Fix handling of broken symlinks in filelib

This fixes a bug introduced in f11aabdc9fec593c31e6c4f3fa25c1707e9c35df where
filelib:eval_read_file_info/2 was made to use file:read_link_info/1 to never
follow symlinks. This fixed wildcard/1 but broke every other function using
eval_read_file_info/2.

Reported-by: Louis-Philippe Gauthier
Reported-by: Danil Zagoskin

3 files changed, 40 insertions, 5 deletions

diff --git a/lib/kernel/src/erl_boot_server.erl b/lib/kernel/src/erl_boot_server.erl
index 9a49655a9f..ef09d86ca4 100644
--- a/lib/kernel/src/erl_boot_server.erl
+++ b/lib/kernel/src/erl_boot_server.erl
@@ -341,9 +341,13 @@ handle_command(S, PS, Msg) ->
 	    send_file_result(S, list_dir, Res),
 	    PS2;
 	{read_file_info,File} ->
-	    {Res, PS2} = erl_prim_loader:prim_read_file_info(PS, File),
+	    {Res, PS2} = erl_prim_loader:prim_read_file_info(PS, File, true),
 	    send_file_result(S, read_file_info, Res),
 	    PS2;
+        {read_link_info,File} ->
+            {Res, PS2} = erl_prim_loader:prim_read_file_info(PS, File, false),
+            send_file_result(S, read_link_info, Res),
+            PS2;
 	get_cwd ->
 	    {Res, PS2} = erl_prim_loader:prim_get_cwd(PS, []),
 	    send_file_result(S, get_cwd, Res),
diff --git a/lib/stdlib/src/filelib.erl b/lib/stdlib/src/filelib.erl
index c0921e4cf1..9efbe8da20 100644
--- a/lib/stdlib/src/filelib.erl
+++ b/lib/stdlib/src/filelib.erl
@@ -265,7 +265,7 @@ do_wildcard(Pattern, Cwd, Mod) ->
     lists:sort(Files).
 
 do_wildcard_1({exists,File}, Mod) ->
-    case eval_read_file_info(File, Mod) of
+    case eval_read_link_info(File, Mod) of
 	{ok,_} -> [File];
 	_ -> []
     end;
@@ -488,7 +488,7 @@ badpattern(Reason) ->
     error({badpattern,Reason}).
 
 eval_read_file_info(File, file) ->
-    file:read_link_info(File);
+    file:read_file_info(File);
 eval_read_file_info(File, erl_prim_loader) ->
     case erl_prim_loader:read_file_info(File) of
 	error -> {error, erl_prim_loader};
@@ -497,6 +497,16 @@ eval_read_file_info(File, erl_prim_loader) ->
 eval_read_file_info(File, Mod) ->
     Mod:read_file_info(File).
 
+eval_read_link_info(File, file) ->
+    file:read_link_info(File);
+eval_read_link_info(File, erl_prim_loader) ->
+    case erl_prim_loader:read_link_info(File) of
+        error -> {error, erl_prim_loader};
+        Res-> Res
+    end;
+eval_read_link_info(File, Mod) ->
+    Mod:read_link_info(File).
+
 eval_list_dir(Dir, file) ->
     file:list_dir(Dir);
 eval_list_dir(Dir, erl_prim_loader) ->
diff --git a/lib/stdlib/test/filelib_SUITE.erl b/lib/stdlib/test/filelib_SUITE.erl
index 8203a03a7a..f1a072194a 100644
--- a/lib/stdlib/test/filelib_SUITE.erl
+++ b/lib/stdlib/test/filelib_SUITE.erl
@@ -23,7 +23,8 @@
 	 init_per_group/2,end_per_group/2,
 	 init_per_testcase/2,end_per_testcase/2,
 	 wildcard_one/1,wildcard_two/1,wildcard_errors/1,
-	 fold_files/1,otp_5960/1,ensure_dir_eexist/1,symlinks/1]).
+	 fold_files/1,otp_5960/1,ensure_dir_eexist/1,ensure_dir_symlink/1,
+     symlinks/1]).
 
 -import(lists, [foreach/2]).
 
@@ -43,7 +44,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [wildcard_one, wildcard_two, wildcard_errors,
-     fold_files, otp_5960, ensure_dir_eexist, symlinks].
+     fold_files, otp_5960, ensure_dir_eexist, ensure_dir_symlink, symlinks].
 
 groups() -> 
     [].
@@ -367,6 +368,26 @@ ensure_dir_eexist(Config) when is_list(Config) ->
     ?line {error, eexist} = filelib:ensure_dir(NeedFileB),
     ok.
 
+ensure_dir_symlink(Config) when is_list(Config) ->
+    PrivDir = ?config(priv_dir, Config),
+    Dir = filename:join(PrivDir, "ensure_dir_symlink"),
+    Name = filename:join(Dir, "same_name_as_file_and_dir"),
+    ok = filelib:ensure_dir(Name),
+    ok = file:write_file(Name, <<"some string\n">>),
+    %% With a symlink to the directory.
+    Symlink = filename:join(PrivDir, "ensure_dir_symlink_link"),
+    case file:make_symlink(Dir, Symlink) of
+        {error,enotsup} ->
+            {skip,"Symlinks not supported on this platform"};
+        {error,eperm} ->
+            {win32,_} = os:type(),
+            {skip,"Windows user not privileged to create symlinks"};
+        ok ->
+            SymlinkedName = filename:join(Symlink, "same_name_as_file_and_dir"),
+            ok = filelib:ensure_dir(SymlinkedName)
+    end.
+
+
 symlinks(Config) when is_list(Config) ->
     PrivDir = ?config(priv_dir, Config),
     Dir = filename:join(PrivDir, ?MODULE_STRING++"_symlinks"),