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