readDir not guardable (can fail even when fileExists succeeds)

[cmahnke]

What version of Hugo are you using (hugo version)?

hugo v0.121.2-6d5b44305eaa9d0a157946492a6f319da38de154+extended darwin/arm64 BuildDate=2024-01-05T12:21:15Z VendorInfo=brew

Does this issue reproduce with the latest release?

Yes

Description

fileExists and os.Stat report a file as existing but readDir fails, maybe the virtual filesystem doesn't apply to readDir?

I haven't test with mounts, but my expectation that either none should work or all.

See https://github.com/cmahnke/hugo-test
The template is in layouts/partials/dir-check.html

[cmahnke]

Trying to use this in https://github.com/cmahnke/hugo-test/blob/main/layouts/partials/dir-check.html#L5

{{- with $codes := readDir $siteDir -}}
  {{- $siteShortcodes = $codes -}}
{{- end -}}

Doesn't help either.

[cmahnke]

The problem seems to be introduced in tpl/os/os.go

The are two variables with filesystem references readFileFs and workFs. readDir operates on workFs while os.Stat and fileExists operate on readFileFs. The later seems to be the union file system composed of the current directory, the theme directory and certainly configured mounts.

Since not even readFile operates on workFs I strongly assume that this is not intentional.