forget: Add policy to keep snapshots before a date

cmd/restic/cmd_forget.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/restic"
@@ -27,13 +28,14 @@ data after 'forget' was run successfully, see the 'prune' command. `,
 
 // ForgetOptions collects all options for the forget command.
 type ForgetOptions struct {
-	Last     int
-	Hourly   int
-	Daily    int
-	Weekly   int
-	Monthly  int
-	Yearly   int
-	KeepTags restic.TagLists
+	Last      int
+	Hourly    int
+	Daily     int
+	Weekly    int
+	Monthly   int
+	Yearly    int
+	NewerThan time.Duration
+	KeepTags  restic.TagLists
 
 	Host    string
 	Tags    restic.TagLists
@@ -58,6 +60,7 @@ func init() {
 	f.IntVarP(&forgetOptions.Weekly, "keep-weekly", "w", 0, "keep the last `n` weekly snapshots")
 	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.DurationVar(&forgetOptions.NewerThan, "keep-newer-than", 0, "keep snapshots that were created within this timeframe")
 
 	f.Var(&forgetOptions.KeepTags, "keep-tag", "keep snapshots with this `taglist` (can be specified multiple times)")
 	// Sadly the commonly used shortcut `H` is already used.
@@ -163,14 +166,20 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		}
 	}
 
+	var ageCutoff time.Time
+	if opts.NewerThan > 0 {
+		ageCutoff = time.Now().Add(-opts.NewerThan)
+	}
+
 	policy := restic.ExpirePolicy{
-		Last:    opts.Last,
-		Hourly:  opts.Hourly,
-		Daily:   opts.Daily,
-		Weekly:  opts.Weekly,
-		Monthly: opts.Monthly,
-		Yearly:  opts.Yearly,
-		Tags:    opts.KeepTags,
+		Last:      opts.Last,
+		Hourly:    opts.Hourly,
+		Daily:     opts.Daily,
+		Weekly:    opts.Weekly,
+		Monthly:   opts.Monthly,
+		Yearly:    opts.Yearly,
+		NewerThan: ageCutoff,
+		Tags:      opts.KeepTags,
 	}
 
 	if policy.Empty() && len(args) == 0 {