Opening a File from a FileInfo

No, a file cannot be opened with just the FileInfo. os.Open only takes a string. You should always have the path or the parent path because that is the only way to get a FileInfo.

As additional info, this is how to constructor the filename string including path:

filename := filepath.Join(path, info.Name())

No. The FileInfo interface simply does not expose the path and all provided methods in the os and ioutil packages accept the pathname as a string.