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 <errno.h>
20 #include <fcntl.h>
21 #include <stdarg.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26
27 #include <memory>
28 #include <string>
29 #include <utility>
30
31 #include <android-base/file.h>
32 #include <android-base/stringprintf.h>
33 #include <android-base/unique_fd.h>
34
35 using android::base::unique_fd;
36
37 namespace android {
38 namespace procinfo {
39
SetError(std::string * error,int errno_value,const char * fmt,...)40 bool SetError(std::string* error, int errno_value, const char* fmt, ...) {
41 if (error == nullptr) return false;
42
43 std::string result;
44 va_list ap;
45 va_start(ap, fmt);
46 android::base::StringAppendV(&result, fmt, ap);
47 va_end(ap);
48
49 if (errno_value != 0) {
50 result += ": ";
51 result += strerror(errno_value);
52 }
53
54 *error = result;
55 return false;
56 }
57
GetProcessInfo(pid_t tid,ProcessInfo * process_info,std::string * error)58 bool GetProcessInfo(pid_t tid, ProcessInfo* process_info, std::string* error) {
59 char path[32];
60 snprintf(path, sizeof(path), "/proc/%d", tid);
61
62 unique_fd dirfd(open(path, O_DIRECTORY | O_RDONLY | O_CLOEXEC));
63 if (dirfd == -1) {
64 return SetError(error, errno, "failed to open %s", path);
65 }
66
67 return GetProcessInfoFromProcPidFd(dirfd.get(), tid, process_info, error);
68 }
69
parse_state(char state)70 static ProcessState parse_state(char state) {
71 switch (state) {
72 case 'R':
73 return kProcessStateRunning;
74 case 'S':
75 return kProcessStateSleeping;
76 case 'D':
77 return kProcessStateUninterruptibleWait;
78 case 'T':
79 return kProcessStateStopped;
80 case 'Z':
81 return kProcessStateZombie;
82 default:
83 return kProcessStateUnknown;
84 }
85 }
86
GetProcessInfoFromProcPidFd(int fd,int pid,ProcessInfo * process_info,std::string * error)87 bool GetProcessInfoFromProcPidFd(int fd, int pid, ProcessInfo* process_info,
88 std::string* error /* can be nullptr */) {
89 int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
90 if (status_fd == -1) {
91 return SetError(error, errno,
92 "failed to open /proc/%d/status in GetProcessInfoFromProcPidFd", pid);
93 }
94
95 std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "re"), fclose);
96 if (!fp) {
97 close(status_fd);
98 return SetError(error, errno, "failed to open FILE for /proc/%d/status in GetProcessInfoFromProcPidFd", pid);
99 }
100
101 int field_bitmap = 0;
102 static constexpr int finished_bitmap = 63;
103 char* line = nullptr;
104 size_t len = 0;
105
106 while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
107 char* tab = strchr(line, '\t');
108 if (tab == nullptr) {
109 continue;
110 }
111
112 size_t header_len = tab - line;
113 std::string header = std::string(line, header_len);
114 if (header == "Name:") {
115 std::string name = line + header_len + 1;
116
117 // line includes the trailing newline.
118 name.pop_back();
119 process_info->name = std::move(name);
120
121 field_bitmap |= 1;
122 } else if (header == "Tgid:") {
123 process_info->pid = atoi(tab + 1);
124 field_bitmap |= 2;
125 } else if (header == "Pid:") {
126 process_info->tid = atoi(tab + 1);
127 field_bitmap |= 4;
128 } else if (header == "TracerPid:") {
129 process_info->tracer = atoi(tab + 1);
130 field_bitmap |= 8;
131 } else if (header == "Uid:") {
132 process_info->uid = atoi(tab + 1);
133 field_bitmap |= 16;
134 } else if (header == "Gid:") {
135 process_info->gid = atoi(tab + 1);
136 field_bitmap |= 32;
137 }
138 }
139
140 free(line);
141 if (field_bitmap != finished_bitmap) {
142 return SetError(error, 0, "failed to parse /proc/%d/status", pid);
143 }
144
145 unique_fd stat_fd(openat(fd, "stat", O_RDONLY | O_CLOEXEC));
146 if (stat_fd == -1) {
147 return SetError(error, errno, "failed to open /proc/%d/stat", pid);
148 }
149
150 std::string stat;
151 if (!android::base::ReadFdToString(stat_fd, &stat)) {
152 return SetError(error, errno, "failed to read /proc/%d/stat", pid);
153 }
154
155 // See man 5 proc. There's no reason comm can't contain ' ' or ')',
156 // so we search backwards for the end of it.
157 const char* end_of_comm = strrchr(stat.c_str(), ')');
158
159 static constexpr const char* pattern =
160 "%c " // state
161 "%d " // ppid
162 "%*d " // pgrp
163 "%*d " // session
164 "%*d " // tty_nr
165 "%*d " // tpgid
166 "%*u " // flags
167 "%*lu " // minflt
168 "%*lu " // cminflt
169 "%*lu " // majflt
170 "%*lu " // cmajflt
171 "%*lu " // utime
172 "%*lu " // stime
173 "%*ld " // cutime
174 "%*ld " // cstime
175 "%*ld " // priority
176 "%*ld " // nice
177 "%*ld " // num_threads
178 "%*ld " // itrealvalue
179 "%llu " // starttime
180 ;
181
182 char state = '\0';
183 int ppid = 0;
184 unsigned long long start_time = 0;
185 int rc = sscanf(end_of_comm + 2, pattern, &state, &ppid, &start_time);
186 if (rc != 3) {
187 return SetError(error, 0, "failed to parse /proc/%d/stat", pid);
188 }
189
190 process_info->state = parse_state(state);
191 process_info->ppid = ppid;
192 process_info->starttime = start_time;
193 return true;
194 }
195
196 } /* namespace procinfo */
197 } /* namespace android */
198