fix(libstore/filetransfer): prevent double callback invocation on interrupt during retry#14418
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edolstra merged 1 commit intoNixOS:masterfrom Oct 30, 2025
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…errupt during retry Fix a race condition where interrupting a download (via Ctrl-C) during a retry attempt could cause a crash. When `enqueueItem()` throws because the download thread is shutting down, the exception would propagate without setting `done=true`, causing the `TransferItem` destructor to invoke the callback a second time. This triggered an assertion failure in `Callback::rethrow()` with: `Assertion '!prev' failed` and the error message `cannot enqueue download request because the download thread is shutting down`. The fix catches the exception from `enqueueItem()` and calls `fail()` to properly complete the transfer, ensuring the callback is invoked exactly once.
tomberek
approved these changes
Oct 29, 2025
2 tasks
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Motivation
Fix a race condition where interrupting a download (via Ctrl-C) during a
retry attempt could cause a crash. When
enqueueItem()throws because thedownload thread is shutting down, the exception would propagate without
setting
done=true, causing theTransferItemdestructor to invoke thecallback a second time.
This triggered an assertion failure in
Callback::rethrow()with:Assertion '!prev' failedand the error messagecannot enqueue download request because the download thread is shutting down.The fix catches the exception from
enqueueItem()and callsfail()toproperly complete the transfer, ensuring the callback is invoked exactly
once.
Context
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