[libcamera-devel] [PATCH v2 7/7] v4l2: v4l2_camera_proxy: Fix segfault on restarting streams

[Paul Elder]

The V4L2 compatibility layer keeps track of the index of the next buffer
to be dequeued, to handle VIDIOC_DQBUF. This index is set to 0 on
startup and incremented (modulo #frames), and is otherwise never reset.
This means that if the last handled frame index is not #frames-1, and
the stream is restarted without restarting libcamera and the V4L2
compatilibity layer, the buffer index number won't match with the
libcamera buffer index number, causing a segfault. Fix this by resetting
the current buffer index to zero on VIDIOC_STREAMON.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>

---
New in v2
---
 src/v4l2/v4l2_camera_proxy.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index 7ee4c0cb..059f3cbe 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -465,6 +465,8 @@ int V4L2CameraProxy::vidioc_streamon(int *arg)
 	if (!validateBufferType(*arg))
 		return -EINVAL;
 
+	currentBuf_ = 0;
+
 	return vcam_->streamOn();
 }
 
-- 
2.20.1