Issue 5174 - Allow '{' and '}' in selectors

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
@@ skipping 85 matching lines @@
     return Type::UNKNOWN;
 
   // Selector part
 
   // Selector shouldn't be empty
   seenSpaces |= scanner.skip(u' ');
   if (scanner.done())
     return Type::UNKNOWN;
 
   data.mSelectorStart = scanner.position() + 1;
-  while (!scanner.done())
-  {
-    switch (scanner.next())
-    {
-      case u'{':
-      case u'}':
-        return Type::UNKNOWN;
-    }
-  }
 
   // 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)
     return Type::ELEMHIDEEMULATION;
 
   return Type::ELEMHIDE;
 }
 
+namespace {
+
+OwnedString EscapeCurlies(String::size_type first, const DependentString& str)
+{
+  OwnedString result;
+
+  String::size_type start = 0;
+  String::size_type i = first;
+  for (; i < str.length(); i++)
+  {
+    if (str[i] == '}' || str[i] == '{')
+    {
+      if (i != start)
+        result.append(str.data() + start, i - start);
+      start = i + 1;
+      switch(str[i])
+      {
+      case '}':
+        result.append("\\x7D ", 5);
+        break;
+      case '{':
+        result.append("\\x7B ", 5);
+        break;
+      default:
+        break;
+      }
+    }
+  }
+  if (start < i)
+    result.append(str.data() + start, i - start);

[Wladimir Palant, 2017/10/17 10:24:33]

This is performing lots of reallocations. Please calculate the string size up
front and allocate the buffer as necessary.

[hub, 2017/10/17 19:22:18]

Done.

+  return result;
+}
+
+}
+
+OwnedString ElemHideBase::GetSelector() const
+{
+  DependentString selector = mData.GetSelector(mText);
+
+  for (String::size_type i = 0; i < selector.length(); i++)
+    if (selector[i] == '}' || selector[i] == '{')
+      return EscapeCurlies(i, selector);
+
+  return OwnedString(selector);
+}
+
 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;
 }