Stop blindly extracting uint8array.buffer after calling compress() #5753
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We were re-wrapping the Buffer into a Uint8Array but discarding the byteOffset and byteLength, so we expanded the returned array to include garbage data. We can just return the Buffer itself, it is a Uint8Array.
We were assuming that the Uint8Array returned from compress() is a view of the entirety of its underlying ArrayBuffer. But that's not necessarily true. Specifically it's not true if gz.ts takes the "node" code path where it uses the node zlib module. We haven't run into this before because our jest environment has browser-like Worker APIs available, so we test the browser code path and the node path doesn't get exercised. But if I change it so that we go down the node path in the tests, then multiple tests in receive-profile.test.ts fail because we pass around compressed buffers with extra garbage bytes at the end. So this fix replaces each of those `.buffer` accesses with a potential copy if that's needed to make sure that the ArrayBuffer doesn't contain any extra data. A cleaner solution might be to stop using ArrayBuffer so much in these tests, but in some of them we simulate the response from a fetch() which definitely has an arrayBuffer() accessor and not a byteArray() accessor.
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #5753 +/- ##
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+ Coverage 85.67% 85.69% +0.02%
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Files 315 315
Lines 31110 31122 +12
Branches 8560 8564 +4
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+ Hits 26654 26671 +17
+ Misses 4026 4021 -5
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We have a node zlib based compression / decompression code path in gz.ts. This path is currently not exercised by our tests. But if I change our Jest environment so that it exercises the node zlib code path, there are test failures in receive-profile.test.ts, for two reasons:
compress/decompresswere discarding thebyteOffsetandbyteLengthof the returned typed array and re-wrapping the entire underlying ArrayBuffer, including potential garbage bytes at the start or at the end. (In practice just at the end.)receive-profile.test.tswere accessing.bufferon the array returned bycompress(), and assuming that the buffer didn't contain any extra data beyond the Uint8Array.So this fix removes the rewrapping, and replaces each of those
.bufferaccesses with a potential copy if that's needed to make sure that the ArrayBuffer doesn't contain any extra data.A cleaner solution might be to stop using ArrayBuffer so much in these tests, but in some of them we simulate the response from a fetch() which definitely has an arrayBuffer() accessor and not a byteArray() accessor.