Files

Andrew Brown f911855612 wiggle: copy guest slices back to shared memory (#5471 )

This change upgrades `UnsafeGuestSlice` in Wiggle to expose more
functionality to be able to use `std::ptr::copy` for writing bytes into
Wasm shared memory. Additionally, it adds a new `GuestCow` type for
delineating between Wasm memory regions that can be borrowed (non-shared
memory) or must be copied (shared memory) in order to maintain Rust
guarantees.

With these in place, it is now possible to implement the `preview1`
"read" functions for shared memory. Previously, these would panic if
attempting to copy to a shared memory. This change removes the panic and
introduces some (rather complex) logic for handling both the shared and
non-shared cases:
- if reading into a Wasm non-shared memory, Wiggle guarantees that no
  other guest pointers will touch the memory region and, in the absence
  of concurrency, a WASI function can write directly to this memory
- if reading into a Wasm shared memory, the memory region can be
  concurrently modified. At @alexcrichton's request re: Rust safety,
  this change copies all of the bytes into an intermediate buffer before
  using `std::ptr::copy` to move them into Wasm memory.

This change only applies to the `preview0` and `preview1`
implementations of `wasi-common`. Fixing up other WASI implementations
(esp. wasi-crypto) is left for later.

2023-01-03 19:51:34 +00:00

generate

wiggle: choose between &mut self and &self (#5428 )

2022-12-13 14:38:47 -08:00

macro

wiggle: choose between &mut self and &self (#5428 )

2022-12-13 14:38:47 -08:00

src

wiggle: copy guest slices back to shared memory (#5471 )

2023-01-03 19:51:34 +00:00

test-helpers

Add release notes for 3.0.1 and update some versions (#5364 )