Extra -mode flags are ignored with a warning

Prior to this change, providing multiple -mode flags to erl would start
the code server as 'interactive', regardless of their value ('-mode
embedded -mode embedded' would start erl as in interactive mode).
With this change, the extra -mode flags are ignored, and a warning gets
logged.

3 files changed, 43 insertions, 6 deletions

diff --git a/lib/kernel/src/code.erl b/lib/kernel/src/code.erl
index 7faef93609..964ede9bc9 100644
--- a/lib/kernel/src/code.erl
+++ b/lib/kernel/src/code.erl
@@ -19,6 +19,8 @@
 %%
 -module(code).
 
+-include_lib("kernel/include/logger.hrl").
+
 %% This is the interface module to the code server. It also contains
 %% some implementation details.  See also related modules: code_*.erl
 %% in this directory.
@@ -707,8 +709,20 @@ do_s(Lib) ->
 
 start_get_mode() ->
     case init:get_argument(mode) of
-	{ok,[["embedded"]]} ->
-	    embedded;
+	{ok, [FirstMode | Rest]} ->
+	    case Rest of
+		[] ->
+		    ok;
+		_ ->
+		    ?LOG_WARNING("Multiple -mode given to erl, using the first, ~p",
+				 [FirstMode])
+	    end,
+	    case FirstMode of
+		["embedded"] ->
+		    embedded;
+		_ ->
+		    interactive
+	    end;
 	_ ->
 	    interactive
     end.
diff --git a/lib/kernel/src/kernel.erl b/lib/kernel/src/kernel.erl
index bfa091a036..1ca2e0fd11 100644
--- a/lib/kernel/src/kernel.erl
+++ b/lib/kernel/src/kernel.erl
@@ -141,7 +141,7 @@ init([]) ->
                   modules => [logger_sup]},
 
     case init:get_argument(mode) of
-        {ok, [["minimal"]]} ->
+        {ok, [["minimal"]|_]} ->
             {ok, {SupFlags,
                   [Code, File, StdError, User, LoggerSup, Config, RefC, SafeSup]}};
         _ ->
diff --git a/lib/kernel/test/code_SUITE.erl b/lib/kernel/test/code_SUITE.erl
index 4f0847084f..6b133f8d6b 100644
--- a/lib/kernel/test/code_SUITE.erl
+++ b/lib/kernel/test/code_SUITE.erl
@@ -41,7 +41,7 @@
 	 big_boot_embedded/1,
          module_status/1,
 	 native_early_modules/1, get_mode/1,
-	 normalized_paths/1]).
+	 normalized_paths/1, mult_embedded_flags/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2,
 	 init_per_suite/1, end_per_suite/1]).
@@ -72,7 +72,8 @@ all() ->
      on_load_purge, on_load_self_call, on_load_pending,
      on_load_deleted,
      module_status,
-     big_boot_embedded, native_early_modules, get_mode, normalized_paths].
+     big_boot_embedded, native_early_modules, get_mode, normalized_paths,
+     mult_embedded_flags].
 
 %% These need to run in order
 groups() -> [{sequence, [sequence], [on_load_update,
@@ -354,7 +355,7 @@ load_abs(Config) when is_list(Config) ->
 ensure_loaded(Config) when is_list(Config) ->
     {module, lists} = code:ensure_loaded(lists),
     case init:get_argument(mode) of
-	{ok, [["embedded"]]} ->
+	{ok, [["embedded"] | _]} ->
 	    {error, embedded} = code:ensure_loaded(code_b_test),
 	    {error, badarg} = code:ensure_loaded(34),
 	    ok;
@@ -1836,6 +1837,28 @@ do_normalized_paths([M|Ms]) ->
 do_normalized_paths([]) ->
     ok.
 
+%% Make sure that the extra -mode flags are ignored
+mult_embedded_flags(_Config) ->
+    Modes = [{" -mode embedded", embedded},
+	     {" -mode interactive", interactive},
+	     {" -mode invalid", interactive}],
+
+    [ begin
+	  {ArgMode, ExpectedMode} = Mode,
+	  {ok, Node} = start_node(mode_test, ArgMode),
+	  ExpectedMode = rpc:call(Node, code, get_mode, []),
+	  true = stop_node(Node)
+      end || Mode <- Modes],
+
+    [ begin
+	  {ArgIgnoredMode, _} = IgnoredMode,
+	  {ArgRelevantMode, ExpectedMode} = RelevantMode,
+	  {ok, Node} = start_node(mode_test, ArgRelevantMode ++ ArgIgnoredMode),
+	  ExpectedMode = rpc:call(Node, code, get_mode, []),
+	  true = stop_node(Node)
+      end || IgnoredMode <- Modes, RelevantMode <- Modes],
+    ok.
+
 %% Test that module_status/1 behaves as expected
 module_status(_Config) ->
     case test_server:is_cover() of