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142 lines
4.6 KiB
Go
142 lines
4.6 KiB
Go
package mount // import "github.com/docker/docker/pkg/mount"
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import (
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"sort"
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"strings"
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"syscall"
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"github.com/sirupsen/logrus"
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)
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// FilterFunc is a type defining a callback function
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// to filter out unwanted entries. It takes a pointer
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// to an Info struct (not fully populated, currently
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// only Mountpoint is filled in), and returns two booleans:
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// - skip: true if the entry should be skipped
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// - stop: true if parsing should be stopped after the entry
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type FilterFunc func(*Info) (skip, stop bool)
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// PrefixFilter discards all entries whose mount points
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// do not start with a prefix specified
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func PrefixFilter(prefix string) FilterFunc {
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return func(m *Info) (bool, bool) {
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skip := !strings.HasPrefix(m.Mountpoint, prefix)
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return skip, false
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}
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}
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// SingleEntryFilter looks for a specific entry
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func SingleEntryFilter(mp string) FilterFunc {
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return func(m *Info) (bool, bool) {
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if m.Mountpoint == mp {
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return false, true // don't skip, stop now
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}
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return true, false // skip, keep going
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}
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}
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// ParentsFilter returns all entries whose mount points
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// can be parents of a path specified, discarding others.
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// For example, given `/var/lib/docker/something`, entries
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// like `/var/lib/docker`, `/var` and `/` are returned.
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func ParentsFilter(path string) FilterFunc {
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return func(m *Info) (bool, bool) {
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skip := !strings.HasPrefix(path, m.Mountpoint)
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return skip, false
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}
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}
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// GetMounts retrieves a list of mounts for the current running process,
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// with an optional filter applied (use nil for no filter).
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func GetMounts(f FilterFunc) ([]*Info, error) {
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return parseMountTable(f)
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}
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// Mounted determines if a specified mountpoint has been mounted.
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// On Linux it looks at /proc/self/mountinfo.
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func Mounted(mountpoint string) (bool, error) {
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entries, err := GetMounts(SingleEntryFilter(mountpoint))
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if err != nil {
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return false, err
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}
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return len(entries) > 0, nil
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}
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// Mount will mount filesystem according to the specified configuration, on the
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// condition that the target path is *not* already mounted. Options must be
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// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
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// flags.go for supported option flags.
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func Mount(device, target, mType, options string) error {
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flag, _ := parseOptions(options)
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if flag&REMOUNT != REMOUNT {
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if mounted, err := Mounted(target); err != nil || mounted {
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return err
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}
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}
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return ForceMount(device, target, mType, options)
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}
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// ForceMount will mount a filesystem according to the specified configuration,
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// *regardless* if the target path is not already mounted. Options must be
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// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
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// flags.go for supported option flags.
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func ForceMount(device, target, mType, options string) error {
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flag, data := parseOptions(options)
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return mount(device, target, mType, uintptr(flag), data)
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}
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// Unmount lazily unmounts a filesystem on supported platforms, otherwise
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// does a normal unmount.
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func Unmount(target string) error {
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err := unmount(target, mntDetach)
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if err == syscall.EINVAL {
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// ignore "not mounted" error
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err = nil
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}
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return err
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}
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// RecursiveUnmount unmounts the target and all mounts underneath, starting with
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// the deepsest mount first.
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func RecursiveUnmount(target string) error {
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mounts, err := parseMountTable(PrefixFilter(target))
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if err != nil {
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return err
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}
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// Make the deepest mount be first
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sort.Slice(mounts, func(i, j int) bool {
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return len(mounts[i].Mountpoint) > len(mounts[j].Mountpoint)
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})
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for i, m := range mounts {
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logrus.Debugf("Trying to unmount %s", m.Mountpoint)
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err = unmount(m.Mountpoint, mntDetach)
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if err != nil {
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// If the error is EINVAL either this whole package is wrong (invalid flags passed to unmount(2)) or this is
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// not a mountpoint (which is ok in this case).
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// Meanwhile calling `Mounted()` is very expensive.
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//
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// We've purposefully used `syscall.EINVAL` here instead of `unix.EINVAL` to avoid platform branching
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// Since `EINVAL` is defined for both Windows and Linux in the `syscall` package (and other platforms),
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// this is nicer than defining a custom value that we can refer to in each platform file.
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if err == syscall.EINVAL {
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continue
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}
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if i == len(mounts)-1 {
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if mounted, e := Mounted(m.Mountpoint); e != nil || mounted {
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return err
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}
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continue
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}
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// This is some submount, we can ignore this error for now, the final unmount will fail if this is a real problem
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logrus.WithError(err).Warnf("Failed to unmount submount %s", m.Mountpoint)
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continue
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}
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logrus.Debugf("Unmounted %s", m.Mountpoint)
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}
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return nil
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}
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