denoland-deno/std/wasi

wasi

This module provides an implementation of the WebAssembly System Interface

Supported Syscalls

wasi_snapshot_preview1

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

Usage

import Context from "https://deno.land/std/wasi/snapshot_preview1.ts";

const context = new Context({
  args: Deno.args,
  env: Deno.env.toObject(),
});

const binary = await Deno.readFile("path/to/your/module.wasm");
const module = await WebAssembly.compile(binary);
const instance = await WebAssembly.instantiate(module, {
  "wasi_snapshot_preview1": context.exports,
});

const {
  _start: start,
  _initialize: initialize,
  memory,
} = instance.exports;

context.memory = memory as WebAssembly.Memory;

if (start instanceof Function) {
  start();
} else if (initialize instanceof Function) {
  initialize();
} else {
  throw new Error(
    "No '_start' or '_initialize' entry point found in WebAssembly module, make sure to compile with wasm32-wasi as the target.",
  );
}

Testing

The test suite for this module spawns rustc processes to compile various example Rust programs. You must have wasm targets enabled:

rustup target add wasm32-wasi
rustup target add wasm32-unknown-unknown