* Adds support for flags datatype
This commit adds support for `FlagsDatatype`. In WASI, flags are
represented as bitfields/bitflags, therefore, it is important
for the type to have bitwise operations implemented, and some
way of checking whether the current set of flags contains some
other set (i.e., they intersect). Thus, this commit automatically
derives `BitAnd`, etc. for the derived flags datatype. It also
automatically provides an `ALL_FLAGS` value which corresponds to
a bitwise-or of all flag values present and is provided for
convenience.
* Simplify read_from_guest
* Add array generation to wiggle-generate crate
This commit:
* adds array generation to `wiggle-generate` crate which implies
that we can now generate arrays from `witx` files
* introduces two test interface functions `foo::reduce_excuses` and
`foo::populate_excuses`, and adds matching prop-tests
* adds an out-of-boundary check to `HostMemory::mem_area_strat` since
now, given we're generating arrays for testing with an arbitrary
but bounded number of elements, it is possible to violate the boundary
* refactors `Region::extend` to a new signature `extend(times: u32)`
which multiplies the current pointer `len` by `times`
* fixes bug in `GuestArray::as_ref` and `GuestArrayMut::as_ref_mut` methods
where we were not validating the first element (we always started the
validation from the second element)
* Fix generation of arrays in witx
This commit fixes how `arrays` are auto-generated from `witx` files.
In particular, the changes include:
* Since by design every `array` in `witx` represents an immutable
slab of memory, we will only ever operate on `GuestArray` in which
case I've gone ahead and removed `GuestArrayMut` so as to unclutter
the code somewhat. If we find ourselves in need for it in the future,
I reckon it will be better to write it from scratch (since the codebase
will inevitably evolve by then considerably) rather than maintaining an
unused implementation.
* I've rewritten `GuestArrayRef<T>` to be a wrapper for `Vec<GuestRef<T>>`.
Also, `GuestArray::as_ref` now borrows each underlying "element" of the
array one-by-one rather than borrowing the entire chunk of memory at once.
This change is motivated by the inability to coerce type parameter `T` in
`GuestArray<T>` in more complicated cases such as arrays of guest pointers
`GuestPtr<T>` to `*const T` for reuse in `std::slice::from_raw_parts` call.
(In general, the size of Wasm32 pointer is 4 bytes, while
```
std::mem::size_of::<T>() == std::mem::size_of::<GuestPtr<S>>() == 16
```
which is problematic; i.e., I can't see how I could properly extract guest
pointers from slices of 4 bytes and at the same time not allocate.)
* I've augmented fuzz tests by (re-)defining two `array` types:
```
(typename $const_excuse_array (array (@witx const_pointer $excuse)))
(typename $excuse_array (array (@witx pointer $excuse)))
```
This should hopefully emulate and test the `iovec` and `ciovec` arrays
present in WASI spec.
* Add some (incomplete set) basic sanity end-to-end tests
This commit adds some (an incomplete set of) basic sanity end-to-end
tests. It uses `test.witx` to autogenerate types and module interface
functions (aka the syscalls), and tests their implementation. For
the host memory, it uses simplistic `&mut [u8]` where we have full
control of the addressing and contents.
* Add sanity test for baz interface func
This commit adds a sanity test for the `Foo::baz` interface func.
* Upcast start/len for Region to avoid overflow
* Reenable alignment checking for memory
* use an array to implement hostmemory
Co-authored-by: Pat Hickey <pat@moreproductive.org>
