04d2caea7b
* Consolidate methods of memory initialization This commit consolidates the few locations that we have which are performing memory initialization. Namely the uffd logic for creating paged memory as well as the memfd logic for creating a memory image now share an implementation to avoid duplicating bounds-checks or other validation conditions. The main purpose of this commit is to fix a fuzz-bug where a multiplication overflowed. The overflow itself was benign but it seemed better to fix the overflow in only one place instead of multiple. The overflow in question is specifically when an initializer is checked to be statically out-of-bounds and multiplies a memory's minimum size by the wasm page size, returning the result as a `u64`. For memory64-memories of size `1 << 48` this multiplication will overflow. This was actually a preexisting bug with the `try_paged_init` function which was copied for memfd, but cropped up here since memfd is used more often than paged initialization. The fix here is to skip validation of the `end` index if the size of memory is `1 << 64` since if the `end` index can be represented as a `u64` then it's in-bounds. This is somewhat of an esoteric case, though, since a memory of minimum size `1 << 64` can't ever exist (we can't even ask the os for that much memory, and even if we could it would fail). * Fix memfd test * Fix some tests * Remove InitMemory enum * Add an `is_segmented` helper method * More clear variable name * Make arguments to `init_memory` more descriptive
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS with a small install script:
$ curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
Features
-
Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.
-
Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
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Configurable. Whether you need to precompile your wasm ahead of time, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.
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WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
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Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders or usewasmtimeConan package - [C++] - the
wasmtime-cpprepository or usewasmtime-cppConan package - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!
It's Wasmtime.