text: /*
   * Copyright (C) 2015 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.
   */
  
  #ifndef ANDROID_BASE_UNIQUE_FD_H
  #define ANDROID_BASE_UNIQUE_FD_H
  
  #include <museum/8.0.0/bionic/libc/unistd.h>
  
  // DO NOT INCLUDE OTHER LIBBASE HEADERS!
  // This file gets used in libbinder, and libbinder is used everywhere.
  // Including other headers from libbase frequently results in inclusion of
  // android-base/macros.h, which causes macro collisions.
  
  // Container for a file descriptor that automatically closes the descriptor as
  // it goes out of scope.
  //
  //      unique_fd ufd(open("/some/path", "r"));
  //      if (ufd.get() == -1) return error;
  //
  //      // Do something useful, possibly including 'return'.
  //
  //      return 0; // Descriptor is closed for you.
  //
  // unique_fd is also known as ScopedFd/ScopedFD/scoped_fd; mentioned here to help
  // you find this class if you're searching for one of those names.
  namespace facebook { namespace museum { namespace MUSEUM_VERSION { namespace android {
  namespace base {
  
  struct DefaultCloser {
    static void Close(int fd) {
      // Even if close(2) fails with EINTR, the fd will have been closed.
      // Using TEMP_FAILURE_RETRY will either lead to EBADF or closing someone
      // else's fd.
      // http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
      ::close(fd);
    }
  };
  
  template <typename Closer>
  class unique_fd_impl final {
   public:
    unique_fd_impl() : value_(-1) {}
  
    explicit unique_fd_impl(int value) : value_(value) {}
    ~unique_fd_impl() { reset(); }
  
    unique_fd_impl(unique_fd_impl&& other) : value_(other.release()) {}
    unique_fd_impl& operator=(unique_fd_impl&& s) {
      reset(s.release());
      return *this;
    }
  
    void reset(int new_value = -1) {
      if (value_ != -1) {
        Closer::Close(value_);
      }
      value_ = new_value;
    }
  
    int get() const { return value_; }
    operator int() const { return get(); }
  
    int release() __attribute__((warn_unused_result)) {
      int ret = value_;
      value_ = -1;
      return ret;
    }
  
   private:
    int value_;
  
    unique_fd_impl(const unique_fd_impl&);
    void operator=(const unique_fd_impl&);
  };
  
  using unique_fd = unique_fd_impl<DefaultCloser>;
  
  }  // namespace base
  } } } } // namespace facebook::museum::MUSEUM_VERSION::android
  
  template <typename T>
  int close(const android::base::unique_fd_impl<T>&)
  #if defined(__clang__)
    __attribute__((__unavailable__(
  #else
    __attribute__((__error__(
  #endif
      "close called on unique_fd"
    )));
  
  #endif  // ANDROID_BASE_UNIQUE_FD_H
  