[libcamera-devel] [PATCH v2 07/10] libcamera: V4L2VideoDevice: Use fd for a file descriptor

[Hirokazu Honda]

Manages file descriptors owned by V4L2VideoDevice by ScopedFD.
This also changes the return type of exportDmabufFd to ScopedFD
from FileDescriptor in order to represent a caller owns the
returned file file descriptor.

Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
---
 include/libcamera/internal/v4l2_videodevice.h |  4 +--
 src/libcamera/v4l2_videodevice.cpp            | 33 ++++++++-----------
 2 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
index 7938343b..925a8e82 100644
--- a/include/libcamera/internal/v4l2_videodevice.h
+++ b/include/libcamera/internal/v4l2_videodevice.h
@@ -30,9 +30,9 @@
 namespace libcamera {
 
 class EventNotifier;
-class FileDescriptor;
 class MediaDevice;
 class MediaEntity;
+class ScopedFD;
 
 struct V4L2Capability final : v4l2_capability {
 	const char *driver() const
@@ -235,7 +235,7 @@ private:
 	int createBuffers(unsigned int count,
 			  std::vector<std::unique_ptr<FrameBuffer>> *buffers);
 	std::unique_ptr<FrameBuffer> createBuffer(unsigned int index);
-	FileDescriptor exportDmabufFd(unsigned int index, unsigned int plane);
+	ScopedFD exportDmabufFd(unsigned int index, unsigned int plane);
 
 	void bufferAvailable(EventNotifier *notifier);
 	FrameBuffer *dequeueBuffer();
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index ce6ad8b5..1dfb011c 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -1274,12 +1274,12 @@ std::unique_ptr<FrameBuffer> V4L2VideoDevice::createBuffer(unsigned int index)
 
 	std::vector<FrameBuffer::Plane> planes;
 	for (unsigned int nplane = 0; nplane < numPlanes; nplane++) {
-		FileDescriptor fd = exportDmabufFd(buf.index, nplane);
+		ScopedFD fd = exportDmabufFd(buf.index, nplane);
 		if (!fd.isValid())
 			return nullptr;
 
 		FrameBuffer::Plane plane;
-		plane.fd = std::move(fd);
+		plane.fd = FileDescriptor(fd.release());
 		plane.length = multiPlanar ?
 			buf.m.planes[nplane].length : buf.length;
 
@@ -1289,7 +1289,7 @@ std::unique_ptr<FrameBuffer> V4L2VideoDevice::createBuffer(unsigned int index)
 	return std::make_unique<FrameBuffer>(std::move(planes));
 }
 
-FileDescriptor V4L2VideoDevice::exportDmabufFd(unsigned int index,
+ScopedFD V4L2VideoDevice::exportDmabufFd(unsigned int index,
 					       unsigned int plane)
 {
 	struct v4l2_exportbuffer expbuf = {};
@@ -1304,10 +1304,10 @@ FileDescriptor V4L2VideoDevice::exportDmabufFd(unsigned int index,
 	if (ret < 0) {
 		LOG(V4L2, Error)
 			<< "Failed to export buffer: " << strerror(-ret);
-		return FileDescriptor();
+		return ScopedFD();
 	}
 
-	return FileDescriptor(std::move(expbuf.fd));
+	return ScopedFD(expbuf.fd);
 }
 
 /**
@@ -1699,39 +1699,32 @@ V4L2M2MDevice::~V4L2M2MDevice()
  */
 int V4L2M2MDevice::open()
 {
-	int fd;
-	int ret;
-
 	/*
 	 * The output and capture V4L2VideoDevice instances use the same file
 	 * handle for the same device node. The local file handle can be closed
 	 * as the V4L2VideoDevice::open() retains a handle by duplicating the
 	 * fd passed in.
 	 */
-	fd = syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(),
-		     O_RDWR | O_NONBLOCK);
-	if (fd < 0) {
-		ret = -errno;
-		LOG(V4L2, Error)
-			<< "Failed to open V4L2 M2M device: " << strerror(-ret);
-		return ret;
+	ScopedFD fd(syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(),
+			    O_RDWR | O_NONBLOCK));
+	if (!fd.isValid()) {
+		LOG(V4L2, Error) << "Failed to open V4L2 M2M device: "
+				 << strerror(errno);
+		return -errno;
 	}
 
-	ret = output_->open(fd, V4L2_BUF_TYPE_VIDEO_OUTPUT);
+	int ret = output_->open(fd.get(), V4L2_BUF_TYPE_VIDEO_OUTPUT);
 	if (ret)
 		goto err;
 
-	ret = capture_->open(fd, V4L2_BUF_TYPE_VIDEO_CAPTURE);
+	ret = capture_->open(fd.get(), V4L2_BUF_TYPE_VIDEO_CAPTURE);
 	if (ret)
 		goto err;
 
-	::close(fd);
-
 	return 0;
 
 err:
 	close();
-	::close(fd);
 
 	return ret;
 }
-- 
2.32.0.rc1.229.g3e70b5a671-goog