base/process/internal_linux.cc

   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/files/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 FilePath GetProcPidDir(pid_t pid) {
  29   return 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 = SplitString(
 101       stats_data.substr(close_parens_idx + 2), " ",
 102       base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 103   for (size_t i = 0; i < other_stats.size(); ++i)
 104     proc_stats->push_back(other_stats[i]);
 105   return true;
 106 }
 107
 108 typedef std::map<std::string, std::string> ProcStatMap;
 109 void ParseProcStat(const std::string& contents, ProcStatMap* output) {
 110   StringPairs key_value_pairs;
 111   SplitStringIntoKeyValuePairs(contents, ' ', '\n', &key_value_pairs);
 112   for (size_t i = 0; i < key_value_pairs.size(); ++i) {
 113     output->insert(key_value_pairs[i]);
 114   }
 115 }
 116
 117 int64 GetProcStatsFieldAsInt64(const std::vector<std::string>& proc_stats,
 118                                ProcStatsFields field_num) {
 119   DCHECK_GE(field_num, VM_PPID);
 120   CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
 121
 122   int64 value;
 123   return StringToInt64(proc_stats[field_num], &value) ? value : 0;
 124 }
 125
 126 size_t GetProcStatsFieldAsSizeT(const std::vector<std::string>& proc_stats,
 127                                 ProcStatsFields field_num) {
 128   DCHECK_GE(field_num, VM_PPID);
 129   CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
 130
 131   size_t value;
 132   return StringToSizeT(proc_stats[field_num], &value) ? value : 0;
 133 }
 134
 135 int64 ReadProcStatsAndGetFieldAsInt64(pid_t pid, ProcStatsFields field_num) {
 136   std::string stats_data;
 137   if (!ReadProcStats(pid, &stats_data))
 138     return 0;
 139   std::vector<std::string> proc_stats;
 140   if (!ParseProcStats(stats_data, &proc_stats))
 141     return 0;
 142   return GetProcStatsFieldAsInt64(proc_stats, field_num);
 143 }
 144
 145 size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
 146                                        ProcStatsFields field_num) {
 147   std::string stats_data;
 148   if (!ReadProcStats(pid, &stats_data))
 149     return 0;
 150   std::vector<std::string> proc_stats;
 151   if (!ParseProcStats(stats_data, &proc_stats))
 152     return 0;
 153   return GetProcStatsFieldAsSizeT(proc_stats, field_num);
 154 }
 155
 156 Time GetBootTime() {
 157   FilePath path("/proc/stat");
 158   std::string contents;
 159   if (!ReadProcFile(path, &contents))
 160     return Time();
 161   ProcStatMap proc_stat;
 162   ParseProcStat(contents, &proc_stat);
 163   ProcStatMap::const_iterator btime_it = proc_stat.find("btime");
 164   if (btime_it == proc_stat.end())
 165     return Time();
 166   int btime;
 167   if (!StringToInt(btime_it->second, &btime))
 168     return Time();
 169   return Time::FromTimeT(btime);
 170 }
 171
 172 TimeDelta ClockTicksToTimeDelta(int clock_ticks) {
 173   // This queries the /proc-specific scaling factor which is
 174   // conceptually the system hertz.  To dump this value on another
 175   // system, try
 176   //   od -t dL /proc/self/auxv
 177   // and look for the number after 17 in the output; mine is
 178   //   0000040          17         100           3   134512692
 179   // which means the answer is 100.
 180   // It may be the case that this value is always 100.
 181   static const int kHertz = sysconf(_SC_CLK_TCK);
 182
 183   return TimeDelta::FromMicroseconds(
 184       Time::kMicrosecondsPerSecond * clock_ticks / kHertz);
 185 }
 186
 187 }  // namespace internal
 188 }  // namespace base