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|
package mount
import (
"golang.org/x/sys/unix"
)
const (
// ptypes is the set propagation types.
ptypes = unix.MS_SHARED | unix.MS_PRIVATE | unix.MS_SLAVE | unix.MS_UNBINDABLE
// pflags is the full set valid flags for a change propagation call.
pflags = ptypes | unix.MS_REC | unix.MS_SILENT
// broflags is the combination of bind and read only
broflags = unix.MS_BIND | unix.MS_RDONLY
)
// isremount returns true if either device name or flags identify a remount request, false otherwise.
func isremount(device string, flags uintptr) bool {
switch {
// We treat device "" and "none" as a remount request to provide compatibility with
// requests that don't explicitly set MS_REMOUNT such as those manipulating bind mounts.
case flags&unix.MS_REMOUNT != 0, device == "", device == "none":
return true
default:
return false
}
}
func mount(device, target, mType string, flags uintptr, data string) error {
oflags := flags &^ ptypes
if !isremount(device, flags) || data != "" {
// Initial call applying all non-propagation flags for mount
// or remount with changed data
if err := unix.Mount(device, target, mType, oflags, data); err != nil {
return &mountError{
op: "mount",
source: device,
target: target,
flags: oflags,
data: data,
err: err,
}
}
}
if flags&ptypes != 0 {
// Change the propagation type.
if err := unix.Mount("", target, "", flags&pflags, ""); err != nil {
return &mountError{
op: "remount",
target: target,
flags: flags & pflags,
err: err,
}
}
}
if oflags&broflags == broflags {
// Remount the bind to apply read only.
if err := unix.Mount("", target, "", oflags|unix.MS_REMOUNT, ""); err != nil {
return &mountError{
op: "remount-ro",
target: target,
flags: oflags | unix.MS_REMOUNT,
err: err,
}
}
}
return nil
}
|
