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 40ae1df 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:

args_get
args_sizes_get
clock_res_get
clock_time_get
environ_get
environ_sizes_get
fd_close
fd_datasync
fd_pread
fd_pwrite
fd_read
fd_renumber
fd_seek
fd_tell
fd_fdstat_get
fd_fdstat_set_flags
fd_fdstat_set_rights
fd_sync
fd_write
fd_advise
fd_allocate
path_create_directory
path_link
path_open
fd_readdir
path_readlink
path_rename
fd_filestat_get
fd_filestat_set_times
fd_filestat_set_size
path_filestat_get
path_filestat_set_times
path_symlink
path_unlink_file
path_remove_directory
poll_oneoff
fd_prestat_get
fd_prestat_dir_name
proc_exit
random_get
sched_yield

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.