How to processing files in user cmodules?

[Walkline80]

I want to open, read, seek and tell existed files which in user's file system, by searching the whole repo I found something like this:

• fopen()
• mp_builtin_open()
• mp_vfs_open()
• mp_stream_seek()
• ......

fopen() is not safe in my testing code, mp_builtin_open() and mp_vfs_open() are related to mp_stream_*() methods, and stream seems like related to socket operations in my mind, I can't tell...

Now I'm confused that which ONE set/group methods is the right way to do my job?