mirror of https://github.com/denoland/deno.git synced 2024-11-23 15:16:54 -05:00

docs(std/wasi): fix usage example (#7808 )

The usage example is a bit out of date and not compatible with the
stricter definition of the WebAssembly namespace.

This fixes that and makes it a bit cleaner.

2020-10-03 15:52:34 +02:00

2 KiB

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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

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