Abort starting the helpers when the recording is stopped

The recording is stopped in a different thread than it is started.
Stopping the recording stops the helpers, like the display, but if they
are stopped at the same time that they are being started there could be
a race condition in which the helper is tried to be stopped in one
thread and, immediately after that, the helper is started in the other
thread. This is now handled by explicitly checking if the recording was
stopped after starting each helper and aborting the start if it was.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/recording/src/nextcloud/talk/recording/Service.py b/recording/src/nextcloud/talk/recording/Service.py
index 802cc6b59..8489c9044 100644
--- a/recording/src/nextcloud/talk/recording/Service.py
+++ b/recording/src/nextcloud/talk/recording/Service.py
@@ -216,10 +216,16 @@ class Service:
             self._display = Display(size=(width, height), manage_global_env=False)
             self._display.start()
 
+            if self._stopped.is_set():
+                raise Exception("Display started after recording was stopped")
+
             # Start new audio sink for the audio output of the browser.
             self._audioModuleIndex, audioSinkIndex = newAudioSink(sanitizedBackend, self.token)
             audioSinkIndex = str(audioSinkIndex)
 
+            if self._stopped.is_set():
+                raise Exception("Audio sink started after recording was stopped")
+
             env = self._display.env()
             env['PULSE_SINK'] = audioSinkIndex
 
@@ -229,6 +235,12 @@ class Service:
             self._logger.debug("Joining call")
             self._participant.joinCall(self.token)
 
+            if self._stopped.is_set():
+                # Not strictly needed, as if the participant is started or the
+                # call is joined after the recording was stopped there will be
+                # no display and it will automatically fail, but just in case.
+                raise Exception("Call joined after recording was stopped")
+
             self._started.set()
 
             BackendNotifier.started(self.backend, self.token, self.status, actorType, actorId)
@@ -245,6 +257,12 @@ class Service:
             # Log recorder output.
             Thread(target=recorderLog, args=[self.backend, self.token, self._process.stdout], daemon=True).start()
 
+            if self._stopped.is_set():
+                # Not strictly needed, as if the recorder is started after the
+                # recording was stopped there will be no display and it will
+                # automatically fail, but just in case.
+                raise Exception("Call joined after recording was stopped")
+
             returnCode = self._process.wait()
 
             # recorder process will be explicitly terminated when needed, which