Fix the config option name in the unsupported-capability panic

[v0ropaev]

Description

getConfigOption in cmd/nvidia-container-runtime-hook/hook_config.go reads the toml tag off a struct field so the panic message can name the config option:

func (c *hookConfig) getConfigOption(fieldName string) string {
	t := reflect.TypeFor[**hookConfig]()
	f, ok := t.FieldByName(fieldName)
	...

reflect.Type.FieldByName panics on anything that is not a struct kind, and **hookConfig is a pointer, so the call panics before it can return anything:

reflect: FieldByName of non-struct type **main.hookConfig

Its one caller is the invalid-capability branch in getHookConfig (hook_config.go:61-64), so starting a container with an unsupported supported-driver-capabilities reports that reflection error instead of

Invalid value for config option 'supported-driver-capabilities'; compute,utility,not-compute (supported: ...)

The existing TestGetHookConfig case for that input asserts only require.Panics, so it passes either way and the wrong message went unnoticed.

This is not from the modernize pass, though that pass touched the line. The original was reflect.TypeOf(&c) with c already a *hookConfig, so it was **hookConfig too.

Reflecting over hookConfig fixes it. FieldByName walks the embedded *Config, so the tag comes back as supported-driver-capabilities.

Checklist

• No secrets, sensitive information, or unrelated changes
• Unit tests passing (make test)
• Lint checks passing (make lint) — golangci-lint is not installed here; gofmt -s -l and go vet on the package are clean
• Test cases are added for new code paths
• Commits are signed-off — DCO yes, not GPG signed

Testing

Reduced the two versions to a standalone program with the same struct shape (sync.Mutex, embedded *Config with the toml tag, embedded containerConfig):

current  -> "PANIC reflect: FieldByName of non-struct type **main.hookConfig"
proposed -> "supported-driver-capabilities"

TestGetConfigOption is the regression test, two cases: a field with a tag, and a field that does not exist (which must fall back to the field name). It panics on current main and passes with the change.

go test ./cmd/nvidia-container-runtime-hook/...   ok
go build ./...                                     ok

go test ./cmd/... ./internal/... has two pre-existing failures, TestGoodInput and TestDuplicateHook in cmd/nvidia-container-runtime. They fail the same way on unmodified main in a worktree here, so they are not from this change. Run on darwin/arm64 with Go 1.27.1, no GPU.

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[v0ropaev]

Signed and force-pushed, the commit shows as verified now. Sign-off is still there, only the signature was added.