Revert "Merge branch 'rickard/null-char-filenames/ERL-370/OTP-14543' into maint"

This reverts commit 0717a2194e863f3a78595184ccc5637697f03353, reversing
changes made to 71a40658a0cef8b3e25df3a8e48a72d0563a89bf.

6 files changed, 5 insertions, 230 deletions

diff --git a/lib/stdlib/doc/src/filelib.xml b/lib/stdlib/doc/src/filelib.xml
index 57c4348745..80c4acffdb 100644
--- a/lib/stdlib/doc/src/filelib.xml
+++ b/lib/stdlib/doc/src/filelib.xml
@@ -45,30 +45,6 @@
 
     <p>For more information about raw filenames, see the
       <seealso marker="kernel:file"><c>file</c></seealso> module.</p>
-
-    <note>
-      <p>
-	Functionality in this module generally assumes valid input and
-	does not necessarily fail on input that does not use a valid
-	encoding. You can validate the encoding of a filename using
-	<seealso marker="stdlib:filename#validate/1">filename:validate/1</seealso>.
-      </p>
-      <p>
-	File operations used to accept filenames containing
-	null characters (integer value zero). This caused
-	the name to be truncated at the first null character.
-	Filenames containing null characters inside the filename
-	are now <em>rejected</em> and will cause primitive
-	file operations fail.
-      </p>
-    </note>
-    <warning><p>
-      Currently null characters at the end of the filename
-      will be accepted by primitive file operations. Such
-      filenames are however still documented as invalid. The
-      implementation will also change in the future and
-      reject such filenames.
-    </p></warning>
   </description>
 
   <datatypes>
diff --git a/lib/stdlib/doc/src/filename.xml b/lib/stdlib/doc/src/filename.xml
index b6028fc066..14fd5ef787 100644
--- a/lib/stdlib/doc/src/filename.xml
+++ b/lib/stdlib/doc/src/filename.xml
@@ -46,10 +46,7 @@
       filename by removing redundant directory separators, use
       <seealso marker="#join/1"><c>join/1</c></seealso>.</p>
 
-    <p>
-      The module supports
-      <seealso marker="unicode_usage#notes-about-raw-filenames">raw
-      filenames</seealso> in the way that if a binary is
+    <p>The module supports raw filenames in the way that if a binary is
       present, or the filename cannot be interpreted according to the return
       value of <seealso marker="kernel:file#native_name_encoding/0">
       <c>file:native_name_encoding/0</c></seealso>, a raw filename is also
@@ -59,30 +56,6 @@
       (the join operation is performed of course). For more information
       about raw filenames, see the
       <seealso marker="kernel:file"><c>file</c></seealso> module.</p>
-
-    <note>
-      <p>
-	Functionality in this module generally assumes valid input and
-	does not necessarily fail on input that does not use a valid
-	encoding. You can validate the encoding of a filename using
-	<seealso marker="#validate/1">filename:validate/1</seealso>.
-      </p>
-      <p>
-	File operations used to accept filenames containing
-	null characters (integer value zero). This caused
-	the name to be truncated at the first null character.
-	Filenames containing null characters inside the filename
-	are now <em>rejected</em> and will cause primitive
-	file operations fail.
-      </p>
-    </note>
-    <warning><p>
-      Currently null characters at the end of the filename
-      will be accepted by primitive file operations. Such
-      filenames are however still documented as invalid. The
-      implementation will also change in the future and
-      reject such filenames.
-    </p></warning>
   </description>
   <datatypes>
       <datatype>
@@ -582,55 +555,6 @@ unsafe</pre>
 ["a:/","msdev","include"]</pre>
       </desc>
     </func>
-
-    <func>
-      <name name="validate" arity="1"/>
-      <fsummary>Validate encoding of filename</fsummary>
-      <desc>
-	<p>
-	  Validates filename encoding. Returns <c>true</c> if
-	  <c><anno>FileName</anno></c> has a valid encoding;
-	  otherwise, returns <c>false</c>.
-	</p>
-	<taglist>
-	  <tag>Ordinary Filename</tag>
-	  <item>
-	    <p>
-	      Type: <c><anno>FileName</anno> = </c><seealso marker="kernel:file#type-name"><c>file:name()</c></seealso>
-	    </p>
-	    <p>
-	      Validates encoding against the
-	      <seealso marker="kernel:file#native_name_encoding/0">native file
-	      name encoding</seealso>, and the
-	      capabilities of the operating system used.
-	      Regardless of configuration and OS, null
-	      characters (integer value zero) will be
-	      rejected by the validation  (even when only
-	      present at the end of the filename).
-	    </p>
-	  </item>
-	  <tag><seealso marker="unicode_usage#notes-about-raw-filenames">Raw
-	  Filename</seealso></tag>
-	  <item>
-	    <p>
-	      Type: <c><anno>FileName</anno> = binary()</c>
-	    </p>
-	    <p>
-	      The encoding will not be interpreted, but
-	      null bytes (integer value zero) will be
-	      rejected by the validation (even when only
-	      present at the end of the filename).
-	    </p>
-	  </item>
-	</taglist>
-	<p>
-	  For information on filename encoding see the documentation
-	  of unicode filenames in
-	  <seealso marker="stdlib:unicode_usage#unicode_file_names">STDLIB
-	  Users Guide ➜ Using Unicode in Erlang ➜ Unicode Filenames</seealso>.
-	</p>
-      </desc>
-    </func>
   </funcs>
 </erlref>
 
diff --git a/lib/stdlib/doc/src/unicode_usage.xml b/lib/stdlib/doc/src/unicode_usage.xml
index ff1f864e22..26dc46719e 100644
--- a/lib/stdlib/doc/src/unicode_usage.xml
+++ b/lib/stdlib/doc/src/unicode_usage.xml
@@ -719,8 +719,8 @@ Eshell V5.10.1  (abort with ^G)
   </section> 
 
   <section>
-    <marker id="unicode_file_names"/>
     <title>Unicode Filenames</title>
+    <marker id="unicode_file_names"/>
     <p>Most modern operating systems support Unicode filenames in some way.
       There are many different ways to do this and Erlang by default treats the
       different approaches differently:</p>
@@ -855,8 +855,8 @@ Eshell V5.10.1  (abort with ^G)
     </note>
 
     <section>
-      <marker id="notes-about-raw-filenames"/>
       <title>Notes About Raw Filenames</title>
+      <marker id="notes-about-raw-filenames"/>
       <p>Raw filenames were introduced together with Unicode filename support
         in ERTS 5.8.2 (Erlang/OTP R14B01). The reason &quot;raw
         filenames&quot; were introduced in the system was
diff --git a/lib/stdlib/src/filename.erl b/lib/stdlib/src/filename.erl
index 1c3ab6d274..9bf4290916 100644
--- a/lib/stdlib/src/filename.erl
+++ b/lib/stdlib/src/filename.erl
@@ -41,7 +41,6 @@
          safe_relative_path/1]).
 -export([find_src/1, find_src/2]). % deprecated
 -export([basedir/2, basedir/3]).
--export([validate/1]).
 
 %% Undocumented and unsupported exports.
 -export([append/2]).
@@ -1136,72 +1135,3 @@ basedir_os_type() ->
         {win32,_}     -> windows;
         _             -> linux
     end.
-
-%%
-%% validate/1
-%%
-
--spec validate(FileName) -> boolean() when
-      FileName :: file:name_all().
-
-validate(FileName) when is_binary(FileName) ->
-    %% Raw filename...
-    validate_bin(FileName);
-validate(FileName) when is_list(FileName);
-                        is_atom(FileName) ->
-    validate_list(FileName,
-                  file:native_name_encoding(),
-                  os:type()).
-
-validate_list(FileName, Enc, Os) ->
-    try
-        true = validate_list(FileName, Enc, Os, 0) > 0
-    catch
-        _ : _ -> false
-    end.
-
-validate_list([], _Enc, _Os, Chars) ->
-    Chars;
-validate_list(C, Enc, Os, Chars) when is_integer(C) ->
-    validate_char(C, Enc, Os),
-    Chars+1;
-validate_list(A, Enc, Os, Chars) when is_atom(A) ->
-    validate_list(atom_to_list(A), Enc, Os, Chars);
-validate_list([H|T], Enc, Os, Chars) ->
-    NewChars = validate_list(H, Enc, Os, Chars),
-    validate_list(T, Enc, Os, NewChars).
-
-%% C is always an integer...
-% validate_char(C, _, _) when not is_integer(C) ->
-%     throw(invalid);
-validate_char(C, _, _) when C < 1 ->
-    throw(invalid); %% No negative or null characters...
-validate_char(C, latin1, _) when C > 255 ->
-    throw(invalid);
-validate_char(C, utf8, _) when C >= 16#110000 ->
-    throw(invalid);
-validate_char(C, utf8, {win32, _}) when C > 16#ffff ->
-    throw(invalid); %% invalid win wchar...
-validate_char(_C, utf8, {win32, _}) ->
-    ok; %% Range below is accepted on windows...
-validate_char(C, utf8, _) when 16#D800 =< C, C =< 16#DFFF ->
-    throw(invalid); %% invalid unicode range...
-validate_char(_, _, _) ->
-    ok.
-
-validate_bin(Bin) ->
-    %% Raw filename. That is, we do not interpret
-    %% the encoding, but we still do not accept
-    %% null characters...
-    try
-        true = validate_bin(Bin, 0) > 0
-    catch
-        _ : _ -> false
-    end.
-
-validate_bin(<<>>, Bs) ->
-    Bs;
-validate_bin(<<0, _Rest/binary>>, _Bs) ->
-    throw(invalid); %% No null characters allowed...
-validate_bin(<<_B, Rest/binary>>, Bs) ->
-    validate_bin(Rest, Bs+1).
diff --git a/lib/stdlib/src/stdlib.app.src b/lib/stdlib/src/stdlib.app.src
index 41c89270aa..3c449d3cb9 100644
--- a/lib/stdlib/src/stdlib.app.src
+++ b/lib/stdlib/src/stdlib.app.src
@@ -107,7 +107,7 @@
                dets]},
   {applications, [kernel]},
   {env, []},
-  {runtime_dependencies, ["sasl-3.0","kernel-5.4.1","erts-9.1.1","crypto-3.3",
+  {runtime_dependencies, ["sasl-3.0","kernel-5.0","erts-9.0","crypto-3.3",
 			  "compiler-5.0"]}
 ]}.
 
diff --git a/lib/stdlib/test/filename_SUITE.erl b/lib/stdlib/test/filename_SUITE.erl
index 4c82ec1c22..fc77593bb8 100644
--- a/lib/stdlib/test/filename_SUITE.erl
+++ b/lib/stdlib/test/filename_SUITE.erl
@@ -30,7 +30,6 @@
 -export([pathtype_bin/1,rootname_bin/1,split_bin/1]).
 -export([t_basedir_api/1, t_basedir_xdg/1, t_basedir_windows/1]).
 -export([safe_relative_path/1]).
--export([validate/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -44,8 +43,7 @@ all() ->
      absname_bin, absname_bin_2,
      {group,p},
      t_basedir_xdg, t_basedir_windows,
-     safe_relative_path,
-     validate].
+     safe_relative_path].
 
 groups() -> 
     [{p, [parallel],
@@ -1013,56 +1011,3 @@ basedir_xdg_def(Type,Home,Name) ->
                         Dir <- ["/usr/local/share/","/usr/share/"]];
         site_config -> [filename:join(["/etc/xdg",Name])]
     end.
-
-validate(Config) when is_list(Config) ->
-    true = filename:validate(blipp),
-    false = filename:validate('bli\0pp'),
-    false = filename:validate('blipp\0'),
-    true = filename:validate("blipp"),
-    false = filename:validate("bli"++[0]++"pp"),
-    false = filename:validate("blipp"++[0]),
-    true = filename:validate(["one ", blipp, "blopp"]),
-    false = filename:validate(["one ", 'bli\0pp', "blopp"]),
-    false = filename:validate(["one ", 'blipp\0', "blopp"]),
-    false = filename:validate(["one ", 'blipp', "blopp\0"]),
-    false = filename:validate([0]),
-    false = filename:validate([]),
-    false = filename:validate([[[]],[[[[],[[[[[[[[]]], '', [[[[[]]]]]]]]]]]]]]),
-    false = filename:validate([16#110000]),
-    false = filename:validate([16#110001]),
-    false = filename:validate([16#110000*2]),
-    case file:native_name_encoding() of
-        latin1 ->
-            true = filename:validate(lists:seq(1, 255)),
-            false = filename:validate([256]);
-        utf8 ->
-            true = filename:validate(lists:seq(1, 16#D7FF)),
-            true = filename:validate(lists:seq(16#E000, 16#FFFF)),
-            true = filename:validate([16#FFFF]),
-            case os:type() of
-                {win32, _} ->
-                    false = filename:validate([16#10000]),
-                    true = filename:validate(lists:seq(16#D800,16#DFFF));
-                _ ->
-                    true = filename:validate([16#10000]),
-                    true = filename:validate([16#10FFFF]),
-                    lists:foreach(fun (C) ->
-                                          false = filename:validate([C])
-                                  end,
-                                  lists:seq(16#D800,16#DFFF))
-            end
-                        
-    end,
-    true = filename:validate(<<1,17,255>>),
-    false = filename:validate(<<1,0,17,255>>),
-    false = filename:validate(<<1,17,255,0>>),
-    false = filename:validate(<<>>),
-    lists:foreach(fun (N) ->
-                          true = filename:validate(N)
-                  end,
-                  code:get_path()),
-    ok.
-
-            
-    
-