Skip to content

nickrum/wasi-libc

 
 

Repository files navigation

wasi-libc

wasi-libc is a libc for WebAssembly programs built on top of WASI system calls. It provides a wide array of POSIX-compatible C APIs, including support for standard I/O, file I/O, filesystem manipulation, memory management, time, string, environment variables, program startup, and many other APIs.

wasi-libc is sufficiently stable and usable for many purposes, as most of the POSIX-compatible APIs are stable, though it is continuing to evolve to better align with wasm and WASI. For example, pthread support is experimentally provided via the wasi-threads proposal.

Usage

The easiest way to get started with this is to use wasi-sdk, which includes a build of wasi-libc in its sysroot.

Building from source

To build a WASI sysroot from source, obtain a WebAssembly-supporting C compiler (currently this is only clang 10+, though we'd like to support other compilers as well), and then run:

make CC=/path/to/clang/with/wasm/support \
     AR=/path/to/llvm-ar \
     NM=/path/to/llvm-nm

This makes a directory called "sysroot" by default. See the top of the Makefile for customization options.

To use the sysroot, use the --sysroot= option:

/path/to/wasm/supporting/c/compiler --sysroot=/path/to/the/newly/built/sysroot ...

to run the compiler using the newly built sysroot.

Note that Clang packages typically don't include cross-compiled builds of compiler-rt, libcxx, or libcxxabi, for libclang_rt.builtins-wasm32.a, libc++.a, or libc++abi.a, respectively, so they may not be usable without extra setup. This is one of the things wasi-sdk simplifies, as it includes cross-compiled builds of compiler-rt, libc++.a, and libc++abi.a.

Building in pthread support

To enable pthreads support via the wasi-threads proposal, follow the above build directions with one addition: make ... THREAD_MODEL=posix. This creates additional artifacts in sysroot/lib/wasm32-wasi-threads to support --target wasm32-wasi-threads.

Arch Linux AUR package

For Arch Linux users, there's an official wasi-libc package tracking this Git repository. You might want to install other WASI related packages as well.

About

WASI libc implementation for WebAssembly

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published

Languages

  • C 92.9%
  • Assembly 3.4%
  • Makefile 1.3%
  • C++ 1.2%
  • Rust 0.8%
  • Awk 0.3%
  • Other 0.1%