lib/repo: Add commit version metadata to summary metadata

The commit metadata `version` key is well established but getting it for
a remote commit is cumbersome since the commit object needs to be
fetched and loaded. Including it in the summary additional metadata
allows a much more convenient view of what each of the remote refs
represents.

src/libostree/ostree-core.h

@@ -164,6 +164,8 @@ typedef enum {
  * The currently defined keys for the `a{sv}` of additional metadata for each commit are:
  *  - key: `ostree.commit.timestamp`, value: `t`, timestamp (seconds since the
  *    Unix epoch in UTC, big-endian) when the commit was committed
+ *  - key: `ostree.commit.version`, value: `s`, the `version` value from the
+ *    commit's metadata if it was defined. Since: 2022.2
  */
 #define OSTREE_SUMMARY_GVARIANT_STRING "(a(s(taya{sv}))a{sv})"
 #define OSTREE_SUMMARY_GVARIANT_FORMAT G_VARIANT_TYPE (OSTREE_SUMMARY_GVARIANT_STRING)

src/libostree/ostree-repo-private.h

@@ -63,6 +63,7 @@ G_BEGIN_DECLS
 /* Well-known keys for the additional metadata field in a commit in a ref entry
  * in a summary file. */
 #define OSTREE_COMMIT_TIMESTAMP "ostree.commit.timestamp"
+#define OSTREE_COMMIT_VERSION "ostree.commit.version"
 
 typedef enum {
   OSTREE_REPO_TEST_ERROR_PRE_COMMIT = (1 << 0),

src/libostree/ostree-repo.c

@@ -6067,10 +6067,11 @@ summary_add_ref_entry (OstreeRepo       *self,
   g_autoptr(GVariant) commit_obj = NULL;
   if (!ostree_repo_load_variant (self, OSTREE_OBJECT_TYPE_COMMIT, checksum, &commit_obj, error))
     return FALSE;
+  g_autoptr(GVariant) orig_metadata = g_variant_get_child_value (commit_obj, 0);
 
   g_variant_dict_init (&commit_metadata_builder, NULL);
 
-  /* Forward the commit’s timestamp if it’s valid. */
+  /* Forward the commit’s timestamp and version if they're valid. */
   guint64 commit_timestamp = ostree_commit_get_timestamp (commit_obj);
   g_autoptr(GDateTime) dt = g_date_time_new_from_unix_utc (commit_timestamp);
 
@@ -6078,6 +6079,10 @@ summary_add_ref_entry (OstreeRepo       *self,
     g_variant_dict_insert_value (&commit_metadata_builder, OSTREE_COMMIT_TIMESTAMP,
                                  g_variant_new_uint64 (GUINT64_TO_BE (commit_timestamp)));
 
+  const char *version = NULL;
+  if (g_variant_lookup (orig_metadata, OSTREE_COMMIT_META_KEY_VERSION, "&s", &version))
+    g_variant_dict_insert (&commit_metadata_builder, OSTREE_COMMIT_VERSION, "s", version);
+
   g_variant_builder_add_value (refs_builder,
                                g_variant_new ("(s(t@ay@a{sv}))", ref,
                                               (guint64) g_variant_get_size (commit_obj),