These functions return information about the entire history list or
individual list entries.
Function: HIST_ENTRY**history_list ()
Return a NULL terminated array of HIST_ENTRY which is the
current input history. Element 0 of this list is the beginning of time.
If there is no history, return NULL.
Function: intwhere_history ()
Returns the offset of the current history element.
Function: HIST_ENTRY*current_history ()
Return the history entry at the current position, as determined by
where_history (). If there is no entry there, return a NULL
pointer.
Function: HIST_ENTRY*history_get (int offset)
Return the history entry at position offset, starting from
history_base. If there is no entry there, or if offset
is greater than the history length, return a NULL pointer.
Function: inthistory_total_bytes ()
Return the number of bytes that the primary history entries are using.
This function returns the sum of the lengths of all the lines in the
history.