1 /*
2  * Copyright (c) 2017 Facebook, Inc.
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 #pragma once
18 
19 #include <unistd.h>
20 
21 namespace ebpf {
22 
23 /// FileDesc is a helper class for managing open file descriptors. Copy is
24 /// disallowed (call dup instead), and cleanup happens automatically.
25 class FileDesc {
26  public:
fd_(fd)27   explicit FileDesc(int fd = -1) : fd_(fd) {}
FileDesc(FileDesc && that)28   FileDesc(FileDesc &&that) : fd_(-1) { *this = std::move(that); }
29   FileDesc(const FileDesc &that) = delete;
30 
~FileDesc()31   ~FileDesc() {
32     if (fd_ >= 0)
33       ::close(fd_);
34   }
35 
36   FileDesc &operator=(int fd) {
37     if (fd_ >= 0)
38       ::close(fd_);
39     fd_ = fd;
40     return *this;
41   }
42   FileDesc &operator=(FileDesc &&that) {
43     if (fd_ >= 0)
44       ::close(fd_);
45     fd_ = that.fd_;
46     that.fd_ = -1;
47     return *this;
48   }
49   FileDesc &operator=(const FileDesc &that) = delete;
50 
dup()51   FileDesc dup() const {
52     if (fd_ >= 0) {
53       int dup_fd = ::dup(fd_);
54       return FileDesc(dup_fd);
55     } else {
56       return FileDesc(-1);
57     }
58   }
59 
60   operator int() { return fd_; }
61   operator int() const { return fd_; }
62 
63  private:
64   int fd_;
65 };
66 
67 }  // namespace ebpf
68