Source/WebCore/contentextensions/ContentExtensionParser.cpp - third_party/webkit - Git at Google

 /*
  * Copyright (C) 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "ContentExtensionParser.h"

 #if ENABLE(CONTENT_EXTENSIONS)

 #include "CSSParser.h"
 #include "CSSParserMode.h"
 #include "CSSSelectorList.h"
 #include "ContentExtensionError.h"
 #include "ContentExtensionRule.h"
 #include "ContentExtensionsBackend.h"
 #include "ContentExtensionsDebugging.h"
 #include <JavaScriptCore/JSCInlines.h>
 #include <JavaScriptCore/JSGlobalObject.h>
 #include <JavaScriptCore/JSONObject.h>
 #include <JavaScriptCore/VM.h>
 #include <wtf/CurrentTime.h>
 #include <wtf/text/WTFString.h>

 using namespace JSC;

 namespace WebCore {

 namespace ContentExtensions {

 static bool containsOnlyASCIIWithNoUppercase(const String& domain)
 {
     for (unsigned i = 0; i < domain.length(); ++i) {
         UChar c = domain.at(i);
         if (!isASCII(c) || isASCIIUpper(c))
             return false;
     }
     return true;
 }

 static std::error_code getDomainList(ExecState& exec, const JSObject* arrayObject, Vector<String>& vector)
 {
     VM& vm = exec.vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     ASSERT(vector.isEmpty());
     if (!arrayObject || !isJSArray(arrayObject))
         return ContentExtensionError::JSONInvalidDomainList;
     const JSArray* array = jsCast<const JSArray*>(arrayObject);

     unsigned length = array->length();
     for (unsigned i = 0; i < length; ++i) {
         const JSValue value = array->getIndex(&exec, i);
         if (scope.exception() || !value.isString())
             return ContentExtensionError::JSONInvalidDomainList;

         // Domains should be punycode encoded lower case.
         const String& domain = jsCast<JSString*>(value)->value(&exec);
         if (domain.isEmpty())
             return ContentExtensionError::JSONInvalidDomainList;
         if (!containsOnlyASCIIWithNoUppercase(domain))
             return ContentExtensionError::JSONDomainNotLowerCaseASCII;
         vector.append(domain);
     }
     return { };
 }

 static std::error_code getTypeFlags(ExecState& exec, const JSValue& typeValue, ResourceFlags& flags, uint16_t (*stringToType)(const String&))
 {
     VM& vm = exec.vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     if (!typeValue.isObject())
         return { };

     const JSObject* object = typeValue.toObject(&exec);
     ASSERT(!scope.exception());
     if (!isJSArray(object))
         return ContentExtensionError::JSONInvalidTriggerFlagsArray;

     const JSArray* array = jsCast<const JSArray*>(object);

     unsigned length = array->length();
     for (unsigned i = 0; i < length; ++i) {
         const JSValue value = array->getIndex(&exec, i);
         if (scope.exception() || !value)
             return ContentExtensionError::JSONInvalidObjectInTriggerFlagsArray;

         String name = value.toWTFString(&exec);
         uint16_t type = stringToType(name);
         if (!type)
             return ContentExtensionError::JSONInvalidStringInTriggerFlagsArray;

         flags |= type;
     }

     return { };
 }

 static std::error_code loadTrigger(ExecState& exec, const JSObject& ruleObject, Trigger& trigger)
 {
     VM& vm = exec.vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     const JSValue triggerObject = ruleObject.get(&exec, Identifier::fromString(&exec, "trigger"));
     if (!triggerObject || scope.exception() || !triggerObject.isObject())
         return ContentExtensionError::JSONInvalidTrigger;

     const JSValue urlFilterObject = triggerObject.get(&exec, Identifier::fromString(&exec, "url-filter"));
     if (!urlFilterObject || scope.exception() || !urlFilterObject.isString())
         return ContentExtensionError::JSONInvalidURLFilterInTrigger;

     String urlFilter = urlFilterObject.toWTFString(&exec);
     if (urlFilter.isEmpty())
         return ContentExtensionError::JSONInvalidURLFilterInTrigger;

     trigger.urlFilter = urlFilter;

     const JSValue urlFilterCaseValue = triggerObject.get(&exec, Identifier::fromString(&exec, "url-filter-is-case-sensitive"));
     if (urlFilterCaseValue && !scope.exception() && urlFilterCaseValue.isBoolean())
         trigger.urlFilterIsCaseSensitive = urlFilterCaseValue.toBoolean(&exec);

     const JSValue resourceTypeValue = triggerObject.get(&exec, Identifier::fromString(&exec, "resource-type"));
     if (!scope.exception() && resourceTypeValue.isObject()) {
         auto typeFlagsError = getTypeFlags(exec, resourceTypeValue, trigger.flags, readResourceType);
         if (typeFlagsError)
             return typeFlagsError;
     } else if (!resourceTypeValue.isUndefined())
         return ContentExtensionError::JSONInvalidTriggerFlagsArray;

     const JSValue loadTypeValue = triggerObject.get(&exec, Identifier::fromString(&exec, "load-type"));
     if (!scope.exception() && loadTypeValue.isObject()) {
         auto typeFlagsError = getTypeFlags(exec, loadTypeValue, trigger.flags, readLoadType);
         if (typeFlagsError)
             return typeFlagsError;
     } else if (!loadTypeValue.isUndefined())
         return ContentExtensionError::JSONInvalidTriggerFlagsArray;

     const JSValue ifDomain = triggerObject.get(&exec, Identifier::fromString(&exec, "if-domain"));
     if (!scope.exception() && ifDomain.isObject()) {
         auto ifDomainError = getDomainList(exec, asObject(ifDomain), trigger.domains);
         if (ifDomainError)
             return ifDomainError;
         if (trigger.domains.isEmpty())
             return ContentExtensionError::JSONInvalidDomainList;
         ASSERT(trigger.domainCondition == Trigger::DomainCondition::None);
         trigger.domainCondition = Trigger::DomainCondition::IfDomain;
     } else if (!ifDomain.isUndefined())
         return ContentExtensionError::JSONInvalidDomainList;

     const JSValue unlessDomain = triggerObject.get(&exec, Identifier::fromString(&exec, "unless-domain"));
     if (!scope.exception() && unlessDomain.isObject()) {
         if (trigger.domainCondition != Trigger::DomainCondition::None)
             return ContentExtensionError::JSONUnlessAndIfDomain;
         auto unlessDomainError = getDomainList(exec, asObject(unlessDomain), trigger.domains);
         if (unlessDomainError)
             return unlessDomainError;
         if (trigger.domains.isEmpty())
             return ContentExtensionError::JSONInvalidDomainList;
         trigger.domainCondition = Trigger::DomainCondition::UnlessDomain;
     } else if (!unlessDomain.isUndefined())
         return ContentExtensionError::JSONInvalidDomainList;

     return { };
 }

 static bool isValidSelector(const String& selector)
 {
     CSSParserContext context(HTMLQuirksMode);
     CSSParser parser(context);
     CSSSelectorList selectorList;
     parser.parseSelector(selector, selectorList);
     return selectorList.isValid();
 }

 static std::error_code loadAction(ExecState& exec, const JSObject& ruleObject, Action& action, bool& validSelector)
 {
     VM& vm = exec.vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     validSelector = true;
     const JSValue actionObject = ruleObject.get(&exec, Identifier::fromString(&exec, "action"));
     if (!actionObject || scope.exception() || !actionObject.isObject())
         return ContentExtensionError::JSONInvalidAction;

     const JSValue typeObject = actionObject.get(&exec, Identifier::fromString(&exec, "type"));
     if (!typeObject || scope.exception() || !typeObject.isString())
         return ContentExtensionError::JSONInvalidActionType;

     String actionType = typeObject.toWTFString(&exec);

     if (actionType == "block")
         action = ActionType::BlockLoad;
     else if (actionType == "ignore-previous-rules")
         action = ActionType::IgnorePreviousRules;
     else if (actionType == "block-cookies")
         action = ActionType::BlockCookies;
     else if (actionType == "css-display-none") {
         JSValue selector = actionObject.get(&exec, Identifier::fromString(&exec, "selector"));
         if (!selector || scope.exception() || !selector.isString())
             return ContentExtensionError::JSONInvalidCSSDisplayNoneActionType;

         String s = selector.toWTFString(&exec);
         if (!isValidSelector(s)) {
             // Skip rules with invalid selectors to be backwards-compatible.
             validSelector = false;
             return { };
         }
         action = Action(ActionType::CSSDisplayNoneSelector, s);
     } else if (actionType == "make-https") {
         action = ActionType::MakeHTTPS;
     } else
         return ContentExtensionError::JSONInvalidActionType;

     return { };
 }

 static std::error_code loadRule(ExecState& exec, const JSObject& ruleObject, Vector<ContentExtensionRule>& ruleList)
 {
     Trigger trigger;
     auto triggerError = loadTrigger(exec, ruleObject, trigger);
     if (triggerError)
         return triggerError;

     Action action;
     bool validSelector;
     auto actionError = loadAction(exec, ruleObject, action, validSelector);
     if (actionError)
         return actionError;

     if (validSelector)
         ruleList.append(ContentExtensionRule(trigger, action));
     return { };
 }

 static std::error_code loadEncodedRules(ExecState& exec, const String& rules, Vector<ContentExtensionRule>& ruleList)
 {
     VM& vm = exec.vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     // FIXME: JSONParse should require callbacks instead of an ExecState.
     const JSValue decodedRules = JSONParse(&exec, rules);

     if (scope.exception() || !decodedRules)
         return ContentExtensionError::JSONInvalid;

     if (!decodedRules.isObject())
         return ContentExtensionError::JSONTopLevelStructureNotAnObject;

     const JSObject* topLevelObject = decodedRules.toObject(&exec);
     if (!topLevelObject || scope.exception())
         return ContentExtensionError::JSONTopLevelStructureNotAnObject;

     if (!isJSArray(topLevelObject))
         return ContentExtensionError::JSONTopLevelStructureNotAnArray;

     const JSArray* topLevelArray = jsCast<const JSArray*>(topLevelObject);

     Vector<ContentExtensionRule> localRuleList;

     unsigned length = topLevelArray->length();
     const unsigned maxRuleCount = 50000;
     if (length > maxRuleCount)
         return ContentExtensionError::JSONTooManyRules;
     for (unsigned i = 0; i < length; ++i) {
         const JSValue value = topLevelArray->getIndex(&exec, i);
         if (scope.exception() || !value)
             return ContentExtensionError::JSONInvalidObjectInTopLevelArray;

         const JSObject* ruleObject = value.toObject(&exec);
         if (!ruleObject || scope.exception())
             return ContentExtensionError::JSONInvalidRule;

         auto error = loadRule(exec, *ruleObject, localRuleList);
         if (error)
             return error;
     }

     ruleList = WTFMove(localRuleList);
     return { };
 }

 std::error_code parseRuleList(const String& rules, Vector<ContentExtensionRule>& ruleList)
 {
 #if CONTENT_EXTENSIONS_PERFORMANCE_REPORTING
     double loadExtensionStartTime = monotonicallyIncreasingTime();
 #endif
     RefPtr<VM> vm = VM::create();

     JSLockHolder locker(vm.get());
     JSGlobalObject* globalObject = JSGlobalObject::create(*vm, JSGlobalObject::createStructure(*vm, jsNull()));

     ExecState* exec = globalObject->globalExec();
     auto error = loadEncodedRules(*exec, rules, ruleList);

     vm = nullptr;

     if (error)
         return error;

     if (ruleList.isEmpty())
         return ContentExtensionError::JSONContainsNoRules;

 #if CONTENT_EXTENSIONS_PERFORMANCE_REPORTING
     double loadExtensionEndTime = monotonicallyIncreasingTime();
     dataLogF("Time spent loading extension %f\n", (loadExtensionEndTime - loadExtensionStartTime));
 #endif

     return { };
 }

 } // namespace ContentExtensions
 } // namespace WebCore

 #endif // ENABLE(CONTENT_EXTENSIONS)
	/*
	* Copyright (C) 2014 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	* THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "ContentExtensionParser.h"

	#if ENABLE(CONTENT_EXTENSIONS)

	#include "CSSParser.h"
	#include "CSSParserMode.h"
	#include "CSSSelectorList.h"
	#include "ContentExtensionError.h"
	#include "ContentExtensionRule.h"
	#include "ContentExtensionsBackend.h"
	#include "ContentExtensionsDebugging.h"
	#include <JavaScriptCore/JSCInlines.h>
	#include <JavaScriptCore/JSGlobalObject.h>
	#include <JavaScriptCore/JSONObject.h>
	#include <JavaScriptCore/VM.h>
	#include <wtf/CurrentTime.h>
	#include <wtf/text/WTFString.h>

	using namespace JSC;

	namespace WebCore {

	namespace ContentExtensions {

	static bool containsOnlyASCIIWithNoUppercase(const String& domain)
	{
	for (unsigned i = 0; i < domain.length(); ++i) {
	UChar c = domain.at(i);
	if (!isASCII(c) \|\| isASCIIUpper(c))
	return false;
	}
	return true;
	}

	static std::error_code getDomainList(ExecState& exec, const JSObject* arrayObject, Vector<String>& vector)
	{
	VM& vm = exec.vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	ASSERT(vector.isEmpty());
	if (!arrayObject \|\| !isJSArray(arrayObject))
	return ContentExtensionError::JSONInvalidDomainList;
	const JSArray* array = jsCast<const JSArray*>(arrayObject);

	unsigned length = array->length();
	for (unsigned i = 0; i < length; ++i) {
	const JSValue value = array->getIndex(&exec, i);
	if (scope.exception() \|\| !value.isString())
	return ContentExtensionError::JSONInvalidDomainList;

	// Domains should be punycode encoded lower case.
	const String& domain = jsCast<JSString*>(value)->value(&exec);
	if (domain.isEmpty())
	return ContentExtensionError::JSONInvalidDomainList;
	if (!containsOnlyASCIIWithNoUppercase(domain))
	return ContentExtensionError::JSONDomainNotLowerCaseASCII;
	vector.append(domain);
	}
	return { };
	}

	static std::error_code getTypeFlags(ExecState& exec, const JSValue& typeValue, ResourceFlags& flags, uint16_t (*stringToType)(const String&))
	{
	VM& vm = exec.vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	if (!typeValue.isObject())
	return { };

	const JSObject* object = typeValue.toObject(&exec);
	ASSERT(!scope.exception());
	if (!isJSArray(object))
	return ContentExtensionError::JSONInvalidTriggerFlagsArray;

	const JSArray* array = jsCast<const JSArray*>(object);

	unsigned length = array->length();
	for (unsigned i = 0; i < length; ++i) {
	const JSValue value = array->getIndex(&exec, i);
	if (scope.exception() \|\| !value)
	return ContentExtensionError::JSONInvalidObjectInTriggerFlagsArray;

	String name = value.toWTFString(&exec);
	uint16_t type = stringToType(name);
	if (!type)
	return ContentExtensionError::JSONInvalidStringInTriggerFlagsArray;

	flags \|= type;
	}

	return { };
	}

	static std::error_code loadTrigger(ExecState& exec, const JSObject& ruleObject, Trigger& trigger)
	{
	VM& vm = exec.vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	const JSValue triggerObject = ruleObject.get(&exec, Identifier::fromString(&exec, "trigger"));
	if (!triggerObject \|\| scope.exception() \|\| !triggerObject.isObject())
	return ContentExtensionError::JSONInvalidTrigger;

	const JSValue urlFilterObject = triggerObject.get(&exec, Identifier::fromString(&exec, "url-filter"));
	if (!urlFilterObject \|\| scope.exception() \|\| !urlFilterObject.isString())
	return ContentExtensionError::JSONInvalidURLFilterInTrigger;

	String urlFilter = urlFilterObject.toWTFString(&exec);
	if (urlFilter.isEmpty())
	return ContentExtensionError::JSONInvalidURLFilterInTrigger;

	trigger.urlFilter = urlFilter;

	const JSValue urlFilterCaseValue = triggerObject.get(&exec, Identifier::fromString(&exec, "url-filter-is-case-sensitive"));
	if (urlFilterCaseValue && !scope.exception() && urlFilterCaseValue.isBoolean())
	trigger.urlFilterIsCaseSensitive = urlFilterCaseValue.toBoolean(&exec);

	const JSValue resourceTypeValue = triggerObject.get(&exec, Identifier::fromString(&exec, "resource-type"));
	if (!scope.exception() && resourceTypeValue.isObject()) {
	auto typeFlagsError = getTypeFlags(exec, resourceTypeValue, trigger.flags, readResourceType);
	if (typeFlagsError)
	return typeFlagsError;
	} else if (!resourceTypeValue.isUndefined())
	return ContentExtensionError::JSONInvalidTriggerFlagsArray;

	const JSValue loadTypeValue = triggerObject.get(&exec, Identifier::fromString(&exec, "load-type"));
	if (!scope.exception() && loadTypeValue.isObject()) {
	auto typeFlagsError = getTypeFlags(exec, loadTypeValue, trigger.flags, readLoadType);
	if (typeFlagsError)
	return typeFlagsError;
	} else if (!loadTypeValue.isUndefined())
	return ContentExtensionError::JSONInvalidTriggerFlagsArray;

	const JSValue ifDomain = triggerObject.get(&exec, Identifier::fromString(&exec, "if-domain"));
	if (!scope.exception() && ifDomain.isObject()) {
	auto ifDomainError = getDomainList(exec, asObject(ifDomain), trigger.domains);
	if (ifDomainError)
	return ifDomainError;
	if (trigger.domains.isEmpty())
	return ContentExtensionError::JSONInvalidDomainList;
	ASSERT(trigger.domainCondition == Trigger::DomainCondition::None);
	trigger.domainCondition = Trigger::DomainCondition::IfDomain;
	} else if (!ifDomain.isUndefined())
	return ContentExtensionError::JSONInvalidDomainList;

	const JSValue unlessDomain = triggerObject.get(&exec, Identifier::fromString(&exec, "unless-domain"));
	if (!scope.exception() && unlessDomain.isObject()) {
	if (trigger.domainCondition != Trigger::DomainCondition::None)
	return ContentExtensionError::JSONUnlessAndIfDomain;
	auto unlessDomainError = getDomainList(exec, asObject(unlessDomain), trigger.domains);
	if (unlessDomainError)
	return unlessDomainError;
	if (trigger.domains.isEmpty())
	return ContentExtensionError::JSONInvalidDomainList;
	trigger.domainCondition = Trigger::DomainCondition::UnlessDomain;
	} else if (!unlessDomain.isUndefined())
	return ContentExtensionError::JSONInvalidDomainList;

	return { };
	}

	static bool isValidSelector(const String& selector)
	{
	CSSParserContext context(HTMLQuirksMode);
	CSSParser parser(context);
	CSSSelectorList selectorList;
	parser.parseSelector(selector, selectorList);
	return selectorList.isValid();
	}

	static std::error_code loadAction(ExecState& exec, const JSObject& ruleObject, Action& action, bool& validSelector)
	{
	VM& vm = exec.vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	validSelector = true;
	const JSValue actionObject = ruleObject.get(&exec, Identifier::fromString(&exec, "action"));
	if (!actionObject \|\| scope.exception() \|\| !actionObject.isObject())
	return ContentExtensionError::JSONInvalidAction;

	const JSValue typeObject = actionObject.get(&exec, Identifier::fromString(&exec, "type"));
	if (!typeObject \|\| scope.exception() \|\| !typeObject.isString())
	return ContentExtensionError::JSONInvalidActionType;

	String actionType = typeObject.toWTFString(&exec);

	if (actionType == "block")
	action = ActionType::BlockLoad;
	else if (actionType == "ignore-previous-rules")
	action = ActionType::IgnorePreviousRules;
	else if (actionType == "block-cookies")
	action = ActionType::BlockCookies;
	else if (actionType == "css-display-none") {
	JSValue selector = actionObject.get(&exec, Identifier::fromString(&exec, "selector"));
	if (!selector \|\| scope.exception() \|\| !selector.isString())
	return ContentExtensionError::JSONInvalidCSSDisplayNoneActionType;

	String s = selector.toWTFString(&exec);
	if (!isValidSelector(s)) {
	// Skip rules with invalid selectors to be backwards-compatible.
	validSelector = false;
	return { };
	}
	action = Action(ActionType::CSSDisplayNoneSelector, s);
	} else if (actionType == "make-https") {
	action = ActionType::MakeHTTPS;
	} else
	return ContentExtensionError::JSONInvalidActionType;

	return { };
	}

	static std::error_code loadRule(ExecState& exec, const JSObject& ruleObject, Vector<ContentExtensionRule>& ruleList)
	{
	Trigger trigger;
	auto triggerError = loadTrigger(exec, ruleObject, trigger);
	if (triggerError)
	return triggerError;

	Action action;
	bool validSelector;
	auto actionError = loadAction(exec, ruleObject, action, validSelector);
	if (actionError)
	return actionError;

	if (validSelector)
	ruleList.append(ContentExtensionRule(trigger, action));
	return { };
	}

	static std::error_code loadEncodedRules(ExecState& exec, const String& rules, Vector<ContentExtensionRule>& ruleList)
	{
	VM& vm = exec.vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	// FIXME: JSONParse should require callbacks instead of an ExecState.
	const JSValue decodedRules = JSONParse(&exec, rules);

	if (scope.exception() \|\| !decodedRules)
	return ContentExtensionError::JSONInvalid;

	if (!decodedRules.isObject())
	return ContentExtensionError::JSONTopLevelStructureNotAnObject;

	const JSObject* topLevelObject = decodedRules.toObject(&exec);
	if (!topLevelObject \|\| scope.exception())
	return ContentExtensionError::JSONTopLevelStructureNotAnObject;

	if (!isJSArray(topLevelObject))
	return ContentExtensionError::JSONTopLevelStructureNotAnArray;

	const JSArray* topLevelArray = jsCast<const JSArray*>(topLevelObject);

	Vector<ContentExtensionRule> localRuleList;

	unsigned length = topLevelArray->length();
	const unsigned maxRuleCount = 50000;
	if (length > maxRuleCount)
	return ContentExtensionError::JSONTooManyRules;
	for (unsigned i = 0; i < length; ++i) {
	const JSValue value = topLevelArray->getIndex(&exec, i);
	if (scope.exception() \|\| !value)
	return ContentExtensionError::JSONInvalidObjectInTopLevelArray;

	const JSObject* ruleObject = value.toObject(&exec);
	if (!ruleObject \|\| scope.exception())
	return ContentExtensionError::JSONInvalidRule;

	auto error = loadRule(exec, *ruleObject, localRuleList);
	if (error)
	return error;
	}

	ruleList = WTFMove(localRuleList);
	return { };
	}

	std::error_code parseRuleList(const String& rules, Vector<ContentExtensionRule>& ruleList)
	{
	#if CONTENT_EXTENSIONS_PERFORMANCE_REPORTING
	double loadExtensionStartTime = monotonicallyIncreasingTime();
	#endif
	RefPtr<VM> vm = VM::create();

	JSLockHolder locker(vm.get());
	JSGlobalObject* globalObject = JSGlobalObject::create(vm, JSGlobalObject::createStructure(vm, jsNull()));

	ExecState* exec = globalObject->globalExec();
	auto error = loadEncodedRules(*exec, rules, ruleList);

	vm = nullptr;

	if (error)
	return error;

	if (ruleList.isEmpty())
	return ContentExtensionError::JSONContainsNoRules;

	#if CONTENT_EXTENSIONS_PERFORMANCE_REPORTING
	double loadExtensionEndTime = monotonicallyIncreasingTime();
	dataLogF("Time spent loading extension %f\n", (loadExtensionEndTime - loadExtensionStartTime));
	#endif

	return { };
	}

	} // namespace ContentExtensions
	} // namespace WebCore

	#endif // ENABLE(CONTENT_EXTENSIONS)