Close directory watcher descriptor when the handler fails#1773
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DirectoryWatcher._startWatching opens an O_EVTONLY descriptor and then runs the change handler before creating the DispatchSource that takes ownership of the descriptor (and closes it on cancellation). If the handler or contentsOfDirectory call throws, the function returns without ever creating the dispatch source, leaking the descriptor. Because startWatching retries roughly once per second whenever the source is still nil, this leaks one descriptor per second on the long-lived host daemon, eventually exhausting file descriptors for the whole system and crashing unrelated host apps with "too many open files". Close the descriptor on the error path and add a regression test that verifies a continuously failing handler does not accumulate open fds. Fixes apple#1097
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Summary
Closes a file-descriptor leak in
DirectoryWatcher. The descriptor is openedbefore the dispatch source that would normally own and close it is created. If
listing the directory or invoking the handler throws, the function returned
without closing that descriptor, and because the watcher retries roughly once
per second, the leak accumulated over time. This adds a
close(descriptor)inthe error path before rethrowing. (The existing cancel-handler close only runs
once the dispatch source has been created, so it does not cover this earlier
failure.)
Testing
make checkpasses (formatting + license headers).DirectoryWatcherTestaddstestFailingHandlerDoesNotLeakDescriptors,which forces a throwing handler through several retry cycles and asserts the
descriptor count stays bounded. Full suite (5 tests) passes.
Fixes #1097