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Change allocation strategy for unfoldrN & add warning for fromListN #387
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After discussion in #301 I think that problem is deeper. Why |
I like this change. @Shimuuar, do you mind if we include it as-is into 0.13 and get the deeper problem with bounds tackled in the future major release? if you can rebase this on master we can merge it in. If you are busy I can do it myself next week, so let me know if you oppose changes in this PR for any reason. |
Not at all. I'll rebase this PR today |
Before functions allocated array of maximum size immediately. This is problem in case when attacker controls size parameter and could lead to DoS. It's also problem when size parameter is just a limit vector is usually shorter. Usual doubling strategy looks more conservative in this function. Fixes haskell#301
Co-authored-by: konsumlamm <[email protected]>
PR is ready. @konsumlamm thanks for proofreading |
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This looks great! Thank you!
# Changes in version 0.13.0.0 * `mkType` from `Data.Vector.Generic` is deprecated in favor of `Data.Data.mkNoRepType` * The role signatures on several `Vector` types were too permissive, so they have been tightened up: * The role signature for `Data.Vector.Mutable.MVector` is now `type role MVector nominal representational` (previously, both arguments were `phantom`). [#224](haskell/vector#224) * The role signature for `Data.Vector.Primitive.Vector` is now `type role Vector nominal` (previously, it was `phantom`). The role signature for `Data.Vector.Primitive.Mutable.MVector` is now `type role MVector nominal nominal` (previously, both arguments were `phantom`). [#316](haskell/vector#316) * The role signature for `Data.Vector.Storable.Vector` is now `type role Vector nominal` (previous, it was `phantom`), and the signature for `Data.Vector.Storable.Mutable.MVector` is now `type role MVector nominal nominal` (previous, both arguments were `phantom`). [#235](haskell/vector#235) We pick `nominal` for the role of the last argument instead of `representational` since the internal structure of a `Storable` vector is determined by the `Storable` instance of the element type, and it is not guaranteed that the `Storable` instances between two representationally equal types will preserve this internal structure. One consequence of this choice is that it is no longer possible to `coerce` between `Storable.Vector a` and `Storable.Vector b` if `a` and `b` are nominally distinct but representationally equal types. We now provide `unsafeCoerce{M}Vector` and `unsafeCast` functions to allow this (the onus is on the user to ensure that no `Storable` invariants are broken when using these functions). * Methods of type classes `Data.Vector.Generic.Mutable.MVector` and `Data.Vector.Generic.Vector` use concrete monads (`ST`, etc) istead of being polymorphic (`PrimMonad`, etc). [#335](haskell/vector#335). This makes it possible to derive `Unbox` with: * `GeneralizedNewtypeDeriving` * via `UnboxViaPrim` and `Prim` instance * via `As` and `IsoUnbox` instance: [#378](haskell/vector#378) * Add `MonadFix` instance for boxed vectors: [#312](haskell/vector#312) * Re-export `PrimMonad` and `RealWorld` from mutable vectors: [#320](haskell/vector#320) * Add `maximumOn` and `minimumOn`: [#356](haskell/vector#356) * The functions `scanl1`, `scanl1'`, `scanr1`, and `scanr1'` for immutable vectors are now defined when given empty vectors as arguments, in which case they return empty vectors. This new behavior is consistent with the one of the corresponding functions in `Data.List`. Prior to this change, applying an empty vector to any of those functions resulted in an error. This change was introduced in: [#382](haskell/vector#382) * Change allocation strategy for `unfoldrN`: [#387](haskell/vector#387) * Remove `CPP` driven error reporting in favor of `HasCallStack`: [#397](haskell/vector#397) * Remove redundant `Storable` constraints on to/from `ForeignPtr` conversions: [#394](haskell/vector#394) * Add `unsafeCast` to `Primitive` vectors: [#401](haskell/vector#401) * Make `(!?)` operator strict: [#402](haskell/vector#402) * Add `readMaybe`: [#425](haskell/vector#425) * Add `groupBy` and `group` for `Data.Vector.Generic` and the specialized version in `Data.Vector`, `Data.Vector.Unboxed`, `Data.Vector.Storable` and `Data.Vector.Primitive`. [#427](haskell/vector#427) * Add `toArraySlice` and `unsafeFromArraySlice` functions for conversion to and from the underlying boxed `Array`: [#434](haskell/vector#434)
This PR changes allocation strategy for
unfoldrN{,M}
toUnknown
and adds warning about possible DoS for fromListN. Here is reasoning from #301@lehins, what's you opinion?
Fixes #301