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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 <limits.h>
      8 #include <unistd.h>
      9 
     10 #include <map>
     11 #include <string>
     12 #include <vector>
     13 
     14 #include "base/files/file_util.h"
     15 #include "base/logging.h"
     16 #include "base/strings/string_number_conversions.h"
     17 #include "base/strings/string_split.h"
     18 #include "base/strings/string_util.h"
     19 #include "base/threading/thread_restrictions.h"
     20 #include "base/time/time.h"
     21 
     22 namespace base {
     23 namespace internal {
     24 
     25 const char kProcDir[] = "/proc";
     26 
     27 const char kStatFile[] = "stat";
     28 
     29 FilePath GetProcPidDir(pid_t pid) {
     30   return FilePath(kProcDir).Append(IntToString(pid));
     31 }
     32 
     33 pid_t ProcDirSlotToPid(const char* d_name) {
     34   int i;
     35   for (i = 0; i < NAME_MAX && d_name[i]; ++i) {
     36     if (!IsAsciiDigit(d_name[i])) {
     37       return 0;
     38     }
     39   }
     40   if (i == NAME_MAX)
     41     return 0;
     42 
     43   // Read the process's command line.
     44   pid_t pid;
     45   std::string pid_string(d_name);
     46   if (!StringToInt(pid_string, &pid)) {
     47     NOTREACHED();
     48     return 0;
     49   }
     50   return pid;
     51 }
     52 
     53 bool ReadProcFile(const FilePath& file, std::string* buffer) {
     54   buffer->clear();
     55   // Synchronously reading files in /proc is safe.
     56   ThreadRestrictions::ScopedAllowIO allow_io;
     57 
     58   if (!ReadFileToString(file, buffer)) {
     59     DLOG(WARNING) << "Failed to read " << file.MaybeAsASCII();
     60     return false;
     61   }
     62   return !buffer->empty();
     63 }
     64 
     65 bool ReadProcStats(pid_t pid, std::string* buffer) {
     66   FilePath stat_file = internal::GetProcPidDir(pid).Append(kStatFile);
     67   return ReadProcFile(stat_file, buffer);
     68 }
     69 
     70 bool ParseProcStats(const std::string& stats_data,
     71                     std::vector<std::string>* proc_stats) {
     72   // |stats_data| may be empty if the process disappeared somehow.
     73   // e.g. http://crbug.com/145811
     74   if (stats_data.empty())
     75     return false;
     76 
     77   // The stat file is formatted as:
     78   // pid (process name) data1 data2 .... dataN
     79   // Look for the closing paren by scanning backwards, to avoid being fooled by
     80   // processes with ')' in the name.
     81   size_t open_parens_idx = stats_data.find(" (");
     82   size_t close_parens_idx = stats_data.rfind(") ");
     83   if (open_parens_idx == std::string::npos ||
     84       close_parens_idx == std::string::npos ||
     85       open_parens_idx > close_parens_idx) {
     86     DLOG(WARNING) << "Failed to find matched parens in '" << stats_data << "'";
     87     NOTREACHED();
     88     return false;
     89   }
     90   open_parens_idx++;
     91 
     92   proc_stats->clear();
     93   // PID.
     94   proc_stats->push_back(stats_data.substr(0, open_parens_idx));
     95   // Process name without parentheses.
     96   proc_stats->push_back(
     97       stats_data.substr(open_parens_idx + 1,
     98                         close_parens_idx - (open_parens_idx + 1)));
     99 
    100   // Split the rest.
    101   std::vector<std::string> other_stats = SplitString(
    102       stats_data.substr(close_parens_idx + 2), " ",
    103       base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
    104   for (size_t i = 0; i < other_stats.size(); ++i)
    105     proc_stats->push_back(other_stats[i]);
    106   return true;
    107 }
    108 
    109 typedef std::map<std::string, std::string> ProcStatMap;
    110 void ParseProcStat(const std::string& contents, ProcStatMap* output) {
    111   StringPairs key_value_pairs;
    112   SplitStringIntoKeyValuePairs(contents, ' ', '\n', &key_value_pairs);
    113   for (size_t i = 0; i < key_value_pairs.size(); ++i) {
    114     output->insert(key_value_pairs[i]);
    115   }
    116 }
    117 
    118 int64_t GetProcStatsFieldAsInt64(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   int64_t value;
    124   return StringToInt64(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 int64_t ReadProcStatsAndGetFieldAsInt64(pid_t pid, ProcStatsFields field_num) {
    137   std::string stats_data;
    138   if (!ReadProcStats(pid, &stats_data))
    139     return 0;
    140   std::vector<std::string> proc_stats;
    141   if (!ParseProcStats(stats_data, &proc_stats))
    142     return 0;
    143   return GetProcStatsFieldAsInt64(proc_stats, field_num);
    144 }
    145 
    146 size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
    147                                        ProcStatsFields field_num) {
    148   std::string stats_data;
    149   if (!ReadProcStats(pid, &stats_data))
    150     return 0;
    151   std::vector<std::string> proc_stats;
    152   if (!ParseProcStats(stats_data, &proc_stats))
    153     return 0;
    154   return GetProcStatsFieldAsSizeT(proc_stats, field_num);
    155 }
    156 
    157 Time GetBootTime() {
    158   FilePath path("/proc/stat");
    159   std::string contents;
    160   if (!ReadProcFile(path, &contents))
    161     return Time();
    162   ProcStatMap proc_stat;
    163   ParseProcStat(contents, &proc_stat);
    164   ProcStatMap::const_iterator btime_it = proc_stat.find("btime");
    165   if (btime_it == proc_stat.end())
    166     return Time();
    167   int btime;
    168   if (!StringToInt(btime_it->second, &btime))
    169     return Time();
    170   return Time::FromTimeT(btime);
    171 }
    172 
    173 TimeDelta ClockTicksToTimeDelta(int clock_ticks) {
    174   // This queries the /proc-specific scaling factor which is
    175   // conceptually the system hertz.  To dump this value on another
    176   // system, try
    177   //   od -t dL /proc/self/auxv
    178   // and look for the number after 17 in the output; mine is
    179   //   0000040          17         100           3   134512692
    180   // which means the answer is 100.
    181   // It may be the case that this value is always 100.
    182   static const int kHertz = sysconf(_SC_CLK_TCK);
    183 
    184   return TimeDelta::FromMicroseconds(
    185       Time::kMicrosecondsPerSecond * clock_ticks / kHertz);
    186 }
    187 
    188 }  // namespace internal
    189 }  // namespace base
    190