Merge branch 'ta/ensure_dir_eexist' into ccase/r13b04_dev

* ta/ensure_dir_eexist:
  filelib_SUITE: strenghten tests of filelib:ensure_dir/1
  Don't return a false {error,eexist} in filelib:ensure_dir/1

OTP-8389  Because of a race condition, using filelib:ensure_dir/1 from
          multiple processes to create the same path or parts of the same
          directory structure, filelib:ensure_dir/1 could return a
          meaningless {error,eexist}. That race condition has been
          eliminated, and {error,eexist} will now be returned only if there
          exists a regular file, device file, or some other non-directory
          file with the same name. (Thanks to Tuncer Ayaz.)

2 files changed, 39 insertions, 13 deletions

diff --git a/lib/stdlib/src/filelib.erl b/lib/stdlib/src/filelib.erl
index d65588f0d1..74c5172137 100644
--- a/lib/stdlib/src/filelib.erl
+++ b/lib/stdlib/src/filelib.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 
 -module(filelib).
@@ -228,7 +228,17 @@ ensure_dir(F) ->
 	    ok;
 	false ->
 	    ensure_dir(Dir),
-	    file:make_dir(Dir)
+	    case file:make_dir(Dir) of
+		{error,eexist}=EExist ->
+		    case do_is_dir(Dir, file) of
+			true ->
+			    ok;
+			false ->
+			    EExist
+		    end;
+		Err ->
+		    Err
+	    end
     end.
 
 
diff --git a/lib/stdlib/test/filelib_SUITE.erl b/lib/stdlib/test/filelib_SUITE.erl
index c9c6054f7b..d54741051f 100644
--- a/lib/stdlib/test/filelib_SUITE.erl
+++ b/lib/stdlib/test/filelib_SUITE.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 2005-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 2005-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 
@@ -21,7 +21,7 @@
 
 -export([all/1,init_per_testcase/2,fin_per_testcase/2,
 	 wildcard_one/1,wildcard_two/1,wildcard_errors/1,
-	 fold_files/1,otp_5960/1]).
+	 fold_files/1,otp_5960/1,ensure_dir_eexist/1]).
 
 -import(lists, [foreach/2]).
 
@@ -38,7 +38,8 @@ fin_per_testcase(_Case, Config) ->
     ok.
 
 all(suite) ->
-    [wildcard_one,wildcard_two,wildcard_errors,fold_files,otp_5960].
+    [wildcard_one,wildcard_two,wildcard_errors,fold_files,otp_5960,
+     ensure_dir_eexist].
 
 wildcard_one(Config) when is_list(Config) ->
     ?line {ok,OldCwd} = file:get_cwd(),
@@ -223,7 +224,9 @@ otp_5960(Config) when is_list(Config) ->
     ?line Name1 = filename:join(Dir, name1),
     ?line Name2 = filename:join(Dir, name2),
     ?line ok = filelib:ensure_dir(Name1), % parent is created
+    ?line ok = filelib:ensure_dir(Name1), % repeating it should be OK
     ?line ok = filelib:ensure_dir(Name2), % parent already exists
+    ?line ok = filelib:ensure_dir(Name2), % repeating it should be OK
     ?line Name3 = filename:join(Name1, name3),
     ?line {ok, FileInfo} = file:read_file_info(Dir),
     case os:type() of
@@ -239,3 +242,16 @@ otp_5960(Config) when is_list(Config) ->
 	    ?line ok = file:write_file_info(Dir, #file_info{mode=Mode}),
 	    ok
     end.
+
+ensure_dir_eexist(Config) when is_list(Config) ->
+    ?line PrivDir = ?config(priv_dir, Config),
+    ?line Dir = filename:join(PrivDir, ensure_dir_eexist),
+    ?line Name = filename:join(Dir, "same_name_as_file_and_dir"),
+    ?line ok = filelib:ensure_dir(Name),
+    ?line ok = file:write_file(Name, <<"some string\n">>),
+
+    %% There already is a file with the name of the directory
+    %% we want to create.
+    ?line NeedFile = filename:join(Name, "file"),
+    ?line {error, eexist} = filelib:ensure_dir(NeedFile),
+    ok.