1// Copyright 2021 The go-ethereum Authors 2// This file is part of the go-ethereum library. 3// 4// The go-ethereum library is free software: you can redistribute it and/or modify 5// it under the terms of the GNU Lesser General Public License as published by 6// the Free Software Foundation, either version 3 of the License, or 7// (at your option) any later version. 8// 9// The go-ethereum library is distributed in the hope that it will be useful, 10// but WITHOUT ANY WARRANTY; without even the implied warranty of 11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12// GNU Lesser General Public License for more details. 13// 14// You should have received a copy of the GNU Lesser General Public License 15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17//go:build !linux 18// +build !linux 19 20package ethash 21 22import ( 23 "os" 24) 25 26// ensureSize expands the file to the given size. This is to prevent runtime 27// errors later on, if the underlying file expands beyond the disk capacity, 28// even though it ostensibly is already expanded, but due to being sparse 29// does not actually occupy the full declared size on disk. 30func ensureSize(f *os.File, size int64) error { 31 // On systems which do not support fallocate, we merely truncate it. 32 // More robust alternatives would be to 33 // - Use posix_fallocate, or 34 // - explicitly fill the file with zeroes. 35 return f.Truncate(size) 36} 37