// doNsenterMount nsenters the host's mount namespace and performs the
// requested mount.
func (n *NsenterMounter) doNsenterMount(source, target, fstype string, options []string) error {
glog.V(5).Infof("nsenter Mounting %s %s %s %v", source, target, fstype, options)
args := n.makeNsenterArgs(source, target, fstype, options)
glog.V(5).Infof("Mount command: %v %v", nsenterPath, args)
exec := exec.New()
outputBytes, err := exec.Command(nsenterPath, args...).CombinedOutput()
if len(outputBytes) != 0 {
glog.V(5).Infof("Output of mounting %s to %s: %v", source, target, string(outputBytes))
}
return err
}
// Unmount runs umount(8) in the host's mount namespace.
func (n *NsenterMounter) Unmount(target string) error {
args := []string{
"--mount=/rootfs/proc/1/ns/mnt",
"--",
n.absHostPath("umount"),
target,
}
glog.V(5).Infof("Unmount command: %v %v", nsenterPath, args)
exec := exec.New()
outputBytes, err := exec.Command(nsenterPath, args...).CombinedOutput()
if len(outputBytes) != 0 {
glog.V(5).Infof("Output of unmounting %s: %v", target, string(outputBytes))
}
return err
}
// IsLikelyNotMountPoint determines whether a path is a mountpoint by calling findmnt
// in the host's root mount namespace.
func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
file, err := filepath.Abs(file)
if err != nil {
return true, err
}
// Check the directory exists
if _, err = os.Stat(file); os.IsNotExist(err) {
glog.V(5).Infof("findmnt: directory %s does not exist", file)
return true, err
}
// Add --first-only option: since we are testing for the absense of a mountpoint, it is sufficient to get only
// the first of multiple possible mountpoints using --first-only.
// Also add fstype output to make sure that the output of target file will give the full path
// TODO: Need more refactoring for this function. Track the solution with issue #26996
args := []string{"--mount=/rootfs/proc/1/ns/mnt", "--", n.absHostPath("findmnt"), "-o", "target,fstype", "--noheadings", "--first-only", "--target", file}
glog.V(5).Infof("findmnt command: %v %v", nsenterPath, args)
exec := exec.New()
out, err := exec.Command(nsenterPath, args...).CombinedOutput()
if err != nil {
glog.V(2).Infof("Failed findmnt command for path %s: %v", file, err)
// Different operating systems behave differently for paths which are not mount points.
// On older versions (e.g. 2.20.1) we'd get error, on newer ones (e.g. 2.26.2) we'd get "/".
// It's safer to assume that it's not a mount point.
return true, nil
}
mountTarget := strings.Split(string(out), " ")[0]
mountTarget = strings.TrimSuffix(mountTarget, "\n")
glog.V(5).Infof("IsLikelyNotMountPoint findmnt output for path %s: %v:", file, mountTarget)
if mountTarget == file {
glog.V(5).Infof("IsLikelyNotMountPoint: %s is a mount point", file)
return false, nil
}
glog.V(5).Infof("IsLikelyNotMountPoint: %s is not a mount point", file)
return true, nil
}