From: Dan Minor Date: Wed, 8 Jul 2020 17:35:00 +0000 Subject: Bug 1650572 - Check V4L2_CAP_DEVICE_CAPS before accessing device_caps; r=ng The capabilities field is for the physical device, device_caps is for the specific /dev/videoX device that has been opened. The device_caps field is only populated if V4L2_CAP_DEVICE_CAPS is set, so we should check that, and fall back to capabilities if it is not set. Differential Revision: https://phabricator.services.mozilla.com/D82377 Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/b5acbf536c46a66c939a61bde34ad93b1977a604 --- modules/video_capture/linux/device_info_v4l2.cc | 17 ++++++++++++----- modules/video_capture/linux/device_info_v4l2.h | 3 +++ 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/modules/video_capture/linux/device_info_v4l2.cc b/modules/video_capture/linux/device_info_v4l2.cc index f87fe53abe..d506f3a448 100644 --- a/modules/video_capture/linux/device_info_v4l2.cc +++ b/modules/video_capture/linux/device_info_v4l2.cc @@ -202,8 +202,7 @@ uint32_t DeviceInfoV4l2::NumberOfDevices() { snprintf(device, sizeof(device), "/dev/video%d", n); if ((fd = open(device, O_RDONLY)) != -1) { // query device capabilities and make sure this is a video capture device - if (ioctl(fd, VIDIOC_QUERYCAP, &cap) < 0 || - !(cap.device_caps & V4L2_CAP_VIDEO_CAPTURE)) { + if (ioctl(fd, VIDIOC_QUERYCAP, &cap) < 0 || !IsVideoCaptureDevice(&cap)) { close(fd); continue; } @@ -235,8 +234,7 @@ int32_t DeviceInfoV4l2::GetDeviceName(uint32_t deviceNumber, sprintf(device, "/dev/video%d", device_index); if ((fd = open(device, O_RDONLY)) != -1) { // query device capabilities and make sure this is a video capture device - if (ioctl(fd, VIDIOC_QUERYCAP, &cap) < 0 || - !(cap.device_caps & V4L2_CAP_VIDEO_CAPTURE)) { + if (ioctl(fd, VIDIOC_QUERYCAP, &cap) < 0 || !IsVideoCaptureDevice(&cap)) { close(fd); continue; } @@ -321,7 +319,7 @@ int32_t DeviceInfoV4l2::CreateCapabilityMap(const char* deviceUniqueIdUTF8) { struct v4l2_capability cap; if (ioctl(fd, VIDIOC_QUERYCAP, &cap) == 0) { // skip devices without video capture capability - if (!(cap.device_caps & V4L2_CAP_VIDEO_CAPTURE)) { + if (!IsVideoCaptureDevice(&cap)) { continue; } @@ -383,6 +381,15 @@ bool DeviceInfoV4l2::IsDeviceNameMatches(const char* name, return false; } +bool DeviceInfoV4l2::IsVideoCaptureDevice(struct v4l2_capability* cap) +{ + if (cap->capabilities & V4L2_CAP_DEVICE_CAPS) { + return cap->device_caps & V4L2_CAP_VIDEO_CAPTURE; + } else { + return cap->capabilities & V4L2_CAP_VIDEO_CAPTURE; + } +} + int32_t DeviceInfoV4l2::FillCapabilities(int fd) { // set image format struct v4l2_format video_fmt; diff --git a/modules/video_capture/linux/device_info_v4l2.h b/modules/video_capture/linux/device_info_v4l2.h index 95432a509d..e3c2395f49 100644 --- a/modules/video_capture/linux/device_info_v4l2.h +++ b/modules/video_capture/linux/device_info_v4l2.h @@ -18,6 +18,8 @@ #include "rtc_base/platform_thread.h" #include +struct v4l2_capability; + namespace webrtc { namespace videocapturemodule { class DeviceInfoV4l2 : public DeviceInfoImpl { @@ -49,6 +51,7 @@ class DeviceInfoV4l2 : public DeviceInfoImpl { private: bool IsDeviceNameMatches(const char* name, const char* deviceUniqueIdUTF8); + bool IsVideoCaptureDevice(struct v4l2_capability* cap); #ifdef WEBRTC_LINUX void HandleEvent(inotify_event* event, int fd); -- 2.34.1