dynamic memory allocation c programming

how can i solve this function void make_persistent(struct tm **time); using fork() ?

The function gmtime () transforms a date and time value (epoch seconds) to a struc- ture in which that value is broken down into year, month, day, hours, etc. by re- turning a pointer to a global tm structure, which contains the converted value. Subsequent calls to gmtime () return the same pointer and only update the global structure. a. Write a function that creates a persistent copy of the supplied tm structure on the heap and updates the caller's pointer to point to the copy. void make_persistent (struct tm **time)