Allow for AsIter(Mut)/AsSlice(Mut) to be implemented in safe Rust #2120
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langston-barrett
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Towards `MapObserver`s in safe Rust.
`Self::Entry` is `Copy`, so there's not much value in returning a reference from `get()`. Futhermore, returning a reference limits the possible implementations of `MapObserver`, because it forces the borrow/reset to outlive the body of the method.
Like the previous commit, this is intended to expand the possible implementations of `MapObserver` to types with interior mutability, which can't necessarily loan out their content.
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I recognise fighting CI is no fun, so if at any point you want me to take over, let me know 🙂 |
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@addisoncrump That'd be awesome! I'm done for the day, I can return to this on Tuesday if you don't have a minute to push it through before then. |
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Also working on AsSlice/AsSliceMut for this pattern as well, since we very likely want to be able to use e.g. SIMD accel on the RefCell maps. |
addisoncrump
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impl MapObserver for RefCellValueObserver in safe Rust
addisoncrump
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Redux of #2000.
Previously,
MapFeedbackrequired theObserverto implementAsIter, and to give out references via.getand.get_mut. This works for all the existing in-repoMapObservers, which useunsafeto pretend that they own the underlying map/vector/array. This lets them loan out items in the array with the same lifetime as&self.This wasn't previously possible for observers using
RefCell, as the loan of the content of aRefCellby definition has a shorter lifetime than theRefCellitself. With the changes here, we can have aMapObserverbuilt in safe Rust, i.e.,RefCellValueObserver<Vec<...>>MapFeedbackalready requires that all the values areCopy, and in practice, they're generally small (in fact, they're generally primitive integers, meaning copying is free). The changes in this PR take advantage of this to remove borrowing values from the interface, thus enabling implementation ofMapObservers in safe Rust.We may want to make similar changes for
AsIterMut, although it doesn't appear to be necessary for this particular use-case.These modifications to the LibAFL library were made under funding provided by the U.S. government. The work represented in this PR is provided under Distribution Statement “A” (Approved for Public Release, Distribution Unlimited.)