Issue 3143 - Filter elements with :-abp-has()

chrome/content/elemHideEmulation.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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/>.
  */
 
 /* globals filterToRegExp */
 
 "use strict";
 
-let propertySelectorRegExp = /\[-abp-properties=(["'])([^"']+)\1\]/;
-
 function splitSelector(selector)
 {
   if (selector.indexOf(",") == -1)
     return [selector];
 
   let selectors = [];
   let start = 0;
   let level = 0;
   let sep = "";
 
@@ skipping 18 matching lines @@
         selectors.push(selector.substring(start, i));
         start = i + 1;
       }
     }
   }
 
   selectors.push(selector.substring(start));
   return selectors;
 }
 
+// Return position of node from parent.
+// 1 base index like for :nth-child()
+function positionInParent(node)
+{
+  let parentNode = node ? node.parentNode : null;
+  if (parentNode == null)
+    return 0;
+
+  let {children} = parentNode;
+  if (!children)
+    return 0;
+  let i = 0;
+  for (i = 0; i < children.length; i++)
+    if (children[i] == node)
+      break;
+  return i + 1;
+}
+
+function makeSelector(node, selector)
+{
+  if (node && node.id && node.id != "")

[hub, 2017/05/12 17:31:18]

I need to check that node.id is a valid CSS identifier. I have seen cases in
real life where the id start with a number causing querySelector() to fail. I
already have a patch for that. Will update review with it.

+  {
+    let newSelector = "#" + node.id;
+    if (selector != "")
+      newSelector += " > ";
+    return newSelector + selector;
+  }
+  let idx = positionInParent(node);
+  if (idx > 0)
+  {
+    let newSelector = `${node.tagName}:nth-child(${idx}) `;
+    if (selector != "")
+      newSelector += "> ";
+    return makeSelector(node.parentNode, newSelector + selector);
+  }
+
+  return selector;
+}
+
+// return the regexString for the properties
+function parsePropSelPattern(propertyExpression)
+{
+  let regexpString;
+  if (propertyExpression.length >= 2 && propertyExpression[0] == "/" &&
+      propertyExpression[propertyExpression.length - 1] == "/")
+    regexpString = propertyExpression.slice(1, -1)
+    .replace("\\x7B ", "{").replace("\\x7D ", "}");
+  else
+    regexpString = filterToRegExp(propertyExpression);
+  return regexpString;
+}
+
+function parseSelector(selector)
+{
+  if (selector.length == 0)
+    return [];
+
+  let abpSelectorIndex = selector.indexOf(":-abp-");
+  if (abpSelectorIndex == -1)
+    return [new PlainSelector(selector)];
+
+  let selectors = [];
+  if (abpSelectorIndex > 0)
+    selectors.push(new PlainSelector(selector.substr(0, abpSelectorIndex)));
+
+  let suffixStart = abpSelectorIndex;
+
+  if (selector.indexOf(":-abp-properties(", abpSelectorIndex) ==
+      abpSelectorIndex)
+  {
+    let startIndex = abpSelectorIndex + 17;
+    let endquoteIndex = selector.indexOf(selector[startIndex], startIndex + 1);
+    if ((endquoteIndex == -1) || (selector[endquoteIndex + 1] != ")"))
+      return null;
+
+    selectors.push(new PropsSelector(
+      selector.substr(startIndex + 1, endquoteIndex - startIndex - 1)));
+    suffixStart = endquoteIndex + 2;
+  }
+  else if (selector.indexOf(":-abp-has(", abpSelectorIndex) ==
+      abpSelectorIndex)
+  {
+    let startIndex = abpSelectorIndex + 10;
+    let parens = 1;
+    let i;
+    for (i = startIndex; i < selector.length; i++)
+    {
+      if (selector[i] == "(")
+        parens++;
+      else if (selector[i] == ")")
+        parens--;
+
+      if (parens == 0)
+        break;
+    }
+    if (parens != 0)
+      return null;
+    selectors.push(new HasSelector(
+      selector.substr(startIndex, i - startIndex)));
+    suffixStart = i + 1;
+  }
+
+  let suffix = parseSelector(selector.substr(suffixStart));

[hub, 2017/05/12 19:48:24]

here, if we had been parsing something matching "-abp-*" then we'd infinite
recursion. I do have a patch too.

+  if (suffix)
+    selectors.push(...suffix);
+
+  return selectors;
+}
+
+function matchStyleProps(style, rule, pattern, selectors, filters)
+{
+  if (pattern.regexp.test(style))
+  {
+    let subSelectors = splitSelector(rule.selectorText);
+    for (let i = 0; i < subSelectors.length; i++)
+    {
+      let subSelector = subSelectors[i];
+      selectors.push(pattern.prefix + subSelector + pattern.suffix);
+      filters.push(pattern.text);
+    }
+  }
+}
+
+function findPropsSelectors(stylesheet, pattern, selectors, filters)
+{
+  let rules = stylesheet.cssRules;
+  if (!rules)
+    return;
+
+  for (let rule of rules)
+  {
+    if (rule.type != rule.STYLE_RULE)
+      continue;
+
+    let style = stringifyStyle(rule.style);
+    matchStyleProps(style, rule, pattern, selectors, filters);
+  }
+}
+
+function stringifyStyle(style)
+{
+  let styles = [];
+  for (let i = 0; i < style.length; i++)
+  {
+    let property = style.item(i);
+    let value = style.getPropertyValue(property);
+    let priority = style.getPropertyPriority(property);
+    styles.push(property + ": " + value + (priority ? " !" + priority : "") +
+                ";");
+  }
+  styles.sort();
+  return styles.join(" ");
+}
+
+function* evaluate(chain, index, prefix, subtree, stylesheet)
+{
+  if (index >= chain.length)
+  {
+    yield prefix;
+    return;
+  }
+  for (let [selector, element] of
+       chain[index].getSelectors(prefix, subtree, stylesheet))
+    yield* evaluate(chain, index + 1, selector, element, stylesheet);
+}
+
+/*
+ * getSelector() is a generator function returning a pair of selector
+ * string and subtree.
+ * getElements() is a generator function returning elements selected.
+ */
+function PlainSelector(selector)
+{
+  this._selector = selector;
+}
+
+PlainSelector.prototype = {
+  *getSelectors(prefix, subtree, stylesheet)
+  {
+    yield [prefix + this._selector, subtree];
+  },
+
+  *getElements(prefix, subtree, stylesheet)
+  {
+    for (let selector of this.getSelectors(prefix, subtree, stylesheet))
+      for (let element of subtree.querySelectorAll(selector[0]))
+        yield element;
+  }
+};
+
+function HasSelector(selector)
+{
+  this._innerSelectors = parseSelector(selector);
+}
+
+HasSelector.prototype = {
+  *getSelectors(prefix, subtree, stylesheet)
+  {
+    for (let element of this.getElements(prefix, subtree, stylesheet))
+      yield [prefix + makeSelector(element, ""), subtree];
+  },
+
+  *getElements(prefix, subtree, stylesheet)
+  {
+    let elements = subtree.querySelectorAll(prefix ? prefix : "*");
+    for (let element of elements)
+    {
+      let newPrefix = makeSelector(element, "");
+      let iter = evaluate(this._innerSelectors, 0, "", element, stylesheet);
+      for (let selector of iter)
+        // we insert a space between the two. It becomes a no-op if selector
+        // doesn't have a combinator
+        if (subtree.querySelector(newPrefix + " " + selector))
+          yield element;
+    }
+  }
+};
+
+function PropsSelector(selector)
+{
+  this._regexp = new RegExp(parsePropSelPattern(selector), "i");
+}
+
+PropsSelector.prototype = {
+  *getSelectors(prefix, subtree, stylesheet)
+  {
+    let selectors = [];
+    let filters = [];
+    let selPattern = {
+      prefix,
+      suffix: "",
+      regexp: this._regexp
+    };
+
+    findPropsSelectors(stylesheet, selPattern, selectors, filters);
+    for (let selector of selectors)
+      yield [selector, subtree];
+  },
+
+  *getElements(prefix, subtree, stylesheet)
+  {
+    for (let [selector, element] of
+         this.getSelectors(prefix, subtree, stylesheet))
+      for (let subElement of element.querySelectorAll(selector))
+        yield subElement;
+  }
+};
+
 function ElemHideEmulation(window, getFiltersFunc, addSelectorsFunc)
 {
   this.window = window;
   this.getFiltersFunc = getFiltersFunc;
   this.addSelectorsFunc = addSelectorsFunc;
 }
 
 ElemHideEmulation.prototype = {
-  stringifyStyle(style)
-  {
-    let styles = [];
-    for (let i = 0; i < style.length; i++)
-    {
-      let property = style.item(i);
-      let value = style.getPropertyValue(property);
-      let priority = style.getPropertyPriority(property);
-      styles.push(property + ": " + value + (priority ? " !" + priority : "") +
-                  ";");
-    }
-    styles.sort();
-    return styles.join(" ");
-  },
 
   isSameOrigin(stylesheet)
   {
     try
     {
       return new URL(stylesheet.href).origin == this.window.location.origin;
     }
     catch (e)
     {
       // Invalid URL, assume that it is first-party.
       return true;
     }
   },
 
-  findSelectors(stylesheet, selectors, filters)
-  {
+  addSelectors(stylesheet)
+  {
+    let selectors = [];
+    let filters = [];
+
     // Explicitly ignore third-party stylesheets to ensure consistent behavior
     // between Firefox and Chrome.
     if (!this.isSameOrigin(stylesheet))
       return;
 
-    let rules = stylesheet.cssRules;
-    if (!rules)
-      return;
-
-    for (let rule of rules)
-    {
-      if (rule.type != rule.STYLE_RULE)
-        continue;
-
-      let style = this.stringifyStyle(rule.style);
-      for (let pattern of this.patterns)
+    for (let patterns of this.selPatterns)
+      for (let selector of
+           evaluate(patterns.selectors, 0, "", document, stylesheet))
       {
-        if (pattern.regexp.test(style))
-        {
-          let subSelectors = splitSelector(rule.selectorText);
-          for (let subSelector of subSelectors)
-          {
-            selectors.push(pattern.prefix + subSelector + pattern.suffix);
-            filters.push(pattern.text);
-          }
-        }
+        selectors.push(selector);
+        filters.push(patterns.text);
       }
-    }
-  },
-
-  addSelectors(stylesheets)
-  {
-    let selectors = [];
-    let filters = [];
-    for (let stylesheet of stylesheets)
-      this.findSelectors(stylesheet, selectors, filters);
+
     this.addSelectorsFunc(selectors, filters);
   },
 
   onLoad(event)
   {
     let stylesheet = event.target.sheet;
     if (stylesheet)
-      this.addSelectors([stylesheet]);
+      this.addSelectors(stylesheet);
   },
 
   apply()
   {
     this.getFiltersFunc(patterns =>
     {
-      this.patterns = [];
+      this.selPatterns = [];
+
       for (let pattern of patterns)
       {
-        let match = propertySelectorRegExp.exec(pattern.selector);
-        if (!match)
-          continue;
-
-        let propertyExpression = match[2];
-        let regexpString;
-        if (propertyExpression.length >= 2 && propertyExpression[0] == "/" &&
-            propertyExpression[propertyExpression.length - 1] == "/")
-        {
-          regexpString = propertyExpression.slice(1, -1)
-              .replace("\\x7B ", "{").replace("\\x7D ", "}");
-        }
-        else
-          regexpString = filterToRegExp(propertyExpression);
-
-        this.patterns.push({
-          text: pattern.text,
-          regexp: new RegExp(regexpString, "i"),
-          prefix: pattern.selector.substr(0, match.index),
-          suffix: pattern.selector.substr(match.index + match[0].length)
-        });
+        let selectors = parseSelector(pattern.selector);
+        if (selectors != null && selectors.length > 0)
+          this.selPatterns.push({selectors, text: pattern.text});
       }
 
-      if (this.patterns.length > 0)
+      if (this.selPatterns.length > 0)
       {
         let {document} = this.window;
-        this.addSelectors(document.styleSheets);
+        for (let stylesheet of document.styleSheets)
+          this.addSelectors(stylesheet);
         document.addEventListener("load", this.onLoad.bind(this), true);
       }
     });
   }
 };