fclose <stdin>: Bad file descriptor

[vyskocilm]

Describe the bug
I experiment with userland unix in Go and your project looks like a perfect match allowing me to run a unix utilities. After I build a few of them and tested them, I have noticed the fclose <stdin>: Bad file descriptor appeared. It happens for os.Stdin, bytes.Buffer or the *io.PipeReader. The io.NopCloser has no effect there. So I believe this is nothing to do with Go, but with the wasi integration of fclose.

To Reproduce
A small C reproducer

#include <stdlib.h>
#include <stdio.h>

int main() {
    int ret = fclose(stdin);
    if (ret != 0) {
        perror("fclose <stdin>");
    }
    exit(ret);
}

To wasm - zig cc --target=wasm32-wasi fclose.c -o fclose.wasm

Run it via this program

//go:embed testdata/fclose.wasm
var fcloseWasm []byte

func main() {
	ctx := context.Background()
	if err := run(ctx); err != nil {
		log.Fatal(err)
	}
}

func run(ctx context.Context) error {
	r := wazero.NewRuntime(ctx)
	defer r.Close(ctx)

	config := wazero.NewModuleConfig().
		WithStdin(io.NopCloser(os.Stdin)).
		WithStdout(os.Stdout).
		WithStderr(os.Stderr)
	wasi_snapshot_preview1.MustInstantiate(ctx, r)

	code, err := r.CompileModule(ctx, fcloseWasm)
	if err != nil {
		return err
	}

	if _, err = r.InstantiateModule(ctx, code, config.WithArgs("wasi")); err != nil {
		if exitErr, ok := err.(*sys.ExitError); ok && exitErr.ExitCode() != 0 {
			fmt.Fprintf(os.Stderr, "exit_code: %d\n", exitErr.ExitCode())
			return err
		} else if !ok {
			return err
		}
	}
	return nil
}

go run main.go 
fclose <stdin>: Bad file descriptor
exit_code: 4294967295
2022/12/21 09:13:07 module "" closed with exit_code(4294967295)
exit status 1

Expected behavior
The stdin is closed, no error message appear and exit code is 0.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the relevant information):

• Go version: go1.19.1 linux/amd64
• wazero Version: github.com/tetratelabs/wazero v1.0.0-pre.5
• Host architecture: amd64
• Runtime mode: compiler

[codefromthecrypt]

ack this is a bug as we special case stdio in ways we shouldn't. e.g. they are pre-opened but not (yet) closable. Thanks for the report!