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)34 bool GetProcessInfo(pid_t tid, ProcessInfo* process_info) {
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 PLOG(ERROR) << "failed to open " << path;
41 return false;
42 }
43
44 return GetProcessInfoFromProcPidFd(dirfd.get(), process_info);
45 }
46
GetProcessInfoFromProcPidFd(int fd,ProcessInfo * process_info)47 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
48 int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
49
50 if (status_fd == -1) {
51 PLOG(ERROR) << "failed to open status fd in GetProcessInfoFromProcPidFd";
52 return false;
53 }
54
55 std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
56 if (!fp) {
57 PLOG(ERROR) << "failed to open status file in GetProcessInfoFromProcPidFd";
58 close(status_fd);
59 return false;
60 }
61
62 int field_bitmap = 0;
63 static constexpr int finished_bitmap = 127;
64 char* line = nullptr;
65 size_t len = 0;
66
67 while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
68 char* tab = strchr(line, '\t');
69 if (tab == nullptr) {
70 continue;
71 }
72
73 size_t header_len = tab - line;
74 std::string header = std::string(line, header_len);
75 if (header == "Name:") {
76 std::string name = line + header_len + 1;
77
78 // line includes the trailing newline.
79 name.pop_back();
80 process_info->name = std::move(name);
81
82 field_bitmap |= 1;
83 } else if (header == "Pid:") {
84 process_info->tid = atoi(tab + 1);
85 field_bitmap |= 2;
86 } else if (header == "Tgid:") {
87 process_info->pid = atoi(tab + 1);
88 field_bitmap |= 4;
89 } else if (header == "PPid:") {
90 process_info->ppid = atoi(tab + 1);
91 field_bitmap |= 8;
92 } else if (header == "TracerPid:") {
93 process_info->tracer = atoi(tab + 1);
94 field_bitmap |= 16;
95 } else if (header == "Uid:") {
96 process_info->uid = atoi(tab + 1);
97 field_bitmap |= 32;
98 } else if (header == "Gid:") {
99 process_info->gid = atoi(tab + 1);
100 field_bitmap |= 64;
101 }
102 }
103
104 free(line);
105 return field_bitmap == finished_bitmap;
106 }
107
108 } /* namespace procinfo */
109 } /* namespace android */
110