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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et 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/. */
#ifndef mozilla_jsipc_JavaScriptShared_h__
#define mozilla_jsipc_JavaScriptShared_h__
#include "mozilla/dom/DOMTypes.h"
#include "mozilla/jsipc/CrossProcessObjectWrappers.h"
#include "mozilla/jsipc/PJavaScript.h"
#include "js/GCHashTable.h"
#include "nsJSUtils.h"
namespace mozilla {
namespace jsipc {
class ObjectId {
public:
// Use 47 bits at most, to be safe, since jsval privates are encoded as
// doubles. See bug 1065811 comment 12 for an explanation.
static const size_t SERIAL_NUMBER_BITS = 47;
static const size_t FLAG_BITS = 1;
static const uint64_t SERIAL_NUMBER_MAX = (uint64_t(1) << SERIAL_NUMBER_BITS) - 1;
explicit ObjectId(uint64_t serialNumber, bool hasXrayWaiver)
: serialNumber_(serialNumber), hasXrayWaiver_(hasXrayWaiver)
{
if (MOZ_UNLIKELY(serialNumber == 0 || serialNumber > SERIAL_NUMBER_MAX))
MOZ_CRASH("Bad CPOW Id");
}
bool operator==(const ObjectId& other) const {
bool equal = serialNumber() == other.serialNumber();
MOZ_ASSERT_IF(equal, hasXrayWaiver() == other.hasXrayWaiver());
return equal;
}
bool isNull() { return !serialNumber_; }
uint64_t serialNumber() const { return serialNumber_; }
bool hasXrayWaiver() const { return hasXrayWaiver_; }
uint64_t serialize() const {
MOZ_ASSERT(serialNumber(), "Don't send a null ObjectId over IPC");
return uint64_t((serialNumber() << FLAG_BITS) | ((hasXrayWaiver() ? 1 : 0) << 0));
}
static ObjectId nullId() { return ObjectId(); }
static ObjectId deserialize(uint64_t data) {
return ObjectId(data >> FLAG_BITS, data & 1);
}
// For use with StructGCPolicy.
void trace(JSTracer*) const {}
bool needsSweep() const { return false; }
private:
ObjectId() : serialNumber_(0), hasXrayWaiver_(false) {}
uint64_t serialNumber_ : SERIAL_NUMBER_BITS;
bool hasXrayWaiver_ : 1;
};
class JavaScriptShared;
// DefaultHasher<T> requires that T coerce to an integral type. We could make
// ObjectId do that, but doing so would weaken our type invariants, so we just
// reimplement it manually.
struct ObjectIdHasher
{
typedef ObjectId Lookup;
static js::HashNumber hash(const Lookup& l) {
return l.serialize();
}
static bool match(const ObjectId& k, const ObjectId& l) {
return k == l;
}
static void rekey(ObjectId& k, const ObjectId& newKey) {
k = newKey;
}
};
// Map ids -> JSObjects
class IdToObjectMap
{
typedef js::HashMap<ObjectId, JS::Heap<JSObject*>, ObjectIdHasher, js::SystemAllocPolicy> Table;
public:
IdToObjectMap();
bool init();
void trace(JSTracer* trc, uint64_t minimumId = 0);
void sweep();
bool add(ObjectId id, JSObject* obj);
JSObject* find(ObjectId id);
JSObject* findPreserveColor(ObjectId id);
void remove(ObjectId id);
void clear();
bool empty() const;
#ifdef DEBUG
bool has(const ObjectId& id, const JSObject* obj) const;
#endif
private:
Table table_;
};
// Map JSObjects -> ids
class ObjectToIdMap
{
using Hasher = js::MovableCellHasher<JS::Heap<JSObject*>>;
using Table = JS::GCHashMap<JS::Heap<JSObject*>, ObjectId, Hasher, js::SystemAllocPolicy>;
public:
bool init();
void trace(JSTracer* trc);
void sweep();
bool add(JSContext* cx, JSObject* obj, ObjectId id);
ObjectId find(JSObject* obj);
void remove(JSObject* obj);
void clear();
private:
Table table_;
};
class Logging;
class JavaScriptShared : public CPOWManager
{
public:
JavaScriptShared();
virtual ~JavaScriptShared();
bool init();
void decref();
void incref();
bool Unwrap(JSContext* cx, const InfallibleTArray<CpowEntry>& aCpows, JS::MutableHandleObject objp);
bool Wrap(JSContext* cx, JS::HandleObject aObj, InfallibleTArray<CpowEntry>* outCpows);
protected:
bool toVariant(JSContext* cx, JS::HandleValue from, JSVariant* to);
bool fromVariant(JSContext* cx, const JSVariant& from, JS::MutableHandleValue to);
bool toJSIDVariant(JSContext* cx, JS::HandleId from, JSIDVariant* to);
bool fromJSIDVariant(JSContext* cx, const JSIDVariant& from, JS::MutableHandleId to);
bool toSymbolVariant(JSContext* cx, JS::Symbol* sym, SymbolVariant* symVarp);
JS::Symbol* fromSymbolVariant(JSContext* cx, const SymbolVariant& symVar);
bool fromDescriptor(JSContext* cx, JS::Handle<JS::PropertyDescriptor> desc,
PPropertyDescriptor* out);
bool toDescriptor(JSContext* cx, const PPropertyDescriptor& in,
JS::MutableHandle<JS::PropertyDescriptor> out);
bool toObjectOrNullVariant(JSContext* cx, JSObject* obj, ObjectOrNullVariant* objVarp);
JSObject* fromObjectOrNullVariant(JSContext* cx, const ObjectOrNullVariant& objVar);
bool convertIdToGeckoString(JSContext* cx, JS::HandleId id, nsString* to);
bool convertGeckoStringToId(JSContext* cx, const nsString& from, JS::MutableHandleId id);
virtual bool toObjectVariant(JSContext* cx, JSObject* obj, ObjectVariant* objVarp) = 0;
virtual JSObject* fromObjectVariant(JSContext* cx, const ObjectVariant& objVar) = 0;
static void ConvertID(const nsID& from, JSIID* to);
static void ConvertID(const JSIID& from, nsID* to);
JSObject* findCPOWById(const ObjectId& objId) {
return cpows_.find(objId);
}
JSObject* findObjectById(JSContext* cx, const ObjectId& objId);
#ifdef DEBUG
bool hasCPOW(const ObjectId& objId, const JSObject* obj) {
return cpows_.has(objId, obj);
}
#endif
static bool LoggingEnabled() { return sLoggingEnabled; }
static bool StackLoggingEnabled() { return sStackLoggingEnabled; }
friend class Logging;
virtual bool isParent() = 0;
virtual JSObject* scopeForTargetObjects() = 0;
protected:
uintptr_t refcount_;
IdToObjectMap objects_;
IdToObjectMap cpows_;
uint64_t nextSerialNumber_;
// nextCPOWNumber_ should be the value of nextSerialNumber_ in the other
// process. The next new CPOW we get should have this serial number.
uint64_t nextCPOWNumber_;
// CPOW references can be weak, and any object we store in a map may be
// GCed (at which point the CPOW will report itself "dead" to the owner).
// This means that we don't want to store any js::Wrappers in the CPOW map,
// because CPOW will die if the wrapper is GCed, even if the underlying
// object is still alive.
//
// This presents a tricky situation for Xray waivers, since they're normally
// represented as a special same-compartment wrapper. We have to strip them
// off before putting them in the id-to-object and object-to-id maps, so we
// need a way of distinguishing them at lookup-time.
//
// For the id-to-object map, we encode waiver-or-not information into the id
// itself, which lets us do the right thing when accessing the object.
//
// For the object-to-id map, we just keep two maps, one for each type.
ObjectToIdMap unwaivedObjectIds_;
ObjectToIdMap waivedObjectIds_;
ObjectToIdMap& objectIdMap(bool waiver) {
return waiver ? waivedObjectIds_ : unwaivedObjectIds_;
}
static bool sLoggingInitialized;
static bool sLoggingEnabled;
static bool sStackLoggingEnabled;
};
} // namespace jsipc
} // namespace mozilla
#endif
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