Roll forward to cl/314549634

Change-Id: I4d1e7eacd5fa4078a094571ad6d5f51e422535ff

cpp/platform/impl/shared/file_impl.cc

@@ -0,0 +1,75 @@
+#include "platform/impl/shared/file_impl.h"
+
+#include <cstddef>
+#include <memory>
+
+namespace location {
+namespace nearby {
+
+// InputFile
+
+InputFileImpl::InputFileImpl(const std::string& path, std::int64_t size)
+    : file_(path), path_(path), total_size_(size) {}
+
+ExceptionOr<ConstPtr<ByteArray>> InputFileImpl::read(int64_t size) {
+  if (!file_.is_open()) {
+    return ExceptionOr<ConstPtr<ByteArray>>(Exception::IO);
+  }
+
+  if (file_.peek() == EOF) {
+    return ExceptionOr<ConstPtr<ByteArray>>(ConstPtr<ByteArray>());
+  }
+
+  if (!file_.good()) {
+    return ExceptionOr<ConstPtr<ByteArray>>(Exception::IO);
+  }
+
+  std::unique_ptr<char[]> read_bytes {new char [size]};
+  file_.read(read_bytes.get(), static_cast<ptrdiff_t>(size));
+  auto num_bytes_read = file_.gcount();
+  if (num_bytes_read == 0) {
+    return ExceptionOr<ConstPtr<ByteArray>>(Exception::IO);
+  }
+
+  return ExceptionOr<ConstPtr<ByteArray>>(
+      MakeConstPtr(new ByteArray(read_bytes.get(), num_bytes_read)));
+}
+
+std::string InputFileImpl::getFilePath() const { return path_; }
+
+std::int64_t InputFileImpl::getTotalSize() const { return total_size_; }
+
+void InputFileImpl::close() {
+  if (file_.is_open()) {
+    file_.close();
+  }
+}
+
+// OutputFile
+
+OutputFileImpl::OutputFileImpl(const std::string& path) : file_(path) {}
+
+Exception::Value OutputFileImpl::write(ConstPtr<ByteArray> data) {
+  ScopedPtr<ConstPtr<ByteArray>> scoped_data(data);
+
+  if (!file_.is_open()) {
+    return Exception::IO;
+  }
+
+  if (!file_.good()) {
+    return Exception::IO;
+  }
+
+  file_.write(data->getData(), data->size());
+  file_.flush();
+  return file_.good() ? Exception::NONE : Exception::IO;
+}
+
+void OutputFileImpl::close() {
+  if (file_.is_open()) {
+    file_.close();
+  }
+}
+
+}  // namespace nearby
+}  // namespace location