package mount // import "github.com/docker/docker/pkg/mount" import ( "sort" "strings" "syscall" "github.com/sirupsen/logrus" ) // 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 { err := unmount(target, mntDetach) if err == syscall.EINVAL { // ignore "not mounted" error err = nil } return err } // 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 the error is EINVAL either this whole package is wrong (invalid flags passed to unmount(2)) or this is // not a mountpoint (which is ok in this case). // Meanwhile calling `Mounted()` is very expensive. // // We've purposefully used `syscall.EINVAL` here instead of `unix.EINVAL` to avoid platform branching // Since `EINVAL` is defined for both Windows and Linux in the `syscall` package (and other platforms), // this is nicer than defining a custom value that we can refer to in each platform file. if err == syscall.EINVAL { continue } if i == len(mounts)-1 { if mounted, e := Mounted(m.Mountpoint); e != nil || mounted { return err } continue } // 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) continue } logrus.Debugf("Unmounted %s", m.Mountpoint) } return nil }