4982878a95
This commit fixes a subtle bug in `fd_readdir` implementation on BSD-style nixes. In particular, the bug only resurfaced when testing in release mode, and I can only assume it was due to a unlucky combination of compiler optimizations and at first sight correct casting of `d_name` pointer from `const* i8` to `const* u8`. This is now fixed by first converting `d_name` to `std::str` by using `std::ffi::CStr::to_str`, and then using the resultant `std::str` to copy the properly validated `u8` contents into the Wasm buffer. Furthermore, this commit fixes incorrect handling of the `readdir` loop break condition. Although undocumented in BSD man pages, the signalling is the same as on Linux where a null ptr returned by `readdir` signals the end of the dir stream when the errno code has not changed since before calling `readdir` inside a loop. Upon a fault such as an invalid file descriptor, the errno *will* change after executing `readdir`.
wasi-common
The wasi-common crate will ultimately serve as a library providing a common implementation of
WASI hostcalls for re-use in any WASI (and potentially non-WASI) runtimes
such as Wasmtime and Lucet.
The library is an adaption of lucet-wasi crate from the Lucet project, and it is currently based on 40ae1df git revision.
Please note that the library requires Rust compiler version at least 1.37.0.
Supported syscalls
*nix
In our *nix implementation, we currently support the entire WASI API with the exception of socket hostcalls:
sock_recvsock_sendsock_shutdown
We expect these to be implemented when network access is standardised.
We also currently do not support the proc_raise hostcall, as it is expected to
be dropped entirely from WASI.
Windows
In our Windows implementation, we currently support the minimal subset of WASI API which allows for running the very basic "Hello world!" style WASM apps. More coming shortly, so stay tuned!
Development hints
When testing the crate, you may want to enable and run full wasm32 integration testsuite. This
requires wasm32-wasi target installed which can be done as follows using rustup
rustup target add wasm32-wasi
Next initiate submodules containing the integration testsuite
git submodule update --init
Now, you should be able to run the integration testsuite by enabling the wasm_tests feature
cargo test --features wasm_tests
Third-Party Code
Significant parts of our hostcall implementations are derived from the C implementations in
cloudabi-utils. See LICENSE.cloudabi-utils for license information.