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package mount // import "github.com/docker/docker/pkg/mount"
import (
"sort"
"strconv"
"strings"
"github.com/sirupsen/logrus"
)
// mountError records an error from mount or unmount operation
type mountError struct {
op string
source, target string
flags uintptr
data string
err error
}
func (e *mountError) Error() string {
out := e.op + " "
if e.source != "" {
out += e.source + ":" + e.target
} else {
out += e.target
}
if e.flags != uintptr(0) {
out += ", flags: 0x" + strconv.FormatUint(uint64(e.flags), 16)
}
if e.data != "" {
out += ", data: " + e.data
}
out += ": " + e.err.Error()
return out
}
// Cause returns the underlying cause of the error
func (e *mountError) Cause() error {
return e.err
}
// FilterFunc is a type defining a callback function
// to filter out unwanted entries. It takes a pointer
// to an Info struct (not fully populated, currently
// only Mountpoint is filled in), and returns two booleans:
// - skip: true if the entry should be skipped
// - stop: true if parsing should be stopped after the entry
type FilterFunc func(*Info) (skip, stop bool)
// PrefixFilter discards all entries whose mount points
// do not start with a prefix specified
func PrefixFilter(prefix string) FilterFunc {
return func(m *Info) (bool, bool) {
skip := !strings.HasPrefix(m.Mountpoint, prefix)
return skip, false
}
}
// SingleEntryFilter looks for a specific entry
func SingleEntryFilter(mp string) FilterFunc {
return func(m *Info) (bool, bool) {
if m.Mountpoint == mp {
return false, true // don't skip, stop now
}
return true, false // skip, keep going
}
}
// ParentsFilter returns all entries whose mount points
// can be parents of a path specified, discarding others.
// For example, given `/var/lib/docker/something`, entries
// like `/var/lib/docker`, `/var` and `/` are returned.
func ParentsFilter(path string) FilterFunc {
return func(m *Info) (bool, bool) {
skip := !strings.HasPrefix(path, m.Mountpoint)
return skip, false
}
}
// GetMounts retrieves a list of mounts for the current running process,
// with an optional filter applied (use nil for no filter).
func GetMounts(f FilterFunc) ([]*Info, error) {
return parseMountTable(f)
}
// Mounted determines if a specified mountpoint has been mounted.
// On Linux it looks at /proc/self/mountinfo.
func Mounted(mountpoint string) (bool, error) {
entries, err := GetMounts(SingleEntryFilter(mountpoint))
if err != nil {
return false, err
}
return len(entries) > 0, nil
}
// Mount will mount filesystem according to the specified configuration, on the
// condition that the target path is *not* already mounted. Options must be
// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
// flags.go for supported option flags.
func Mount(device, target, mType, options string) error {
flag, _ := parseOptions(options)
if flag&REMOUNT != REMOUNT {
if mounted, err := Mounted(target); err != nil || mounted {
return err
}
}
return ForceMount(device, target, mType, options)
}
// ForceMount will mount a filesystem according to the specified configuration,
// *regardless* if the target path is not already mounted. Options must be
// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
// flags.go for supported option flags.
func ForceMount(device, target, mType, options string) error {
flag, data := parseOptions(options)
return mount(device, target, mType, uintptr(flag), data)
}
// Unmount lazily unmounts a filesystem on supported platforms, otherwise
// does a normal unmount.
func Unmount(target string) error {
return unmount(target, mntDetach)
}
// RecursiveUnmount unmounts the target and all mounts underneath, starting with
// the deepsest mount first.
func RecursiveUnmount(target string) error {
mounts, err := parseMountTable(PrefixFilter(target))
if err != nil {
return err
}
// Make the deepest mount be first
sort.Slice(mounts, func(i, j int) bool {
return len(mounts[i].Mountpoint) > len(mounts[j].Mountpoint)
})
for i, m := range mounts {
logrus.Debugf("Trying to unmount %s", m.Mountpoint)
err = unmount(m.Mountpoint, mntDetach)
if err != nil {
if i == len(mounts)-1 { // last mount
if mounted, e := Mounted(m.Mountpoint); e != nil || mounted {
return err
}
} else {
// This is some submount, we can ignore this error for now, the final unmount will fail if this is a real problem
logrus.WithError(err).Warnf("Failed to unmount submount %s", m.Mountpoint)
}
}
logrus.Debugf("Unmounted %s", m.Mountpoint)
}
return nil
}