Don't expand plugins that are already unpacked

This prevents creating unnecessary files when running in embedded
mode, and in development mode it keeps code path clean and compatible
with different interactive tools.

Author: Alexey Lebedeff

src/rabbit_plugins.erl

@@ -103,7 +103,7 @@ setup() ->
 
 %% @doc Lists the plugins which are currently running.
 active() ->
-    InstalledPlugins = plugin_names(list(plugins_expand_dir())),
+    InstalledPlugins = plugin_names(list(plugins_dist_dir())),
     [App || {App, _, _} <- rabbit_misc:which_applications(),
             lists:member(App, InstalledPlugins)].
 
@@ -200,9 +200,6 @@ prepare_plugins(Enabled) ->
     end,
 
     [prepare_plugin(Plugin, ExpandDir) || Plugin <- WantedPlugins],
-
-    [prepare_dir_plugin(PluginAppDescPath) ||
-        PluginAppDescPath <- filelib:wildcard(ExpandDir ++ "/*/ebin/*.app")],
     Wanted.
 
 clean_plugins(Plugins) ->
@@ -250,11 +247,37 @@ delete_recursively(Fn) ->
         {error, {Path, E}} -> {error, {cannot_delete, Path, E}}
     end.
 
-prepare_plugin(#plugin{type = ez, location = Location}, ExpandDir) ->
-    zip:unzip(Location, [{cwd, ExpandDir}]);
-prepare_plugin(#plugin{type = dir, name = Name, location = Location},
-               ExpandDir) ->
-    rabbit_file:recursive_copy(Location, filename:join([ExpandDir, Name])).
+find_unzipped_app_file(ExpandDir, Files) ->
+    StripComponents = length(filename:split(ExpandDir)),
+    [ X || X <- Files,
+           [_AppName, "ebin", MaybeAppFile] <-
+               [lists:nthtail(StripComponents, filename:split(X))],
+           lists:suffix(".app", MaybeAppFile)
+    ].
+
+prepare_plugin(#plugin{type = ez, name = Name, location = Location}, ExpandDir) ->
+    case zip:unzip(Location, [{cwd, ExpandDir}]) of
+        {ok, Files} ->
+            case find_unzipped_app_file(ExpandDir, Files) of
+                [PluginAppDescPath|_] ->
+                    prepare_dir_plugin(PluginAppDescPath);
+                _ ->
+                    rabbit_log:error("Plugin archive '~s' doesn't contain .app file~n", [Location]),
+                    throw({no_plugin_app_file_in_archive, Name, Location})
+            end;
+        {error, Reason} ->
+            rabbit_log:error("Plugin archive '~s' unpacking failed: ~p~n", [Location, Reason]),
+            throw({plugin_unpack_failed, Name, Location, Reason})
+    end;
+prepare_plugin(#plugin{type = dir, location = Location, name = Name},
+               _ExpandDir) ->
+    case filelib:wildcard(Location ++ "/ebin/*.app") of
+        [PluginAppDescPath|_] ->
+            prepare_dir_plugin(PluginAppDescPath);
+        _ ->
+            rabbit_log:error("Plugin directory '~s' doesn't contain an .app file~n", [Location]),
+            throw({no_plugin_app_file_in_directory, Name, Location})
+    end.
 
 plugin_info({ez, EZ}) ->
     case read_app_file(EZ) of