 FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_FILE_IO_H_
+#define FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_FILE_IO_H_
+
+#include <string>
+
+namespace firebase {
+namespace database {
+namespace internal {
+
+class FileIoInterface {
+ public:
+  virtual ~FileIoInterface() = 0;
+  virtual bool ClearFile(const char* name) = 0;
+  virtual bool AppendToFile(const char* name, const char* buffer,
+                            size_t size) = 0;
+  virtual bool ReadFromFile(const char* name, std::string* buffer) = 0;
+  virtual bool SetByte(const char* name, size_t offset, uint8_t byte) = 0;
+};
+
+class FileIo : public FileIoInterface {
+ public:
+  ~FileIo() override;
+  bool ClearFile(const char* name) override;
+  bool AppendToFile(const char* name, const char* buffer, size_t size) override;
+  bool ReadFromFile(const char* name, std::string* buffer) override;
+  bool SetByte(const char* name, size_t offset, uint8_t byte) override;
+};
+
+}  // namespace internal
+}  // namespace database
+}  // namespace firebase
+
+#endif  // FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_FILE_IO_H_