dst = append(dst, pre) // Only add non-empty fragments
		}
		pre.Offset = cur.endOffset()
	}
	pre.Length = size - pre.Offset // Possibly the only empty fragment
	return append(dst, pre)
}

// fileState tracks the number of logical (includes sparse holes) and physical
// (actual in tar archive) bytes remaining for the current file.
//
// Invariant: logicalRemaining >= physicalRemaining
type fileState interface {

	if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
		return nil, ErrHeader
	}

	// Parse for all member entries.
	// numEntries is trusted after this since a potential attacker must have
	// committed resources proportional to what this library used.
	if err := feedTokens(2 * numEntries); err != nil {
		return nil, err
	}
	spd := make(sparseDatas, 0, numEntries)