1 files changed, 569 insertions, 0 deletions
diff --git a/js/src/vm/Compartment.cpp b/js/src/vm/Compartment.cpp
new file mode 100644
index 0000000000..59f2112746
--- /dev/null
+++ b/js/src/vm/Compartment.cpp
@@ -0,0 +1,569 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * 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 "vm/Compartment-inl.h"
+
+#include "mozilla/MemoryReporting.h"
+
+#include <stddef.h>
+
+#include "jsfriendapi.h"
+
+#include "debugger/DebugAPI.h"
+#include "gc/Policy.h"
+#include "gc/PublicIterators.h"
+#include "gc/Zone.h"
+#include "js/Date.h"
+#include "js/friend/StackLimits.h"  // js::CheckSystemRecursionLimit
+#include "js/friend/WindowProxy.h"  // js::IsWindow, js::IsWindowProxy, js::ToWindowProxyIfWindow
+#include "js/Proxy.h"
+#include "js/RootingAPI.h"
+#include "js/StableStringChars.h"
+#include "js/Wrapper.h"
+#include "proxy/DeadObjectProxy.h"
+#include "proxy/DOMProxy.h"
+#include "vm/Iteration.h"
+#include "vm/JSContext.h"
+#include "vm/WrapperObject.h"
+
+#include "gc/GC-inl.h"
+#include "gc/Marking-inl.h"
+#include "gc/WeakMap-inl.h"
+#include "vm/JSAtom-inl.h"
+#include "vm/JSFunction-inl.h"
+#include "vm/JSObject-inl.h"
+#include "vm/JSScript-inl.h"
+#include "vm/NativeObject-inl.h"
+
+using namespace js;
+
+using JS::AutoStableStringChars;
+
+Compartment::Compartment(Zone* zone, bool invisibleToDebugger)
+    : zone_(zone),
+      runtime_(zone->runtimeFromAnyThread()),
+      invisibleToDebugger_(invisibleToDebugger),
+      crossCompartmentObjectWrappers(zone, 0),
+      realms_(zone) {}
+
+#ifdef JSGC_HASH_TABLE_CHECKS
+
+void Compartment::checkObjectWrappersAfterMovingGC() {
+  for (ObjectWrapperEnum e(this); !e.empty(); e.popFront()) {
+    // Assert that the postbarriers have worked and that nothing is left in the
+    // wrapper map that points into the nursery, and that the hash table entries
+    // are discoverable.
+    auto key = e.front().key();
+    CheckGCThingAfterMovingGC(key);
+
+    auto ptr = crossCompartmentObjectWrappers.lookup(key);
+    MOZ_RELEASE_ASSERT(ptr.found() && &*ptr == &e.front());
+  }
+}
+
+#endif  // JSGC_HASH_TABLE_CHECKS
+
+bool Compartment::putWrapper(JSContext* cx, JSObject* wrapped,
+                             JSObject* wrapper) {
+  MOZ_ASSERT(!js::IsProxy(wrapper) || js::GetProxyHandler(wrapper)->family() !=
+                                          js::GetDOMRemoteProxyHandlerFamily());
+
+  if (!crossCompartmentObjectWrappers.put(wrapped, wrapper)) {
+    ReportOutOfMemory(cx);
+    return false;
+  }
+
+  return true;
+}
+
+bool Compartment::putWrapper(JSContext* cx, JSString* wrapped,
+                             JSString* wrapper) {
+  if (!zone()->crossZoneStringWrappers().put(wrapped, wrapper)) {
+    ReportOutOfMemory(cx);
+    return false;
+  }
+
+  return true;
+}
+
+void Compartment::removeWrapper(js::ObjectWrapperMap::Ptr p) {
+  JSObject* key = p->key();
+  JSObject* value = p->value().unbarrieredGet();
+  if (js::gc::detail::GetDelegate(value) == key) {
+    key->zone()->beforeClearDelegate(value, key);
+  }
+
+  crossCompartmentObjectWrappers.remove(p);
+}
+
+static JSString* CopyStringPure(JSContext* cx, JSString* str) {
+  /*
+   * Directly allocate the copy in the destination compartment, rather than
+   * first flattening it (and possibly allocating in source compartment),
+   * because we don't know whether the flattening will pay off later.
+   */
+
+  size_t len = str->length();
+  JSString* copy;
+  if (str->isLinear()) {
+    /* Only use AutoStableStringChars if the NoGC allocation fails. */
+    if (str->hasLatin1Chars()) {
+      JS::AutoCheckCannotGC nogc;
+      copy = NewStringCopyN<NoGC>(cx, str->asLinear().latin1Chars(nogc), len);
+    } else {
+      JS::AutoCheckCannotGC nogc;
+      copy = NewStringCopyNDontDeflate<NoGC>(
+          cx, str->asLinear().twoByteChars(nogc), len);
+    }
+    if (copy) {
+      return copy;
+    }
+
+    AutoStableStringChars chars(cx);
+    if (!chars.init(cx, str)) {
+      return nullptr;
+    }
+
+    return chars.isLatin1() ? NewStringCopyN<CanGC>(
+                                  cx, chars.latin1Range().begin().get(), len)
+                            : NewStringCopyNDontDeflate<CanGC>(
+                                  cx, chars.twoByteRange().begin().get(), len);
+  }
+
+  if (str->hasLatin1Chars()) {
+    UniquePtr<Latin1Char[], JS::FreePolicy> copiedChars =
+        str->asRope().copyLatin1Chars(cx, js::StringBufferArena);
+    if (!copiedChars) {
+      return nullptr;
+    }
+
+    return NewString<CanGC>(cx, std::move(copiedChars), len);
+  }
+
+  UniqueTwoByteChars copiedChars =
+      str->asRope().copyTwoByteChars(cx, js::StringBufferArena);
+  if (!copiedChars) {
+    return nullptr;
+  }
+
+  return NewStringDontDeflate<CanGC>(cx, std::move(copiedChars), len);
+}
+
+bool Compartment::wrap(JSContext* cx, MutableHandleString strp) {
+  MOZ_ASSERT(cx->compartment() == this);
+
+  /* If the string is already in this compartment, we are done. */
+  JSString* str = strp;
+  if (str->zoneFromAnyThread() == zone()) {
+    return true;
+  }
+
+  /*
+   * If the string is an atom, we don't have to copy, but we do need to mark
+   * the atom as being in use by the new zone.
+   */
+  if (str->isAtom()) {
+    cx->markAtom(&str->asAtom());
+    return true;
+  }
+
+  /* Check the cache. */
+  if (StringWrapperMap::Ptr p = lookupWrapper(str)) {
+    strp.set(p->value().get());
+    return true;
+  }
+
+  /* No dice. Make a copy, and cache it. */
+  JSString* copy = CopyStringPure(cx, str);
+  if (!copy) {
+    return false;
+  }
+  if (!putWrapper(cx, strp, copy)) {
+    return false;
+  }
+
+  strp.set(copy);
+  return true;
+}
+
+bool Compartment::wrap(JSContext* cx, MutableHandleBigInt bi) {
+  MOZ_ASSERT(cx->compartment() == this);
+
+  if (bi->zone() == cx->zone()) {
+    return true;
+  }
+
+  BigInt* copy = BigInt::copy(cx, bi);
+  if (!copy) {
+    return false;
+  }
+  bi.set(copy);
+  return true;
+}
+
+bool Compartment::getNonWrapperObjectForCurrentCompartment(
+    JSContext* cx, HandleObject origObj, MutableHandleObject obj) {
+  // Ensure that we have entered a realm.
+  MOZ_ASSERT(cx->global());
+
+  // If we have a cross-compartment wrapper, make sure that the cx isn't
+  // associated with the self-hosting zone. We don't want to create
+  // wrappers for objects in other runtimes, which may be the case for the
+  // self-hosting zone.
+  MOZ_ASSERT(!cx->zone()->isSelfHostingZone());
+  MOZ_ASSERT(!obj->zone()->isSelfHostingZone());
+
+  // The object is already in the right compartment. Normally same-
+  // compartment returns the object itself, however, windows are always
+  // wrapped by a proxy, so we have to check for that case here manually.
+  if (obj->compartment() == this) {
+    obj.set(ToWindowProxyIfWindow(obj));
+    return true;
+  }
+
+  // Note that if the object is same-compartment, but has been wrapped into a
+  // different compartment, we need to unwrap it and return the bare same-
+  // compartment object. Note again that windows are always wrapped by a
+  // WindowProxy even when same-compartment so take care not to strip this
+  // particular wrapper.
+  RootedObject objectPassedToWrap(cx, obj);
+  obj.set(UncheckedUnwrap(obj, /* stopAtWindowProxy = */ true));
+  if (obj->compartment() == this) {
+    MOZ_ASSERT(!IsWindow(obj));
+    return true;
+  }
+
+  // Disallow creating new wrappers if we nuked the object's realm or the
+  // current compartment.
+  if (!AllowNewWrapper(this, obj)) {
+    obj.set(NewDeadProxyObject(cx, IsCallableFlag(obj->isCallable()),
+                               IsConstructorFlag(obj->isConstructor())));
+    return !!obj;
+  }
+
+  // Use the WindowProxy instead of the Window here, so that we don't have to
+  // deal with this in the rest of the wrapping code.
+  if (IsWindow(obj)) {
+    obj.set(ToWindowProxyIfWindow(obj));
+
+    // ToWindowProxyIfWindow can return a CCW if |obj| was a navigated-away-from
+    // Window. Strip any CCWs.
+    obj.set(UncheckedUnwrap(obj));
+
+    if (JS_IsDeadWrapper(obj)) {
+      obj.set(NewDeadProxyObject(cx, obj));
+      return !!obj;
+    }
+
+    MOZ_ASSERT(IsWindowProxy(obj) || IsDOMRemoteProxyObject(obj));
+
+    // We crossed a compartment boundary there, so may now have a gray object.
+    // This function is not allowed to return gray objects, so don't do that.
+    ExposeObjectToActiveJS(obj);
+  }
+
+  // If the object is a dead wrapper, return a new dead wrapper rather than
+  // trying to wrap it for a different compartment.
+  if (JS_IsDeadWrapper(obj)) {
+    obj.set(NewDeadProxyObject(cx, obj));
+    return !!obj;
+  }
+
+  // Invoke the prewrap callback. The prewrap callback is responsible for
+  // doing similar reification as above, but can account for any additional
+  // embedder requirements.
+  //
+  // We're a bit worried about infinite recursion here, so we do a check -
+  // see bug 809295.
+  auto preWrap = cx->runtime()->wrapObjectCallbacks->preWrap;
+  if (!CheckSystemRecursionLimit(cx)) {
+    return false;
+  }
+  if (preWrap) {
+    preWrap(cx, cx->global(), origObj, obj, objectPassedToWrap, obj);
+    if (!obj) {
+      return false;
+    }
+  }
+  MOZ_ASSERT(!IsWindow(obj));
+
+  return true;
+}
+
+bool Compartment::getOrCreateWrapper(JSContext* cx, HandleObject existing,
+                                     MutableHandleObject obj) {
+  // If we already have a wrapper for this value, use it.
+  if (ObjectWrapperMap::Ptr p = lookupWrapper(obj)) {
+    obj.set(p->value().get());
+    MOZ_ASSERT(obj->is<CrossCompartmentWrapperObject>());
+    return true;
+  }
+
+  // Ensure that the wrappee is exposed in case we are creating a new wrapper
+  // for a gray object.
+  ExposeObjectToActiveJS(obj);
+
+  // Create a new wrapper for the object.
+  auto wrap = cx->runtime()->wrapObjectCallbacks->wrap;
+  RootedObject wrapper(cx, wrap(cx, existing, obj));
+  if (!wrapper) {
+    return false;
+  }
+
+  // We maintain the invariant that the key in the cross-compartment wrapper
+  // map is always directly wrapped by the value.
+  MOZ_ASSERT(Wrapper::wrappedObject(wrapper) == obj);
+
+  if (!putWrapper(cx, obj, wrapper)) {
+    // Enforce the invariant that all cross-compartment wrapper object are
+    // in the map by nuking the wrapper if we couldn't add it.
+    // Unfortunately it's possible for the wrapper to still be marked if we
+    // took this path, for example if the object metadata callback stashes a
+    // reference to it.
+    if (wrapper->is<CrossCompartmentWrapperObject>()) {
+      NukeCrossCompartmentWrapper(cx, wrapper);
+    }
+    return false;
+  }
+
+  obj.set(wrapper);
+  return true;
+}
+
+bool Compartment::wrap(JSContext* cx, MutableHandleObject obj) {
+  MOZ_ASSERT(cx->compartment() == this);
+
+  if (!obj) {
+    return true;
+  }
+
+  AutoDisableProxyCheck adpc;
+
+  // Anything we're wrapping has already escaped into script, so must have
+  // been unmarked-gray at some point in the past.
+  JS::AssertObjectIsNotGray(obj);
+
+  // The passed object may already be wrapped, or may fit a number of special
+  // cases that we need to check for and manually correct.
+  if (!getNonWrapperObjectForCurrentCompartment(cx, /* origObj = */ nullptr,
+                                                obj)) {
+    return false;
+  }
+
+  // If the reification above did not result in a same-compartment object,
+  // get or create a new wrapper object in this compartment for it.
+  if (obj->compartment() != this) {
+    if (!getOrCreateWrapper(cx, nullptr, obj)) {
+      return false;
+    }
+  }
+
+  // Ensure that the wrapper is also exposed.
+  ExposeObjectToActiveJS(obj);
+  return true;
+}
+
+bool Compartment::rewrap(JSContext* cx, MutableHandleObject obj,
+                         HandleObject existingArg) {
+  MOZ_ASSERT(cx->compartment() == this);
+  MOZ_ASSERT(obj);
+  MOZ_ASSERT(existingArg);
+  MOZ_ASSERT(existingArg->compartment() == cx->compartment());
+  MOZ_ASSERT(IsDeadProxyObject(existingArg));
+
+  AutoDisableProxyCheck adpc;
+
+  // It may not be possible to re-use existing; if so, clear it so that we
+  // are forced to create a new wrapper. Note that this cannot call out to
+  // |wrap| because of the different gray unmarking semantics.
+  RootedObject existing(cx, existingArg);
+  if (existing->hasStaticPrototype() ||
+      // Note: Class asserted above, so all that's left to check is callability
+      existing->isCallable() || obj->isCallable()) {
+    existing.set(nullptr);
+  }
+
+  // The passed object may already be wrapped, or may fit a number of special
+  // cases that we need to check for and manually correct. We pass in
+  // |existingArg| instead of |existing|, because the purpose is to get the
+  // address of the object we are transplanting onto, not to find a wrapper
+  // to reuse.
+  if (!getNonWrapperObjectForCurrentCompartment(cx, existingArg, obj)) {
+    return false;
+  }
+
+  // If the reification above resulted in a same-compartment object, we do
+  // not need to create or return an existing wrapper.
+  if (obj->compartment() == this) {
+    return true;
+  }
+
+  return getOrCreateWrapper(cx, existing, obj);
+}
+
+bool Compartment::wrap(JSContext* cx,
+                       MutableHandle<JS::PropertyDescriptor> desc) {
+  if (!wrap(cx, desc.object())) {
+    return false;
+  }
+
+  if (desc.hasGetterObject()) {
+    if (!wrap(cx, desc.getterObject())) {
+      return false;
+    }
+  }
+  if (desc.hasSetterObject()) {
+    if (!wrap(cx, desc.setterObject())) {
+      return false;
+    }
+  }
+
+  return wrap(cx, desc.value());
+}
+
+bool Compartment::wrap(JSContext* cx, MutableHandle<GCVector<Value>> vec) {
+  for (size_t i = 0; i < vec.length(); ++i) {
+    if (!wrap(cx, vec[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+static inline bool ShouldTraceWrapper(JSObject* wrapper,
+                                      Compartment::EdgeSelector whichEdges) {
+  if (whichEdges == Compartment::AllEdges) {
+    return true;
+  }
+
+  bool isGray = wrapper->isMarkedGray();
+  return (whichEdges == Compartment::NonGrayEdges && !isGray) ||
+         (whichEdges == Compartment::GrayEdges && isGray);
+}
+
+void Compartment::traceWrapperTargetsInCollectedZones(JSTracer* trc,
+                                                      EdgeSelector whichEdges) {
+  // Trace cross compartment wrapper private pointers into collected zones to
+  // either mark or update them. Wrapped object pointers are updated by
+  // sweepCrossCompartmentObjectWrappers().
+
+  MOZ_ASSERT(JS::RuntimeHeapIsMajorCollecting());
+  MOZ_ASSERT(!zone()->isCollectingFromAnyThread() ||
+             trc->runtime()->gc.isHeapCompacting());
+
+  for (WrappedObjectCompartmentEnum c(this); !c.empty(); c.popFront()) {
+    Zone* zone = c.front()->zone();
+    if (!zone->isCollectingFromAnyThread()) {
+      continue;
+    }
+
+    for (ObjectWrapperEnum e(this, c); !e.empty(); e.popFront()) {
+      JSObject* obj = e.front().value().unbarrieredGet();
+      ProxyObject* wrapper = &obj->as<ProxyObject>();
+      if (ShouldTraceWrapper(wrapper, whichEdges)) {
+        ProxyObject::traceEdgeToTarget(trc, wrapper);
+      }
+    }
+  }
+}
+
+/* static */
+void Compartment::traceIncomingCrossCompartmentEdgesForZoneGC(
+    JSTracer* trc, EdgeSelector whichEdges) {
+  MOZ_ASSERT(JS::RuntimeHeapIsMajorCollecting());
+
+  for (ZonesIter zone(trc->runtime(), SkipAtoms); !zone.done(); zone.next()) {
+    if (zone->isCollectingFromAnyThread()) {
+      continue;
+    }
+
+    for (CompartmentsInZoneIter c(zone); !c.done(); c.next()) {
+      c->traceWrapperTargetsInCollectedZones(trc, whichEdges);
+    }
+  }
+
+  // Currently we trace all debugger edges as black.
+  if (whichEdges != GrayEdges) {
+    DebugAPI::traceCrossCompartmentEdges(trc);
+  }
+}
+
+void Compartment::sweepAfterMinorGC(JSTracer* trc) {
+  crossCompartmentObjectWrappers.sweepAfterMinorGC(trc);
+
+  for (RealmsInCompartmentIter r(this); !r.done(); r.next()) {
+    r->sweepAfterMinorGC();
+  }
+}
+
+// Remove dead wrappers from the table or update pointers to moved objects.
+void Compartment::sweepCrossCompartmentObjectWrappers() {
+  crossCompartmentObjectWrappers.sweep();
+}
+
+void Compartment::fixupCrossCompartmentObjectWrappersAfterMovingGC(
+    JSTracer* trc) {
+  MOZ_ASSERT(trc->runtime()->gc.isHeapCompacting());
+
+  // Sweep the wrapper map to update keys (wrapped values) in other
+  // compartments that may have been moved.
+  sweepCrossCompartmentObjectWrappers();
+
+  // Trace the wrappers in the map to update their cross-compartment edges
+  // to wrapped values in other compartments that may have been moved.
+  traceWrapperTargetsInCollectedZones(trc, AllEdges);
+}
+
+void Compartment::fixupAfterMovingGC(JSTracer* trc) {
+  MOZ_ASSERT(zone()->isGCCompacting());
+
+  for (RealmsInCompartmentIter r(this); !r.done(); r.next()) {
+    r->fixupAfterMovingGC(trc);
+  }
+
+  // Sweep the wrapper map to update values (wrapper objects) in this
+  // compartment that may have been moved.
+  sweepCrossCompartmentObjectWrappers();
+}
+
+void Compartment::addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf,
+                                         size_t* compartmentObjects,
+                                         size_t* crossCompartmentWrappersTables,
+                                         size_t* compartmentsPrivateData) {
+  *compartmentObjects += mallocSizeOf(this);
+  *crossCompartmentWrappersTables +=
+      crossCompartmentObjectWrappers.sizeOfExcludingThis(mallocSizeOf);
+
+  if (auto callback = runtime_->sizeOfIncludingThisCompartmentCallback) {
+    *compartmentsPrivateData += callback(mallocSizeOf, this);
+  }
+}
+
+GlobalObject& Compartment::firstGlobal() const {
+  for (Realm* realm : realms_) {
+    if (!realm->hasLiveGlobal()) {
+      continue;
+    }
+    GlobalObject* global = realm->maybeGlobal();
+    ExposeObjectToActiveJS(global);
+    return *global;
+  }
+  MOZ_CRASH("If all our globals are dead, why is someone expecting a global?");
+}
+
+JS_FRIEND_API JSObject* js::GetFirstGlobalInCompartment(JS::Compartment* comp) {
+  return &comp->firstGlobal();
+}
+
+JS_FRIEND_API bool js::CompartmentHasLiveGlobal(JS::Compartment* comp) {
+  MOZ_ASSERT(comp);
+  for (Realm* r : comp->realms()) {
+    if (r->hasLiveGlobal()) {
+      return true;
+    }
+  }
+  return false;
+}