Back up old metadata.xml files when we are about to save a new version of them.

diff --git a/src/lib/film.cc b/src/lib/film.cc
index e7861a032c12ce1a3688454b0febe533e827b4cb..f1d066f34e369a178a8cd380606ffb5ad7e0e7a3 100644 (file)
--- a/src/lib/film.cc
+++ b/src/lib/film.cc
@@ -454,6 +454,16 @@ Film::read_metadata (optional<boost::filesystem::path> path)
        _state_version = f.number_child<int> ("Version");
        if (_state_version > current_state_version) {
                throw runtime_error (_("This film was created with a newer version of DCP-o-matic, and it cannot be loaded into this version.  Sorry!"));
+       } else if (_state_version < current_state_version) {
+               /* This is an older version; save a copy (if we haven't already) */
+               boost::filesystem::path const older = path->parent_path() / String::compose("metadata.%1.xml", _state_version);
+               if (!boost::filesystem::is_regular_file(older)) {
+                       try {
+                               boost::filesystem::copy_file(*path, older);
+                       } catch (...) {
+                               /* Never mind; at least we tried */
+                       }
+               }
        }
 
        _name = f.string_child ("Name");