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`.
Wasmtime: a WebAssembly Runtime.
Wasmtime is a standalone wasm-only optimizing runtime for WebAssembly and WASI. It runs WebAssembly code outside of the Web, and can be used both as a command-line utility or as a library embedded in a larger application.
To get started, visit wasmtime.dev.
There are Rust, C, and C++ toolchains that can compile programs with WASI. See the WASI intro for more information, and the WASI tutorial for a tutorial on compiling and running programs using WASI and wasmtime, as well as an overview of the filesystem sandboxing system.
Wasmtime passes the WebAssembly spec testsuite. To run it, update the
spec_testsuite submodule with git submodule update --remote, and it will
be run as part of cargo test.
Wasmtime does not yet implement Spectre mitigations, however this is a subject of ongoing research.
Additional goals for Wasmtime include:
- Support a variety of host APIs (not just WASI), with fast calling sequences, and develop proposals for additional API modules to be part of WASI.
- Facilitate development and testing around the Cranelift and Lightbeam JITs, and other WebAssembly execution strategies.
- Develop a native ABI used for compiling WebAssembly suitable for use in both JIT and AOT to native object files.
Including Wasmtime in your project
Wasmtime exposes an API for embedding as a library through the wasmtime-api subcrate,
which contains both a high-level and safe Rust API, as well as a C-compatible API
compatible with the proposed WebAssembly C API.
For more information, see the Rust API embedding chapter of the Wasmtime documentation.
It's Wasmtime.