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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef NETUTILS_FD_H
     18 #define NETUTILS_FD_H
     19 
     20 #include <ostream>
     21 
     22 #include "netdutils/Status.h"
     23 
     24 namespace android {
     25 namespace netdutils {
     26 
     27 // Strongly typed wrapper for file descriptors with value semantics.
     28 // This class should typically hold unowned file descriptors.
     29 class Fd {
     30   public:
     31     constexpr Fd() = default;
     32 
     33     constexpr Fd(int fd) : mFd(fd) {}
     34 
     35     int get() const { return mFd; }
     36 
     37     bool operator==(const Fd& other) const { return get() == other.get(); }
     38     bool operator!=(const Fd& other) const { return get() != other.get(); }
     39 
     40   private:
     41     int mFd = -1;
     42 };
     43 
     44 // Return true if fd appears valid (non-negative)
     45 inline bool isWellFormed(const Fd fd) {
     46     return fd.get() >= 0;
     47 }
     48 
     49 std::ostream& operator<<(std::ostream& os, const Fd& fd);
     50 
     51 }  // namespace netdutils
     52 }  // namespace android
     53 
     54 #endif /* NETUTILS_FD_H */
     55