copy an array in c

I have a function, it accepts a char**, what is the quickest and most efficient way of making a local copy of the array in the function scope?

That is, i have , for example:

void funk(char **x){

char **b;

/*How do i make a separate copy of x to b?*/
}

Take pity on me internets, I'm a noob :) Thanks.

>>4
what if you don't know y?