[LINUX] Extract the name and id of the device and send it along the device attach message.

chrome/browser/media_gallery/media_device_notifications_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.
 
 // MediaDeviceNotificationsLinux implementation.
 
 #include "chrome/browser/media_gallery/media_device_notifications_linux.h"
 
+#include <libudev.h>
 #include <mntent.h>
 #include <stdio.h>
 
 #include <vector>
 
 #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"
 
 namespace {
 
+using base::SystemMonitor;
+
 // List of file systems we care about.
 const char* const kKnownFileSystems[] = {
   "ext2",
   "ext3",
   "ext4",
   "fat",
   "hfsplus",
   "iso9660",
   "msdos",
   "ntfs",
   "udf",
   "vfat",
 };
 
+// Device property constants.
+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 kVendor[] = "ID_VENDOR";
+const char kVendorID[] = "ID_VENDOR_ID";
+
+// Delimiter constants.
+const char kSpaceDelim[] = " ";
+const char kUnderscoreDelim[] = "_";
+
+// Unique id prefix constants.
+const char kFSUniqueIdPrefix[] = "UUID:";
+const char kModelIdPrefix[] = "MID:";
+const char kSerialShortIdPrefix[] = "SSID:";
+const char kVendorIdPrefix[] = "VID:";
+
+// Device mount point details.
+struct MountPointEntryInfo {
+  std::string mount_point;
+  int entry_pos;
+};
+
+// 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 std::string& device_path,
+                   std::string* id,
+                   string16* name) {
+  DCHECK(!device_path.empty());
+
+  ScopedGenericObj<struct udev*, ScopedReleaseUdevObject> udev_ptr(udev_new());
+  CHECK(udev_ptr.get());
+
+  struct stat st;
+  if (stat(device_path.c_str(), &st) < 0)
+    return false;
+
+  char device_type;
+  if (S_ISCHR(st.st_mode))
+    device_type = 'c';
+  else if (S_ISBLK(st.st_mode))
+    device_type = 'b';
+  else
+    return false;  // Not a supported type.
+
+  ScopedGenericObj<struct udev_device*, ScopedReleaseUdevDeviceObject>
+      device(udev_device_new_from_devnum(udev_ptr, device_type, st.st_rdev));
+  if (!device.get())
+    return false;
+
+  // Construct a device name using label or manufacturer(vendor and model)
+  // details.
+  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;
+    }
+  }
+
+  CHECK(IsStringUTF8(device_label));
+  *name = UTF8ToUTF16(device_label);
+
+  const char* uuid  = NULL;
+  if ((uuid = udev_device_get_property_value(device, kFsUUID))) {
+    *id += kFSUniqueIdPrefix;
+    *id += uuid;
+  } else {
+    // Format: VendorInfo_ModelInfo_SerialShortInfo
+    // E.g.: Kn_DataTravel_12.10_8000000000006CB02CDB
+    const char* vendor = NULL;
+    if ((vendor = udev_device_get_property_value(device, kVendorID))) {
+      *id += kVendorIdPrefix;

[vandebo (ex-Chrome), 2012/08/11 00:55:20]

It'd be pretty tough to parse these inline, but all the prefixes at the start.
And you really only have to prefixes, uuid and the other one.  If one of the
vendor, model, short serial is missing that's ok, it's value in the string is
just empty.

E.g.: VendorModelSerial:Kn_DataTravel_134891
E.g.: VendorModelSerial:Kn__134891
E.g.: VendorModelSerial:Kn_DataTravel_

[kmadhusu, 2012/08/12 02:52:04]

Sure and also made code changes to use ":" as our delim. I was testing with a
different device today and noticed that the ID_MODEL had a "_" in it.

+      *id += vendor;
+    }
+    const char* model = NULL;
+    if ((model = udev_device_get_property_value(device, kModelID))) {
+      if (!id->empty())
+        *id += kUnderscoreDelim;
+      *id += kModelIdPrefix;
+      *id += model;
+    }
+    const char* serial_short = NULL;
+    if ((serial_short = udev_device_get_property_value(device, kSerialShort))) {
+      if (!id->empty())
+        *id += kUnderscoreDelim;
+      *id += kSerialShortIdPrefix;
+      *id += serial_short;
+    }
+  }
+
+  return true;
+}
+
 }  // namespace
 
 namespace chrome {
 
 using base::SystemMonitor;
 using content::BrowserThread;
 
 MediaDeviceNotificationsLinux::MediaDeviceNotificationsLinux(
     const FilePath& path)
     : initialized_(false),
       mtab_path_(path),
-      current_device_id_(0U) {
-  CHECK(!path.empty());
+      get_device_info_func_(&GetDeviceInfo) {
+}
 
-  // 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]);
-  }
+MediaDeviceNotificationsLinux::MediaDeviceNotificationsLinux(
+    const FilePath& path,
+    GetDeviceInfoFunc get_device_info_func)
+    : initialized_(false),
+      mtab_path_(path),
+      get_device_info_func_(get_device_info_func) {
 }
 
 MediaDeviceNotificationsLinux::~MediaDeviceNotificationsLinux() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
 void MediaDeviceNotificationsLinux::Init() {
+  CHECK(!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(&MediaDeviceNotificationsLinux::InitOnFileThread, this));
 }
 
 void MediaDeviceNotificationsLinux::OnFilePathChanged(const FilePath& path,
                                                       bool error) {
   if (path != mtab_path_) {
     // This cannot happen unless FilePathWatcher is buggy. Just ignore this
     // notification and do nothing.
@@ skipping 24 matching lines @@
     LOG(ERROR) << "Adding watch for " << mtab_path_.value() << " failed";
     return;
   }
 
   UpdateMtab();
 }
 
 void MediaDeviceNotificationsLinux::UpdateMtab() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
-  MountMap new_mtab;
+  MountPointDeviceMap new_mtab;
   ReadMtab(&new_mtab);
 
   // Check existing mtab entries for unaccounted mount points.
   // These mount points must have been removed in the new mtab.
   std::vector<std::string> mount_points_to_erase;
-  for (MountMap::const_iterator it = mtab_.begin(); it != mtab_.end(); ++it) {
+  for (MountMap::const_iterator it = mount_info_map_.begin();
+       it != mount_info_map_.end(); ++it) {
     const std::string& mount_point = it->first;
-    // |mount_point| not in |new_mtab|.
-    if (!ContainsKey(new_mtab, mount_point)) {
-      const std::string& device_id = it->second.second;
-      RemoveOldDevice(device_id);
+    const std::string& mount_device = it->second.mount_device;
+    MountPointDeviceMap::iterator newiter = new_mtab.find(mount_point);
+    // |mount_point| not in |new_mtab| or |mount_device| is no longer mounted at
+    // |mount_point|.
+    if (newiter == new_mtab.end() || (newiter->second != mount_device)) {
+      RemoveOldDevice(it->second.device_id);
       mount_points_to_erase.push_back(mount_point);
     }
   }
-  // Erase the |mtab_| 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.
+  // 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 (size_t i = 0; i < mount_points_to_erase.size(); ++i)
-    mtab_.erase(mount_points_to_erase[i]);
+    mount_info_map_.erase(mount_points_to_erase[i]);
 
   // Check new mtab entries against existing ones.
-  for (MountMap::iterator newiter = new_mtab.begin();
+  for (MountPointDeviceMap::iterator newiter = new_mtab.begin();
        newiter != new_mtab.end();
        ++newiter) {
     const std::string& mount_point = newiter->first;
-    const MountDeviceAndId& mount_device_and_id = newiter->second;
-    const std::string& mount_device = mount_device_and_id.first;
-    std::string& id = newiter->second.second;
-    MountMap::iterator olditer = mtab_.find(mount_point);
-    // Check to see if it is a new mount point.
-    if (olditer == mtab_.end()) {
-      if (IsMediaDevice(mount_point)) {
-        AddNewDevice(mount_device, mount_point, &id);
-        mtab_.insert(std::make_pair(mount_point, mount_device_and_id));
-      }
+    const std::string& mount_device = newiter->second;
+    MountMap::iterator olditer = mount_info_map_.find(mount_point);
+    if (olditer != mount_info_map_.end() &&
+        olditer->second.mount_device == mount_device) {
+      // Existing mount point entry with same device.
       continue;
     }
-
-    // Existing mount point. Check to see if a new device is mounted there.
-    const MountDeviceAndId& old_mount_device_and_id = olditer->second;
-    if (mount_device == old_mount_device_and_id.first)
-      continue;
-
-    // New device mounted.
-    RemoveOldDevice(old_mount_device_and_id.second);
-    if (IsMediaDevice(mount_point)) {
-      AddNewDevice(mount_device, mount_point, &id);
-      olditer->second = mount_device_and_id;
-    }
+    // New mount point found or an existing mount point found with a new device.
+    CheckAndAddMediaDevice(mount_device, mount_point);
   }
 }
 
-void MediaDeviceNotificationsLinux::ReadMtab(MountMap* mtab) {
+void MediaDeviceNotificationsLinux::ReadMtab(MountPointDeviceMap* mtab) {
   FILE* fp = setmntent(mtab_path_.value().c_str(), "r");
   if (!fp)
     return;
 
-  MountMap& new_mtab = *mtab;
   mntent entry;
   char buf[512];
-  int mount_position = 0;
-  typedef std::pair<std::string, std::string> MountPointAndId;
-  typedef std::map<std::string, MountPointAndId> DeviceMap;
+
+  // Keep track of mount point entry positions in mtab file.
+  int entry_pos = 0;
+
+  // Helper map to store the device mount point details.
+  // (mount device, MountPointEntryInfo)
+  typedef std::map<std::string, MountPointEntryInfo> DeviceMap;
   DeviceMap device_map;
   while (getmntent_r(fp, &entry, buf, sizeof(buf))) {
     // We only care about real file systems.
     if (!ContainsKey(known_file_systems_, entry.mnt_type))
       continue;
+
     // Add entries, but overwrite entries for the same mount device. Keep track
-    // of the entry positions in the device id field and use that below to
-    // resolve multiple devices mounted at the same mount point.
-    MountPointAndId mount_point_and_id =
-        std::make_pair(entry.mnt_dir, base::IntToString(mount_position++));
-    DeviceMap::iterator it = device_map.find(entry.mnt_fsname);
-    if (it == device_map.end()) {
-      device_map.insert(std::make_pair(entry.mnt_fsname, mount_point_and_id));
-    } else {
-      it->second = mount_point_and_id;
-    }
+    // of the entry positions in |entry_info| and use that below to resolve
+    // multiple devices mounted at the same mount point.
+    MountPointEntryInfo entry_info;
+    entry_info.mount_point = entry.mnt_dir;
+    entry_info.entry_pos = entry_pos++;
+    device_map[entry.mnt_fsname /* mount device */] = entry_info;
   }
   endmntent(fp);
 
+  // Helper map to store  mount point entries.
+  // (mount point, entry position in mtab file)
+  typedef std::map<std::string, int> MountPointsInfoMap;
+  MountPointsInfoMap mount_points_info_map;
+  MountPointDeviceMap& new_mtab = *mtab;
   for (DeviceMap::const_iterator device_it = device_map.begin();
        device_it != device_map.end();
        ++device_it) {
-    const std::string& device = device_it->first;
-    const std::string& mount_point = device_it->second.first;
-    const std::string& position = device_it->second.second;
+    // Add entries, but overwrite entries for the same mount point. Keep track
+    // of the entry positions and use that information to resolve multiple
+    // devices mounted at the same mount point.
+    const std::string& mount_device = device_it->first;
+    const std::string& mount_point = device_it->second.mount_point;
+    const int entry_pos = device_it->second.entry_pos;
+    MountPointDeviceMap::iterator new_it = new_mtab.find(mount_point);
+    MountPointsInfoMap::iterator mount_point_info_map_it =
+        mount_points_info_map.find(mount_point);
 
-    // No device at |mount_point|, save |device| to it.
-    MountMap::iterator mount_it = new_mtab.find(mount_point);
-    if (mount_it == new_mtab.end()) {
-      new_mtab.insert(std::make_pair(mount_point,
-                                     std::make_pair(device, position)));
-      continue;
+    // New mount point entry found or there is already a device mounted at
+    // |mount_point| and the existing mount entry is older than the current one.
+    if (new_it == new_mtab.end() ||
+        (mount_point_info_map_it != mount_points_info_map.end() &&
+         mount_point_info_map_it->second < entry_pos)) {
+      new_mtab[mount_point] = mount_device;
+      mount_points_info_map[mount_point] = entry_pos;
     }
-
-    // There is already a device mounted at |mount_point|. Check to see if
-    // the existing mount entry is newer than the current one.
-    std::string& existing_device = mount_it->second.first;
-    std::string& existing_position = mount_it->second.second;
-    if (existing_position > position)
-      continue;
-
-    // The current entry is newer, update the mount point entry.
-    existing_device = device;
-    existing_position = position;
   }
 }
 
-void MediaDeviceNotificationsLinux::AddNewDevice(
+void MediaDeviceNotificationsLinux::CheckAndAddMediaDevice(
     const std::string& mount_device,
-    const std::string& mount_point,
-    std::string* device_id) {
-  *device_id = base::IntToString(current_device_id_++);
+    const std::string& mount_point) {
+  if (!IsMediaDevice(mount_point))
+    return;
+
+  std::string device_id;
+  string16 device_name;
+  bool result = (*get_device_info_func_)(mount_device, &device_id,
+                                         &device_name);
+
+  // 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",
+                        !device_id.empty());
+  UMA_HISTOGRAM_BOOLEAN("MediaDeviceNotification.device_name_available",
+                        !device_name.empty());
+
+  if (device_id.empty() || device_name.empty())
+    return;
+
+  MountDeviceAndId mount_device_and_id;
+  mount_device_and_id.mount_device = mount_device;
+  mount_device_and_id.device_id = device_id;
+  mount_info_map_[mount_point] = mount_device_and_id;
+
   base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
-  system_monitor->ProcessMediaDeviceAttached(*device_id,
-                                             UTF8ToUTF16(mount_device),
+  system_monitor->ProcessMediaDeviceAttached(device_id,
+                                             device_name,
                                              SystemMonitor::TYPE_PATH,
                                              mount_point);
 }
 
 void MediaDeviceNotificationsLinux::RemoveOldDevice(
     const std::string& device_id) {
   base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
   system_monitor->ProcessMediaDeviceDetached(device_id);
 }
 
 }  // namespace chrome