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Rename IsMountPoint to IsLikelyNotMountPoint

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IsLikelyNotMountPoint determines if a directory is not a mountpoint.
It is fast but not necessarily ALWAYS correct. If the path is in fact
a bind mount from one part of a mount to another it will not be detected.
mkdir /tmp/a /tmp/b; mount --bin /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
will return true. When in fact /tmp/b is a mount point. So this patch
renames the function and switches it from a positive to a negative (I
could think of a good positive name). This should make future users of
this function aware that it isn't quite perfect, but probably good
enough.
This commit is contained in:
Eric Paris
2015-04-16 19:49:53 -04:00
parent eed655a6e6
commit f125ad88ce
19 changed files with 116 additions and 109 deletions
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6
pkg/util/mount/fake.go
View File

@@ -62,11 +62,11 @@ func (f *FakeMounter) List() ([]MountPoint, error) {
return f.MountPoints, nil
}
func (f *FakeMounter) IsMountPoint(file string) (bool, error) {
func (f *FakeMounter) IsLikelyNotMountPoint(file string) (bool, error) {
for _, mp := range f.MountPoints {
if mp.Path == file {
return true, nil
return false, nil
}
}
return false, nil
return true, nil
}

4
pkg/util/mount/mount.go
View File

@@ -30,8 +30,8 @@ type Interface interface {
// it could change between chunked reads). This is guaranteed to be
// consistent.
List() ([]MountPoint, error)
// IsMountPoint determines if a directory is a mountpoint.
IsMountPoint(file string) (bool, error)
// IsLikelyNotMountPoint determines if a directory is a mountpoint.
IsLikelyNotMountPoint(file string) (bool, error)
}
// This represents a single line in /proc/mounts or /etc/fstab.

23
pkg/util/mount/mount_linux.go
View File

@@ -141,20 +141,27 @@ func (*Mounter) List() ([]MountPoint, error) {
return listProcMounts(procMountsPath)
}
// IsMountPoint determines if a directory is a mountpoint, by comparing the device for the
// directory with the device for it's parent. If they are the same, it's not a mountpoint,
// if they're different, it is.
func (mounter *Mounter) IsMountPoint(file string) (bool, error) {
// IsLikelyNotMountPoint determines if a directory is not a mountpoint.
// It is fast but not necessarily ALWAYS correct. If the path is in fact
// a bind mount from one part of a mount to another it will not be detected.
// mkdir /tmp/a /tmp/b; mount --bin /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
// will return true. When in fact /tmp/b is a mount point. If this situation
// if of interest to you, don't use this function...
func (mounter *Mounter) IsLikelyNotMountPoint(file string) (bool, error) {
stat, err := os.Stat(file)
if err != nil {
return false, err
return true, err
}
rootStat, err := os.Lstat(file + "/..")
if err != nil {
return false, err
return true, err
}
// If the directory has the same device as parent, then it's not a mountpoint.
return stat.Sys().(*syscall.Stat_t).Dev != rootStat.Sys().(*syscall.Stat_t).Dev, nil
// If the directory has a different device as parent, then it is a mountpoint.
if stat.Sys().(*syscall.Stat_t).Dev != rootStat.Sys().(*syscall.Stat_t).Dev {
return false, nil
}
return true, nil
}
func listProcMounts(mountFilePath string) ([]MountPoint, error) {

4
pkg/util/mount/mount_unsupported.go
View File

@@ -32,6 +32,6 @@ func (mounter *Mounter) List() ([]MountPoint, error) {
return []MountPoint{}, nil
}
func (mounter *Mounter) IsMountPoint(file string) (bool, error) {
return false, nil
func (mounter *Mounter) IsLikelyNotMountPoint(file string) (bool, error) {
return true, nil
}

14
pkg/util/mount/nsenter_mount.go
View File

@@ -162,12 +162,12 @@ func (*NsenterMounter) List() ([]MountPoint, error) {
return listProcMounts(hostProcMountsPath)
}
// IsMountPoint determines whether a path is a mountpoint by calling findmnt
// IsLikelyNotMountPoint determines whether a path is a mountpoint by calling findmnt
// in the host's root mount namespace.
func (n *NsenterMounter) IsMountPoint(file string) (bool, error) {
func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
file, err := filepath.Abs(file)
if err != nil {
return false, err
return true, err
}
args := []string{"--mount=/rootfs/proc/1/ns/mnt", "--", n.absHostPath("findmnt"), "-o", "target", "--noheadings", "--target", file}
@@ -177,16 +177,16 @@ func (n *NsenterMounter) IsMountPoint(file string) (bool, error) {
out, err := exec.Command(nsenterPath, args...).CombinedOutput()
if err != nil {
// If findmnt didn't run, just claim it's not a mount point.
return false, nil
return true, nil
}
strOut := strings.TrimSuffix(string(out), "\n")
glog.V(5).Infof("IsMountPoint findmnt output: %v", strOut)
glog.V(5).Infof("IsLikelyNotMountPoint findmnt output: %v", strOut)
if strOut == file {
return true, nil
return false, nil
}
return false, nil
return true, nil
}
func (n *NsenterMounter) absHostPath(command string) string {

4
pkg/util/mount/nsenter_mount_unsupported.go
View File

@@ -38,6 +38,6 @@ func (*NsenterMounter) List() ([]MountPoint, error) {
return []MountPoint{}, nil
}
func (*NsenterMounter) IsMountPoint(file string) (bool, error) {
return false, nil
func (*NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
return true, nil
}