WASI support for Webassembly

[dnsco]

I'd love to be able to use Deno as the glue for a bunch of backend wasm modules. The wasi interfaces is a systems interface for webassembly in non-web uses.

https://github.com/CraneStation/wasmtime is a wasi-implementing wasm runtime in rust, though It has a different sandboxing model than v8's.

I've seen WASI support mentioned in a few other issues, so I wanted to centralize that part of the discussion.

related: #2552 #672 #1325

[kitsonk]

Yes, agreed, though WASI is still real early in its development. I think we would want to keep it quite experimental in Deno, even Deno being experimental, as I suspect there will be a lot of churn. We might also want to consider getting involved in the working group as well.

[syrusakbary]

We will release soon a TypeScript package to run WASI modules very easily both in server-side and client-side. Perhaps Deno can be a great use case for integrating it!

Apart from this, the Wasmer runtime can also embedded easily in Rust. However it might make more sense to use v8 with a wrapper on top to be able to run WASI.

Either way, I'd love to help in any way!

[syrusakbary]

And here we go!

Here's the @wasmer/wasi package: https://github.com/wasmerio/wasmer-js/tree/master/packages/wasi (npm package)

The announcement is here: https://medium.com/wasmer/wasmer-js-9a53e837b80

Hope you can find it useful!!

[rsp]

Node already has an experimental WASI support in v13:

• https://nodejs.org/api/wasi.html

It may be useful to see how it is implemented and used. Example:

const wasi = new WASI({
  args: process.argv,
  env: process.env,
  preopens: {
    '/sandbox': '/some/real/path/that/wasm/can/access'
  }
});

[caspervonb]

Published https://deno.land/x/wasi yesterday, it is still a work in progress as not every syscall can be mapped efficiently at the moment, for example:

• Deno.read needs to be able to take an optional offset for a reasonable fd_pread implementation (want: add file.readAt() and file.writeAt() #3508).
• Deno.write needs to be able to take an optional offset for a reasonable fd_pwrite implementation (want: add file.readAt() and file.writeAt() #3508).

But everything should be implementable as plain modules as Deno matures to have a set of sound syscalls.

[caspervonb]

A little while later (exactly one month of work to be precise); the current implementation status of snapshot_preview1 looks something like this

Name	Status	Notes
args_get	✓
args_sizes_get	✓
environ_get	✓
environ_sizes_get	✓
clock_res_get	✓
clock_time_get	✓
fd_advise		This has no obvious path to implementation at this time.
fd_allocate		This has no obvious path to implementation at this time.
fd_close	✓
fd_datasync		This is blocking on getting fdatasync(2) implemented upstream in Deno.
fd_fdstat_get	✓	This currently does not write flags and rights as we do not track those at the moment.
fd_fdstat_set_flags		This has no obvious path to implementation at this time.
fd_fdstat_set_rights
fd_filestat_get		This is blocking on getting fstat implemented upstream in Deno.
fd_filestat_set_size		This is blocking on getting ftruncate implemented upstream in Deno.
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	✓	This is blocking on getting fsync(2) implemented upstream in Deno.
fd_tell	✓
fd_write	✓
path_create_directory	✓
path_filestat_get	✓
path_filestat_set_times	✓
path_link	✓
path_open	✓	Opening directories is not portable
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

Most of these blockers are in master already so will be working moving this into std soon.

[banocean]

A little while later (exactly one month of work to be precise); the current implementation status of snapshot_preview1 looks something like this
Name Status Notes
args_get ✓
args_sizes_get ✓
environ_get ✓
environ_sizes_get ✓
clock_res_get ✓
clock_time_get ✓
fd_advise This has no obvious path to implementation at this time.
fd_allocate This has no obvious path to implementation at this time.
fd_close ✓
fd_datasync This is blocking on getting fdatasync(2) implemented upstream in Deno.
fd_fdstat_get ✓ This currently does not write flags and rights as we do not track those at the moment.
fd_fdstat_set_flags This has no obvious path to implementation at this time.
fd_fdstat_set_rights
fd_filestat_get This is blocking on getting fstat implemented upstream in Deno.
fd_filestat_set_size This is blocking on getting ftruncate implemented upstream in Deno.
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 ✓ This is blocking on getting fsync(2) implemented upstream in Deno.
fd_tell ✓
fd_write ✓
path_create_directory ✓
path_filestat_get ✓
path_filestat_set_times ✓
path_link ✓
path_open ✓ Opening directories is not portable
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

Most of these blockers are in master already so will be working moving this into std soon.

There us wasi preview 2 rn and it covers a more of apis