components/metrics/drive_metrics_provider_linux.cc

   1 // Copyright 2015 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 "components/metrics/drive_metrics_provider.h"
   6
   7 #include <linux/kdev_t.h>  // For MAJOR()/MINOR().
   8 #include <sys/stat.h>
   9 #include <string>
  10
  11 #include "base/files/file.h"
  12 #include "base/files/file_path.h"
  13 #include "base/files/file_util.h"
  14 #include "base/strings/stringprintf.h"
  15
  16 #if defined(OS_CHROMEOS)
  17 #include "base/sys_info.h"
  18 #endif
  19
  20 namespace metrics {
  21
  22 namespace {
  23
  24 // See http://www.kernel.org/doc/Documentation/devices.txt for more info.
  25 const int kFirstScsiMajorNumber = 8;
  26 const int kPartitionsPerScsiDevice = 16;
  27 const char kRotationalFormat[] = "/sys/block/sd%c/queue/rotational";
  28
  29 }  // namespace
  30
  31 // static
  32 bool DriveMetricsProvider::HasSeekPenalty(const base::FilePath& path,
  33                                           bool* has_seek_penalty) {
  34 #if defined(OS_CHROMEOS)
  35   std::string board = base::SysInfo::GetLsbReleaseBoard();
  36   if (board != "unknown" && board != "parrot") {
  37     // All ChromeOS devices have SSDs. Except some parrots.
  38     *has_seek_penalty = false;
  39     return true;
  40   }
  41 #endif
  42
  43   base::File file(path, base::File::FLAG_OPEN | base::File::FLAG_READ);
  44   if (!file.IsValid())
  45     return false;
  46
  47   struct stat path_stat;
  48   int error = fstat(file.GetPlatformFile(), &path_stat);
  49   if (error < 0 || MAJOR(path_stat.st_dev) != kFirstScsiMajorNumber) {
  50     // TODO(dbeam): support more SCSI major numbers (e.g. /dev/sdq+) and LVM?
  51     return false;
  52   }
  53
  54   char sdX = 'a' + MINOR(path_stat.st_dev) / kPartitionsPerScsiDevice;
  55   std::string rotational_path = base::StringPrintf(kRotationalFormat, sdX);
  56   std::string rotates;
  57   if (!base::ReadFileToString(base::FilePath(rotational_path), &rotates))
  58     return false;
  59
  60   *has_seek_penalty = rotates.substr(0, 1) == "1";
  61   return true;
  62 }
  63
  64 }  // namespace metrics