Files
nearby/cpp/platform/impl/shared/file.cc
T

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3.2 KiB
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// Copyright 2020 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
//
// https://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 "platform/impl/shared/file.h"
#include <cstddef>
#include <memory>
#include "absl/strings/string_view.h"
#include "platform/base/exception.h"
namespace location {
namespace nearby {
namespace shared {
// InputFile
InputFile::InputFile(const char* file_path) : file_path_(file_path) {
// Open the file with the current location at eof (std::ios::ate)
// std::ios::binary - specifies binary access mode
// std::ios::in - allows input (read operations) from a stream
// std::ios::ate - sets the stream's position indicator to the
// end of the stream on opening.
file_.open(std::string(file_path),
std::ios::binary | std::ios::in | std::ios::ate);
// Read the current position in the file and use that for total size.
total_size_ = file_.tellg();
// Reset to the beginning of the file.
file_.seekg(0);
}
ExceptionOr<ByteArray> InputFile::Read(std::int64_t size) {
if (!file_.is_open()) {
return ExceptionOr<ByteArray>{Exception::kIo};
}
if (file_.peek() == EOF) {
return ExceptionOr<ByteArray>{ByteArray{}};
}
if (!file_.good()) {
return ExceptionOr<ByteArray>{Exception::kIo};
}
ByteArray bytes(size);
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<ByteArray>{Exception::kIo};
}
return ExceptionOr<ByteArray>(ByteArray(read_bytes.get(), num_bytes_read));
}
Exception InputFile::Close() {
if (file_.is_open()) {
file_.close();
}
return {Exception::kSuccess};
}
// OutputFile
OutputFile::OutputFile(const char* file_path) {
// std::ios::binary - specifies binary access mode
// std::ios::out - allows output (read operations) from
// a stream
// std::ios::trunc - when the file is opened, the old
// contents are immediately removed.
file_ = std::ofstream(file_path,
std::ios::binary | std::ios::out | std::ios::trunc);
}
Exception OutputFile::Write(const ByteArray& data) {
if (!file_.is_open()) {
return {Exception::kIo};
}
if (!file_.good()) {
return {Exception::kIo};
}
file_.write(data.data(), data.size());
file_.flush();
return {file_.good() ? Exception::kSuccess : Exception::kIo};
}
Exception OutputFile::Flush() {
file_.flush();
return {file_.good() ? Exception::kSuccess : Exception::kIo};
}
Exception OutputFile::Close() {
if (file_.is_open()) {
file_.close();
}
return {Exception::kSuccess};
}
} // namespace shared
} // namespace nearby
} // namespace location