fix: base64DecodeBytes unsigned byte values + improve JMH benchmark config#705
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fix: base64DecodeBytes unsigned byte values + improve JMH benchmark config#705He-Pin wants to merge 1 commit intodatabricks:masterfrom
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This was referenced Apr 6, 2026
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- Add regression test base64DecodeBytes_unsigned.jsonnet verifying that bytes >= 128 are returned as unsigned values (0-255). This serves as a guard against regressions after the & 0xff fix was merged in master. - Increase JMH RegressionBenchmark warmup/measurement iterations from 1 to 3, providing more stable and reliable benchmark results. 🤖 Generated with [Qoder][https://qoder.com]
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Closing this PR since the Note: The regression test |
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Motivation
std.base64DecodeByteswas returning signed Java byte values (-128..127) instead of the Jsonnet-standard unsigned range (0..255). Bytes with the high bit set (≥128) were returned as negative numbers, violating the specification.Key Design Decision
Apply
& 0xffmask to convert signed Java bytes to unsigned integers, matching the Jsonnet specification and behavior of the C++, Go, and Rust implementations.Modification
sjsonnet/src/sjsonnet/stdlib/EncodingModule.scala(base64DecodeBytes):& 0xffmask:decoded(i) & 0xffconverts signed byte (-128..127) to unsigned int (0..255)Test:
new_test_suite/base64DecodeBytes_unsigned.jsonnet— verifies bytes ≥ 128 are returned as unsigned (e.g., 0xff → 255, not -1)Benchmark Results
This is a correctness fix, not a performance optimization. No benchmark impact expected.
Analysis
bytetype is signed (-128..127).Base64.getDecoder.decode()returnsbyte[]. Without masking, values ≥ 128 are negative.[0, 255]range.References
bytetype: signed, -128 to 127& 0xffmask: standard Java idiom for unsigned byte conversionResult
Fixes
std.base64DecodeBytesto return unsigned byte values (0-255) per the Jsonnet specification.