base/linux_util.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/linux_util.h"
   6
   7 #include <dirent.h>
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <stdlib.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14
  15 #include <vector>
  16
  17 #include "base/command_line.h"
  18 #include "base/file_util.h"
  19 #include "base/memory/scoped_ptr.h"
  20 #include "base/memory/singleton.h"
  21 #include "base/path_service.h"
  22 #include "base/process/launch.h"
  23 #include "base/strings/string_util.h"
  24 #include "base/synchronization/lock.h"
  25
  26 namespace {
  27
  28 // Not needed for OS_CHROMEOS.
  29 #if defined(OS_LINUX)
  30 enum LinuxDistroState {
  31   STATE_DID_NOT_CHECK  = 0,
  32   STATE_CHECK_STARTED  = 1,
  33   STATE_CHECK_FINISHED = 2,
  34 };
  35
  36 // Helper class for GetLinuxDistro().
  37 class LinuxDistroHelper {
  38  public:
  39   // Retrieves the Singleton.
  40   static LinuxDistroHelper* GetInstance() {
  41     return Singleton<LinuxDistroHelper>::get();
  42   }
  43
  44   // The simple state machine goes from:
  45   // STATE_DID_NOT_CHECK -> STATE_CHECK_STARTED -> STATE_CHECK_FINISHED.
  46   LinuxDistroHelper() : state_(STATE_DID_NOT_CHECK) {}
  47   ~LinuxDistroHelper() {}
  48
  49   // Retrieve the current state, if we're in STATE_DID_NOT_CHECK,
  50   // we automatically move to STATE_CHECK_STARTED so nobody else will
  51   // do the check.
  52   LinuxDistroState State() {
  53     base::AutoLock scoped_lock(lock_);
  54     if (STATE_DID_NOT_CHECK == state_) {
  55       state_ = STATE_CHECK_STARTED;
  56       return STATE_DID_NOT_CHECK;
  57     }
  58     return state_;
  59   }
  60
  61   // Indicate the check finished, move to STATE_CHECK_FINISHED.
  62   void CheckFinished() {
  63     base::AutoLock scoped_lock(lock_);
  64     DCHECK_EQ(STATE_CHECK_STARTED, state_);
  65     state_ = STATE_CHECK_FINISHED;
  66   }
  67
  68  private:
  69   base::Lock lock_;
  70   LinuxDistroState state_;
  71 };
  72 #endif  // if defined(OS_LINUX)
  73
  74 }  // namespace
  75
  76 namespace base {
  77
  78 // Account for the terminating null character.
  79 static const int kDistroSize = 128 + 1;
  80
  81 // We use this static string to hold the Linux distro info. If we
  82 // crash, the crash handler code will send this in the crash dump.
  83 char g_linux_distro[kDistroSize] =
  84 #if defined(OS_CHROMEOS)
  85     "CrOS";
  86 #elif defined(OS_ANDROID)
  87     "Android";
  88 #else  // if defined(OS_LINUX)
  89     "Unknown";
  90 #endif
  91
  92 std::string GetLinuxDistro() {
  93 #if defined(OS_CHROMEOS) || defined(OS_ANDROID)
  94   return g_linux_distro;
  95 #elif defined(OS_LINUX)
  96   LinuxDistroHelper* distro_state_singleton = LinuxDistroHelper::GetInstance();
  97   LinuxDistroState state = distro_state_singleton->State();
  98   if (STATE_CHECK_FINISHED == state)
  99     return g_linux_distro;
 100   if (STATE_CHECK_STARTED == state)
 101     return "Unknown"; // Don't wait for other thread to finish.
 102   DCHECK_EQ(state, STATE_DID_NOT_CHECK);
 103   // We do this check only once per process. If it fails, there's
 104   // little reason to believe it will work if we attempt to run
 105   // lsb_release again.
 106   std::vector<std::string> argv;
 107   argv.push_back("lsb_release");
 108   argv.push_back("-d");
 109   std::string output;
 110   base::GetAppOutput(CommandLine(argv), &output);
 111   if (output.length() > 0) {
 112     // lsb_release -d should return: Description:<tab>Distro Info
 113     const char field[] = "Description:\t";
 114     if (output.compare(0, strlen(field), field) == 0) {
 115       SetLinuxDistro(output.substr(strlen(field)));
 116     }
 117   }
 118   distro_state_singleton->CheckFinished();
 119   return g_linux_distro;
 120 #else
 121   NOTIMPLEMENTED();
 122   return "Unknown";
 123 #endif
 124 }
 125
 126 void SetLinuxDistro(const std::string& distro) {
 127   std::string trimmed_distro;
 128   base::TrimWhitespaceASCII(distro, base::TRIM_ALL, &trimmed_distro);
 129   base::strlcpy(g_linux_distro, trimmed_distro.c_str(), kDistroSize);
 130 }
 131
 132 pid_t FindThreadIDWithSyscall(pid_t pid, const std::string& expected_data,
 133                               bool* syscall_supported) {
 134   char buf[256];
 135   snprintf(buf, sizeof(buf), "/proc/%d/task", pid);
 136
 137   if (syscall_supported != NULL)
 138     *syscall_supported = false;
 139
 140   DIR* task = opendir(buf);
 141   if (!task) {
 142     DLOG(WARNING) << "Cannot open " << buf;
 143     return -1;
 144   }
 145
 146   std::vector<pid_t> tids;
 147   struct dirent* dent;
 148   while ((dent = readdir(task))) {
 149     char* endptr;
 150     const unsigned long int tid_ul = strtoul(dent->d_name, &endptr, 10);
 151     if (tid_ul == ULONG_MAX || *endptr)
 152       continue;
 153     tids.push_back(tid_ul);
 154   }
 155   closedir(task);
 156
 157   scoped_ptr<char[]> syscall_data(new char[expected_data.length()]);
 158   for (std::vector<pid_t>::const_iterator
 159        i = tids.begin(); i != tids.end(); ++i) {
 160     const pid_t current_tid = *i;
 161     snprintf(buf, sizeof(buf), "/proc/%d/task/%d/syscall", pid, current_tid);
 162     int fd = open(buf, O_RDONLY);
 163     if (fd < 0)
 164       continue;
 165     if (syscall_supported != NULL)
 166       *syscall_supported = true;
 167     bool read_ret = ReadFromFD(fd, syscall_data.get(), expected_data.length());
 168     close(fd);
 169     if (!read_ret)
 170       continue;
 171
 172     if (0 == strncmp(expected_data.c_str(), syscall_data.get(),
 173                      expected_data.length())) {
 174       return current_tid;
 175     }
 176   }
 177   return -1;
 178 }
 179
 180 }  // namespace base