This repo 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 5d3efb6005 git revision.

Please note that the library requires Rust compiler version at least 1.34.0.

Supported syscalls

We support a subset of the WASI API, though we are working on new hostcalls on a regular basis. We currently implement:

__wasi_args_get
__wasi_args_sizes_get
__wasi_clock_res_get
__wasi_clock_time_get
__wasi_environ_get
__wasi_environ_sizes_get
__wasi_fd_close
__wasi_fd_fdstat_get
__wasi_fd_fdstat_set_flags
__wasi_fd_filestat_get
__wasi_fd_prestat_dir_name
__wasi_fd_prestat_get
__wasi_fd_read
__wasi_fd_seek
__wasi_fd_write
__wasi_path_open
__wasi_path_filestat_get
__wasi_path_create_directory
__wasi_path_unlink_file
__wasi_poll_oneoff
__wasi_proc_exit
__wasi_random_get

This is enough to run basic C and Rust programs, including those that use command-line arguments, environment variables, stdio, and basic file operations.

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.