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 #include <procinfo/process.h>
18
19 #include <fcntl.h>
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <unistd.h>
24
25 #include <string>
26
27 #include <android-base/unique_fd.h>
28
29 using android::base::unique_fd;
30
31 namespace android {
32 namespace procinfo {
33
GetProcessInfo(pid_t tid,ProcessInfo * process_info,std::string * error)34 bool GetProcessInfo(pid_t tid, ProcessInfo* process_info, std::string* error) {
35 char path[PATH_MAX];
36 snprintf(path, sizeof(path), "/proc/%d", tid);
37
38 unique_fd dirfd(open(path, O_DIRECTORY | O_RDONLY));
39 if (dirfd == -1) {
40 if (error != nullptr) {
41 *error = std::string("failed to open ") + path;
42 }
43 return false;
44 }
45
46 return GetProcessInfoFromProcPidFd(dirfd.get(), process_info, error);
47 }
48
parse_state(char state)49 static ProcessState parse_state(char state) {
50 switch (state) {
51 case 'R':
52 return kProcessStateRunning;
53 case 'S':
54 return kProcessStateSleeping;
55 case 'D':
56 return kProcessStateUninterruptibleWait;
57 case 'T':
58 return kProcessStateStopped;
59 case 'Z':
60 return kProcessStateZombie;
61 default:
62 return kProcessStateUnknown;
63 }
64 }
65
GetProcessInfoFromProcPidFd(int fd,ProcessInfo * process_info,std::string * error)66 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info,
67 std::string* error /* can be nullptr */) {
68 int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
69
70 auto set_error = [&error](const char* err) {
71 if (error != nullptr) {
72 *error = err;
73 }
74 };
75
76 if (status_fd == -1) {
77 set_error("failed to open status fd in GetProcessInfoFromProcPidFd");
78 return false;
79 }
80
81 std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
82 if (!fp) {
83 set_error("failed to open status file in GetProcessInfoFromProcPidFd");
84 close(status_fd);
85 return false;
86 }
87
88 int field_bitmap = 0;
89 static constexpr int finished_bitmap = 63;
90 char* line = nullptr;
91 size_t len = 0;
92
93 while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
94 char* tab = strchr(line, '\t');
95 if (tab == nullptr) {
96 continue;
97 }
98
99 size_t header_len = tab - line;
100 std::string header = std::string(line, header_len);
101 if (header == "Name:") {
102 std::string name = line + header_len + 1;
103
104 // line includes the trailing newline.
105 name.pop_back();
106 process_info->name = std::move(name);
107
108 field_bitmap |= 1;
109 } else if (header == "Tgid:") {
110 process_info->pid = atoi(tab + 1);
111 field_bitmap |= 2;
112 } else if (header == "Pid:") {
113 process_info->tid = atoi(tab + 1);
114 field_bitmap |= 4;
115 } else if (header == "TracerPid:") {
116 process_info->tracer = atoi(tab + 1);
117 field_bitmap |= 8;
118 } else if (header == "Uid:") {
119 process_info->uid = atoi(tab + 1);
120 field_bitmap |= 16;
121 } else if (header == "Gid:") {
122 process_info->gid = atoi(tab + 1);
123 field_bitmap |= 32;
124 }
125 }
126
127 free(line);
128 if (field_bitmap != finished_bitmap) {
129 set_error("failed to parse /proc/<pid>/status");
130 return false;
131 }
132
133 unique_fd stat_fd(openat(fd, "stat", O_RDONLY | O_CLOEXEC));
134 if (stat_fd == -1) {
135 set_error("failed to open /proc/<pid>/stat");
136 }
137
138 std::string stat;
139 if (!android::base::ReadFdToString(stat_fd, &stat)) {
140 set_error("failed to read /proc/<pid>/stat");
141 return false;
142 }
143
144 // See man 5 proc. There's no reason comm can't contain ' ' or ')',
145 // so we search backwards for the end of it.
146 const char* end_of_comm = strrchr(stat.c_str(), ')');
147
148 static constexpr const char* pattern =
149 "%c " // state
150 "%d " // ppid
151 "%*d " // pgrp
152 "%*d " // session
153 "%*d " // tty_nr
154 "%*d " // tpgid
155 "%*u " // flags
156 "%*lu " // minflt
157 "%*lu " // cminflt
158 "%*lu " // majflt
159 "%*lu " // cmajflt
160 "%*lu " // utime
161 "%*lu " // stime
162 "%*ld " // cutime
163 "%*ld " // cstime
164 "%*ld " // priority
165 "%*ld " // nice
166 "%*ld " // num_threads
167 "%*ld " // itrealvalue
168 "%llu " // starttime
169 ;
170
171 char state = '\0';
172 int ppid = 0;
173 unsigned long long start_time = 0;
174 int rc = sscanf(end_of_comm + 2, pattern, &state, &ppid, &start_time);
175 if (rc != 3) {
176 set_error("failed to parse /proc/<pid>/stat");
177 return false;
178 }
179
180 process_info->state = parse_state(state);
181 process_info->ppid = ppid;
182 process_info->starttime = start_time;
183 return true;
184 }
185
186 } /* namespace procinfo */
187 } /* namespace android */
188