Storing a doubly linked list index for a file

I have an index for a datafile that consists of a doubly linked list of doubly linked lists. I need to write this index to file when the program is shut down so it can be restored when the program is reopened (as is normally done with any program). What I am attempting to do is write a variable length buffer class. Is there a better/easier way to do this?? Any help would be appreciated.

Thanks,

Joe