forked from TrueCloudLab/restic
Merge pull request #3119 from restic/keep-mountpoints
Keep mountpoints as empty directories for --one-file-system
This commit is contained in:
commit
a7b49c4889
3 changed files with 149 additions and 26 deletions
12
changelog/unreleased/issue-909
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12
changelog/unreleased/issue-909
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Enhancement: Keep mountpoints as empty directories
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When the `--one-file-system` option is specified to `restic backup`, it
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ignores all file systems mounted below one of the target directories. This
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means that when a snapshot is restored, users needed to manually recreate the
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mountpoint directories.
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Restic now keeps mountpoints as empty directories and therefore implements
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the same approach as `tar`.
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https://github.com/restic/restic/issues/909
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https://github.com/restic/restic/pull/3119
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@ -199,12 +199,17 @@ func isDirExcludedByFile(dir, tagFilename, header string) bool {
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return true
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}
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// gatherDevices returns the set of unique device ids of the files and/or
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// directory paths listed in "items".
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func gatherDevices(items []string) (deviceMap map[string]uint64, err error) {
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deviceMap = make(map[string]uint64)
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for _, item := range items {
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item, err = filepath.Abs(filepath.Clean(item))
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// DeviceMap is used to track allowed source devices for backup. This is used to
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// check for crossing mount points during backup (for --one-file-system). It
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// maps the name of a source path to its device ID.
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type DeviceMap map[string]uint64
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// NewDeviceMap creates a new device map from the list of source paths.
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func NewDeviceMap(allowedSourcePaths []string) (DeviceMap, error) {
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deviceMap := make(map[string]uint64)
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for _, item := range allowedSourcePaths {
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item, err := filepath.Abs(filepath.Clean(item))
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if err != nil {
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return nil, err
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}
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@ -213,30 +218,63 @@ func gatherDevices(items []string) (deviceMap map[string]uint64, err error) {
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if err != nil {
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return nil, err
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}
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id, err := fs.DeviceID(fi)
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if err != nil {
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return nil, err
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}
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deviceMap[item] = id
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}
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if len(deviceMap) == 0 {
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return nil, errors.New("zero allowed devices")
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}
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return deviceMap, nil
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}
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// IsAllowed returns true if the path is located on an allowed device.
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func (m DeviceMap) IsAllowed(item string, deviceID uint64) (bool, error) {
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for dir := item; ; dir = filepath.Dir(dir) {
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debug.Log("item %v, test dir %v", item, dir)
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// find a parent directory that is on an allowed device (otherwise
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// we would not traverse the directory at all)
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allowedID, ok := m[dir]
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if !ok {
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if dir == filepath.Dir(dir) {
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// arrived at root, no allowed device found. this should not happen.
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break
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}
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continue
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}
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// if the item has a different device ID than the parent directory,
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// we crossed a file system boundary
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if allowedID != deviceID {
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debug.Log("item %v (dir %v) on disallowed device %d", item, dir, deviceID)
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return false, nil
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}
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// item is on allowed device, accept it
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debug.Log("item %v allowed", item)
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return true, nil
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}
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return false, fmt.Errorf("item %v (device ID %v) not found, deviceMap: %v", item, deviceID, m)
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}
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// rejectByDevice returns a RejectFunc that rejects files which are on a
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// different file systems than the files/dirs in samples.
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func rejectByDevice(samples []string) (RejectFunc, error) {
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allowed, err := gatherDevices(samples)
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deviceMap, err := NewDeviceMap(samples)
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if err != nil {
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return nil, err
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}
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debug.Log("allowed devices: %v\n", allowed)
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debug.Log("allowed devices: %v\n", deviceMap)
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return func(item string, fi os.FileInfo) bool {
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item = filepath.Clean(item)
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id, err := fs.DeviceID(fi)
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if err != nil {
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// This should never happen because gatherDevices() would have
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@ -244,26 +282,55 @@ func rejectByDevice(samples []string) (RejectFunc, error) {
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panic(err)
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}
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for dir := item; ; dir = filepath.Dir(dir) {
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debug.Log("item %v, test dir %v", item, dir)
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allowedID, ok := allowed[dir]
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if !ok {
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if dir == filepath.Dir(dir) {
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break
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}
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continue
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}
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if allowedID != id {
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debug.Log("path %q on disallowed device %d", item, id)
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return true
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allowed, err := deviceMap.IsAllowed(filepath.Clean(item), id)
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if err != nil {
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// this should not happen
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panic(fmt.Sprintf("error checking device ID of %v: %v", item, err))
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}
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if allowed {
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// accept item
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return false
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}
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panic(fmt.Sprintf("item %v, device id %v not found, allowedDevs: %v", item, id, allowed))
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// reject everything except directories
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if !fi.IsDir() {
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return true
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}
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// special case: make sure we keep mountpoints (directories which
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// contain a mounted file system). Test this by checking if the parent
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// directory would be included.
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parentDir := filepath.Dir(filepath.Clean(item))
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parentFI, err := fs.Lstat(parentDir)
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if err != nil {
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debug.Log("item %v: error running lstat() on parent directory: %v", item, err)
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// if in doubt, reject
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return true
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}
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parentDeviceID, err := fs.DeviceID(parentFI)
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if err != nil {
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debug.Log("item %v: getting device ID of parent directory: %v", item, err)
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// if in doubt, reject
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return true
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}
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parentAllowed, err := deviceMap.IsAllowed(parentDir, parentDeviceID)
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if err != nil {
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debug.Log("item %v: error checking parent directory: %v", item, err)
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// if in doubt, reject
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return true
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}
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if parentAllowed {
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// we found a mount point, so accept the directory
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return false
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}
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// reject everything else
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return true
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}, nil
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}
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@ -318,3 +318,47 @@ func TestIsExcludedByFileSize(t *testing.T) {
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}
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}
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}
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func TestDeviceMap(t *testing.T) {
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deviceMap := DeviceMap{
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filepath.FromSlash("/"): 1,
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filepath.FromSlash("/usr/local"): 5,
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}
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var tests = []struct {
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item string
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deviceID uint64
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allowed bool
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}{
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{"/root", 1, true},
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{"/usr", 1, true},
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{"/proc", 2, false},
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{"/proc/1234", 2, false},
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{"/usr", 3, false},
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{"/usr/share", 3, false},
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{"/usr/local", 5, true},
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{"/usr/local/foobar", 5, true},
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{"/usr/local/foobar/submount", 23, false},
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{"/usr/local/foobar/submount/file", 23, false},
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{"/usr/local/foobar/outhersubmount", 1, false},
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{"/usr/local/foobar/outhersubmount/otherfile", 1, false},
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}
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for _, test := range tests {
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t.Run("", func(t *testing.T) {
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res, err := deviceMap.IsAllowed(filepath.FromSlash(test.item), test.deviceID)
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if err != nil {
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t.Fatal(err)
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}
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if res != test.allowed {
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t.Fatalf("wrong result returned by IsAllowed(%v): want %v, got %v", test.item, test.allowed, res)
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}
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})
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}
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}
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