feat(rcserver): allow for cat operation on /backup/schema files

For Scylla 6.0, schema is backed up in a json file which needs to be opened and applied to cluster via cql session by SM during restore.

pkg/rclone/rcserver/rc.go

@@ -331,7 +331,7 @@ func init() {
 	rc.Add(rc.Call{
 		Path:         "operations/cat",
 		AuthRequired: true,
-		Fn:           wrap(rcCat, pathHasPrefix("backup/meta/")),
+		Fn:           wrap(rcCat, pathHasPrefix("backup/meta/", "backup/schema/")),
 		Title:        "Concatenate any files and send them in response",
 		Help: `This takes the following parameters
 

pkg/rclone/rcserver/rchardening.go

@@ -26,7 +26,7 @@ func wrap(fn rc.Func, v paramsValidator) rc.Func {
 
 // pathHasPrefix reads "fs" and "remote" params, evaluates absolute path and
 // ensures it has the required prefix.
-func pathHasPrefix(prefix string) paramsValidator {
+func pathHasPrefix(prefixes ...string) paramsValidator {
 	return func(ctx context.Context, in rc.Params) error {
 		_, p, err := joined(in, "fs", "remote")
 		if err != nil {
@@ -37,10 +37,13 @@ func pathHasPrefix(prefix string) paramsValidator {
 		i := strings.Index(p, "/")
 		p = p[i+1:]
 
-		if !strings.HasPrefix(p, prefix) {
-			return fs.ErrorPermissionDenied
+		for _, prefix := range prefixes {
+			if strings.HasPrefix(p, prefix) {
+				return nil
+			}
 		}
-		return nil
+
+		return fs.ErrorPermissionDenied
 	}
 }