ArrayWriter.EnsureBufferCapacity must account for _start #6266
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Hey @atykhyy thank you for the fix! Can you also write a small unit test for that? |
michaelstaib
approved these changes
Jun 28, 2023
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Thank you for contributing! |
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Currently,
HotChocolate.Utilities.ArrayWriter.GetMemory()/GetSpan()can throw in rare cases becauseEnsureBufferCapacityallocates insufficient memory. Example: suppose the array writer has a 16k buffer (_buffer.Length == 0x4000) to which 8k bytes is already written (_start == 0x2000) andGetMemory(0x7000)is invoked, in turn callingEnsureBufferCapacity(0x7000). It will double the size of the buffer to0x8000and think did it's job because0x7000 < 0x8000, but then_buffer.AsSpan().Slice(0x2000,0x7000)throws.The one-liner PR fixes this without danger of integer overflow by subtracting
_startwhen comparing needed capacity to newly available capacity.