[release/6.0] Manually backporting #74599 to 6.0 #78247
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* Manually backporting dotnet#74599 to 7.0 for RC2. * Fix a couple mis-copied lines of code and a couple nits.
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When this is ready, please send an email to Tactics requesting approval, add the |
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/azp run runtime-community |
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Azure Pipelines successfully started running 1 pipeline(s). |
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@StephenMolloy today is the deadline for merging backports that should go into December release. Please get an M2 sign-off, then send an email to Tactics to request backport approval, and add the |
HongGit
approved these changes
Nov 16, 2022
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Approved by Tactics via email. |
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Approved by Tactics (6.0.14). |
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Backporting #75366 which was a backport of #74599 to 7.0 for RC2 from 8.0.
Customer Impact
DataContractSerializer has not been properly accounting for big-or-little endian-ness when writing a few types "to the wire." This has not previously been an issue, since to my knowledge there have not been any commonly used big-endian platforms with .Net. DCS writes little-endian on the wire, so not accounting for endian-ness has simply worked because little-endian platforms write little-endian on the wire as expected. IBM helped bring .Net to their big-endian s360 platform in 6.0 however, causing failures when serializing between different platforms.
Testing
Tests were added to check the correct little-endian output for affected types and arrays of types.
Regression
No... but kind of yes. Strictly speaking, the code has always missed this -endian handling for these types and was not regressed. But the introduction of big-endian implementations of dotnet in 6.0 has exposed this issue. So in a sense, DCS was fine in 5.0 and now is not correct on some platforms in 6.0 and later.
Risk
Low. The change is faithful to current execution for little-endian platforms and only does different things on a big-endian platform... which is currently broken without this fix.