build: wasip1 wasmtime builder is broken

[johanbrandhorst]

This is a tracking issue for problems relating to the wasip1-wasmtime builder. The wasmtime runner fails a number of tests, because of differences in how wasmtime and wazero (the primary wasip1 runner) have implemented the wasi_snapshot_preview1 syscall API.

This issue will track efforts to make the wasip1 port and wasmtime runner pass the standard library tests, or document which tests are impossible to fix because of runtime issues.

List of known failing tests on wasmtime:

Package	Test name	Error	Test log	Fixed
archive/tar	TestFileInfoHeaderSymlink	Symlink permission error	Test log	✔️
archive/zip	TestOpenReaderInsecurePath	Directory open error	Test log	✔️
archive/zip	FuzzReader	Directory open error	Test log	✔️
net/http/pprof	Unknown	Text file busy	Test log	✔️
cmd/internal/testdir	Test/env.go	PATH is empty	Test log	✔️

[ianlancetaylor]

Just checking: is wasmtime supposed to implement wasi preview 1? We already confused ourselves quite a bit before coming up with GOOS=wasip1. I would want a really good reason before we start having to support multiple different versions of wasip1. Thanks.

[johanbrandhorst]

Yes, wasmtime does support preview 1, we did test it extensively during the implementation phase, but ran into some tests that were hard or impossible to satisfy on both runtimes (mostly because the Go tests tend to assume POSIX like behavior from the OS and wasmtime seems to have a slightly different philosophy to implementing certain things). We'll document each of the failings here once we get the runner up and running, so we can discuss how to proceed.

[ianlancetaylor]

Thanks.

[dr2chase]

CC @golang/wasm (I realize this is redundant for the bug submitter).

[mathetake]

@johanbrandhorst would you mind listing the failing tests here (or notable ones)? That would be helpful for both of wazero and wasmtime to recognize the differences.

[gopherbot]

Change https://go.dev/cl/485615 mentions this issue: misc/wasm: support wasmtime in wasip1

[gopherbot]

Change https://go.dev/cl/485556 mentions this issue: dashboard: set RUNTIME in wasmtime builder

[gopherbot]

Change https://go.dev/cl/487015 mentions this issue: os/user: skip tests that invoke Current if it returns an expected error

[johanbrandhorst]

As @bcmills noted in https://go-review.googlesource.com/c/go/+/485615/comments/7b08ced3_cf6d1646, the first real error on wasmtime was due to a symlink permission error. He suggested we add a runtime probe on wasip1 to internal/testenv.hasSymlink to check for this error and skip tests accordingly. I will try this in a follow up CL.

I've also added a table to track test failures to the original topic.