/* * Map the logical cluster number of a file into a physical disk sector * that is filesystem relative. * * dep - address of denode representing the file of interest * findcn - file relative cluster whose filesystem relative cluster number * and/or block number are/is to be found * bnp - address of where to place the file system relative block number. * If this pointer is null then don't return this quantity. * cnp - address of where to place the file system relative cluster number. * If this pointer is null then don't return this quantity. * * NOTE: Either bnp or cnp must be non-null. * This function has one side effect. If the requested file relative cluster * is beyond the end of file, then the actual number of clusters in the file * is returned in *cnp. This is useful for determining how long a directory is. * If cnp is null, nothing is returned. */