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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/process/internal_linux.h"
      6 
      7 #include <unistd.h>
      8 
      9 #include <map>
     10 #include <string>
     11 #include <vector>
     12 
     13 #include "base/file_util.h"
     14 #include "base/logging.h"
     15 #include "base/strings/string_number_conversions.h"
     16 #include "base/strings/string_split.h"
     17 #include "base/strings/string_util.h"
     18 #include "base/threading/thread_restrictions.h"
     19 #include "base/time/time.h"
     20 
     21 namespace base {
     22 namespace internal {
     23 
     24 const char kProcDir[] = "/proc";
     25 
     26 const char kStatFile[] = "stat";
     27 
     28 base::FilePath GetProcPidDir(pid_t pid) {
     29   return base::FilePath(kProcDir).Append(IntToString(pid));
     30 }
     31 
     32 pid_t ProcDirSlotToPid(const char* d_name) {
     33   int i;
     34   for (i = 0; i < NAME_MAX && d_name[i]; ++i) {
     35     if (!IsAsciiDigit(d_name[i])) {
     36       return 0;
     37     }
     38   }
     39   if (i == NAME_MAX)
     40     return 0;
     41 
     42   // Read the process's command line.
     43   pid_t pid;
     44   std::string pid_string(d_name);
     45   if (!StringToInt(pid_string, &pid)) {
     46     NOTREACHED();
     47     return 0;
     48   }
     49   return pid;
     50 }
     51 
     52 bool ReadProcFile(const FilePath& file, std::string* buffer) {
     53   buffer->clear();
     54   // Synchronously reading files in /proc is safe.
     55   ThreadRestrictions::ScopedAllowIO allow_io;
     56 
     57   if (!ReadFileToString(file, buffer)) {
     58     DLOG(WARNING) << "Failed to read " << file.MaybeAsASCII();
     59     return false;
     60   }
     61   return !buffer->empty();
     62 }
     63 
     64 bool ReadProcStats(pid_t pid, std::string* buffer) {
     65   FilePath stat_file = internal::GetProcPidDir(pid).Append(kStatFile);
     66   return ReadProcFile(stat_file, buffer);
     67 }
     68 
     69 bool ParseProcStats(const std::string& stats_data,
     70                     std::vector<std::string>* proc_stats) {
     71   // |stats_data| may be empty if the process disappeared somehow.
     72   // e.g. http://crbug.com/145811
     73   if (stats_data.empty())
     74     return false;
     75 
     76   // The stat file is formatted as:
     77   // pid (process name) data1 data2 .... dataN
     78   // Look for the closing paren by scanning backwards, to avoid being fooled by
     79   // processes with ')' in the name.
     80   size_t open_parens_idx = stats_data.find(" (");
     81   size_t close_parens_idx = stats_data.rfind(") ");
     82   if (open_parens_idx == std::string::npos ||
     83       close_parens_idx == std::string::npos ||
     84       open_parens_idx > close_parens_idx) {
     85     DLOG(WARNING) << "Failed to find matched parens in '" << stats_data << "'";
     86     NOTREACHED();
     87     return false;
     88   }
     89   open_parens_idx++;
     90 
     91   proc_stats->clear();
     92   // PID.
     93   proc_stats->push_back(stats_data.substr(0, open_parens_idx));
     94   // Process name without parentheses.
     95   proc_stats->push_back(
     96       stats_data.substr(open_parens_idx + 1,
     97                         close_parens_idx - (open_parens_idx + 1)));
     98 
     99   // Split the rest.
    100   std::vector<std::string> other_stats;
    101   SplitString(stats_data.substr(close_parens_idx + 2), ' ', &other_stats);
    102   for (size_t i = 0; i < other_stats.size(); ++i)
    103     proc_stats->push_back(other_stats[i]);
    104   return true;
    105 }
    106 
    107 typedef std::map<std::string, std::string> ProcStatMap;
    108 void ParseProcStat(const std::string& contents, ProcStatMap* output) {
    109   typedef std::pair<std::string, std::string> StringPair;
    110   std::vector<StringPair> key_value_pairs;
    111   SplitStringIntoKeyValuePairs(contents, ' ', '\n', &key_value_pairs);
    112   for (size_t i = 0; i < key_value_pairs.size(); ++i) {
    113     const StringPair& key_value_pair = key_value_pairs[i];
    114     output->insert(key_value_pair);
    115   }
    116 }
    117 
    118 int GetProcStatsFieldAsInt(const std::vector<std::string>& proc_stats,
    119                            ProcStatsFields field_num) {
    120   DCHECK_GE(field_num, VM_PPID);
    121   CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
    122 
    123   int value;
    124   return StringToInt(proc_stats[field_num], &value) ? value : 0;
    125 }
    126 
    127 size_t GetProcStatsFieldAsSizeT(const std::vector<std::string>& proc_stats,
    128                                 ProcStatsFields field_num) {
    129   DCHECK_GE(field_num, VM_PPID);
    130   CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
    131 
    132   size_t value;
    133   return StringToSizeT(proc_stats[field_num], &value) ? value : 0;
    134 }
    135 
    136 int ReadProcStatsAndGetFieldAsInt(pid_t pid,
    137                                   ProcStatsFields field_num) {
    138   std::string stats_data;
    139   if (!ReadProcStats(pid, &stats_data))
    140     return 0;
    141   std::vector<std::string> proc_stats;
    142   if (!ParseProcStats(stats_data, &proc_stats))
    143     return 0;
    144   return GetProcStatsFieldAsInt(proc_stats, field_num);
    145 }
    146 
    147 size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
    148                                        ProcStatsFields field_num) {
    149   std::string stats_data;
    150   if (!ReadProcStats(pid, &stats_data))
    151     return 0;
    152   std::vector<std::string> proc_stats;
    153   if (!ParseProcStats(stats_data, &proc_stats))
    154     return 0;
    155   return GetProcStatsFieldAsSizeT(proc_stats, field_num);
    156 }
    157 
    158 Time GetBootTime() {
    159   FilePath path("/proc/stat");
    160   std::string contents;
    161   if (!ReadProcFile(path, &contents))
    162     return Time();
    163   ProcStatMap proc_stat;
    164   ParseProcStat(contents, &proc_stat);
    165   ProcStatMap::const_iterator btime_it = proc_stat.find("btime");
    166   if (btime_it == proc_stat.end())
    167     return Time();
    168   int btime;
    169   if (!StringToInt(btime_it->second, &btime))
    170     return Time();
    171   return Time::FromTimeT(btime);
    172 }
    173 
    174 TimeDelta ClockTicksToTimeDelta(int clock_ticks) {
    175   // This queries the /proc-specific scaling factor which is
    176   // conceptually the system hertz.  To dump this value on another
    177   // system, try
    178   //   od -t dL /proc/self/auxv
    179   // and look for the number after 17 in the output; mine is
    180   //   0000040          17         100           3   134512692
    181   // which means the answer is 100.
    182   // It may be the case that this value is always 100.
    183   static const int kHertz = sysconf(_SC_CLK_TCK);
    184 
    185   return TimeDelta::FromMicroseconds(
    186       Time::kMicrosecondsPerSecond * clock_ticks / kHertz);
    187 }
    188 
    189 }  // namespace internal
    190 }  // namespace base
    191