Teach filename:find_src/1,2 to handle slim or stripped BEAM files

filename:find_src/1,2 will crash when asked to find the source
corresponding to a BEAM with no compilation options. A BEAM file
can be missing compilation options if it has been stripped using
beam_lib:strip/1 or compiled using the undocumented 'slim' option.

Why this matters: If ERL_COMPILE_OPTIONS is set to +slim before
building Erlang/OTP, there will be a crash in 'igor' during the
building of the public_key application. ('igor' merges several
source code files, and uses filename:find_src/1,2 to find the
source code.)

Change filename:find_src/1,2 to return an empty option list if
there are no options in the BEAM file.

Noticed-by: Per Hedeland

2 files changed, 21 insertions, 2 deletions

diff --git a/lib/stdlib/src/filename.erl b/lib/stdlib/src/filename.erl
index 7144781843..dbfcbea4f7 100644
--- a/lib/stdlib/src/filename.erl
+++ b/lib/stdlib/src/filename.erl
@@ -836,8 +836,11 @@ try_file(undefined, ObjFilename, Mod, Rules) ->
 	Error -> Error
     end;
 try_file(Src, _ObjFilename, Mod, _Rules) ->
-    List = Mod:module_info(compile),
-    {options, Options} = lists:keyfind(options, 1, List),
+    List = case Mod:module_info(compile) of
+	       none -> [];
+	       List0 -> List0
+	   end,
+    Options = proplists:get_value(options, List, []),
     {ok, Cwd} = file:get_cwd(),
     AbsPath = make_abs_path(Cwd, Src),
     {AbsPath, filter_options(dirname(AbsPath), Options, [])}.
diff --git a/lib/stdlib/test/filename_SUITE.erl b/lib/stdlib/test/filename_SUITE.erl
index 70b0d413dc..4cfa589660 100644
--- a/lib/stdlib/test/filename_SUITE.erl
+++ b/lib/stdlib/test/filename_SUITE.erl
@@ -483,6 +483,22 @@ find_src(Config) when is_list(Config) ->
     
     %% Try to find the source for a preloaded module.
     ?line {error,{preloaded,init}} = filename:find_src(init),
+
+    %% Make sure that find_src works for a slim BEAM file.
+    OldPath = code:get_path(),
+    try
+	PrivDir = ?config(priv_dir, Config),
+	code:add_patha(PrivDir),
+	Src = "simple",
+	SrcPath = filename:join(PrivDir, Src) ++ ".erl",
+	SrcContents = "-module(simple).\n",
+	ok = file:write_file(SrcPath, SrcContents),
+	{ok,simple} = compile:file(SrcPath, [slim,{outdir,PrivDir}]),
+	BeamPath = filename:join(PrivDir, Src),
+	{BeamPath,[]} = filename:find_src(simple)
+    after
+	code:set_path(OldPath)
+    end,
     ok.
 
 %%