Basic functionality implemented

rust/src/sysroot_upgrade.rs

@@ -191,3 +191,59 @@ pub(crate) fn purge_refspec(repo: &crate::FFIOstreeRepo, imgref: &str) -> CxxRes
     }
     Ok(())
 }
+
+pub(crate) fn compare_local_to_remote_container(
+    repo: &crate::FFIOstreeRepo,
+    cancellable: &crate::FFIGCancellable,
+    imgref: &str,
+    remote_repo: &str,
+    remote_imgref: &str,
+) -> Result<String> {
+    let repo = &repo.glib_reborrow();
+    let cancellable = cancellable.glib_reborrow();
+    let imgref = &OstreeImageReference::try_from(imgref)?;
+    let r = Handle::current().block_on(async {
+        crate::utils::run_with_cancellable(
+            async { get_container_manifest_diff(repo, imgref, remote_repo, remote_imgref).await },
+            &cancellable,
+        )
+        .await
+    })?;
+    Ok(r)
+}
+
+pub async fn get_container_manifest_diff(
+    repo: &ostree::Repo,
+    imgref: &OstreeImageReference,
+    remote_repo: &str,
+    remote_imgref: &str,
+) -> Result<String> {
+    use ostree_ext::container::ImageReference;
+    use ostree_ext::container::ManifestDiff;
+    use ostree_ext::container::OstreeImageReference;
+    use ostree_ext::container::SignatureSource;
+    use ostree_ext::container::Transport;
+    use ostree_ext::oci_spec::image::ImageManifest;
+
+    let previous_state = ostree_ext::container::store::query_image_ref(&repo, &imgref.imgref)
+        .unwrap()
+        .unwrap();
+
+    let sigverify = SignatureSource::OstreeRemote(String::from(remote_repo));
+    let transport = Transport::Registry;
+    let new_imgref = ImageReference {
+        transport,
+        name: String::from(remote_imgref),
+    };
+    let container = OstreeImageReference {
+        sigverify,
+        imgref: new_imgref,
+    };
+    let manifest = ostree_ext::container::fetch_manifest(&container)
+        .await
+        .unwrap();
+
+    let diff = ManifestDiff::new(&previous_state.manifest, &manifest.0);
+
+    Ok(diff.export_as_string())
+}

src/daemon/rpmostree-sysroot-upgrader.cxx

@@ -433,13 +433,33 @@ rpmostree_sysroot_upgrader_pull_base (RpmOstreeSysrootUpgrader *self, const char
         if (override_commit)
           return glnx_throw (error, "Specifying commit overrides for container-image-reference "
                                     "type refspecs is not supported");
+
         if (check)
-          return glnx_throw (error, "Cannot currently check for updates without downloading");
+          {
+            g_autofree char *origin_remote = NULL;
+            g_autofree char *origin_ref = NULL;
+            if (!ostree_parse_refspec (r.refspec.c_str (), &origin_remote, &origin_ref, error))
+              return FALSE;
 
-        CXX_TRY_VAR (import,
-                     rpmostreecxx::pull_container (*self->repo, *cancellable, r.refspec.c_str ()),
-                     error);
-        new_base_rev = g_strdup (import->merge_commit.c_str ());
+            CXX_TRY_VAR (
+                res,
+                rpmostreecxx::compare_local_to_remote_container (
+                    *self->repo, *cancellable, r.refspec.c_str (), origin_remote, origin_ref),
+                error);
+
+            rpmostree_output_message ("%s", res.c_str ());
+            *out_changed = TRUE;
+            return TRUE;
+          }
+        else
+          {
+            CXX_TRY_VAR (
+                import,
+                rpmostreecxx::pull_container (*self->repo, *cancellable, r.refspec.c_str ()),
+                error);
+
+            new_base_rev = g_strdup (import->merge_commit.c_str ());
+          }
         break;
       }
     case rpmostreecxx::RefspecType::Checksum: