Merge pull request #1090 from middelink/fix-1081

Update HasTags() and HasPaths() to follow #1081 feature request

CHANGELOG.md

@@ -48,6 +48,11 @@ Small changes
    https://github.com/restic/restic/pull/1080
    https://github.com/restic/restic/pull/1112
 
+ * The semantic for the `--tags` option to `forget` and `snapshots` was
+   clarified:
+   https://github.com/restic/restic/issues/1081
+   https://github.com/restic/restic/pull/1090
+
 Important Changes in 0.7.0
 ==========================
 

doc/manual.rst

@@ -526,18 +526,20 @@ specified with ``--stdin-filename``, e.g. like this:
 
     $ mysqldump [...] | restic -r /tmp/backup backup --stdin --stdin-filename production.sql
 
-Tags
-~~~~
+Tags for backup
+~~~~~~~~~~~~~~~
 
 Snapshots can have one or more tags, short strings which add identifying
-information. Just specify the tags for a snapshot with ``--tag``:
+information. Just specify the tags for a snapshot one by one with ``--tag``:
 
 .. code-block:: console
 
-    $ restic -r /tmp/backup backup --tag projectX ~/shared/work/web
+    $ restic -r /tmp/backup backup --tag projectX -tag foo --tag bar ~/shared/work/web
     [...]
 
-The tags can later be used to keep (or forget) snapshots.
+The tags can later be used to keep (or forget) snapshots with the ``forget``
+command. The command ``tag`` can be used to modify tags on an existing
+snapshot.
 
 List all snapshots
 ------------------
@@ -644,7 +646,7 @@ command does that:
 
 .. code-block:: console
 
-    $ restic -r /tmp/backup tag --set NL,CH 590c8fc8
+    $ restic -r /tmp/backup tag --set NL --set CH 590c8fc8
     Create exclusive lock for repository
     Modified tags on 1 snapshots
 
@@ -872,7 +874,26 @@ The ``forget`` command accepts the following parameters:
 Additionally, you can restrict removing snapshots to those which have a
 particular hostname with the ``--hostname`` parameter, or tags with the
 ``--tag`` option. When multiple tags are specified, only the snapshots
-which have all the tags are considered.
+which have all the tags are considered. For example, the following command
+removes all but the latest snapshot of all snapshots that have the tag ``foo``:
+
+.. code-block:: console
+
+   $ restic forget --tag foo --keep-last 1
+
+This command removes all but the last snapshot of all snapshots that have
+either the ``foo`` or ``bar`` tag set:
+
+.. code-block:: console
+
+   $ restic forget --tag foo --tag bar --keep-last 1
+
+To only keep the last snapshot of all snapshots with both the tag ``foo`` and
+``bar`` set use:
+
+.. code-block:: console
+
+   $ restic forget --tag foo,tag bar --keep-last 1
 
 All the ``--keep-*`` options above only count
 hours/days/weeks/months/years which have a snapshot, so those without a

src/cmds/restic/cmd_backup.go

@@ -68,12 +68,12 @@ func init() {
 	f := cmdBackup.Flags()
 	f.StringVar(&backupOptions.Parent, "parent", "", "use this parent snapshot (default: last snapshot in the repo that has the same target files/directories)")
 	f.BoolVarP(&backupOptions.Force, "force", "f", false, `force re-reading the target files/directories (overrides the "parent" flag)`)
-	f.StringSliceVarP(&backupOptions.Excludes, "exclude", "e", nil, "exclude a `pattern` (can be specified multiple times)")
-	f.StringSliceVar(&backupOptions.ExcludeFiles, "exclude-file", nil, "read exclude patterns from a `file` (can be specified multiple times)")
+	f.StringArrayVarP(&backupOptions.Excludes, "exclude", "e", nil, "exclude a `pattern` (can be specified multiple times)")
+	f.StringArrayVar(&backupOptions.ExcludeFiles, "exclude-file", nil, "read exclude patterns from a `file` (can be specified multiple times)")
 	f.BoolVarP(&backupOptions.ExcludeOtherFS, "one-file-system", "x", false, "exclude other file systems")
 	f.BoolVar(&backupOptions.Stdin, "stdin", false, "read backup from stdin")
 	f.StringVar(&backupOptions.StdinFilename, "stdin-filename", "stdin", "file name to use when reading from stdin")
-	f.StringSliceVar(&backupOptions.Tags, "tag", nil, "add a `tag` for the new snapshot (can be specified multiple times)")
+	f.StringArrayVar(&backupOptions.Tags, "tag", nil, "add a `tag` for the new snapshot (can be specified multiple times)")
 	f.StringVar(&backupOptions.Hostname, "hostname", hostname, "set the `hostname` for the snapshot manually")
 	f.StringVar(&backupOptions.FilesFrom, "files-from", "", "read the files to backup from file (can be combined with file args)")
 }
@@ -392,7 +392,7 @@ func runBackup(opts BackupOptions, gopts GlobalOptions, args []string) error {
 
 	// Find last snapshot to set it as parent, if not already set
 	if !opts.Force && parentSnapshotID == nil {
-		id, err := restic.FindLatestSnapshot(context.TODO(), repo, target, opts.Tags, opts.Hostname)
+		id, err := restic.FindLatestSnapshot(context.TODO(), repo, target, []restic.TagList{opts.Tags}, opts.Hostname)
 		if err == nil {
 			parentSnapshotID = &id
 		} else if err != restic.ErrNoSnapshotFound {

src/cmds/restic/cmd_find.go

@@ -34,7 +34,7 @@ type FindOptions struct {
 	ListLong        bool
 	Host            string
 	Paths           []string
-	Tags            []string
+	Tags            restic.TagLists
 }
 
 var findOptions FindOptions
@@ -45,13 +45,13 @@ func init() {
 	f := cmdFind.Flags()
 	f.StringVarP(&findOptions.Oldest, "oldest", "O", "", "oldest modification date/time")
 	f.StringVarP(&findOptions.Newest, "newest", "N", "", "newest modification date/time")
-	f.StringSliceVarP(&findOptions.Snapshots, "snapshot", "s", nil, "snapshot `id` to search in (can be given multiple times)")
+	f.StringArrayVarP(&findOptions.Snapshots, "snapshot", "s", nil, "snapshot `id` to search in (can be given multiple times)")
 	f.BoolVarP(&findOptions.CaseInsensitive, "ignore-case", "i", false, "ignore case for pattern")
 	f.BoolVarP(&findOptions.ListLong, "long", "l", false, "use a long listing format showing size and mode")
 
 	f.StringVarP(&findOptions.Host, "host", "H", "", "only consider snapshots for this `host`, when no snapshot ID is given")
-	f.StringSliceVar(&findOptions.Tags, "tag", nil, "only consider snapshots which include this `tag`, when no snapshot-ID is given")
-	f.StringSliceVar(&findOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot-ID is given")
+	f.Var(&findOptions.Tags, "tag", "only consider snapshots which include this `taglist`, when no snapshot-ID is given")
+	f.StringArrayVar(&findOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot-ID is given")
 }
 
 type findPattern struct {

src/cmds/restic/cmd_forget.go

@@ -31,10 +31,10 @@ type ForgetOptions struct {
 	Weekly   int
 	Monthly  int
 	Yearly   int
-	KeepTags []string
+	KeepTags restic.TagLists
 
 	Host  string
-	Tags  []string
+	Tags  restic.TagLists
 	Paths []string
 
 	GroupByTags bool
@@ -55,14 +55,14 @@ func init() {
 	f.IntVarP(&forgetOptions.Monthly, "keep-monthly", "m", 0, "keep the last `n` monthly snapshots")
 	f.IntVarP(&forgetOptions.Yearly, "keep-yearly", "y", 0, "keep the last `n` yearly snapshots")
 
-	f.StringSliceVar(&forgetOptions.KeepTags, "keep-tag", []string{}, "keep snapshots with this `tag` (can be specified multiple times)")
+	f.Var(&forgetOptions.KeepTags, "keep-tag", "keep snapshots with this `taglist` (can be specified multiple times)")
 	f.BoolVarP(&forgetOptions.GroupByTags, "group-by-tags", "G", false, "Group by host,paths,tags instead of just host,paths")
 	// Sadly the commonly used shortcut `H` is already used.
 	f.StringVar(&forgetOptions.Host, "host", "", "only consider snapshots with the given `host`")
 	// Deprecated since 2017-03-07.
 	f.StringVar(&forgetOptions.Host, "hostname", "", "only consider snapshots with the given `hostname` (deprecated)")
-	f.StringSliceVar(&forgetOptions.Tags, "tag", nil, "only consider snapshots which include this `tag` (can be specified multiple times)")
-	f.StringSliceVar(&forgetOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path` (can be specified multiple times)")
+	f.Var(&forgetOptions.Tags, "tag", "only consider snapshots which include this `taglist` in the format `tag[,tag,...]` (can be specified multiple times)")
+	f.StringArrayVar(&forgetOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path` (can be specified multiple times)")
 
 	f.BoolVarP(&forgetOptions.DryRun, "dry-run", "n", false, "do not delete anything, just print what would be done")
 	f.BoolVar(&forgetOptions.Prune, "prune", false, "automatically run the 'prune' command if snapshots have been removed")

src/cmds/restic/cmd_ls.go

@@ -28,7 +28,7 @@ The special snapshot-ID "latest" can be used to list files and directories of th
 type LsOptions struct {
 	ListLong bool
 	Host     string
-	Tags     []string
+	Tags     restic.TagLists
 	Paths    []string
 }
 
@@ -41,8 +41,8 @@ func init() {
 	flags.BoolVarP(&lsOptions.ListLong, "long", "l", false, "use a long listing format showing size and mode")
 
 	flags.StringVarP(&lsOptions.Host, "host", "H", "", "only consider snapshots for this `host`, when no snapshot ID is given")
-	flags.StringSliceVar(&lsOptions.Tags, "tag", nil, "only consider snapshots which include this `tag`, when no snapshot ID is given")
-	flags.StringSliceVar(&lsOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot ID is given")
+	flags.Var(&lsOptions.Tags, "tag", "only consider snapshots which include this `taglist`, when no snapshot ID is given")
+	flags.StringArrayVar(&lsOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot ID is given")
 }
 
 func printTree(repo *repository.Repository, id *restic.ID, prefix string) error {

src/cmds/restic/cmd_mount.go

@@ -6,6 +6,7 @@ package main
 import (
 	"context"
 	"os"
+	"restic"
 
 	"github.com/spf13/cobra"
 
@@ -37,7 +38,7 @@ type MountOptions struct {
 	AllowRoot  bool
 	AllowOther bool
 	Host       string
-	Tags       []string
+	Tags       restic.TagLists
 	Paths      []string
 }
 
@@ -52,8 +53,8 @@ func init() {
 	mountFlags.BoolVar(&mountOptions.AllowOther, "allow-other", false, "allow other users to access the data in the mounted directory")
 
 	mountFlags.StringVarP(&mountOptions.Host, "host", "H", "", `only consider snapshots for this host`)
-	mountFlags.StringSliceVar(&mountOptions.Tags, "tag", nil, "only consider snapshots which include this `tag`")
-	mountFlags.StringSliceVar(&mountOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`")
+	mountFlags.Var(&mountOptions.Tags, "tag", "only consider snapshots which include this `taglist`")
+	mountFlags.StringArrayVar(&mountOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`")
 }
 
 func mount(opts MountOptions, gopts GlobalOptions, mountpoint string) error {

src/cmds/restic/cmd_restore.go

@@ -31,7 +31,7 @@ type RestoreOptions struct {
 	Target  string
 	Host    string
 	Paths   []string
-	Tags    []string
+	Tags    restic.TagLists
 }
 
 var restoreOptions RestoreOptions
@@ -40,13 +40,13 @@ func init() {
 	cmdRoot.AddCommand(cmdRestore)
 
 	flags := cmdRestore.Flags()
-	flags.StringSliceVarP(&restoreOptions.Exclude, "exclude", "e", nil, "exclude a `pattern` (can be specified multiple times)")
-	flags.StringSliceVarP(&restoreOptions.Include, "include", "i", nil, "include a `pattern`, exclude everything else (can be specified multiple times)")
+	flags.StringArrayVarP(&restoreOptions.Exclude, "exclude", "e", nil, "exclude a `pattern` (can be specified multiple times)")
+	flags.StringArrayVarP(&restoreOptions.Include, "include", "i", nil, "include a `pattern`, exclude everything else (can be specified multiple times)")
 	flags.StringVarP(&restoreOptions.Target, "target", "t", "", "directory to extract data to")
 
 	flags.StringVarP(&restoreOptions.Host, "host", "H", "", `only consider snapshots for this host when the snapshot ID is "latest"`)
-	flags.StringSliceVar(&restoreOptions.Tags, "tag", nil, "only consider snapshots which include this `tag` for snapshot ID \"latest\"")
-	flags.StringSliceVar(&restoreOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path` for snapshot ID \"latest\"")
+	flags.Var(&restoreOptions.Tags, "tag", "only consider snapshots which include this `taglist` for snapshot ID \"latest\"")
+	flags.StringArrayVar(&restoreOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path` for snapshot ID \"latest\"")
 }
 
 func runRestore(opts RestoreOptions, gopts GlobalOptions, args []string) error {

src/cmds/restic/cmd_snapshots.go

@@ -26,7 +26,7 @@ The "snapshots" command lists all snapshots stored in the repository.
 // SnapshotOptions bundles all options for the snapshots command.
 type SnapshotOptions struct {
 	Host  string
-	Tags  []string
+	Tags  restic.TagLists
 	Paths []string
 }
 
@@ -37,8 +37,8 @@ func init() {
 
 	f := cmdSnapshots.Flags()
 	f.StringVarP(&snapshotOptions.Host, "host", "H", "", "only consider snapshots for this `host`")
-	f.StringSliceVar(&snapshotOptions.Tags, "tag", nil, "only consider snapshots which include this `tag` (can be specified multiple times)")
-	f.StringSliceVar(&snapshotOptions.Paths, "path", nil, "only consider snapshots for this `path` (can be specified multiple times)")
+	f.Var(&snapshotOptions.Tags, "tag", "only consider snapshots which include this `taglist` (can be specified multiple times)")
+	f.StringArrayVar(&snapshotOptions.Paths, "path", nil, "only consider snapshots for this `path` (can be specified multiple times)")
 }
 
 func runSnapshots(opts SnapshotOptions, gopts GlobalOptions, args []string) error {

src/cmds/restic/cmd_tag.go

@@ -31,7 +31,7 @@ When no snapshot-ID is given, all snapshots matching the host, tag and path filt
 type TagOptions struct {
 	Host       string
 	Paths      []string
-	Tags       []string
+	Tags       restic.TagLists
 	SetTags    []string
 	AddTags    []string
 	RemoveTags []string
@@ -48,8 +48,8 @@ func init() {
 	tagFlags.StringSliceVar(&tagOptions.RemoveTags, "remove", nil, "`tag` which will be removed from the existing tags (can be given multiple times)")
 
 	tagFlags.StringVarP(&tagOptions.Host, "host", "H", "", "only consider snapshots for this `host`, when no snapshot ID is given")
-	tagFlags.StringSliceVar(&tagOptions.Tags, "tag", nil, "only consider snapshots which include this `tag`, when no snapshot-ID is given")
-	tagFlags.StringSliceVar(&tagOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot-ID is given")
+	tagFlags.Var(&tagOptions.Tags, "tag", "only consider snapshots which include this `taglist`, when no snapshot-ID is given")
+	tagFlags.StringArrayVar(&tagOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path`, when no snapshot-ID is given")
 }
 
 func changeTags(repo *repository.Repository, sn *restic.Snapshot, setTags, addTags, removeTags []string) (bool, error) {

src/cmds/restic/find.go

@@ -8,7 +8,7 @@ import (
 )
 
 // FindFilteredSnapshots yields Snapshots, either given explicitly by `snapshotIDs` or filtered from the list of all snapshots.
-func FindFilteredSnapshots(ctx context.Context, repo *repository.Repository, host string, tags []string, paths []string, snapshotIDs []string) <-chan *restic.Snapshot {
+func FindFilteredSnapshots(ctx context.Context, repo *repository.Repository, host string, tags []restic.TagList, paths []string, snapshotIDs []string) <-chan *restic.Snapshot {
 	out := make(chan *restic.Snapshot)
 	go func() {
 		defer close(out)

src/restic/fuse/root.go

@@ -16,7 +16,7 @@ import (
 type Config struct {
 	OwnerIsRoot bool
 	Host        string
-	Tags        []string
+	Tags        []restic.TagList
 	Paths       []string
 }
 

src/restic/snapshot.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os/user"
 	"path/filepath"
+	"restic/debug"
 	"time"
 )
 
@@ -130,46 +131,65 @@ func (sn *Snapshot) RemoveTags(removeTags []string) (changed bool) {
 	return
 }
 
-// HasTags returns true if the snapshot has at least all of tags.
-func (sn *Snapshot) HasTags(tags []string) bool {
-nextTag:
-	for _, tag := range tags {
+func (sn *Snapshot) hasTag(tag string) bool {
 	for _, snTag := range sn.Tags {
 		if tag == snTag {
-				continue nextTag
+			return true
+		}
+	}
+	return false
+}
+
+// HasTags returns true if the snapshot has all the tags in l.
+func (sn *Snapshot) HasTags(l []string) bool {
+	for _, tag := range l {
+		if !sn.hasTag(tag) {
+			return false
+		}
+	}
+
+	return true
+}
+
+// HasTagList returns true if the snapshot satisfies at least one TagList,
+// so there is a TagList in l for which all tags are included in sn.
+func (sn *Snapshot) HasTagList(l []TagList) bool {
+	debug.Log("testing snapshot with tags %v against list: %v", sn.Tags, l)
+
+	if len(l) == 0 {
+		return true
+	}
+
+	for _, tags := range l {
+		if sn.HasTags(tags) {
+			debug.Log("  snapshot satisfies %v", tags, l)
+			return true
 		}
 	}
 
 	return false
 }
 
-	return true
-}
-
-// HasPaths returns true if the snapshot has at least all of paths.
-func (sn *Snapshot) HasPaths(paths []string) bool {
-nextPath:
-	for _, path := range paths {
+func (sn *Snapshot) hasPath(path string) bool {
 	for _, snPath := range sn.Paths {
 		if path == snPath {
-				continue nextPath
+			return true
 		}
 	}
+	return false
+}
 
+// HasPaths returns true if the snapshot has all of the paths.
+func (sn *Snapshot) HasPaths(paths []string) bool {
+	for _, path := range paths {
+		if !sn.hasPath(path) {
 			return false
 		}
+	}
 
 	return true
 }
 
-// SamePaths returns true if the snapshot matches the entire paths set
-func (sn *Snapshot) SamePaths(paths []string) bool {
-	if len(sn.Paths) != len(paths) {
-		return false
-	}
-	return sn.HasPaths(paths)
-}
-
 // Snapshots is a list of snapshots.
 type Snapshots []*Snapshot
 

src/restic/snapshot_find.go

@@ -12,7 +12,7 @@ import (
 var ErrNoSnapshotFound = errors.New("no snapshot found")
 
 // FindLatestSnapshot finds latest snapshot with optional target/directory, tags and hostname filters.
-func FindLatestSnapshot(ctx context.Context, repo Repository, targets []string, tags []string, hostname string) (ID, error) {
+func FindLatestSnapshot(ctx context.Context, repo Repository, targets []string, tagLists []TagList, hostname string) (ID, error) {
 	var (
 		latest   time.Time
 		latestID ID
@@ -24,12 +24,22 @@ func FindLatestSnapshot(ctx context.Context, repo Repository, targets []string,
 		if err != nil {
 			return ID{}, errors.Errorf("Error listing snapshot: %v", err)
 		}
-		if snapshot.Time.After(latest) && (hostname == "" || hostname == snapshot.Hostname) && snapshot.HasTags(tags) && snapshot.HasPaths(targets) {
+		if snapshot.Time.Before(latest) || (hostname != "" && hostname != snapshot.Hostname) {
+			continue
+		}
+
+		if !snapshot.HasTagList(tagLists) {
+			continue
+		}
+
+		if !snapshot.HasPaths(targets) {
+			continue
+		}
+
 		latest = snapshot.Time
 		latestID = snapshotID
 		found = true
 	}
-	}
 
 	if !found {
 		return ID{}, ErrNoSnapshotFound
@@ -53,7 +63,7 @@ func FindSnapshot(repo Repository, s string) (ID, error) {
 
 // FindFilteredSnapshots yields Snapshots filtered from the list of all
 // snapshots.
-func FindFilteredSnapshots(ctx context.Context, repo Repository, host string, tags []string, paths []string) Snapshots {
+func FindFilteredSnapshots(ctx context.Context, repo Repository, host string, tags []TagList, paths []string) Snapshots {
 	results := make(Snapshots, 0, 20)
 
 	for id := range repo.List(ctx, SnapshotFile) {
@@ -62,7 +72,7 @@ func FindFilteredSnapshots(ctx context.Context, repo Repository, host string, ta
 			fmt.Fprintf(os.Stderr, "could not load snapshot %v: %v\n", id.Str(), err)
 			continue
 		}
-		if (host != "" && host != sn.Hostname) || !sn.HasTags(tags) || !sn.HasPaths(paths) {
+		if (host != "" && host != sn.Hostname) || !sn.HasTagList(tags) || !sn.HasPaths(paths) {
 			continue
 		}
 

src/restic/snapshot_policy.go

@@ -14,7 +14,7 @@ type ExpirePolicy struct {
 	Weekly  int       // keep the last n weekly snapshots
 	Monthly int       // keep the last n monthly snapshots
 	Yearly  int       // keep the last n yearly snapshots
-	Tags    []string // keep all snapshots with these tags
+	Tags    []TagList // keep all snapshots that include at least one of the tag lists.
 }
 
 // Sum returns the maximum number of snapshots to be kept according to this
@@ -94,11 +94,12 @@ func ApplyPolicy(list Snapshots, p ExpirePolicy) (keep, remove Snapshots) {
 		var keepSnap bool
 
 		// Tags are handled specially as they are not counted.
-		if len(p.Tags) > 0 {
-			if cur.HasTags(p.Tags) {
+		for _, l := range p.Tags {
+			if cur.HasTags(l) {
 				keepSnap = true
 			}
 		}
+
 		// Now update the other buckets and see if they have some counts left.
 		for i, b := range buckets {
 			if b.Count > 0 {

src/restic/snapshot_policy_test.go

@@ -27,7 +27,7 @@ func TestExpireSnapshotOps(t *testing.T) {
 		p           *restic.ExpirePolicy
 	}{
 		{true, 0, &restic.ExpirePolicy{}},
-		{true, 0, &restic.ExpirePolicy{Tags: []string{}}},
+		{true, 0, &restic.ExpirePolicy{Tags: []restic.TagList{}}},
 		{false, 22, &restic.ExpirePolicy{Daily: 7, Weekly: 2, Monthly: 3, Yearly: 10}},
 	}
 	for i, d := range data {
@@ -163,8 +163,9 @@ var expireTests = []restic.ExpirePolicy{
 	{Daily: 2, Weekly: 2, Monthly: 6},
 	{Yearly: 10},
 	{Daily: 7, Weekly: 2, Monthly: 3, Yearly: 10},
-	{Tags: []string{"foo"}},
-	{Tags: []string{"foo", "bar"}},
+	{Tags: []restic.TagList{{"foo"}}},
+	{Tags: []restic.TagList{{"foo", "bar"}}},
+	{Tags: []restic.TagList{{"foo"}, {"bar"}}},
 }
 
 func TestApplyPolicy(t *testing.T) {

src/restic/tag_list.go

@@ -0,0 +1,62 @@
+package restic
+
+import (
+	"fmt"
+	"strings"
+)
+
+// TagList is a list of tags.
+type TagList []string
+
+// splitTagList splits a string into a list of tags. The tags in the string
+// need to be separated by commas. Whitespace is stripped around the individual
+// tags.
+func splitTagList(s string) (l TagList) {
+	for _, t := range strings.Split(s, ",") {
+		l = append(l, strings.TrimSpace(t))
+	}
+	return l
+}
+
+func (l TagList) String() string {
+	return "[" + strings.Join(l, ", ") + "]"
+}
+
+// Set updates the TagList's value.
+func (l *TagList) Set(s string) error {
+	*l = splitTagList(s)
+	return nil
+}
+
+// Type returns a description of the type.
+func (TagList) Type() string {
+	return "TagList"
+}
+
+// TagLists consists of several TagList.
+type TagLists []TagList
+
+// splitTagLists splits a slice of strings into a slice of TagLists using
+// SplitTagList.
+func splitTagLists(s []string) (l TagLists) {
+	l = make([]TagList, 0, len(s))
+	for _, t := range s {
+		l = append(l, splitTagList(t))
+	}
+	return l
+}
+
+func (l TagLists) String() string {
+	return fmt.Sprintf("%v", []TagList(l))
+}
+
+// Set updates the TagList's value.
+func (l *TagLists) Set(s string) error {
+	*l = append(*l, splitTagList(s))
+	return nil
+}
+
+// Type returns a description of the type.
+func (TagLists) Type() string {
+	return "TagLists"
+}

src/restic/testdata/policy_keep_snapshots_20

@@ -0,0 +1,131 @@
+[
+  {
+    "time": "2014-11-15T10:20:30Z",
+    "tree": null,
+    "paths": null,
+    "tags": [
+      "foo",
+      "bar"
+    ]
+  },
+  {
+    "time": "2014-11-13T10:20:30.1Z",
+    "tree": null,
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