github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/cmd/snap/fallocate_linux.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2018 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package main
    21  
    22  import (
    23  	"os"
    24  	"syscall"
    25  )
    26  
    27  func maybeReserveDiskSpace(f *os.File, size int64) error {
    28  	const fallocKeepSize = 1 // This is FALLOC_FL_KEEP_SIZE
    29  	if err := syscall.Fallocate(int(f.Fd()), fallocKeepSize, 0, size); err != nil {
    30  		if err != syscall.EOPNOTSUPP && err != syscall.ENOSYS {
    31  			return err
    32  		}
    33  	}
    34  	return nil
    35  }