Make the Linux System Monitor implementation track all devices

chrome/browser/media_gallery/disk_mount_watcher_linux.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// DiskMountWatcherLinux implementation.
+
+#include "chrome/browser/media_gallery/disk_mount_watcher_linux.h"
+
+#include <libudev.h>
+#include <mntent.h>
+#include <stdio.h>
+
+#include <list>
+
+#include "base/bind.h"
+#include "base/file_path.h"
+#include "base/memory/scoped_generic_obj.h"
+#include "base/metrics/histogram.h"
+#include "base/stl_util.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "base/system_monitor/system_monitor.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/browser/media_gallery/media_device_notifications_utils.h"
+#include "chrome/browser/media_gallery/media_storage_util.h"
+
+namespace chrome {
+
+using base::SystemMonitor;
+using content::BrowserThread;
+
+namespace {
+
+static DiskMountWatcherLinux* g_disk_mount_watcher_linux = NULL;
+
+// List of file systems we care about.
+const char* const kKnownFileSystems[] = {
+  "ext2",
+  "ext3",
+  "ext4",
+  "fat",
+  "hfsplus",
+  "iso9660",
+  "msdos",
+  "ntfs",
+  "udf",
+  "vfat",
+};
+
+// udev device property constants.
+const char kBus[] = "ID_BUS";
+const char kDevName[] = "DEVNAME";
+const char kFsUUID[] = "ID_FS_UUID";
+const char kLabel[] = "ID_FS_LABEL";
+const char kModel[] = "ID_MODEL";
+const char kModelID[] = "ID_MODEL_ID";
+const char kSerial[] = "ID_SERIAL";
+const char kSerialShort[] = "ID_SERIAL_SHORT";
+const char kUsbBus[] = "usb";
+const char kVendor[] = "ID_VENDOR";
+const char kVendorID[] = "ID_VENDOR_ID";
+
+// Delimiter constants.
+const char kNonSpaceDelim[] = ":";
+const char kSpaceDelim[] = " ";
+
+// Unique id prefix constants.
+const char kFSUniqueIdPrefix[] = "UUID:";
+const char kVendorModelSerialPrefix[] = "VendorModelSerial:";
+
+// (mount point, mount device)
+// A mapping from mount point to mount device, as extracted from the mtab
+// file.
+typedef std::map<FilePath, FilePath> MountPointDeviceMap;
+
+// Reads mtab file entries into |mtab|.
+void ReadMtab(FilePath mtab_path,
+              std::set<std::string> interesting_file_systems,
+              MountPointDeviceMap* mtab) {
+  FILE* fp = setmntent(mtab_path.value().c_str(), "r");
+  if (!fp)
+    return;
+
+  mtab->clear();
+
+  mntent entry;
+  char buf[512];
+
+  // We return the same device mounted to multiple locations, but hide
+  // devices that have been mounted over.
+  while (getmntent_r(fp, &entry, buf, sizeof(buf))) {
+    // We only care about real file systems.
+    if (!ContainsKey(interesting_file_systems, entry.mnt_type))
+      continue;
+
+    (*mtab)[FilePath(entry.mnt_dir)] = FilePath(entry.mnt_fsname);
+  }
+  endmntent(fp);
+}
+
+
+// ScopedGenericObj functor for UdevObjectRelease().
+class ScopedReleaseUdevObject {
+ public:
+  void operator()(struct udev* udev) const {
+    udev_unref(udev);
+  }
+};
+
+// ScopedGenericObj functor for UdevDeviceObjectRelease().
+class ScopedReleaseUdevDeviceObject {
+ public:
+  void operator()(struct udev_device* device) const {
+    udev_device_unref(device);
+  }
+};
+
+// Get the device information using udev library.
+// On success, returns true and fill in |id| and |name|.
+bool GetDeviceInfo(const FilePath& device_path, std::string* unique_id,
+                   string16* name, bool* usb) {
+  DCHECK(!device_path.empty());
+
+  ScopedGenericObj<struct udev*, ScopedReleaseUdevObject> udev_obj(udev_new());
+  if (!udev_obj.get())
+    return false;
+
+  struct stat device_stat;
+  if (stat(device_path.value().c_str(), &device_stat) < 0)
+    return false;
+
+  char device_type;
+  if (S_ISCHR(device_stat.st_mode))
+    device_type = 'c';
+  else if (S_ISBLK(device_stat.st_mode))
+    device_type = 'b';
+  else
+    return false;  // Not a supported type.
+
+  ScopedGenericObj<struct udev_device*, ScopedReleaseUdevDeviceObject>
+      device(udev_device_new_from_devnum(udev_obj, device_type,
+                                         device_stat.st_rdev));
+  if (!device.get())
+    return false;
+
+  // Construct a device name using label or manufacturer(vendor and model)
+  // details.
+  if (name) {
+    std::string device_label;
+    const char* device_name = NULL;
+    if ((device_name = udev_device_get_property_value(device, kLabel)) ||
+        (device_name = udev_device_get_property_value(device, kSerial))) {
+      device_label = device_name;
+    } else {
+      // Format: VendorInfo ModelInfo
+      // E.g.: KnCompany Model2010
+      const char* vendor_name = NULL;
+      if ((vendor_name = udev_device_get_property_value(device, kVendor)))
+        device_label = vendor_name;
+
+      const char* model_name = NULL;
+      if ((model_name = udev_device_get_property_value(device, kModel))) {
+        if (!device_label.empty())
+          device_label += kSpaceDelim;
+        device_label += model_name;
+      }
+    }
+
+    if (IsStringUTF8(device_label))
+      *name = UTF8ToUTF16(device_label);
+  }
+
+  if (unique_id) {
+    const char* uuid  = NULL;
+    if ((uuid = udev_device_get_property_value(device, kFsUUID))) {
+      *unique_id = std::string(kFSUniqueIdPrefix) + uuid;
+    } else {
+      // If one of the vendor, model, serial information is missing, its value
+      // in the string is empty.
+      // Format: VendorModelSerial:VendorInfo:ModelInfo:SerialShortInfo
+      // E.g.: VendorModelSerial:Kn:DataTravel_12.10:8000000000006CB02CDB
+      const char* vendor = udev_device_get_property_value(device, kVendorID);
+      const char* model = udev_device_get_property_value(device, kModelID);
+      const char* serial_short = udev_device_get_property_value(device,
+                                                                kSerialShort);
+      if (!vendor && !model && !serial_short)
+        return false;
+
+      *unique_id = std::string(kVendorModelSerialPrefix) +
+                   (vendor ? vendor : "") + kNonSpaceDelim +
+                   (model ? model : "") + kNonSpaceDelim +
+                   (serial_short ? serial_short : "");
+    }
+    /*
+    MediaStorageUtil::Type type;
+    if (std::string(kUsbBus) == bus) {
+      if (has_dcim) {
+        type = MediaStorageUtil::USB_MASS_STORAGE_WITH_DCIM;
+      } else {
+        type = MediaStorageUtil::USB_MASS_STORAGE_NO_DCIM;
+      }
+    } else {
+      type = MediaStorageUtil::OTHER_MASS_STORAGE;
+    }
+    */
+  }
+
+  if (usb) {

[Lei Zhang, 2012/08/25 01:22:19]

FWIW, you can do:

const char* removable = udev_device_get_sysattr_value(device, "removable");
if (removable) {
  return atoi(removable) != 0;
}

However, |device| may be a partition on a disk, it may not have the removable
attribute at all. You'll need to walk up the tree with
udev_device_get_parent_with_subsystem_devtype(device, "block", "disk");

[vandebo (ex-Chrome), 2012/08/27 19:42:38]

Done.

+    const char* bus = udev_device_get_property_value(device, kBus);
+    *usb = (std::string(kUsbBus) == bus);
+  }
+
+  return true;
+}
+
+}  // namespace
+
+DiskMountWatcherLinux::DiskMountWatcherLinux(const FilePath& path)
+    : initialized_(false),
+      mtab_path_(path),
+      get_device_info_func_(&GetDeviceInfo) {
+  DCHECK(g_disk_mount_watcher_linux == NULL);
+  g_disk_mount_watcher_linux = this;
+}
+
+DiskMountWatcherLinux::DiskMountWatcherLinux(const FilePath& path,
+    GetDeviceInfoFunc get_device_info_func)
+    : initialized_(false),
+      mtab_path_(path),
+      get_device_info_func_(get_device_info_func) {
+  DCHECK(g_disk_mount_watcher_linux == NULL);
+  g_disk_mount_watcher_linux = this;
+}
+
+DiskMountWatcherLinux::~DiskMountWatcherLinux() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  DCHECK(g_disk_mount_watcher_linux != NULL);
+  g_disk_mount_watcher_linux = NULL;
+}
+
+// static
+DiskMountWatcherLinux* DiskMountWatcherLinux::GetInstance() {
+  return g_disk_mount_watcher_linux;
+}
+
+void DiskMountWatcherLinux::Init() {
+  DCHECK(!mtab_path_.empty());
+
+  // Put |kKnownFileSystems| in std::set to get O(log N) access time.
+  for (size_t i = 0; i < arraysize(kKnownFileSystems); ++i)
+    known_file_systems_.insert(kKnownFileSystems[i]);
+
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&DiskMountWatcherLinux::InitOnFileThread, this));
+}
+
+FilePath DiskMountWatcherLinux::GetDeviceMountPoint(
+    const std::string& device_id) const {
+
+  MediaStorageUtil::Type type;
+  MediaStorageUtil::CrackDeviceId(device_id, &type, NULL);
+  if (type == MediaStorageUtil::USB_MTP)
+    return FilePath();
+
+  FilePath mount_device = FilePath();
+  for (MountMap::const_iterator it = mount_info_map_.begin();
+       it != mount_info_map_.end();
+       ++it) {
+    if (it->second.device_id == device_id) {
+      mount_device = it->second.mount_device;
+      break;
+    }
+  }
+  if (mount_device.empty()) {
+    NOTREACHED();
+    return mount_device;
+  }
+
+  const ReferencedMountPoint& referenced_info =
+      mount_priority_map_.find(mount_device)->second;
+  for (ReferencedMountPoint::const_iterator it = referenced_info.begin();
+       it != referenced_info.end();
+       ++it) {
+    if (it->second)
+      return it->first;
+  }
+  // If none of them are default, just return the first.
+  return FilePath(
+      mount_priority_map_.find(mount_device)->second.begin()->first);
+}
+
+std::string DiskMountWatcherLinux::GetDeviceIdForPath(
+    const FilePath& path, FilePath* mount_point) const {
+  if (!path.IsAbsolute())
+    return std::string();
+
+  FilePath current = path;
+  for (FilePath current = path;
+       mount_info_map_.find(current) == mount_info_map_.end() &&
+          current != current.DirName();
+       current = current.DirName()) {}
+
+  if (mount_info_map_.find(current) == mount_info_map_.end())
+    return std::string();
+
+  if (mount_point)
+    *mount_point = current;
+
+  return mount_info_map_.find(current)->second.device_id;
+}
+
+void DiskMountWatcherLinux::OnFilePathChanged(const FilePath& path,
+                                              bool error) {
+  if (path != mtab_path_) {
+    // This cannot happen unless FilePathWatcher is buggy. Just ignore this
+    // notification and do nothing.
+    NOTREACHED();
+    return;
+  }
+  if (error) {
+    LOG(ERROR) << "Error watching " << mtab_path_.value();
+    return;
+  }
+
+  UpdateMtab();
+}
+
+void DiskMountWatcherLinux::InitOnFileThread() {
+  DCHECK(!initialized_);
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  initialized_ = true;
+
+  // The callback passed to Watch() has to be unretained. Otherwise
+  // DiskMountWatcherLinux will live longer than expected, and
+  // FilePathWatcher will get in trouble at shutdown time.
+  bool ret = file_watcher_.Watch(
+      mtab_path_,
+      base::Bind(&DiskMountWatcherLinux::OnFilePathChanged,
+                 base::Unretained(this)));
+  if (!ret) {
+    LOG(ERROR) << "Adding watch for " << mtab_path_.value() << " failed";
+    return;
+  }
+
+  UpdateMtab();
+}
+
+void DiskMountWatcherLinux::UpdateMtab() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  MountPointDeviceMap new_mtab;
+  ReadMtab(mtab_path_, known_file_systems_, &new_mtab);
+
+  // Check existing mtab entries for unaccounted mount points.
+  // These mount points must have been removed in the new mtab.
+  std::list<FilePath> mount_points_to_erase;
+  std::list<FilePath> multiple_mounted_devices_needing_reattachment;
+  for (MountMap::const_iterator old_iter = mount_info_map_.begin();
+       old_iter != mount_info_map_.end(); ++old_iter) {
+    const FilePath& mount_point = old_iter->first;
+    const FilePath& mount_device = old_iter->second.mount_device;
+    MountPointDeviceMap::iterator new_iter = new_mtab.find(mount_point);
+    // |mount_point| not in |new_mtab| or |mount_device| is no longer mounted at
+    // |mount_point|.
+    if (new_iter == new_mtab.end() || (new_iter->second != mount_device)) {
+      if (old_iter->second.has_dcim) {
+        MountPriorityMap::iterator priority =
+            mount_priority_map_.find(mount_device);
+        DCHECK(priority != mount_priority_map_.end());
+        ReferencedMountPoint::const_iterator has_priority =
+            priority->second.find(mount_point);
+        DCHECK(has_priority != priority->second.end());
+        if (has_priority->second)
+          RemoveMediaMount(old_iter->second.device_id);
+        priority->second.erase(mount_point);
+        if (mount_priority_map_.find(mount_device)->second.empty()) {
+          mount_priority_map_.erase(mount_device);
+        } else {
+          multiple_mounted_devices_needing_reattachment.push_back(mount_device);
+        }
+
+      }
+      mount_points_to_erase.push_back(mount_point);
+    }
+  }
+
+  // Erase the |mount_info_map_| entries afterwards. Erasing in the loop above
+  // using the iterator is slightly more efficient, but more tricky, since
+  // calling std::map::erase() on an iterator invalidates it.
+  for (std::list<FilePath>::const_iterator it = mount_points_to_erase.begin();
+       it != mount_points_to_erase.end();
+       ++it) {
+    mount_info_map_.erase(*it);
+  }
+
+  // For any multiply mounted device where the mount that we had notified
+  // got detached, send a notification of attachment for one of the other
+  // mount points.
+  for (std::list<FilePath>::const_iterator it =
+           multiple_mounted_devices_needing_reattachment.begin();
+       it != multiple_mounted_devices_needing_reattachment.end();
+       ++it) {
+    const FilePath& mount_point = mount_priority_map_[*it].begin()->first;
+    mount_priority_map_[*it].begin()->second = true;
+    DCHECK(mount_info_map_[mount_point].has_dcim);
+    base::SystemMonitor::Get()->ProcessMediaDeviceAttached(
+        mount_info_map_[mount_point].device_id,
+        mount_info_map_[mount_point].device_name,
+        mount_point.value());
+  }
+
+  // Check new mtab entries against existing ones.
+  for (MountPointDeviceMap::iterator new_iter = new_mtab.begin();
+       new_iter != new_mtab.end(); ++new_iter) {
+    const FilePath& mount_point = new_iter->first;
+    const FilePath& mount_device = new_iter->second;
+    MountMap::iterator old_iter = mount_info_map_.find(mount_point);
+    if (old_iter == mount_info_map_.end() ||
+        old_iter->second.mount_device != mount_device) {
+      // New mount point found or an existing mount point found with a new
+      // device.
+      AddNewMount(mount_device, mount_point);
+    }
+  }
+}
+
+void DiskMountWatcherLinux::AddNewMount(const FilePath& mount_device,
+                                        const FilePath& mount_point) {
+  if (mount_priority_map_.find(mount_device) != mount_priority_map_.end()) {
+    const FilePath& other_mount_point =
+        mount_priority_map_[mount_device].begin()->first;
+    mount_priority_map_[mount_device][mount_point] = false;
+    mount_info_map_[mount_point] = mount_info_map_[other_mount_point];
+    return;
+  }
+
+  std::string unique_id;
+  string16 name;
+  bool usb;
+  bool result = (*get_device_info_func_)(mount_device, &unique_id, &name, &usb);
+
+  // Keep track of GetDeviceInfo result, to see how often we fail to get device
+  // details.
+  UMA_HISTOGRAM_BOOLEAN("MediaDeviceNotification.device_info_available",
+                        result);
+  if (!result)
+    return;
+
+  // Keep track of device uuid, to see how often we receive empty values.
+  UMA_HISTOGRAM_BOOLEAN("MediaDeviceNotification.device_uuid_available",
+                        !unique_id.empty());
+  UMA_HISTOGRAM_BOOLEAN("MediaDeviceNotification.device_name_available",
+                        !name.empty());
+
+  if (unique_id.empty() || name.empty())
+    return;
+
+  bool has_dcim = IsMediaDevice(mount_point.value());
+  MediaStorageUtil::Type type;
+  if (usb) {
+    if (has_dcim) {
+      type = MediaStorageUtil::USB_MASS_STORAGE_WITH_DCIM;
+    } else {
+      type = MediaStorageUtil::USB_MASS_STORAGE_NO_DCIM;
+    }
+  } else {
+    type = MediaStorageUtil::OTHER_MASS_STORAGE;
+  }
+  std::string device_id = MediaStorageUtil::MakeDeviceId(type, unique_id);
+
+  MountPointInfo mount_point_info;
+  mount_point_info.mount_device = mount_device;
+  mount_point_info.device_id = device_id;
+  mount_point_info.device_name = name;
+  mount_point_info.has_dcim = has_dcim;
+
+  mount_info_map_[mount_point] = mount_point_info;
+  mount_priority_map_[mount_device][mount_point] = true;
+
+  if (mount_point_info.has_dcim) {
+    base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+    system_monitor->ProcessMediaDeviceAttached(device_id, name,
+                                               mount_point.value());
+  }
+}
+
+void DiskMountWatcherLinux::RemoveMediaMount(const std::string& device_id) {
+  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+  system_monitor->ProcessMediaDeviceDetached(device_id);
+}
+
+}  // namespace chrome