libs/androidfw/include/androidfw/FileStream.h

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.
 */

#pragma once

#include <memory>
#include <string>
#include <unistd.h>

#include "Streams.h"
#include "android-base/macros.h"
#include "android-base/unique_fd.h"

namespace android {

constexpr size_t kDefaultBufferCapacity = 4096u;

class FileInputStream : public InputStream {
 public:
  explicit FileInputStream(const std::string& path,
                           size_t buffer_capacity = kDefaultBufferCapacity);

  // Take ownership of `fd`.
  explicit FileInputStream(int fd, size_t buffer_capacity = kDefaultBufferCapacity);

  // Take ownership of `fd`.
  explicit FileInputStream(android::base::borrowed_fd fd,
                           size_t buffer_capacity = kDefaultBufferCapacity);

  ~FileInputStream() {
    if (should_close_ && (fd_ != -1)) {
      close(fd_);
    }
  }

  bool Next(const void** data, size_t* size) override;

  void BackUp(size_t count) override;

  size_t ByteCount() const override;

  bool HadError() const override;

  std::string GetError() const override;

  bool ReadFullyAtOffset(void* data, size_t byte_count, off64_t offset) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(FileInputStream);

  int fd_ = -1;
  std::string error_;
  bool should_close_;
  std::unique_ptr<uint8_t[]> buffer_;
  size_t buffer_capacity_ = 0u;
  size_t buffer_offset_ = 0u;
  size_t buffer_size_ = 0u;
  size_t total_byte_count_ = 0u;
};

class FileOutputStream : public OutputStream {
 public:
  explicit FileOutputStream(const std::string& path,
                            size_t buffer_capacity = kDefaultBufferCapacity);

  // Does not take ownership of `fd`.
  explicit FileOutputStream(int fd, size_t buffer_capacity = kDefaultBufferCapacity);

  // Takes ownership of `fd`.
  explicit FileOutputStream(android::base::unique_fd fd,
                            size_t buffer_capacity = kDefaultBufferCapacity);

  ~FileOutputStream();

  bool Next(void** data, size_t* size) override;

  // Immediately flushes out the contents of the buffer to disk.
  bool Flush();

  void BackUp(size_t count) override;

  size_t ByteCount() const override;

  bool HadError() const override;

  std::string GetError() const override;

 private:
  DISALLOW_COPY_AND_ASSIGN(FileOutputStream);

  bool FlushImpl();

  android::base::unique_fd owned_fd_;
  int fd_;
  std::string error_;
  std::unique_ptr<uint8_t[]> buffer_;
  size_t buffer_capacity_ = 0u;
  size_t buffer_offset_ = 0u;
  size_t total_byte_count_ = 0u;
};

}  // namespace android