1/*
2 * Copyright 2009 Google Inc.
3 * Author: lexnikitin@google.com (Alexey Nikitin)
4 *
5 * V4LLookup provides basic functionality to work with V2L2 devices in Linux
6 * The functionality is implemented as a class with virtual methods for
7 * the purpose of unit testing.
8 */
9#include "talk/media/devices/v4llookup.h"
10
11#include <errno.h>
12#include <fcntl.h>
13#include <linux/types.h>
14#include <linux/videodev2.h>
15#include <string.h>
16#include <sys/ioctl.h>
17#include <sys/stat.h>
18#include <sys/types.h>
19#include <unistd.h>
20
21#include "webrtc/base/logging.h"
22
23namespace cricket {
24
25V4LLookup *V4LLookup::v4l_lookup_ = NULL;
26
27bool V4LLookup::CheckIsV4L2Device(const std::string& device_path) {
28  // check device major/minor numbers are in the range for video devices.
29  struct stat s;
30
31  if (lstat(device_path.c_str(), &s) != 0 || !S_ISCHR(s.st_mode)) return false;
32
33  int video_fd = -1;
34  bool is_v4l2 = false;
35
36  // check major/minur device numbers are in range for video device
37  if (major(s.st_rdev) == 81) {
38    dev_t num = minor(s.st_rdev);
39    if (num <= 63) {
40      video_fd = ::open(device_path.c_str(), O_RDONLY | O_NONBLOCK);
41      if ((video_fd >= 0) || (errno == EBUSY)) {
42        ::v4l2_capability video_caps;
43        memset(&video_caps, 0, sizeof(video_caps));
44
45        if ((errno == EBUSY) ||
46            (::ioctl(video_fd, VIDIOC_QUERYCAP, &video_caps) >= 0 &&
47            (video_caps.capabilities & V4L2_CAP_VIDEO_CAPTURE))) {
48          LOG(LS_INFO) << "Found V4L2 capture device " << device_path;
49
50          is_v4l2 = true;
51        } else {
52          LOG_ERRNO(LS_ERROR) << "VIDIOC_QUERYCAP failed for " << device_path;
53        }
54      } else {
55        LOG_ERRNO(LS_ERROR) << "Failed to open " << device_path;
56      }
57    }
58  }
59
60  if (video_fd >= 0)
61    ::close(video_fd);
62
63  return is_v4l2;
64}
65
66};  // namespace cricket
67