[ostree] admin: Add ot_admin_checksum_version to get a dup of the version for a commit

[Colin Walters <walters src gnome org>]

commit 52c0d89a8cd53cfec20041fa0e1a4fe382a1a2d2
Author: James Antill <james and org>
Date:   Wed Oct 22 01:21:14 2014 -0400

    admin: Add ot_admin_checksum_version to get a dup of the version for a commit

 src/ostree/ot-admin-functions.c |   23 +++++++++++++++++++++++
 src/ostree/ot-admin-functions.h |    4 ++++
 2 files changed, 27 insertions(+), 0 deletions(-)
---
diff --git a/src/ostree/ot-admin-functions.c b/src/ostree/ot-admin-functions.c
index 34e5c6b..ff62357 100644
--- a/src/ostree/ot-admin-functions.c
+++ b/src/ostree/ot-admin-functions.c
@@ -48,3 +48,26 @@ ot_admin_require_booted_deployment_or_osname (OstreeSysroot       *sysroot,
  out:
   return ret;
 }
+
+/**
+ * ot_admin_checksum_version:
+ * @checksum: A GVariant from an ostree checksum.
+ *
+ *
+ * Get the version metadata string from a commit variant object, if it exists.
+ *
+ * Returns: A newly allocated string of the version, or %NULL is none
+ */
+char *
+ot_admin_checksum_version (GVariant *checksum)
+{
+  gs_unref_variant GVariant *metadata = NULL;
+  const char *ret = NULL;
+
+  metadata = g_variant_get_child_value (checksum, 0);
+
+  if (!g_variant_lookup (metadata, "version", "&s", &ret))
+    return NULL;
+
+  return g_strdup (ret);
+}
diff --git a/src/ostree/ot-admin-functions.h b/src/ostree/ot-admin-functions.h
index ab83036..ea147c8 100644
--- a/src/ostree/ot-admin-functions.h
+++ b/src/ostree/ot-admin-functions.h
@@ -32,5 +32,9 @@ ot_admin_require_booted_deployment_or_osname (OstreeSysroot       *sysroot,
                                               const char          *osname,
                                               GCancellable        *cancellable,
                                               GError             **error);
+
+char *
+ot_admin_checksum_version (GVariant *checksum);
+
 G_END_DECLS