Included config files relative to sys.config dir

Change the way included config files are searched in sys.config.
Search first relative to sys.config directory, then relative
to current working directory, for backward compatibility.

This permit same result when using a sys.config file in a release
or starting manually a node with -config.

Credit to Siri Hansen for test case.

3 files changed, 67 insertions, 13 deletions

diff --git a/lib/kernel/doc/src/config.xml b/lib/kernel/doc/src/config.xml
index fdb2d29f63..d331b755f5 100644
--- a/lib/kernel/doc/src/config.xml
+++ b/lib/kernel/doc/src/config.xml
@@ -86,8 +86,13 @@
       <tag><c>File = string()</c></tag>
       <item>Name of another <c>.config</c> file.
         Extension <c>.config</c> can be omitted. It is
-        recommended to use absolute paths. A relative path is
-        relative the current working directory of the emulator.</item>
+        recommended to use absolute paths. If a relative path is used,
+        <c>File</c> is searched, first, relative from <c>sys.config</c> directory, then relative
+        to the current working directory of the emulator, for backward compatibility.
+        This allow to use a <c>sys.config</c> pointing out other <c>.config</c> files in a release
+        or in a node started manually using <c>-config ...</c> with same result whatever
+        the current working directory.
+        </item>
     </taglist>
     <p>When traversing the contents of <c>sys.config</c> and a filename
       is encountered, its contents are read and merged with the result
diff --git a/lib/kernel/src/application_controller.erl b/lib/kernel/src/application_controller.erl
index 3b642f5873..abea329f84 100644
--- a/lib/kernel/src/application_controller.erl
+++ b/lib/kernel/src/application_controller.erl
@@ -1819,8 +1819,9 @@ check_conf() ->
 				   %% Therefore read and merge contents.
 				   if
 				       BFName =:= "sys" ->
+					   DName = filename:dirname(FName),
 					   {ok, SysEnv, Errors} =
-					       check_conf_sys(NewEnv),
+					       check_conf_sys(NewEnv, [], [], DName),
 
 					   %% Report first error, if any, and
 					   %% terminate
@@ -1842,20 +1843,31 @@ check_conf() ->
     end.
 
 check_conf_sys(Env) ->
-    check_conf_sys(Env, [], []).
+    check_conf_sys(Env, [], [], []).
 
-check_conf_sys([File|T], SysEnv, Errors) when is_list(File) ->
+check_conf_sys([File|T], SysEnv, Errors, DName) when is_list(File),is_list(DName) ->
     BFName = filename:basename(File, ".config"),
     FName = filename:join(filename:dirname(File), BFName ++ ".config"),
-    case load_file(FName) of
+    LName = case filename:pathtype(FName) of
+               relative when (DName =/= []) ->
+                  % Check if relative to sys.config dir otherwise use legacy mode,
+                  % i.e relative to cwd.
+                  RName = filename:join(DName, FName),
+                  case erl_prim_loader:read_file_info(RName) of
+                     {ok, _} -> RName ;
+                     error   -> FName
+                  end;
+		_          -> FName
+	    end,
+    case load_file(LName) of
 	{ok, NewEnv} ->
-	    check_conf_sys(T, merge_env(SysEnv, NewEnv), Errors);
+	    check_conf_sys(T, merge_env(SysEnv, NewEnv), Errors, DName);
 	{error, {Line, _Mod, Str}} ->
-	    check_conf_sys(T, SysEnv, [{error, {FName, Line, Str}}|Errors])
+	    check_conf_sys(T, SysEnv, [{error, {LName, Line, Str}}|Errors], DName)
     end;
-check_conf_sys([Tuple|T], SysEnv, Errors) ->
-    check_conf_sys(T, merge_env(SysEnv, [Tuple]), Errors);
-check_conf_sys([], SysEnv, Errors) ->
+check_conf_sys([Tuple|T], SysEnv, Errors, DName) ->
+    check_conf_sys(T, merge_env(SysEnv, [Tuple]), Errors, DName);
+check_conf_sys([], SysEnv, Errors, _) ->
     {ok, SysEnv, lists:reverse(Errors)}.
 
 load_file(File) ->
diff --git a/lib/kernel/test/application_SUITE.erl b/lib/kernel/test/application_SUITE.erl
index 866043cfb4..e497ff65ad 100644
--- a/lib/kernel/test/application_SUITE.erl
+++ b/lib/kernel/test/application_SUITE.erl
@@ -37,7 +37,8 @@
 -export([config_change/1, persistent_env/1,
 	 distr_changed_tc1/1, distr_changed_tc2/1,
 	 ensure_started/1, ensure_all_started/1,
-	 shutdown_func/1, do_shutdown/1, shutdown_timeout/1, shutdown_deadlock/1]).
+	 shutdown_func/1, do_shutdown/1, shutdown_timeout/1, shutdown_deadlock/1,
+         config_relative_paths/1]).
 
 -define(TESTCASE, testcase_name).
 -define(testcase, proplists:get_value(?TESTCASE, Config)).
@@ -55,7 +56,7 @@ all() ->
      script_start, nodedown_start, permit_false_start_local,
      permit_false_start_dist, get_key, get_env, ensure_all_started,
      {group, distr_changed}, config_change, shutdown_func, shutdown_timeout,
-     shutdown_deadlock,
+     shutdown_deadlock, config_relative_paths,
      persistent_env].
 
 groups() -> 
@@ -2078,6 +2079,42 @@ shutdown_deadlock(Config) when is_list(Config) ->
 
 
 %%-----------------------------------------------------------------
+%% Relative paths in sys.config
+%%-----------------------------------------------------------------
+config_relative_paths(Config) ->
+    Dir = ?config(priv_dir,Config),
+    SubDir = filename:join(Dir,"subdir"),
+    Sys = filename:join(SubDir,"sys.config"),
+    ok = filelib:ensure_dir(Sys),
+    ok = file:write_file(Sys,"[\"../up.config\",\"current\"].\n"),
+
+    Up = filename:join(Dir,"up.config"),
+    ok = file:write_file(Up,"[{app1,[{key1,value}]}].\n"),
+
+    {ok,Cwd} = file:get_cwd(),
+    Current1 = filename:join(Cwd,"current.config"),
+    ok = file:write_file(Current1,"[{app1,[{key2,value1}]}].\n"),
+
+    N1 = list_to_atom(lists:concat([?FUNCTION_NAME,"_1"])),
+    {ok,Node1} = start_node(N1,filename:rootname(Sys)),
+    ok = rpc:call(Node1, application, load, [app1()]),
+    {ok, value} = rpc:call(Node1, application, get_env,[app1,key1]),
+    {ok, value1} = rpc:call(Node1, application, get_env,[app1,key2]),
+
+    Current2 = filename:join(SubDir,"current.config"),
+    ok = file:write_file(Current2,"[{app1,[{key2,value2}]}].\n"),
+
+    N2 = list_to_atom(lists:concat([?FUNCTION_NAME,"_2"])),
+    {ok, Node2} = start_node(N2,filename:rootname(Sys)),
+    ok = rpc:call(Node2, application, load, [app1()]),
+    {ok, value} = rpc:call(Node2, application, get_env,[app1,key1]),
+    {ok, value2} = rpc:call(Node2, application, get_env,[app1,key2]),
+
+    stop_node_nice([Node1,Node2]),
+
+    ok.
+
+%%-----------------------------------------------------------------
 %% Utility functions
 %%-----------------------------------------------------------------
 app0() ->