Remove undefined behavior from JSTypedArray.GetJSValueForMemory #295
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@microsoft-github-policy-service agree |
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Thanks for the PR! This is a great clean-up, as the previous code there (that I wrote) was certainly dubious. I guess I just did not discover the |
jasongin
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May 14, 2024
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The
GetJSValueForMemorymethod currently uses unsafe code to access the internals of theMemory<T>type, resulting in undefined behavior.Contrary to the comments inside, there has always been a public API to access the
MemoryManager<T>backing aMemory<T>instance:MemoryMarshal.TryGetMemoryManager<T, TManager>. This PR replaces the implementation with one using that API to remove the undefined behavior.With this new implementation, it is no longer necessary to strip the high bit from the index (it is an implementation detail that the
MemoryMarshalAPIs do not expose). Technically it wasn't necessary to begin with as that bit is only set forMemory<T>instances backed by pinned arrays, which are already ruled out by checking for aMemoryManagerinstance.