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// 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.
#include "chrome/browser/chromeos/camera_detector.h"
#include "base/bind.h"
#include "base/file_util.h"
#include "base/location.h"
#include "base/string_split.h"
#include "base/string_util.h"
#include "base/threading/worker_pool.h"
#include "chrome/browser/system_monitor/udev_util_linux.h"
namespace chromeos {
namespace {
// Sysfs directory containing V4L devices.
const char kV4LSubsystemDir[] = "/sys/class/video4linux/";
// Name of the udev property with V4L capabilities.
const char kV4LCapabilities[] = "ID_V4L_CAPABILITIES";
// Delimiter character for udev V4L capabilities.
const char kV4LCapabilitiesDelim = ':';
// V4L capability that denotes a capture-enabled device.
const char kV4LCaptureCapability[] = "capture";
} // namespace
CameraDetector::CameraPresence CameraDetector::camera_presence_ =
CameraDetector::kCameraPresenceUnknown;
bool CameraDetector::presence_check_in_progress_ = false;
void CameraDetector::StartPresenceCheck(const base::Closure& check_done) {
DVLOG(1) << "Starting camera presence check";
if (!presence_check_in_progress_) {
presence_check_in_progress_ = true;
base::WorkerPool::PostTaskAndReply(
FROM_HERE,
base::Bind(&CameraDetector::CheckPresence),
check_done,
/* task_is_slow= */ false);
}
}
void CameraDetector::CheckPresence() {
bool present = false;
// We do a quick check using udev database because opening each /dev/videoX
// device may trigger costly device initialization.
using file_util::FileEnumerator;
FileEnumerator file_enum(
FilePath(kV4LSubsystemDir), false /* not recursive */,
FileEnumerator::FILES | FileEnumerator::SHOW_SYM_LINKS);
for (FilePath path = file_enum.Next(); !path.empty();
path = file_enum.Next()) {
std::string v4l_capabilities;
if (chrome::GetUdevDevicePropertyValueByPath(
path, kV4LCapabilities, &v4l_capabilities)) {
std::vector<std::string> caps;
base::SplitString(v4l_capabilities, kV4LCapabilitiesDelim, &caps);
if (find(caps.begin(), caps.end(), kV4LCaptureCapability) != caps.end()) {
present = true;
break;
}
}
}
camera_presence_ = present ? kCameraPresent : kCameraAbsent;
presence_check_in_progress_ = false;
DVLOG(1) << "Camera presence state: " << camera_presence_;
}
} // namespace chromeos
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