| /* |
| * Copyright (C) 2015 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. ``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 |
| * 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 "PropertyCondition.h" |
| |
| #include "GetterSetter.h" |
| #include "JSCInlines.h" |
| #include "TrackedReferences.h" |
| |
| namespace JSC { |
| |
| static bool verbose = false; |
| |
| void PropertyCondition::dumpInContext(PrintStream& out, DumpContext* context) const |
| { |
| if (!*this) { |
| out.print("<invalid>"); |
| return; |
| } |
| |
| out.print(m_kind, " of ", m_uid); |
| switch (m_kind) { |
| case Presence: |
| out.print(" at ", offset(), " with attributes ", attributes()); |
| return; |
| case Absence: |
| case AbsenceOfSetter: |
| out.print(" with prototype ", inContext(JSValue(prototype()), context)); |
| return; |
| case Equivalence: |
| out.print(" with ", inContext(requiredValue(), context)); |
| return; |
| } |
| RELEASE_ASSERT_NOT_REACHED(); |
| } |
| |
| void PropertyCondition::dump(PrintStream& out) const |
| { |
| dumpInContext(out, nullptr); |
| } |
| |
| bool PropertyCondition::isStillValidAssumingImpurePropertyWatchpoint( |
| Structure* structure, JSObject* base) const |
| { |
| if (verbose) { |
| dataLog( |
| "Determining validity of ", *this, " with structure ", pointerDump(structure), " and base ", |
| JSValue(base), " assuming impure property watchpoints are set.\n"); |
| } |
| |
| if (!*this) { |
| if (verbose) |
| dataLog("Invalid because unset.\n"); |
| return false; |
| } |
| |
| if (!structure->propertyAccessesAreCacheable()) { |
| if (verbose) |
| dataLog("Invalid because accesses are not cacheable.\n"); |
| return false; |
| } |
| |
| switch (m_kind) { |
| case Presence: { |
| unsigned currentAttributes; |
| PropertyOffset currentOffset = structure->getConcurrently(uid(), currentAttributes); |
| if (currentOffset != offset() || currentAttributes != attributes()) { |
| if (verbose) { |
| dataLog( |
| "Invalid because we need offset, attributes to be ", offset(), ", ", attributes(), |
| " but they are ", currentOffset, ", ", currentAttributes, "\n"); |
| } |
| return false; |
| } |
| return true; |
| } |
| |
| case Absence: { |
| if (structure->isDictionary()) { |
| if (verbose) |
| dataLog("Invalid because it's a dictionary.\n"); |
| return false; |
| } |
| |
| PropertyOffset currentOffset = structure->getConcurrently(uid()); |
| if (currentOffset != invalidOffset) { |
| if (verbose) |
| dataLog("Invalid because the property exists at offset: ", currentOffset, "\n"); |
| return false; |
| } |
| |
| if (structure->storedPrototypeObject() != prototype()) { |
| if (verbose) { |
| dataLog( |
| "Invalid because the prototype is ", structure->storedPrototype(), " even though " |
| "it should have been ", JSValue(prototype()), "\n"); |
| } |
| return false; |
| } |
| |
| return true; |
| } |
| |
| case AbsenceOfSetter: { |
| if (structure->isDictionary()) { |
| if (verbose) |
| dataLog("Invalid because it's a dictionary.\n"); |
| return false; |
| } |
| |
| unsigned currentAttributes; |
| PropertyOffset currentOffset = structure->getConcurrently(uid(), currentAttributes); |
| if (currentOffset != invalidOffset) { |
| if (currentAttributes & (Accessor | CustomAccessor)) { |
| if (verbose) { |
| dataLog( |
| "Invalid because we expected not to have a setter, but we have one at offset ", |
| currentOffset, " with attributes ", currentAttributes, "\n"); |
| } |
| return false; |
| } |
| } |
| |
| if (structure->storedPrototypeObject() != prototype()) { |
| if (verbose) { |
| dataLog( |
| "Invalid because the prototype is ", structure->storedPrototype(), " even though " |
| "it should have been ", JSValue(prototype()), "\n"); |
| } |
| return false; |
| } |
| |
| return true; |
| } |
| |
| case Equivalence: { |
| if (!base || base->structure() != structure) { |
| // Conservatively return false, since we cannot verify this one without having the |
| // object. |
| if (verbose) { |
| dataLog( |
| "Invalid because we don't have a base or the base has the wrong structure: ", |
| RawPointer(base), "\n"); |
| } |
| return false; |
| } |
| |
| // FIXME: This is somewhat racy, and maybe more risky than we want. |
| // https://bugs.webkit.org/show_bug.cgi?id=134641 |
| |
| PropertyOffset currentOffset = structure->getConcurrently(uid()); |
| if (currentOffset == invalidOffset) { |
| if (verbose) { |
| dataLog( |
| "Invalid because the base no long appears to have ", uid(), " on its structure: ", |
| RawPointer(base), "\n"); |
| } |
| return false; |
| } |
| |
| JSValue currentValue = base->getDirect(currentOffset); |
| if (currentValue != requiredValue()) { |
| if (verbose) { |
| dataLog( |
| "Invalid because the value is ", currentValue, " but we require ", requiredValue(), |
| "\n"); |
| } |
| return false; |
| } |
| |
| return true; |
| } } |
| |
| RELEASE_ASSERT_NOT_REACHED(); |
| return false; |
| } |
| |
| bool PropertyCondition::validityRequiresImpurePropertyWatchpoint(Structure* structure) const |
| { |
| if (!*this) |
| return false; |
| |
| switch (m_kind) { |
| case Presence: |
| case Absence: |
| case Equivalence: |
| return structure->needImpurePropertyWatchpoint(); |
| default: |
| return false; |
| } |
| } |
| |
| bool PropertyCondition::isStillValid(Structure* structure, JSObject* base) const |
| { |
| if (!isStillValidAssumingImpurePropertyWatchpoint(structure, base)) |
| return false; |
| |
| // Currently we assume that an impure property can cause a property to appear, and can also |
| // "shadow" an existing JS property on the same object. Hence it affects both presence and |
| // absence. It doesn't affect AbsenceOfSetter because impure properties aren't ever setters. |
| switch (m_kind) { |
| case Absence: |
| if (structure->typeInfo().getOwnPropertySlotIsImpure() || structure->typeInfo().getOwnPropertySlotIsImpureForPropertyAbsence()) |
| return false; |
| break; |
| case Presence: |
| case Equivalence: |
| if (structure->typeInfo().getOwnPropertySlotIsImpure()) |
| return false; |
| break; |
| default: |
| break; |
| } |
| |
| return true; |
| } |
| |
| bool PropertyCondition::isWatchableWhenValid( |
| Structure* structure, WatchabilityEffort effort) const |
| { |
| if (structure->transitionWatchpointSetHasBeenInvalidated()) |
| return false; |
| |
| switch (m_kind) { |
| case Equivalence: { |
| PropertyOffset offset = structure->getConcurrently(uid()); |
| |
| // This method should only be called when some variant of isValid returned true, which |
| // implies that we already confirmed that the structure knows of the property. We should |
| // also have verified that the Structure is a cacheable dictionary, which means we |
| // shouldn't have a TOCTOU race either. |
| RELEASE_ASSERT(offset != invalidOffset); |
| |
| WatchpointSet* set = nullptr; |
| switch (effort) { |
| case MakeNoChanges: |
| set = structure->propertyReplacementWatchpointSet(offset); |
| break; |
| case EnsureWatchability: |
| set = structure->ensurePropertyReplacementWatchpointSet( |
| *Heap::heap(structure)->vm(), offset); |
| break; |
| } |
| |
| if (!set || !set->isStillValid()) |
| return false; |
| |
| break; |
| } |
| |
| default: |
| break; |
| } |
| |
| return true; |
| } |
| |
| bool PropertyCondition::isWatchableAssumingImpurePropertyWatchpoint( |
| Structure* structure, JSObject* base, WatchabilityEffort effort) const |
| { |
| return isStillValidAssumingImpurePropertyWatchpoint(structure, base) |
| && isWatchableWhenValid(structure, effort); |
| } |
| |
| bool PropertyCondition::isWatchable( |
| Structure* structure, JSObject* base, WatchabilityEffort effort) const |
| { |
| return isStillValid(structure, base) |
| && isWatchableWhenValid(structure, effort); |
| } |
| |
| bool PropertyCondition::isStillLive() const |
| { |
| if (hasPrototype() && prototype() && !Heap::isMarked(prototype())) |
| return false; |
| |
| if (hasRequiredValue() |
| && requiredValue() |
| && requiredValue().isCell() |
| && !Heap::isMarked(requiredValue().asCell())) |
| return false; |
| |
| return true; |
| } |
| |
| void PropertyCondition::validateReferences(const TrackedReferences& tracked) const |
| { |
| if (hasPrototype()) |
| tracked.check(prototype()); |
| |
| if (hasRequiredValue()) |
| tracked.check(requiredValue()); |
| } |
| |
| bool PropertyCondition::isValidValueForAttributes(JSValue value, unsigned attributes) |
| { |
| bool attributesClaimAccessor = !!(attributes & Accessor); |
| bool valueClaimsAccessor = !!jsDynamicCast<GetterSetter*>(value); |
| return attributesClaimAccessor == valueClaimsAccessor; |
| } |
| |
| bool PropertyCondition::isValidValueForPresence(JSValue value) const |
| { |
| return isValidValueForAttributes(value, attributes()); |
| } |
| |
| PropertyCondition PropertyCondition::attemptToMakeEquivalenceWithoutBarrier(JSObject* base) const |
| { |
| Structure* structure = base->structure(); |
| if (!structure->isValidOffset(offset())) |
| return PropertyCondition(); |
| JSValue value = base->getDirect(offset()); |
| if (!isValidValueForPresence(value)) |
| return PropertyCondition(); |
| return equivalenceWithoutBarrier(uid(), value); |
| } |
| |
| } // namespace JSC |
| |
| namespace WTF { |
| |
| void printInternal(PrintStream& out, JSC::PropertyCondition::Kind condition) |
| { |
| switch (condition) { |
| case JSC::PropertyCondition::Presence: |
| out.print("Presence"); |
| return; |
| case JSC::PropertyCondition::Absence: |
| out.print("Absence"); |
| return; |
| case JSC::PropertyCondition::AbsenceOfSetter: |
| out.print("Absence"); |
| return; |
| case JSC::PropertyCondition::Equivalence: |
| out.print("Equivalence"); |
| return; |
| } |
| RELEASE_ASSERT_NOT_REACHED(); |
| } |
| |
| } // namespace WTF |
