backend/hasher: add read-only flag

backend/hasher/hasher.go

@@ -50,6 +50,10 @@ func init() {
 			Advanced: true,
 			Default:  fs.SizeSuffix(0),
 			Help:     "Auto-update checksum for files smaller than this size (disabled by default).",
+		}, {
+			Name:    "read_only",
+			Default: false,
+			Help:    "Set the db in read only mode",
 		}},
 	})
 }
@@ -60,6 +64,7 @@ type Options struct {
 	Hashes   fs.CommaSepList `config:"hashes"`
 	AutoSize fs.SizeSuffix   `config:"auto_size"`
 	MaxAge   fs.Duration     `config:"max_age"`
+	ReadOnly bool            `config:"read_only"`
 }
 
 // Fs represents a wrapped fs.Fs

backend/hasher/object.go

@@ -11,6 +11,7 @@ import (
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/hash"
 	"github.com/rclone/rclone/fs/operations"
+	"github.com/rclone/rclone/lib/kv"
 )
 
 // obtain hash for an object
@@ -58,12 +59,17 @@ func (o *Object) putHashes(ctx context.Context, rawHashes hashMap) error {
 
 // set hashes for a path without any validation
 func (f *Fs) putRawHashes(ctx context.Context, key, fp string, hashes operations.HashSums) error {
-	return f.db.Do(true, &kvPut{
+	err := f.db.Do(true, &kvPut{
 		key:    key,
 		fp:     fp,
 		hashes: hashes,
 		age:    time.Duration(f.opt.MaxAge),
 	})
+	if f.opt.ReadOnly && errors.Is(err, kv.ErrReadOnly) {
+		fs.Debugf(nil, "database in read only mode")
+		return nil
+	}
+	return err
 }
 
 // Hash returns the selected checksum of the file or "" if unavailable.