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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 
     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 
     47 static ProcessState parse_state(const char* state) {
     48   switch (*state) {
     49     case 'R':
     50       return kProcessStateRunning;
     51     case 'S':
     52       return kProcessStateSleeping;
     53     case 'D':
     54       return kProcessStateUninterruptibleWait;
     55     case 'T':
     56       return kProcessStateStopped;
     57     case 'Z':
     58       return kProcessStateZombie;
     59     default:
     60       LOG(ERROR) << "unknown process state: " << *state;
     61       return kProcessStateUnknown;
     62   }
     63 }
     64 
     65 bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
     66   int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
     67 
     68   if (status_fd == -1) {
     69     PLOG(ERROR) << "failed to open status fd in GetProcessInfoFromProcPidFd";
     70     return false;
     71   }
     72 
     73   std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
     74   if (!fp) {
     75     PLOG(ERROR) << "failed to open status file in GetProcessInfoFromProcPidFd";
     76     close(status_fd);
     77     return false;
     78   }
     79 
     80   int field_bitmap = 0;
     81   static constexpr int finished_bitmap = 255;
     82   char* line = nullptr;
     83   size_t len = 0;
     84 
     85   while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
     86     char* tab = strchr(line, '\t');
     87     if (tab == nullptr) {
     88       continue;
     89     }
     90 
     91     size_t header_len = tab - line;
     92     std::string header = std::string(line, header_len);
     93     if (header == "Name:") {
     94       std::string name = line + header_len + 1;
     95 
     96       // line includes the trailing newline.
     97       name.pop_back();
     98       process_info->name = std::move(name);
     99 
    100       field_bitmap |= 1;
    101     } else if (header == "Pid:") {
    102       process_info->tid = atoi(tab + 1);
    103       field_bitmap |= 2;
    104     } else if (header == "Tgid:") {
    105       process_info->pid = atoi(tab + 1);
    106       field_bitmap |= 4;
    107     } else if (header == "PPid:") {
    108       process_info->ppid = atoi(tab + 1);
    109       field_bitmap |= 8;
    110     } else if (header == "TracerPid:") {
    111       process_info->tracer = atoi(tab + 1);
    112       field_bitmap |= 16;
    113     } else if (header == "Uid:") {
    114       process_info->uid = atoi(tab + 1);
    115       field_bitmap |= 32;
    116     } else if (header == "Gid:") {
    117       process_info->gid = atoi(tab + 1);
    118       field_bitmap |= 64;
    119     } else if (header == "State:") {
    120       process_info->state = parse_state(tab + 1);
    121       field_bitmap |= 128;
    122     }
    123   }
    124 
    125   free(line);
    126   return field_bitmap == finished_bitmap;
    127 }
    128 
    129 } /* namespace procinfo */
    130 } /* namespace android */
    131