Allow sideload-repos to link to the root of a USB

Currently we only support links in /var/lib/flatpak/sideload-repos,
/run/flatpak/sideload-repos, etc. to be actual ostree repos, but this
commit makes it so you can also link to the root directory of a USB,
and Flatpak will check the subpaths "ostree/repo", ".ostree/repo", and
".ostree/repos.d" for compatibility with "flatpak create-usb". This will
allow the logic in the following commit to be much simpler, where we're
linking to hot-plugged drives in a script run by systemd.

Note that we still only allow actual repos in the other places where a
sideload path can be specified, such as the --sideload-repo CLI option.

2 files changed, 37 insertions, 5 deletions

diff --git a/common/flatpak-dir.c b/common/flatpak-dir.c
index 36690c64..bfbf994b 100644
--- a/common/flatpak-dir.c
+++ b/common/flatpak-dir.c
@@ -11885,7 +11885,8 @@ flatpak_dir_list_remote_config_keys (FlatpakDir *self,
 
 static void
 add_subdirs (GPtrArray *res,
-             GFile     *parent)
+             GFile     *parent,
+             gboolean   recurse)
 {
   g_autoptr(GFileEnumerator) dir_enum = NULL;
 
@@ -11906,8 +11907,37 @@ add_subdirs (GPtrArray *res,
           info == NULL)
         break;
 
+      /* Here we support either a plain repo or, if @recurse is TRUE, the root
+       * directory of a USB created with "flatpak create-usb"
+       */
       if (g_file_info_get_file_type (info) == G_FILE_TYPE_DIRECTORY)
-        g_ptr_array_add (res, g_object_ref (path));
+        {
+          g_autoptr(OstreeRepo) repo = ostree_repo_new (path);
+
+          if (ostree_repo_open (repo, NULL, NULL))
+            g_ptr_array_add (res, g_object_ref (path));
+          else if (recurse)
+            {
+              g_autoptr(GFile) ostree_repo_subpath = NULL;
+              g_autoptr(GFile) dot_ostree_repo_subpath = NULL;
+              g_autoptr(GFile) dot_ostree_repo_d_subpath = NULL;
+              g_autoptr(OstreeRepo) ostree_repo_subpath_repo = NULL;
+              g_autoptr(OstreeRepo) dot_ostree_repo_subpath_repo = NULL;
+
+              ostree_repo_subpath = g_file_resolve_relative_path (path, "ostree/repo");
+              ostree_repo_subpath_repo = ostree_repo_new (ostree_repo_subpath);
+              if (ostree_repo_open (ostree_repo_subpath_repo, NULL, NULL))
+                g_ptr_array_add (res, g_object_ref (ostree_repo_subpath));
+
+              dot_ostree_repo_subpath = g_file_resolve_relative_path (path, ".ostree/repo");
+              dot_ostree_repo_subpath_repo = ostree_repo_new (dot_ostree_repo_subpath);
+              if (ostree_repo_open (dot_ostree_repo_subpath_repo, NULL, NULL))
+                g_ptr_array_add (res, g_object_ref (dot_ostree_repo_subpath));
+
+              dot_ostree_repo_d_subpath = g_file_resolve_relative_path (path, ".ostree/repos.d");
+              add_subdirs (res, dot_ostree_repo_d_subpath, FALSE);
+            }
+        }
     }
 }
 
@@ -11918,8 +11948,8 @@ flatpak_dir_get_sideload_repo_paths (FlatpakDir *self)
   g_autoptr(GFile) runtime_sideload_repos_dir = flatpak_dir_get_runtime_sideload_repos_dir (self);
   g_autoptr(GPtrArray) res = g_ptr_array_new_with_free_func (g_object_unref);
 
-  add_subdirs (res, sideload_repos_dir);
-  add_subdirs (res, runtime_sideload_repos_dir);
+  add_subdirs (res, sideload_repos_dir, TRUE);
+  add_subdirs (res, runtime_sideload_repos_dir, TRUE);
 
   return g_steal_pointer (&res);
 }
diff --git a/doc/flatpak.xml b/doc/flatpak.xml
index fb4f3fec..e0af8724 100644
--- a/doc/flatpak.xml
+++ b/doc/flatpak.xml
@@ -97,7 +97,9 @@
             <filename>/var/lib/flatpak/sideload-repos</filename>). Additionally
             symlinks can be created in <filename>/run/flatpak/sideload-repos</filename>
             (overridable by <envar>FLATPAK_RUN_DIR</envar>) which is a better location
-            for non-persistent sources (as it is cleared on reboot).
+            for non-persistent sources (as it is cleared on reboot). These symlinks can point to either the
+            directory given to <command>flatpak create-usb</command> which by default writes to the subpath
+            <filename>.ostree/repo</filename>, or directly to an ostree repo.
         </para>
 
     </refsect1>