The Tor Browser: dom/xslt/xpath/txPathExpr.cpp@97036ab72558 (annotated)

dom/xslt/xpath/txPathExpr.cpp@97036ab72558 (annotated)

dom/xslt/xpath/txPathExpr.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "txExpr.h"
 #include "txNodeSet.h"
 #include "txNodeSetContext.h"
 #include "txSingleNodeContext.h"
 #include "txXMLUtils.h"
 #include "txXPathTreeWalker.h"
   //------------/
  //- PathExpr -/
 //------------/
 /**
  * Adds the Expr to this PathExpr
  * @param expr the Expr to add to this PathExpr
 **/
 nsresult
 PathExpr::addExpr(Expr* aExpr, PathOperator aPathOp)
 {
     NS_ASSERTION(!mItems.IsEmpty() || aPathOp == RELATIVE_OP,
                  "First step has to be relative in PathExpr");
     PathExprItem* pxi = mItems.AppendElement();
     if (!pxi) {
         return NS_ERROR_OUT_OF_MEMORY;
     }
     pxi->expr = aExpr;
     pxi->pathOp = aPathOp;
     return NS_OK;
 }
     //-----------------------------/
   //- Virtual methods from Expr -/
 //-----------------------------/
 /**
  * Evaluates this Expr based on the given context node and processor state
  * @param context the context node for evaluation of this Expr
  * @param ps the ContextState containing the stack information needed
  * for evaluation
  * @return the result of the evaluation
 **/
 nsresult
 PathExpr::evaluate(txIEvalContext* aContext, txAExprResult** aResult)
 {
     *aResult = nullptr;
     // We need to evaluate the first step with the current context since it
     // can depend on the context size and position. For example:
     // key('books', concat('book', position()))
     nsRefPtr<txAExprResult> res;
     nsresult rv = mItems[0].expr->evaluate(aContext, getter_AddRefs(res));
     NS_ENSURE_SUCCESS(rv, rv);
     NS_ENSURE_TRUE(res->getResultType() == txAExprResult::NODESET,
                    NS_ERROR_XSLT_NODESET_EXPECTED);
     nsRefPtr<txNodeSet> nodes = static_cast<txNodeSet*>
                                            (static_cast<txAExprResult*>
                                                        (res));
     if (nodes->isEmpty()) {
         res.swap(*aResult);
         return NS_OK;
     }
     res = nullptr; // To allow recycling
     // Evaluate remaining steps
     uint32_t i, len = mItems.Length();
     for (i = 1; i < len; ++i) {
         PathExprItem& pxi = mItems[i];
         nsRefPtr<txNodeSet> tmpNodes;
         txNodeSetContext eContext(nodes, aContext);
         while (eContext.hasNext()) {
             eContext.next();
             nsRefPtr<txNodeSet> resNodes;
             if (pxi.pathOp == DESCENDANT_OP) {
                 rv = aContext->recycler()->getNodeSet(getter_AddRefs(resNodes));
                 NS_ENSURE_SUCCESS(rv, rv);
                 rv = evalDescendants(pxi.expr, eContext.getContextNode(),
                                      &eContext, resNodes);
                 NS_ENSURE_SUCCESS(rv, rv);
             }
             else {
                 nsRefPtr<txAExprResult> res;
                 rv = pxi.expr->evaluate(&eContext, getter_AddRefs(res));
                 NS_ENSURE_SUCCESS(rv, rv);
                 if (res->getResultType() != txAExprResult::NODESET) {
                     //XXX ErrorReport: report nonnodeset error
                     return NS_ERROR_XSLT_NODESET_EXPECTED;
                 }
                 resNodes = static_cast<txNodeSet*>
                                       (static_cast<txAExprResult*>
                                                   (res));
             }
             if (tmpNodes) {
                 if (!resNodes->isEmpty()) {
                     nsRefPtr<txNodeSet> oldSet;
                     oldSet.swap(tmpNodes);
                     rv = aContext->recycler()->
                         getNonSharedNodeSet(oldSet, getter_AddRefs(tmpNodes));
                     NS_ENSURE_SUCCESS(rv, rv);
                     oldSet.swap(resNodes);
                     rv = aContext->recycler()->
                         getNonSharedNodeSet(oldSet, getter_AddRefs(resNodes));
                     NS_ENSURE_SUCCESS(rv, rv);
                     tmpNodes->addAndTransfer(resNodes);
                 }
             }
             else {
                 tmpNodes = resNodes;
             }
         }
         nodes = tmpNodes;
         if (nodes->isEmpty()) {
             break;
         }
     }
     *aResult = nodes;
     NS_ADDREF(*aResult);
     return NS_OK;
 } //-- evaluate
 /**
  * Selects from the descendants of the context node
  * all nodes that match the Expr
 **/
 nsresult
 PathExpr::evalDescendants(Expr* aStep, const txXPathNode& aNode,
                           txIMatchContext* aContext, txNodeSet* resNodes)
 {
     txSingleNodeContext eContext(aNode, aContext);
     nsRefPtr<txAExprResult> res;
     nsresult rv = aStep->evaluate(&eContext, getter_AddRefs(res));
     NS_ENSURE_SUCCESS(rv, rv);
     if (res->getResultType() != txAExprResult::NODESET) {
         //XXX ErrorReport: report nonnodeset error
         return NS_ERROR_XSLT_NODESET_EXPECTED;
     }
     txNodeSet* oldSet = static_cast<txNodeSet*>
                                    (static_cast<txAExprResult*>(res));
     nsRefPtr<txNodeSet> newSet;
     rv = aContext->recycler()->getNonSharedNodeSet(oldSet,
                                                    getter_AddRefs(newSet));
     NS_ENSURE_SUCCESS(rv, rv);
     resNodes->addAndTransfer(newSet);
     bool filterWS = aContext->isStripSpaceAllowed(aNode);
     txXPathTreeWalker walker(aNode);
     if (!walker.moveToFirstChild()) {
         return NS_OK;
     }
     do {
         const txXPathNode& node = walker.getCurrentPosition();
         if (!(filterWS && txXPathNodeUtils::isText(node) &&
               txXPathNodeUtils::isWhitespace(node))) {
             rv = evalDescendants(aStep, node, aContext, resNodes);
             NS_ENSURE_SUCCESS(rv, rv);
         }
     } while (walker.moveToNextSibling());
     return NS_OK;
 } //-- evalDescendants
 Expr::ExprType
 PathExpr::getType()
 {
   return PATH_EXPR;
 }
 TX_IMPL_EXPR_STUBS_BASE(PathExpr, NODESET_RESULT)
 Expr*
 PathExpr::getSubExprAt(uint32_t aPos)
 {
     return aPos < mItems.Length() ? mItems[aPos].expr.get() : nullptr;
 }
 void
 PathExpr::setSubExprAt(uint32_t aPos, Expr* aExpr)
 {
     NS_ASSERTION(aPos < mItems.Length(), "setting bad subexpression index");
     mItems[aPos].expr.forget();
     mItems[aPos].expr = aExpr;
 }
 bool
 PathExpr::isSensitiveTo(ContextSensitivity aContext)
 {
     if (mItems[0].expr->isSensitiveTo(aContext)) {
         return true;
     }
     // We're creating a new node/nodeset so we can ignore those bits.
     Expr::ContextSensitivity context =
         aContext & ~(Expr::NODE_CONTEXT | Expr::NODESET_CONTEXT);
     if (context == NO_CONTEXT) {
         return false;
     }
     uint32_t i, len = mItems.Length();
     for (i = 0; i < len; ++i) {
         NS_ASSERTION(!mItems[i].expr->isSensitiveTo(Expr::NODESET_CONTEXT),
                      "Step cannot depend on nodeset-context");
         if (mItems[i].expr->isSensitiveTo(context)) {
             return true;
         }
     }
     return false;
 }
 #ifdef TX_TO_STRING
 void
 PathExpr::toString(nsAString& dest)
 {
     if (!mItems.IsEmpty()) {
         NS_ASSERTION(mItems[0].pathOp == RELATIVE_OP,
                      "First step should be relative");
         mItems[0].expr->toString(dest);
     }
     uint32_t i, len = mItems.Length();
     for (i = 1; i < len; ++i) {
         switch (mItems[i].pathOp) {
             case DESCENDANT_OP:
                 dest.AppendLiteral("//");
                 break;
             case RELATIVE_OP:
                 dest.Append(char16_t('/'));
                 break;
         }
         mItems[i].expr->toString(dest);
     }
 }
 #endif

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dom/xslt/xpath/txPathExpr.cpp@97036ab72558 (annotated)

dom/xslt/xpath/txPathExpr.cpp