1 /*
2  * Copyright (C) 2019 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 #pragma once
18 
19 #include <dirent.h>
20 #include <sys/types.h>
21 
22 #include <iterator>
23 #include <memory>
24 #include <vector>
25 
26 namespace android {
27 namespace base {
28 
29 class AllPids {
30   class PidIterator {
31    public:
PidIterator(DIR * dir)32     PidIterator(DIR* dir) : dir_(dir, closedir) { Increment(); }
33     PidIterator& operator++() {
34       Increment();
35       return *this;
36     }
37     bool operator==(const PidIterator& other) const { return pid_ == other.pid_; }
38     bool operator!=(const PidIterator& other) const { return !(*this == other); }
39     long operator*() const { return pid_; }
40     // iterator traits
41     using difference_type = pid_t;
42     using value_type = pid_t;
43     using pointer = const pid_t*;
44     using reference = const pid_t&;
45     using iterator_category = std::input_iterator_tag;
46 
47    private:
48     void Increment();
49 
50     pid_t pid_ = -1;
51     std::unique_ptr<DIR, decltype(&closedir)> dir_;
52   };
53 
54  public:
begin()55   PidIterator begin() { return opendir("/proc"); }
end()56   PidIterator end() { return nullptr; }
57 };
58 
59 }  // namespace base
60 }  // namespace android
61