//     Say we are rotating abcdefgh by 5. We start with abcde|fgh. The smaller block is [fgh]:
    //     [abc]de|[fgh] -> [fgh]de|[abc]. Now [fgh] is in the right place, but we need to swap [de]
    //     with [abc]: fgh[de]|a[bc] -> fgh[bc]|a[de]. Now we need to swap [a] with [bc]:
    //     fgh[b]c|[a]de -> fgh[a]c|[b]de. Finally we need to swap [c] with [b]:
    //     fgha[c]|[b]de -> fgha[b]|[c]de. Because these two blocks are the same size, we are done.

//		{Offset: 21, Length: 4},  // Hole fragment for 21..24
//	}
//
// Then the content of the resulting sparse file with a Header.Size of 25 is:
//
//	var sparseFile = "\x00"*2 + "abcde" + "\x00"*11 + "fgh" + "\x00"*4
type (
	sparseDatas []sparseEntry
	sparseHoles []sparseEntry
)

// validateSparseEntries reports whether sp is a valid sparse map.