Using WASI from wasmer cli

[ljulliar]

Hi all,

I'm generating WASM module from a compiler of my own. In one of the module I wrote I'd like to use the WASI interface. I am therefore importing the various WASI functions from the module wasi_unstable but when I try to execute this model with the wasmer runtime through the command line I get the following error:

error: failed to run `../rlang_apps/base64_benchmark/rlang_base64_benchmark.wasm`
╰─▶ 1: Error while importing "wasi_unstable"."args_sizes_get": unknown import. Expected Function(FunctionType { params: [I32, I32], results: [I32] })

Is it that I am importing the wrong module name ? Or is there an option on the wasmer CLI to "activate" the WASI module at execution time ?

Thanks for your help.

[jcaesar]

In general, this should work, WASI is active by default. One suspicion though: You're not by any chance using wasmer run --invoke _foobar? Because using --invoke deactivates WASI.

For reference: You can save this file as test.wat and execute it with wasmer run test.wat just fine (not that it does anything):

(module
  (import "wasi_unstable" "args_sizes_get"
    (func $__wasi_args_sizes_get (param i32 i32) (result i32)))
  (func $_start)
  (memory 1)
  (export "memory" (memory 0))
  (export "_start" (func $_start))
)

(If --invoke was the problem: I think this is the second issue I've seen along these lines. Might as well leave it open and make a PR that enables WASI even with invoke.)

[ljulliar]

Ah, Ah... Nice catch. yes I'm using the --invoke. Let me try without that.

…

On Wed, Jun 29, 2022 at 8:58 AM jcaesar ***@***.***> wrote: In general, this should work, WASI is active by default. One suspicion though: You're not by any chance using wasmer run --invoke _foobar? Because using --invoke deactivates WASI. For reference: You can save this file as test.wat and execute it with wasmer run test.wat just fine (not that it does anything): (module (import "wasi_unstable" "args_sizes_get" (func $__wasi_args_sizes_get (param i32 i32) (result i32))) (func $_start) (memory 1) (export "memory" (memory 0)) (export "_start" (func $_start)) ) — Reply to this email directly, view it on GitHub <#2978 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAED4KYFJ257PKUUUPFY43VRPXZ7ANCNFSM5Z6PG22Q> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[jcaesar]

Possibly related to #1716.

[jcaesar]

@fschutt Thank you for fixing this. For reference, an easy way to reproduce this problem from a rust-compiled binary is

#[no_mangle]
pub extern "system" fn invokeme() {
    println!("Hello, world!");
}

You'll have to compile that as a [lib] with crate-type = ["cdylib"].

[syrusakbary]

Thanks for opening the issue @ljulliar. It seems this may be fixed by #2997.
If not, it might be caused by not attaching the WASI imports when instantiating the instance.

If you have code we can look at that will help on debugging the issue!

[fschutt]

@syrusakbary it is fixed by #2997. See my unit test: https://github.com/wasmerio/wasmer/pull/2997/files#diff-656fd19689c83035f9a1f76eb557544908fcd6399a3784cd924c4e69e3d244afR68