Fix handling of single dot in filename:join/2

The reference manual says that filename:join(A,B) is equivalent to
filename:join([A,B]). In some rare cases this turns out not to be
true:

1> filename:join("/a/.","b").
"/a/./b"
2> filename:join(["/a/.","b"]).
"/a/b"

In general, filename:join/1,2 removes single dots from the resulting
path, except dots that occur at the beginning or end of the path. The
problem above occurs when the first argument to join/2 ends with a
dot, then it is not removed even if the second argument differs from
an empty string and thus the dot ends up in "the middle" of the path.

This commit corrects this problem. A single dot is now only kept if it
occurs at the very beginning or the very end of the resulting path.

Test of filename:join/1,2 are added in filename_SUITE. In addition,
filelib_SUITE is updated with more tests of filelib:wildcard/2 since
this failed when the given current directory (second argument) ended
with a dot.

2 files changed, 99 insertions, 18 deletions

diff --git a/lib/stdlib/test/filelib_SUITE.erl b/lib/stdlib/test/filelib_SUITE.erl
index 040ae1effc..3fd96142d9 100644
--- a/lib/stdlib/test/filelib_SUITE.erl
+++ b/lib/stdlib/test/filelib_SUITE.erl
@@ -77,7 +77,8 @@ wildcard_one(Config) when is_list(Config) ->
 			  L = filelib:wildcard(Wc),
 			  L = filelib:wildcard(Wc, erl_prim_loader),
 			  L = filelib:wildcard(Wc, "."),
-			  L = filelib:wildcard(Wc, Dir)
+			  L = filelib:wildcard(Wc, Dir),
+			  L = filelib:wildcard(Wc, Dir++"/.")
 		  end),
     ?line file:set_cwd(OldCwd),
     ?line ok = file:del_dir(Dir),
diff --git a/lib/stdlib/test/filename_SUITE.erl b/lib/stdlib/test/filename_SUITE.erl
index ecd9cff9f9..6f1d1a891d 100644
--- a/lib/stdlib/test/filename_SUITE.erl
+++ b/lib/stdlib/test/filename_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1997-2012. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2014. 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
@@ -287,38 +287,66 @@ extension(Config) when is_list(Config) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     
 join(Config) when is_list(Config) ->
+    %% Whenever joining two elements, test the equivalence between
+    %% join/1 and join/2 (OTP-12158) by using help function
+    %% filename_join/2.
     ?line "/" = filename:join(["/"]),
     ?line "/" = filename:join(["//"]),
-    ?line "usr/foo.erl" = filename:join("usr","foo.erl"),
-    ?line "/src/foo.erl" = filename:join(usr, "/src/foo.erl"),
-    ?line "/src/foo.erl" = filename:join(["/src/",'foo.erl']),
-    ?line "/src/foo.erl" = filename:join(usr, ["/sr", 'c/foo.erl']),
-    ?line "/src/foo.erl" = filename:join("usr", "/src/foo.erl"),
+    "usr/foo.erl" = filename_join("usr","foo.erl"),
+    "/src/foo.erl" = filename_join(usr, "/src/foo.erl"),
+    "/src/foo.erl" = filename_join("/src/",'foo.erl'),
+    "/src/foo.erl" = filename_join(usr, ["/sr", 'c/foo.erl']),
+    "/src/foo.erl" = filename_join("usr", "/src/foo.erl"),
 
     %% Make sure that redundant slashes work too.
     ?line "a/b/c/d/e/f/g" = filename:join(["a//b/c/////d//e/f/g"]),
-    ?line "a/b/c/d/e/f/g" = filename:join(["a//b/c/", "d//e/f/g"]),
-    ?line "a/b/c/d/e/f/g" = filename:join(["a//b/c", "d//e/f/g"]),
-    ?line "/d/e/f/g" = filename:join(["a//b/c", "/d//e/f/g"]),
-    ?line "/d/e/f/g" = filename:join(["a//b/c", "//d//e/f/g"]),
-
-    ?line "foo/bar" = filename:join([$f,$o,$o,$/,[]], "bar"),
+    "a/b/c/d/e/f/g" = filename_join("a//b/c/", "d//e/f/g"),
+    "a/b/c/d/e/f/g" = filename_join("a//b/c", "d//e/f/g"),
+    "/d/e/f/g" = filename_join("a//b/c", "/d//e/f/g"),
+    "/d/e/f/g" = filename:join("a//b/c", "//d//e/f/g"),
+
+    "foo/bar" = filename_join([$f,$o,$o,$/,[]], "bar"),
+
+    %% Single dots - should be removed if in the middle of the path,
+    %% but not at the end of the path.
+    "/." = filename:join(["/."]),
+    "/" = filename:join(["/./"]),
+    "/." = filename:join(["/./."]),
+    "./." = filename:join(["./."]),
+
+    "/a/b" = filename_join("/a/.","b"),
+    "/a/b/." = filename_join("/a/.","b/."),
+    "/a/." = filename_join("/a/.","."),
+    "/a/." = filename_join("/a","."),
+    "/a/." = filename_join("/a/.",""),
+    "./." = filename_join("./.","."),
+    "./." = filename_join("./","."),
+    "./." = filename_join("./.",""),
+    "." = filename_join(".",""),
+    "./." = filename_join(".","."),
+
+    %% Trailing slash shall be removed - except the root
+    "/" = filename:join(["/"]),
+    "/" = filename:join(["/./"]),
+    "/a" = filename:join(["/a/"]),
+    "/b" = filename_join("/a/","/b/"),
+    "/a/b" = filename_join("/a/","b/"),
 
     ?line case os:type() of
 	      {win32, _} ->
 		  ?line "d:/" = filename:join(["D:/"]),
 		  ?line "d:/" = filename:join(["D:\\"]),
-		  ?line "d:/abc" = filename:join(["D:/", "abc"]),
-		  ?line "d:abc" = filename:join(["D:", "abc"]),
+		  "d:/abc" = filename_join("D:/", "abc"),
+		  "d:abc" = filename_join("D:", "abc"),
 		  ?line "a/b/c/d/e/f/g" =
 		      filename:join(["a//b\\c//\\/\\d/\\e/f\\g"]),
 		  ?line "a:usr/foo.erl" =
 		      filename:join(["A:","usr","foo.erl"]),
 		  ?line "/usr/foo.erl" =
 		      filename:join(["A:","/usr","foo.erl"]),
-		  ?line "c:usr" = filename:join("A:","C:usr"),
-		  ?line "a:usr" = filename:join("A:","usr"),
-		  ?line "c:/usr" = filename:join("A:", "C:/usr"),
+		  "c:usr" = filename_join("A:","C:usr"),
+		  "a:usr" = filename_join("A:","usr"),
+		  "c:/usr" = filename_join("A:", "C:/usr"),
 		  ?line "c:/usr/foo.erl" =
 		      filename:join(["A:","C:/usr","foo.erl"]),
 		  ?line "c:usr/foo.erl" =
@@ -329,6 +357,11 @@ join(Config) when is_list(Config) ->
 		  ok
 	  end.
 
+%% Make sure join([A,B]) is equivalent to join(A,B) (OTP-12158)
+filename_join(A,B) ->
+    Res = filename:join(A,B),
+    Res = filename:join([A,B]).
+
 pathtype(Config) when is_list(Config) ->
     ?line relative = filename:pathtype(".."),
     ?line relative = filename:pathtype("foo"),
@@ -633,6 +666,53 @@ join_bin(Config) when is_list(Config) ->
 
     ?line <<"foo/bar">> = filename:join([$f,$o,$o,$/,[]], <<"bar">>),
 
+    %% Single dots - should be removed if in the middle of the path,
+    %% but not at the end of the path.
+    %% Also test equivalence between join/1 and join/2 (OTP-12158)
+    <<"/.">> = filename:join([<<"/.">>]),
+    <<"/">> = filename:join([<<"/./">>]),
+    <<"/.">> = filename:join([<<"/./.">>]),
+    <<"./.">> = filename:join([<<"./.">>]),
+
+    <<"/a/b">> = filename:join([<<"/a/.">>,<<"b">>]),
+    <<"/a/b">> = filename:join(<<"/a/.">>,<<"b">>),
+
+    <<"/a/b/.">> = filename:join([<<"/a/.">>,<<"b/.">>]),
+    <<"/a/b/.">> = filename:join(<<"/a/.">>,<<"b/.">>),
+
+    <<"/a/.">> = filename:join([<<"/a/.">>,<<".">>]),
+    <<"/a/.">> = filename:join(<<"/a/.">>,<<".">>),
+
+    <<"/a/.">> = filename:join([<<"/a">>,<<".">>]),
+    <<"/a/.">> = filename:join(<<"/a">>,<<".">>),
+
+    <<"/a/.">> = filename:join([<<"/a/.">>,<<"">>]),
+    <<"/a/.">> = filename:join(<<"/a/.">>,<<"">>),
+
+    <<"./.">> = filename:join([<<"./.">>,<<".">>]),
+    <<"./.">> = filename:join(<<"./.">>,<<".">>),
+
+    <<"./.">> = filename:join([<<"./">>,<<".">>]),
+    <<"./.">> = filename:join(<<"./">>,<<".">>),
+
+    <<"./.">> = filename:join([<<"./.">>,<<"">>]),
+    <<"./.">> = filename:join(<<"./.">>,<<"">>),
+
+    <<".">> = filename:join([<<".">>,<<"">>]),
+    <<".">> = filename:join(<<".">>,<<"">>),
+
+    <<"./.">> = filename:join([<<".">>,<<".">>]),
+    <<"./.">> = filename:join(<<".">>,<<".">>),
+
+    %% Trailing slash shall be removed - except the root
+    <<"/">> = filename:join([<<"/">>]),
+    <<"/">> = filename:join([<<"/./">>]),
+    <<"/a">> = filename:join([<<"/a/">>]),
+    <<"/b">> = filename:join([<<"/a/">>,<<"/b/">>]),
+    <<"/b">> = filename:join(<<"/a/">>,<<"/b/">>),
+    <<"/a/b">> = filename:join([<<"/a/">>,<<"b/">>]),
+    <<"/a/b">> = filename:join(<<"/a/">>,<<"b/">>),
+
     ?line case os:type() of
 	      {win32, _} ->
 		  ?line <<"d:/">> = filename:join([<<"D:/">>]),