libcamera: Open files with O_CLOEXEC

Files opened internally in libcamera without the O_CLOEXEC file will
remain open upon a call to one of the exec(3) functions. As exec()
doesn't destroy local or global objects, this can lead to various side
effects. Avoid this by opening file descriptors with O_CLOEXEC for all
internal files.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/media_device.cpp

@@ -477,7 +477,7 @@ int MediaDevice::open()
 		return -EBUSY;
 	}
 
-	fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR));
+	fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR | O_CLOEXEC));
 	if (!fd_.isValid()) {
 		int ret = -errno;
 		LOG(MediaDevice, Error)