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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(const char * state)49 static ProcessState parse_state(const 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       LOG(ERROR) << "unknown process state: " << *state;
63       return kProcessStateUnknown;
64   }
65 }
66 
GetProcessInfoFromProcPidFd(int fd,ProcessInfo * process_info,std::string * error)67 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info, std::string* error) {
68   int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
69 
70   if (status_fd == -1) {
71     if (error != nullptr) {
72       *error = "failed to open status fd in GetProcessInfoFromProcPidFd";
73     }
74     return false;
75   }
76 
77   std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
78   if (!fp) {
79     if (error != nullptr) {
80       *error = "failed to open status file in GetProcessInfoFromProcPidFd";
81     }
82     close(status_fd);
83     return false;
84   }
85 
86   int field_bitmap = 0;
87   static constexpr int finished_bitmap = 255;
88   char* line = nullptr;
89   size_t len = 0;
90 
91   while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
92     char* tab = strchr(line, '\t');
93     if (tab == nullptr) {
94       continue;
95     }
96 
97     size_t header_len = tab - line;
98     std::string header = std::string(line, header_len);
99     if (header == "Name:") {
100       std::string name = line + header_len + 1;
101 
102       // line includes the trailing newline.
103       name.pop_back();
104       process_info->name = std::move(name);
105 
106       field_bitmap |= 1;
107     } else if (header == "Pid:") {
108       process_info->tid = atoi(tab + 1);
109       field_bitmap |= 2;
110     } else if (header == "Tgid:") {
111       process_info->pid = atoi(tab + 1);
112       field_bitmap |= 4;
113     } else if (header == "PPid:") {
114       process_info->ppid = atoi(tab + 1);
115       field_bitmap |= 8;
116     } else if (header == "TracerPid:") {
117       process_info->tracer = atoi(tab + 1);
118       field_bitmap |= 16;
119     } else if (header == "Uid:") {
120       process_info->uid = atoi(tab + 1);
121       field_bitmap |= 32;
122     } else if (header == "Gid:") {
123       process_info->gid = atoi(tab + 1);
124       field_bitmap |= 64;
125     } else if (header == "State:") {
126       process_info->state = parse_state(tab + 1);
127       field_bitmap |= 128;
128     }
129   }
130 
131   free(line);
132   return field_bitmap == finished_bitmap;
133 }
134 
135 } /* namespace procinfo */
136 } /* namespace android */
137