1 /*
2  * Copyright (C) 2016 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 <fcntl.h>
21 #include <stdlib.h>
22 #include <sys/types.h>
23 #include <unistd.h>
24 
25 #include <memory>
26 #include <string>
27 #include <type_traits>
28 
29 #include <android-base/logging.h>
30 #include <android-base/parseint.h>
31 #include <android-base/unique_fd.h>
32 
33 namespace android {
34 namespace procinfo {
35 
36 #if defined(__linux__)
37 
38 struct ProcessInfo {
39   std::string name;
40   pid_t tid;
41   pid_t pid;
42   pid_t ppid;
43   pid_t tracer;
44   uid_t uid;
45   uid_t gid;
46 };
47 
48 // Parse the contents of /proc/<tid>/status into |process_info|.
49 bool GetProcessInfo(pid_t tid, ProcessInfo* process_info);
50 
51 // Parse the contents of <fd>/status into |process_info|.
52 // |fd| should be an fd pointing at a /proc/<pid> directory.
53 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info);
54 
55 // Fetch the list of threads from a given process's /proc/<pid> directory.
56 // |fd| should be an fd pointing at a /proc/<pid> directory.
57 template <typename Collection>
58 auto GetProcessTidsFromProcPidFd(int fd, Collection* out) ->
59     typename std::enable_if<sizeof(typename Collection::value_type) >= sizeof(pid_t), bool>::type {
60   out->clear();
61 
62   int task_fd = openat(fd, "task", O_DIRECTORY | O_RDONLY | O_CLOEXEC);
63   std::unique_ptr<DIR, int (*)(DIR*)> dir(fdopendir(task_fd), closedir);
64   if (!dir) {
65     PLOG(ERROR) << "failed to open task directory";
66     return false;
67   }
68 
69   struct dirent* dent;
70   while ((dent = readdir(dir.get()))) {
71     if (strcmp(dent->d_name, ".") != 0 && strcmp(dent->d_name, "..") != 0) {
72       pid_t tid;
73       if (!android::base::ParseInt(dent->d_name, &tid, 1, std::numeric_limits<pid_t>::max())) {
74         LOG(ERROR) << "failed to parse task id: " << dent->d_name;
75         return false;
76       }
77 
78       out->insert(out->end(), tid);
79     }
80   }
81 
82   return true;
83 }
84 
85 template <typename Collection>
86 auto GetProcessTids(pid_t pid, Collection* out) ->
87     typename std::enable_if<sizeof(typename Collection::value_type) >= sizeof(pid_t), bool>::type {
88   char task_path[PATH_MAX];
89   if (snprintf(task_path, PATH_MAX, "/proc/%d", pid) >= PATH_MAX) {
90     LOG(ERROR) << "task path overflow (pid = " << pid << ")";
91     return false;
92   }
93 
94   android::base::unique_fd fd(open(task_path, O_DIRECTORY | O_RDONLY | O_CLOEXEC));
95   if (fd == -1) {
96     PLOG(ERROR) << "failed to open " << task_path;
97     return false;
98   }
99 
100   return GetProcessTidsFromProcPidFd(fd.get(), out);
101 }
102 
103 #endif
104 
105 } /* namespace procinfo */
106 } /* namespace android */
107