1 /*
2  * Copyright (C) 2023 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 <sys/types.h>
20 #include <unistd.h>
21 
22 #include <string>
23 #include <unordered_map>
24 #include <vector>
25 
26 #include "common/libs/utils/result.h"
27 
28 /**
29  * @file Utility functions to retrieve information from proc filesystem
30  *
31  * As of now, the major consumer is cvd.
32  */
33 namespace cuttlefish {
34 
35 static constexpr char kProcDir[] = "/proc";
36 
37 struct ProcInfo {
38   pid_t pid_;
39   uid_t real_owner_;
40   uid_t effective_owner_;
41   std::string actual_exec_path_;
42   std::unordered_map<std::string, std::string> envs_;
43   std::vector<std::string> args_;
44 };
45 Result<ProcInfo> ExtractProcInfo(const pid_t pid);
46 
47 // collects all pids whose owner is uid
48 Result<std::vector<pid_t>> CollectPids(const uid_t uid = getuid());
49 
50 /* collects all pids that meet the following:
51  *
52  * 1. Belongs to the uid
53  * 2. cpp_basename(readlink(/proc/<pid>/exe)) == exec_name
54  *
55  */
56 Result<std::vector<pid_t>> CollectPidsByExecName(const std::string& exec_name,
57                                                  const uid_t uid = getuid());
58 
59 /* collects all pids that meet the following:
60  *
61  * 1. Belongs to the uid
62  * 2. readlink(/proc/<pid>/exe) == exec_name
63  *
64  */
65 Result<std::vector<pid_t>> CollectPidsByExecPath(const std::string& exec_path,
66                                                  const uid_t uid = getuid());
67 
68 /**
69  * When argv[0] != exec_path, collects PIDs based on argv[0]
70  *
71  */
72 Result<std::vector<pid_t>> CollectPidsByArgv0(const std::string& expected_argv0,
73                                               const uid_t uid = getuid());
74 
75 Result<uid_t> OwnerUid(const pid_t pid);
76 
77 // retrieves command line args for the pid
78 Result<std::vector<std::string>> GetCmdArgs(const pid_t pid);
79 
80 // retrieves the path to the executable file used for the pid
81 // this does not work for the defunct processes
82 Result<std::string> GetExecutablePath(const pid_t pid);
83 
84 // retrieves the environment variables of the process, pid
85 Result<std::unordered_map<std::string, std::string>> GetEnvs(const pid_t pid);
86 
87 Result<pid_t> Ppid(const pid_t pid);
88 
89 }  // namespace cuttlefish
90