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libcamera: v4l2_videodevice: Pass FileDescriptor to open()

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The V4L2VideoDevice::open() function that takes an open file handle
duplicates it internally, and leaves the original handle untouched. This
is documented but not enforced through language constructs. Fix it by
passing a FileDescriptor to the function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
This commit is contained in:
Laurent Pinchart
2021-11-29 20:14:14 +02:00
parent a62a886a7d
commit 415ac12399
2 changed files with 10 additions and 14 deletions
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2
include/libcamera/internal/v4l2_videodevice.h
View File

@@ -184,7 +184,7 @@ public:
~V4L2VideoDevice();
int open();
int open(int handle, enum v4l2_buf_type type);
int open(FileDescriptor handle, enum v4l2_buf_type type);
void close();
const char *driverName() const { return caps_.driver(); }

22
src/libcamera/v4l2_videodevice.cpp
View File

@@ -612,16 +612,14 @@ int V4L2VideoDevice::open()
* its type from the capabilities. This can be used to force a given device type
* for memory-to-memory devices.
*
* The file descriptor \a handle is duplicated, and the caller is responsible
* for closing the \a handle when it has no further use for it. The close()
* function will close the duplicated file descriptor, leaving \a handle
* untouched.
* The file descriptor \a handle is duplicated, no reference to the original
* handle is kept.
*
* \return 0 on success or a negative error code otherwise
*/
int V4L2VideoDevice::open(int handle, enum v4l2_buf_type type)
int V4L2VideoDevice::open(FileDescriptor handle, enum v4l2_buf_type type)
{
UniqueFD newFd(dup(handle));
UniqueFD newFd = handle.dup();
if (!newFd.isValid()) {
LOG(V4L2, Error) << "Failed to duplicate file handle: "
<< strerror(errno);
@@ -1900,12 +1898,10 @@ int V4L2M2MDevice::open()
/*
* 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.
* handle for the same device node.
*/
UniqueFD fd(syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(),
O_RDWR | O_NONBLOCK));
FileDescriptor fd(syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(),
O_RDWR | O_NONBLOCK));
if (!fd.isValid()) {
ret = -errno;
LOG(V4L2, Error) << "Failed to open V4L2 M2M device: "
@@ -1913,11 +1909,11 @@ int V4L2M2MDevice::open()
return ret;
}
ret = output_->open(fd.get(), V4L2_BUF_TYPE_VIDEO_OUTPUT);
ret = output_->open(fd, V4L2_BUF_TYPE_VIDEO_OUTPUT);
if (ret)
goto err;
ret = capture_->open(fd.get(), V4L2_BUF_TYPE_VIDEO_CAPTURE);
ret = capture_->open(fd, V4L2_BUF_TYPE_VIDEO_CAPTURE);
if (ret)
goto err;