Stream: wasi

Topic: How to handle poll.poll empty poll list

view this post on Zulip appcypher (Apr 24 2024 at 09:02):

wasi:io/poll.poll wit definition contains this part:

This function does not return a result; polling in itself does not
do any I/O so it doesn't fail.

but there is at least one invariant:

The result list<u32> contains one or more indices of handles in the
argument list that is ready for I/O.

How should we handle the case where the pollable list argument is empty?
wasmtime_wasi returns an error.

wasmtime/crates/wasi/src/poll.rs at b5089d1d893cc1e838b0c5d76f4cc2c6c543f12c · bytecodealliance/wasmtime
A fast and secure runtime for WebAssembly. Contribute to bytecodealliance/wasmtime development by creating an account on GitHub.

view this post on Zulip Dave Bakker (badeend) (Apr 24 2024 at 09:09):

Wasmtime traps. There is a open PR to codify this in the spec:
https://github.com/WebAssembly/wasi-io/pull/69

poll: Require there to be at least one item. by badeend · Pull Request #69 · WebAssembly/wasi-io
Fixes #67

view this post on Zulip appcypher (Apr 24 2024 at 09:57):

Dave Bakker (badeend) said:

Wasmtime traps. There is a open PR to codify this in the spec:
https://github.com/WebAssembly/wasi-io/pull/69

Thanks. I will also go with trapping for now.

Last updated: Dec 06 2025 at 06:05 UTC