Prevent file handles from leaking on failed open. (#67)

* Prevent file handles from leaking on failed open.

Since the webcam open function only returns the open fh on success, we need to close
the FH ourselves in the event that the subsequent tests fail.

---------

Co-authored-by: Brian Stark <[email protected]>

webcam.go

@@ -35,14 +35,21 @@ type Control struct {
 // Checks if device is a v4l2 device and if it is
 // capable to stream video
 func Open(path string) (*Webcam, error) {
-
 	handle, err := unix.Open(path, unix.O_RDONLY|unix.O_NONBLOCK, 0666)
 	if err != nil {
 		return nil, err
 	}
 	if handle < 0 {
 		return nil, fmt.Errorf("failed to open %v", path)
 	}
+	// At this point the handle is valid and must be return or closed
+	success := false // If this is not set true prior to function exit we assume error and close the handle
+	defer func() {
+		if !success {
+			// Since the handle is not returned on error we must close it or leak
+			unix.Close(handle)
+		}
+	}()
 	fd := uintptr(handle)
 
 	supportsVideoCapture, supportsVideoStreaming, err := checkCapabilities(fd)
@@ -63,6 +70,7 @@ func Open(path string) (*Webcam, error) {
 	w.fd = fd
 	w.bufcount = 256
 	w.pollFds = []unix.PollFd{{Fd: int32(fd), Events: unix.POLLIN}}
+	success = true
 	return w, nil
 }