5 ms·

I think this doesn't work because `aligned + size` may wrap all the way around into the valid region again. For example if aligned == ptr + 1, and size is usize

I think this doesn't work because `aligned + size` may wrap all the way around into the valid region again. For example if aligned == ptr + 1, and size is usize::MAX, we will end up with new_ptr == ptr and the allocation will wrongly succeed.

loeg 3y ago
The straightforward answer is: don't tolerate ridiculous alignments.
- saagarjha 3y ago
  You'd need to check for that, though.
  - loeg 3y ago
    No, just restrict the domain of the alignment input to like, u8. Maybe u16. Either way, it is easy to ensure your bump allocation space is far enough away from SIZE_MAX.
dev_dwarf 3y ago
Interesting point. I modified my example to test what you described. I had to play with the compilation flags to get the allocs to not be optimized out and to not panic when the integer overflow happens, but otherwise I didn't change the logic. I'm pretty sure my implementation is correctly handling the case you mention, evidenced by it returning a null pointer. Link: https://godbolt.org/z/f1jGW6Pa3 https://godbolt.org/z/f1jGW6Pa3 Update: NVM, definitely not being handled correctly. https://godbolt.org/z/cMTe1o979 https://godbolt.org/z/cMTe1o979
- deleted 3y ago
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