package main

import (
    "archive/zip"
    "bytes"
    "golang.org/x/tools/godoc/vfs/zipfs"
    "io"
    "log"
)

func main() {

    // example files to use
    files := map[string]string{"foo": "foo", "bar/baz": "baz"}

    // create test zip file from above files
    b := new(bytes.Buffer)
    zw := zip.NewWriter(b)
    for file, contents := range files {
        w, err := zw.Create(file)
        if err != nil {
            log.Fatal(err)
        }
        _, err = io.WriteString(w, contents)
        if err != nil {
            log.Fatal(err)
        }
    }
    zw.Close()

    // create zipfs from zip file
    zr, err := zip.NewReader(bytes.NewReader(b.Bytes()), int64(b.Len()))
    if err != nil {
        log.Fatal(err)
    }
    rc := &zip.ReadCloser{
        Reader: *zr,
    }
    fs := zipfs.New(rc, "foo")

    // try to list contents of root directory
    // FAILS HERE!
    infos, err := fs.ReadDir("/")
    if err != nil {
        log.Fatal(err)
    }
    for _, info := range infos {
        log.Printf("Found: %v\n", info.Name())
    }
}