Improve CborStreamReader Logic to Handle Nesting and End-of-Buffer Corner Cases #3956
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muhammad-othman
commented
Aug 13, 2025
| @@ -106,13 +106,6 @@ private void RefillBuffer(int bytesToSkip = 0) | |||
| // Update the total size of valid data in our buffer. | |||
| _currentChunkSize = leftoverBytesCount + bytesReadFromStream; | |||
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| // Check for a malformed stream: if we have leftovers but the stream is empty, | |||
| // it means the CBOR data was truncated. | |||
| if (bytesReadFromStream == 0 && leftoverBytesCount > 0) | |||
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This check isn't valid anymore since the current logic does call RefillBuffer multiple times to make sure we are really at the end of the stream not just the current buffer, so we will fall back to the outer ExecuteRead to catch when a stream is ending with an incomplete CBOR data item.
muhammad-othman
commented
Aug 13, 2025
| @@ -139,7 +132,7 @@ private T ExecuteRead<T>(Func<CborReader, T> readOperation) | |||
| { | |||
| return readOperation(_internalCborReader); | |||
| } | |||
| catch (CborContentException ex) | |||
| catch (Exception ex) when (ex is InvalidOperationException || ex is CborContentException) | |||
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Catching InvalidOperationException to account when CBOR reader assumes that we are reading a different type because of how the current buffer ends.
muhammad-othman
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Description
This PR updates the
CborStreamReaderstreaming logic to correctly handle scenarios where the buffer ends just after an item was read, particularly when working with nested containers.Previously, the streaming CBOR reader could incorrectly signal completion when the current buffer segment ended but nested containers were still open. This caused issues with large or segmented CBOR payloads where container boundaries did not align with buffer boundaries.
PeekState() == Finishedas a final read state when there are still open containers in the nesting stack.EndArrayorEndMapis explicitly read when end-of-current-buffer-part scenarios.Motivation and Context
DOTNET-8252Testing
DRY_RUN-08c395ab-328f-4d34-8928-282cecedfd90Screenshots (if appropriate)
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Checklist
License