feat(Storage): Enable full object checksum validation for resumable uploads

[mahendra-google]

This PR enables full object checksum validation (specifically CRC32C) for JSON-based resumable uploads, ensuring end-to-end data integrity for multi-chunk transfers. Please see b/461996128

[gemini-code-assist]

Summary of Changes

Hello @mahendra-google, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces robust data integrity checks for resumable uploads by integrating CRC32C checksum validation. This enhancement ensures that multi-chunk transfers to Google Cloud Storage are verified end-to-end, preventing data corruption. The changes also update the client's error handling to align with the server's response to checksum mismatches.

Highlights

• Enabled CRC32C Checksum Validation: Implemented end-to-end CRC32C checksum validation for JSON-based resumable uploads, ensuring data integrity for multi-chunk transfers.
• Updated Upload Validation Behavior: Modified integration tests to reflect the new behavior where invalid checksums during resumable uploads now result in a GoogleApiException with a BadRequest status, indicating server-side rejection.
• Enhanced Stream Handling for Checksum Calculation: Improved the LengthOnlyStream implementation to support seeking and reading, which is crucial for calculating the full CRC32C hash of the stream before the final chunk is sent.

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[gemini-code-assist]

Code Review

This pull request enables full object checksum validation for resumable uploads by introducing a Crc32cHashInterceptor. This interceptor calculates the CRC32C hash of the upload stream and attaches it to the final chunk of a resumable upload, ensuring end-to-end data integrity. The implementation is solid, with proper handling of the interceptor's lifecycle. The integration tests have been correctly updated to reflect the new server-side validation behavior, where the server now rejects corrupted uploads with a BadRequest status. Additionally, LengthOnlyStream has been updated to be a more compliant Stream implementation. My review includes a couple of suggestions to optimize performance by avoiding string allocations in the new parsing logic.

[krishnamd-jkp]

Adding this globally to the http client which is not ideal. Every single request GET, LIST, DELETE made by this client must now run through the URI check in InterceptAsync. Also if there is an exception and if OnProgressChanged is not triggered, the interceptor stays in the client forever.

[krishnamd-jkp]

On the final chunk, you are calculating the hash for entire stream which could be in Gbs. This will cause a performance regression for huge data. Incase of retries, this logic will be computed multiple times again

[krishnamd-jkp]

You're not checking if the user has disabled this (using UploadValidationMode.None) crc32c validation here.

[krishnamd-jkp]

I think you are modifying the global stream's position here which could be a side effect. If this stream is used concurrently somewhere, that could lead to an issue

[krishnamd-jkp]

Can you use UploadStreamInterceptor which already calculates the hash and use it here instead of recomputing the hash on final chunk?