Merge branch 'maint'

* maint:
  filename: Add safe_relative_path/1

Conflicts:
	lib/stdlib/src/filename.erl

1 files changed, 36 insertions, 1 deletions

diff --git a/lib/stdlib/src/filename.erl b/lib/stdlib/src/filename.erl
index 2a2f25dcd2..b5df5c9d37 100644
--- a/lib/stdlib/src/filename.erl
+++ b/lib/stdlib/src/filename.erl
@@ -37,7 +37,8 @@
 -export([absname/1, absname/2, absname_join/2, 
 	 basename/1, basename/2, dirname/1,
 	 extension/1, join/1, join/2, pathtype/1,
-	 rootname/1, rootname/2, split/1, flatten/1, nativename/1]).
+         rootname/1, rootname/2, split/1, flatten/1, nativename/1,
+         safe_relative_path/1]).
 -export([find_src/1, find_src/2]). % deprecated
 -export([basedir/2, basedir/3]).
 
@@ -753,12 +754,46 @@ separators() ->
 	_ -> {false, false}
     end.
 
+-spec safe_relative_path(Filename) -> 'unsafe' | SafeFilename when
+      Filename :: file:name_all(),
+      SafeFilename :: file:name_all().
+
+safe_relative_path(Path) ->
+    case pathtype(Path) of
+        relative ->
+            Cs0 = split(Path),
+            safe_relative_path_1(Cs0, []);
+        _ ->
+            unsafe
+    end.
+
+safe_relative_path_1(["."|T], Acc) ->
+    safe_relative_path_1(T, Acc);
+safe_relative_path_1([<<".">>|T], Acc) ->
+    safe_relative_path_1(T, Acc);
+safe_relative_path_1([".."|T], Acc) ->
+    climb(T, Acc);
+safe_relative_path_1([<<"..">>|T], Acc) ->
+    climb(T, Acc);
+safe_relative_path_1([H|T], Acc) ->
+    safe_relative_path_1(T, [H|Acc]);
+safe_relative_path_1([], []) ->
+    [];
+safe_relative_path_1([], Acc) ->
+    join(lists:reverse(Acc)).
+
+climb(_, []) ->
+    unsafe;
+climb(T, [_|Acc]) ->
+    safe_relative_path_1(T, Acc).
+
 %% NOTE: The find_src/1/2 functions are deprecated; they try to do too much
 %% at once and are not a good fit for this module. Parts of the code have
 %% been moved to filelib:find_file/2 instead. Only this part of this
 %% module is allowed to call the filelib module; such mutual dependency
 %% should otherwise be avoided! This code should eventually be removed.
 %%
+
 %% find_src(Module) --
 %% find_src(Module, Rules) --
 %%