feat: Add io.Writer-based API to restore and fetch cmds

cmd/stbak/cmd/operation_restore.go

@@ -1,6 +1,10 @@
 package cmd
 
 import (
+	"io"
+	"io/fs"
+	"os"
+
 	"github.com/pojntfx/stfs/internal/keys"
 	"github.com/pojntfx/stfs/internal/logging"
 	"github.com/pojntfx/stfs/internal/persisters"
@@ -93,6 +97,22 @@ var operationRestoreCmd = &cobra.Command{
 		)
 
 		return ops.Restore(
+			func(path string, mode fs.FileMode) (io.WriteCloser, error) {
+				dstFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, mode)
+				if err != nil {
+					return nil, err
+				}
+
+				if err := dstFile.Truncate(0); err != nil {
+					return nil, err
+				}
+
+				return dstFile, nil
+			},
+			func(path string, mode fs.FileMode) error {
+				return os.MkdirAll(path, mode)
+			},
+
 			viper.GetString(fromFlag),
 			viper.GetString(toFlag),
 			viper.GetBool(flattenFlag),

cmd/stbak/cmd/recovery_fetch.go

@@ -1,6 +1,10 @@
 package cmd
 
 import (
+	"io"
+	"io/fs"
+	"os"
+
 	"github.com/pojntfx/stfs/internal/keys"
 	"github.com/pojntfx/stfs/internal/logging"
 	"github.com/pojntfx/stfs/pkg/config"
@@ -80,6 +84,22 @@ var recoveryFetchCmd = &cobra.Command{
 				Password:  viper.GetString(passwordFlag),
 			},
 
+			func(path string, mode fs.FileMode) (io.WriteCloser, error) {
+				dstFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, mode)
+				if err != nil {
+					return nil, err
+				}
+
+				if err := dstFile.Truncate(0); err != nil {
+					return nil, err
+				}
+
+				return dstFile, nil
+			},
+			func(path string, mode fs.FileMode) error {
+				return os.MkdirAll(path, mode)
+			},
+
 			viper.GetInt(recordSizeFlag),
 			viper.GetInt(recordFlag),
 			viper.GetInt(blockFlag),