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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2019 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package mount
import (
"math/bits"
"syscall"
)
type flagInfo struct {
mask uint32
name string
}
func knownMask(knownFlags []flagInfo) uint32 {
var mask uint32
for _, fi := range knownFlags {
mask |= fi.mask
}
return mask
}
// UMOUNT_NOFOLLOW is not defined in go's syscall package
const UMOUNT_NOFOLLOW = 8
var mountFlags = []flagInfo{
{name: "MS_REMOUNT", mask: syscall.MS_REMOUNT},
{name: "MS_BIND", mask: syscall.MS_BIND},
{name: "MS_REC", mask: syscall.MS_REC},
{name: "MS_RDONLY", mask: syscall.MS_RDONLY},
{name: "MS_SHARED", mask: syscall.MS_SHARED},
{name: "MS_SLAVE", mask: syscall.MS_SLAVE},
{name: "MS_PRIVATE", mask: syscall.MS_PRIVATE},
{name: "MS_UNBINDABLE", mask: syscall.MS_UNBINDABLE},
}
var mountFlagsMask = knownMask(mountFlags)
var unmountFlags = []flagInfo{
{name: "UMOUNT_NOFOLLOW", mask: UMOUNT_NOFOLLOW},
{name: "MNT_FORCE", mask: syscall.MNT_FORCE},
{name: "MNT_DETACH", mask: syscall.MNT_DETACH},
{name: "MNT_EXPIRE", mask: syscall.MNT_EXPIRE},
}
var unmountFlagsMask = knownMask(unmountFlags)
func flagOptSearch(flags int, knownFlags []flagInfo, knownMask uint32) (opts []string, unknown int) {
var f uint32 = uint32(flags)
for _, fi := range knownFlags {
if f&knownMask == 0 {
break
}
if f&fi.mask != 0 {
if opts == nil {
opts = make([]string, 0, bits.OnesCount32(f))
}
f ^= fi.mask
opts = append(opts, fi.name)
}
}
return opts, int(f)
}
// MountFlagsToOpts returns the symbolic representation of mount flags.
func MountFlagsToOpts(flags int) (opts []string, unknown int) {
return flagOptSearch(flags, mountFlags, mountFlagsMask)
}
// UnmountFlagsToOpts returns the symbolic representation of unmount flags.
func UnmountFlagsToOpts(flags int) (opts []string, unknown int) {
return flagOptSearch(flags, unmountFlags, unmountFlagsMask)
}
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