LibWeb: Track fetching-related tasks in FetchController for cancellation

The HTMLMediaElement, for example, contains spec text which states any
ongoing fetch process must be "stopped". The spec does not indicate how
to do this, so our implementation is rather ad-hoc.

Our current implementation may cause a crash in places that assume one
of the fetch algorithms that we set to null is *not* null. For example:

    if (fetch_params.process_response) {
        queue_fetch_task([]() {
            fetch_params.process_response();
        };
    }

If the fetch process is stopped after queuing the fetch task, but not
before the fetch task is run, we will crash when running this fetch
algorithm.

We now track queued fetch tasks on the fetch controller. When the fetch
process is stopped, we cancel any such pending task.

It is a little bit awkward maintaining a fetch task ID. Ideally, we
could use the underlying task ID throughout. But we do not have access
to the underlying task nor its ID when the task is running, at which
point we need some ID to remove from the pending task list.
This commit is contained in:
Timothy Flynn 2024-03-22 15:28:41 -04:00 committed by Andreas Kling
parent 4806cf9527
commit 7b3ddd5e15
Notes: sideshowbarker 2024-07-17 07:43:44 +09:00
7 changed files with 66 additions and 7 deletions

View file

@ -627,7 +627,7 @@ WebIDL::ExceptionOr<void> fetch_response_handover(JS::Realm& realm, Infrastructu
auto task_destination = fetch_params.task_destination().get<JS::NonnullGCPtr<JS::Object>>();
// 5. Queue a fetch task to run processResponseEndOfBodyTask with fetchParamss task destination.
Infrastructure::queue_fetch_task(task_destination, move(process_response_end_of_body_task));
Infrastructure::queue_fetch_task(fetch_params.controller(), task_destination, move(process_response_end_of_body_task));
};
// FIXME: Handle 'parallel queue' task destination
@ -636,7 +636,7 @@ WebIDL::ExceptionOr<void> fetch_response_handover(JS::Realm& realm, Infrastructu
// 4. If fetchParamss process response is non-null, then queue a fetch task to run fetchParamss process response
// given response, with fetchParamss task destination.
if (fetch_params.algorithms()->process_response()) {
Infrastructure::queue_fetch_task(task_destination, [&fetch_params, &response]() {
Infrastructure::queue_fetch_task(fetch_params.controller(), task_destination, [&fetch_params, &response]() {
fetch_params.algorithms()->process_response()(response);
});
}
@ -674,7 +674,7 @@ WebIDL::ExceptionOr<void> fetch_response_handover(JS::Realm& realm, Infrastructu
// 3. If internalResponse's body is null, then queue a fetch task to run processBody given null, with
// fetchParamss task destination.
if (!internal_response->body()) {
Infrastructure::queue_fetch_task(task_destination, [process_body = move(process_body)]() {
Infrastructure::queue_fetch_task(fetch_params.controller(), task_destination, [process_body = move(process_body)]() {
process_body({});
});
}