Issue 5870 - Implement the new ElemHideEmulation filter type

compiled/filter/ElemHideBase.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <cstring>
+
 #include "ElemHideBase.h"
 #include "../StringScanner.h"
 
 namespace
 {
   void NormalizeWhitespace(DependentString& text, String::size_type& domainsEnd,
       String::size_type& selectorStart)
   {
     // For element hiding filters we only want to remove spaces preceding the
     // selector part. The positions we've determined already have to be adjusted
@@ skipping 12 matching lines @@
       // Only spaces before selectorStart position should be removed.
       if (pos < selectorStart && text[pos] == ' ')
         delta++;
       else
         text[pos - delta] = text[pos];
     }
     selectorStart -= delta;
 
     text.reset(text, 0, len - delta);
   }
+
+  // Convert filter from the old syntax to the new.
+  OwnedString ConvertFilter(const String& text, String::size_type at)
+  {
+    static const auto propsSelector = u"[-abp-properties="_str;
+    static const auto newPropsSelector = u":-abp-properties("_str;
+    auto selectorPos = text.find(propsSelector, at);
+    if (selectorPos != text.npos)
+    {
+      auto length = text.length();
+      auto properties = selectorPos + propsSelector.length();
+      String::value_type quote = 0;
+      bool escape = false;
+      String::size_type removed = 0; // how many chars we remove
+      String::size_type end = properties;
+      String::size_type quote_start = 0;
+      String::size_type quote_end = 0;
+      for (auto index = properties;
+           index < length && end == properties; index++)
+      {
+        if (escape)
+        {
+          escape = false;
+          continue;
+        }
+
+        auto c = text[index];
+        switch (c)
+        {
+        case '\\':
+          escape = true;
+          break;
+        case '"':
+        case '\'':
+          if (quote == 0)
+          {
+            quote = c;
+            quote_start = index + 1;
+          }
+          else if (quote == c)
+          {
+            // end of quoted.
+            quote = 0;
+            removed += 2;
+            quote_end = index;
+          }
+          break;
+        case ']':
+          if (quote == 0)
+            end = index + 1; // end of properties (after ])
+          break;
+        default:
+          break;
+        }
+      }
+
+      if (quote != 0)
+        quote_end = end - 1;
+      else if (quote_end <= quote_start)
+      {
+        // we likely didn't find a quoted content so we just take it as is.
+        quote_start = properties;
+        quote_end = end - 1;
+      }
+
+      OwnedString converted(length - removed);
+      String::size_type offset = 0;
+      std::memcpy(converted.data(), text.data(),
+                  selectorPos * sizeof(String::value_type));
+      offset += selectorPos;
+
+      std::memcpy(converted.data() + offset, newPropsSelector.data(),
+                  newPropsSelector.length() * sizeof(String::value_type));
+      offset += newPropsSelector.length();
+
+      std::memcpy(converted.data() + offset, text.data() + quote_start,
+                  (quote_end - quote_start) * sizeof(String::value_type));
+      offset += quote_end - quote_start;
+
+      std::memcpy(converted.data() + offset, u")", sizeof(String::value_type));
+      offset++;
+
+      std::memcpy(converted.data() + offset, text.data() + end,
+                  (length - end) * sizeof(String::value_type));
+      offset += (length - end) * sizeof(String::value_type);
+
+      return converted;
+    }
+
+    return OwnedString(text);
+  }
 }
 
 ElemHideBase::ElemHideBase(Type type, const String& text, const ElemHideData& data)
-    : ActiveFilter(type, text, false), mData(data)
+    : ActiveFilter(type, ConvertFilter(text, data.mSelectorStart), false),
+      mData(data)
 {
   if (mData.HasDomains())
     ParseDomains(mData.GetDomainsSource(mText), u',');
 }
 
 Filter::Type ElemHideBase::Parse(DependentString& text, ElemHideData& data)
 {
   StringScanner scanner(text);
 
   // Domains part
@@ skipping 16 matching lines @@
       case u'"':
       case u'!':
         return Type::UNKNOWN;
       case u' ':
         seenSpaces = true;
         break;
     }
   }
 
   seenSpaces |= scanner.skip(u' ');
+  bool emulation = false;
   bool exception = scanner.skipOne(u'@');
   if (exception)
     seenSpaces |= scanner.skip(u' ');
+  else
+    emulation = scanner.skipOne(u'?');
 
   String::value_type next = scanner.next();
   if (next != u'#')
     return Type::UNKNOWN;
 
   // Selector part
 
   // Selector shouldn't be empty
   seenSpaces |= scanner.skip(u' ');
   if (scanner.done())
@@ skipping 11 matching lines @@
   }
 
   // We are done validating, now we can normalize whitespace and the domain part
   if (seenSpaces)
     NormalizeWhitespace(text, data.mDomainsEnd, data.mSelectorStart);
   DependentString(text, 0, data.mDomainsEnd).toLower();
 
   if (exception)
     return Type::ELEMHIDEEXCEPTION;
 
-  if (text.find(u"[-abp-properties="_str, data.mSelectorStart) != text.npos)
+  if (emulation)
     return Type::ELEMHIDEEMULATION;
 
   return Type::ELEMHIDE;
 }
 
 OwnedString ElemHideBase::GetSelectorDomain() const
 {
   /* TODO this is inefficient */
   OwnedString result;
   if (mDomains)
   {
     for (const auto& item : *mDomains)
     {
       if (item.second && !item.first.empty())
       {
         if (!result.empty())
           result.append(u',');
         result.append(item.first);
       }
     }
   }
   return result;
 }