* src/xml.erl: Better escaping management with CDATA. We only add CDATA enclosure...

SVN Revision: 844

diff --git a/ChangeLog b/ChangeLog
index 31f888b52ae584ed6e6ba04ee37f82688d716616..56e19a51b8a9999ce9a108723daf2cfaa85f2b02 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2007-07-30  Mickael Remond  <mickael.remond@process-one.net>
 
+       * src/xml.erl: Better escaping management with CDATA. We only add
+       CDATA enclosure when needed. CDATA end token is properly escaped.
+
        * src/xml.erl: Only wrap xmldata nodes in xml cdata "tag" if
        bigger than 50 bytes. Shorter xmlcdata nodes will be escaped.
        

diff --git a/src/xml.erl b/src/xml.erl
index 2108d6920da7a88adfd173b8d93b325a589cfed2..1e869be6ad6c6444ea8124417c830cb165d41bf3 100644 (file)
--- a/src/xml.erl
+++ b/src/xml.erl
@@ -20,9 +20,6 @@
         get_path_s/2,
         replace_tag_attr/3]).
 
-%% XML CDATA bigger than this will be enclosed in CDATA XML "tag"
--define(CDATA_BINARY_THRESHOLD, 50).
-
 element_to_string(El) ->
     case El of
        {xmlelement, Name, Attrs, Els} ->
@@ -35,11 +32,9 @@ element_to_string(El) ->
                    [$<, Name, attrs_to_list(Attrs), $/, $>]
               end;
        %% We do not crypt CDATA binary, but we enclose it in XML CDATA
-       %% if they are long enough to be worth it.
-       {xmlcdata, CData} when binary(CData), size(CData) > ?CDATA_BINARY_THRESHOLD ->
-           CDATA1 = <<"<![CDATA[">>,
-           CDATA2 = <<"]]>">>,
-           concat_binary([CDATA1, CData, CDATA2]);
+       {xmlcdata, CData}
+       when binary(CData) ->
+           make_text_node(CData);
        %% We crypt list and short binaries (implies a conversion to
        %% list).
        {xmlcdata, CData} ->
@@ -63,6 +58,71 @@ crypt(S) when is_list(S) ->
      end || C <- S];
 crypt(S) when is_binary(S) ->
     crypt(binary_to_list(S)).
+
+%% Make a cdata_binary depending on what characters it contains
+make_text_node(CData) ->
+    case cdata_need_escape(CData) of
+       cdata ->
+           CDATA1 = <<"<![CDATA[">>,
+           CDATA2 = <<"]]>">>,
+           concat_binary([CDATA1, CData, CDATA2]);
+       none ->
+           CData;
+       {cdata, EndTokens} ->
+           EscapedCData = escape_cdata(CData, EndTokens),
+           concat_binary(EscapedCData)
+    end.
+
+%% Returns escape type needed for the text node
+%% none, cdata, {cdata, [Positions]}
+%% Positions is a list a integer containing positions of CDATA end
+%% tokens, so that they can be escaped
+cdata_need_escape(CData) ->
+    cdata_need_escape(CData, 0, false, []).
+cdata_need_escape(<<>>, _, false, _) ->
+    none;
+cdata_need_escape(<<>>, _, true, []) ->
+    cdata;
+cdata_need_escape(<<>>, _, true, CDataEndTokens) ->
+    {cdata, lists:reverse(CDataEndTokens)};
+cdata_need_escape(<<$],$],$>,Rest/binary>>, CurrentPosition,
+                  _XMLEscape, CDataEndTokens) ->
+    NewPosition = CurrentPosition + 3,
+    cdata_need_escape(Rest, NewPosition, true,
+                      [CurrentPosition+1|CDataEndTokens]);
+%% Only <, & need to be escaped in XML text node
+%% See reference: http://www.w3.org/TR/xml11/#syntax
+cdata_need_escape(<<$<,Rest/binary>>, CurrentPosition,
+                  _XMLEscape, CDataEndTokens) ->
+    cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
+cdata_need_escape(<<$&,Rest/binary>>, CurrentPosition,
+                  _XMLEscape, CDataEndTokens) ->
+    cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
+cdata_need_escape(<<_:8,Rest/binary>>, CurrentPosition,
+                 XMLEscape, CDataEndTokens) ->
+    cdata_need_escape(Rest, CurrentPosition+1, XMLEscape,
+                      CDataEndTokens).
+
+%% escape cdata that contain CDATA end tokens
+%% EndTokens is a list of position of end tokens (integer)
+%% This is supposed to be a very rare case: You need to generate several
+%% fields, splitting it in the middle of the end token.
+%% See example: http://en.wikipedia.org/wiki/CDATA#Uses_of_CDATA_sections
+escape_cdata(CData, EndTokens) ->
+    escape_cdata(CData, 0, EndTokens, []).
+escape_cdata(<<>>, _CurrentPosition, [], Acc) ->
+    lists:reverse(Acc);
+escape_cdata(Rest, CurrentPosition, [], Acc) ->
+    CDATA1 = <<"<![CDATA[">>,
+    CDATA2 = <<"]]>">>,
+    escape_cdata(<<>>, CurrentPosition, [], [CDATA2, Rest, CDATA1|Acc]);
+escape_cdata(CData, Index, [Pos|Positions], Acc) ->
+    CDATA1 = <<"<![CDATA[">>,
+    CDATA2 = <<"]]>">>,
+    Split = Pos-Index,
+    {Part, Rest} = split_binary(CData, Split+1),
+    %% Note: We build the list in reverse to optimize construction
+    escape_cdata(Rest, Pos+1, Positions, [CDATA2, Part, CDATA1|Acc]).
         
 remove_cdata_p({xmlelement, _Name, _Attrs, _Els}) -> true;
 remove_cdata_p(_) -> false.