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Bug 1065811 - Track Xray waivers with CPOWs. r=billm

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This commit is contained in:
Bobby Holley
2014-09-25 13:13:29 +02:00
parent 4088e55174
commit f2b9845ecb
8 changed files with 56 additions and 25 deletions
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39
js/ipc/JavaScriptShared.h
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@@ -24,8 +24,8 @@ class ObjectId {
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 isCallable)
: serialNumber_(serialNumber), isCallable_(isCallable)
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");
@@ -33,17 +33,17 @@ class ObjectId {
bool operator==(const ObjectId &other) const {
bool equal = serialNumber() == other.serialNumber();
MOZ_ASSERT_IF(equal, isCallable() == other.isCallable());
MOZ_ASSERT_IF(equal, hasXrayWaiver() == other.hasXrayWaiver());
return equal;
}
bool isNull() { return !serialNumber_; }
uint64_t serialNumber() const { return serialNumber_; }
bool isCallable() const { return isCallable_; }
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) | ((isCallable() ? 1 : 0) << 0));
return uint64_t((serialNumber() << FLAG_BITS) | ((hasXrayWaiver() ? 1 : 0) << 0));
}
static ObjectId nullId() { return ObjectId(); }
@@ -52,10 +52,10 @@ class ObjectId {
}
private:
ObjectId() : serialNumber_(0), isCallable_(false) {}
ObjectId() : serialNumber_(0), hasXrayWaiver_(false) {}
uint64_t serialNumber_ : SERIAL_NUMBER_BITS;
bool isCallable_ : 1;
bool hasXrayWaiver_ : 1;
};
class JavaScriptShared;
@@ -174,9 +174,6 @@ class JavaScriptShared
JSObject *findCPOWById(const ObjectId &objId) {
return cpows_.find(objId);
}
JSObject *findObjectById(const ObjectId &objId) {
return objects_.find(objId);
}
JSObject *findObjectById(JSContext *cx, const ObjectId &objId);
static bool LoggingEnabled() { return sLoggingEnabled; }
@@ -196,7 +193,27 @@ class JavaScriptShared
IdToObjectMap cpows_;
uint64_t nextSerialNumber_;
ObjectToIdMap objectIds_;
// 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;