C++ XPCNativeInterface类代码示例

// static
XPCNativeSet*
XPCNativeSet::NewInstance(XPCCallContext& ccx,
                          XPCNativeInterface** array,
                          uint16_t count)
{
    XPCNativeSet* obj = nullptr;

    if (!array || !count)
        return nullptr;

    // We impose the invariant:
    // "All sets have exactly one nsISupports interface and it comes first."
    // This is the place where we impose that rule - even if given inputs
    // that don't exactly follow the rule.

    XPCNativeInterface* isup = XPCNativeInterface::GetISupports(ccx);
    uint16_t slots = count+1;

    uint16_t i;
    XPCNativeInterface** pcur;

    for (i = 0, pcur = array; i < count; i++, pcur++) {
        if (*pcur == isup)
            slots--;
    }

    // Use placement new to create an object with the right amount of space
    // to hold the members array
    int size = sizeof(XPCNativeSet);
    if (slots > 1)
        size += (slots - 1) * sizeof(XPCNativeInterface*);
    void* place = new char[size];
    if (place)
        obj = new(place) XPCNativeSet();

    if (obj) {
        // Stick the nsISupports in front and skip additional nsISupport(s)
        XPCNativeInterface** inp = array;
        XPCNativeInterface** outp = (XPCNativeInterface**) &obj->mInterfaces;
        uint16_t memberCount = 1;   // for the one member in nsISupports

        *(outp++) = isup;

        for (i = 0; i < count; i++) {
            XPCNativeInterface* cur;

            if (isup == (cur = *(inp++)))
                continue;
            *(outp++) = cur;
            memberCount += cur->GetMemberCount();
        }
        obj->mMemberCount = memberCount;
        obj->mInterfaceCount = slots;
    }

    return obj;
}

XPCWrappedNative*
XPCCallContext::UnwrapThisIfAllowed(HandleObject obj, HandleObject fun, unsigned argc)
{
    // We should only get here for objects that aren't safe to unwrap.
    MOZ_ASSERT(!js::CheckedUnwrap(obj));
    MOZ_ASSERT(js::IsObjectInContextCompartment(obj, mJSContext));

    // We can't do anything here without a function.
    if (!fun)
        return nullptr;

    // Determine if we're allowed to unwrap the security wrapper to invoke the
    // method.
    //
    // We have the Interface and Member that this corresponds to, but
    // unfortunately our access checks are based on the object class name and
    // property name. So we cheat a little bit here - we verify that the object
    // does indeed implement the method's Interface, and then just check that we
    // can successfully access property with method's name from the object.

    // First, get the XPCWN out of the underlying object. We should have a wrapper
    // here, potentially an outer window proxy, and then an XPCWN.
    MOZ_ASSERT(js::IsWrapper(obj));
    RootedObject unwrapped(mJSContext, js::UncheckedUnwrap(obj, /* stopAtOuter = */ false));
    MOZ_ASSERT(unwrapped == JS_ObjectToInnerObject(mJSContext, js::Wrapper::wrappedObject(obj)));

    // Make sure we have an XPCWN, and grab it.
    if (!IS_WN_REFLECTOR(unwrapped))
        return nullptr;
    XPCWrappedNative *wn = (XPCWrappedNative*)js::GetObjectPrivate(unwrapped);

    // Next, get the call info off the function object.
    XPCNativeInterface *interface;
    XPCNativeMember *member;
    XPCNativeMember::GetCallInfo(fun, &interface, &member);

    // To be extra safe, make sure that the underlying native implements the
    // interface before unwrapping. Even if we didn't check this, we'd still
    // theoretically fail during tearoff lookup for mismatched methods.
    if (!wn->HasInterfaceNoQI(*interface->GetIID()))
        return nullptr;

    // See if the access is permitted.
    //
    // NB: This calculation of SET vs GET is a bit wonky, but that's what
    // XPC_WN_GetterSetter does.
    bool set = argc && argc != NO_ARGS && member->IsWritableAttribute();
    js::Wrapper::Action act = set ? js::Wrapper::SET : js::Wrapper::GET;
    js::Wrapper *handler = js::Wrapper::wrapperHandler(obj);
    bool ignored;
    JS::Rooted<jsid> id(mJSContext, member->GetName());
    if (!handler->enter(mJSContext, obj, id, act, &ignored))
        return nullptr;

    // Ok, this call is safe.
    return wn;
}

// static
void
XPCThrower::Verbosify(XPCCallContext& ccx,
                      char** psz, PRBool own)
{
    char* sz = nsnull;

    if(ccx.HasInterfaceAndMember())
    {
        XPCNativeInterface* iface = ccx.GetInterface();
#ifdef XPC_IDISPATCH_SUPPORT
        NS_ASSERTION(ccx.GetIDispatchMember() == nsnull || 
                        ccx.GetMember() == nsnull,
                     "Both IDispatch member and regular XPCOM member "
                     "were set in XPCCallContext");
        char const * name;
        if(ccx.GetIDispatchMember())
        {
            XPCDispInterface::Member * member = 
                reinterpret_cast<XPCDispInterface::Member*>(ccx.GetIDispatchMember());
            if(member && JSVAL_IS_STRING(member->GetName()))
            {
                name = JS_GetStringBytes(JSVAL_TO_STRING(member->GetName()));
            }
            else
                name = "Unknown";
        }
        else
            name = iface->GetMemberName(ccx, ccx.GetMember());
        sz = JS_smprintf("%s [%s.%s]",
                         *psz,
                         iface->GetNameString(),
                         name);
#else
        sz = JS_smprintf("%s [%s.%s]",
                         *psz,
                         iface->GetNameString(),
                         iface->GetMemberName(ccx, ccx.GetMember()));
#endif
    }

    if(sz)
    {
        if(own)
            JS_smprintf_free(*psz);
        *psz = sz;
    }
}

// static
void
XPCThrower::Verbosify(XPCCallContext& ccx,
                      char** psz, PRBool own)
{
    char* sz = nsnull;

    if(ccx.HasInterfaceAndMember())
    {
        XPCNativeInterface* iface = ccx.GetInterface();
        jsid id = JSID_VOID;
#ifdef XPC_IDISPATCH_SUPPORT
        NS_ASSERTION(ccx.GetIDispatchMember() == nsnull || 
                        ccx.GetMember() == nsnull,
                     "Both IDispatch member and regular XPCOM member "
                     "were set in XPCCallContext");
        if(ccx.GetIDispatchMember())
        {
            XPCDispInterface::Member * member = 
                reinterpret_cast<XPCDispInterface::Member*>(ccx.GetIDispatchMember());
            if(member && JSID_IS_STRING(member->GetName()))
            {
                id = member->GetName();
            }
        }
        else
#endif
        {
            id = ccx.GetMember()->GetName();
        }
        JSAutoByteString bytes;
        const char *name = JSID_IS_VOID(id) ? "Unknown" : bytes.encode(ccx, JSID_TO_STRING(id));
        if(!name)
        {
            name = "";
        }
        sz = JS_smprintf("%s [%s.%s]", *psz, iface->GetNameString(), name);
    }

    if(sz)
    {
        if(own)
            JS_smprintf_free(*psz);
        *psz = sz;
    }
}

/**
 * Get the interface name and member name (for error messages).
 *
 * We could instead have each quick stub pass its name to the error-handling
 * functions, as that name is statically known.  But that would be redundant;
 * the information is handy at runtime anyway.  Also, this code often produces
 * a more specific error message, e.g. "[nsIDOMHTMLDocument.appendChild]"
 * rather than "[nsIDOMNode.appendChild]".
 */
static void
GetMemberInfo(JSObject *obj,
              jsval memberId,
              const char **ifaceName,
              const char **memberName)
{
    // Get the interface name.  From DefinePropertyIfFound (in
    // xpcwrappednativejsops.cpp) and XPCThrower::Verbosify.
    //
    // We could instead make the quick stub could pass in its interface name,
    // but this code often produces a more specific error message, e.g.
    *ifaceName = "Unknown";

    NS_ASSERTION(IS_WRAPPER_CLASS(STOBJ_GET_CLASS(obj)) ||
                 STOBJ_GET_CLASS(obj) == &XPC_WN_Tearoff_JSClass ||
                 IS_SLIM_WRAPPER(obj),
                 "obj must be a wrapper");
    XPCWrappedNativeProto *proto;
    if(IS_SLIM_WRAPPER(obj))
    {
        proto = GetSlimWrapperProto(obj);
    }
    else
    {
        XPCWrappedNative *wrapper = (XPCWrappedNative *) obj->getPrivate();
        proto = wrapper->GetProto();
    }
    if(proto)
    {
        XPCNativeSet *set = proto->GetSet();
        if(set)
        {
            XPCNativeMember *member;
            XPCNativeInterface *iface;

            if(set->FindMember(memberId, &member, &iface))
                *ifaceName = iface->GetNameString();
        }
    }

    *memberName = (JSVAL_IS_STRING(memberId)
                   ? JS_GetStringBytes(JSVAL_TO_STRING(memberId))
                   : "unknown");
}

NativeInterfaceSweeper(JSDHashTable *table, JSDHashEntryHdr *hdr,
                       uint32 number, void *arg)
{
    CX_AND_XPCRT_Data* data = (CX_AND_XPCRT_Data*) arg;
    XPCNativeInterface* iface = ((IID2NativeInterfaceMap::Entry*)hdr)->value;
    if(iface->IsMarked())
    {
        iface->Unmark();
        return JS_DHASH_NEXT;
    }

#ifdef XPC_REPORT_NATIVE_INTERFACE_AND_SET_FLUSHING
    printf("- Destroying XPCNativeInterface for %s\n",
            JS_GetStringBytes(JSVAL_TO_STRING(iface->GetName())));
#endif

    XPCNativeInterface::DestroyInstance(data->cx, data->rt, iface);
    return JS_DHASH_REMOVE;
}

static bool
XPC_WN_TearOff_Enumerate(JSContext* cx, HandleObject obj)
{
    XPCCallContext ccx(cx, obj);
    XPCWrappedNative* wrapper = ccx.GetWrapper();
    THROW_AND_RETURN_IF_BAD_WRAPPER(cx, wrapper);

    XPCWrappedNativeTearOff* to = ccx.GetTearOff();
    XPCNativeInterface* iface;

    if (!to || nullptr == (iface = to->GetInterface()))
        return Throw(NS_ERROR_XPC_BAD_OP_ON_WN_PROTO, cx);

    uint16_t member_count = iface->GetMemberCount();
    for (uint16_t k = 0; k < member_count; k++) {
        if (!xpc_ForcePropertyResolve(cx, obj, iface->GetMemberAt(k)->GetName()))
            return false;
    }

    return true;
}

NativeSetSweeper(JSDHashTable *table, JSDHashEntryHdr *hdr,
                 uint32 number, void *arg)
{
    XPCNativeSet* set = ((NativeSetMap::Entry*)hdr)->key_value;
    if(set->IsMarked())
    {
        set->Unmark();
        return JS_DHASH_NEXT;
    }

#ifdef XPC_REPORT_NATIVE_INTERFACE_AND_SET_FLUSHING
    printf("- Destroying XPCNativeSet for:\n");
    PRUint16 count = set->GetInterfaceCount();
    for(PRUint16 k = 0; k < count; k++)
    {
        XPCNativeInterface* iface = set->GetInterfaceAt(k);
        printf("    %s\n",JS_GetStringBytes(JSVAL_TO_STRING(iface->GetName())));
    }
#endif

    XPCNativeSet::DestroyInstance(set);
    return JS_DHASH_REMOVE;
}

// static
void
XPCThrower::Verbosify(XPCCallContext& ccx,
                      char** psz, bool own)
{
    char* sz = nullptr;

    if (ccx.HasInterfaceAndMember()) {
        XPCNativeInterface* iface = ccx.GetInterface();
        jsid id = ccx.GetMember()->GetName();
        JSAutoByteString bytes;
        const char* name = JSID_IS_VOID(id) ? "Unknown" : bytes.encodeLatin1(ccx, JSID_TO_STRING(id));
        if (!name) {
            name = "";
        }
        sz = JS_smprintf("%s [%s.%s]", *psz, iface->GetNameString(), name);
    }

    if (sz) {
        if (own)
            JS_smprintf_free(*psz);
        *psz = sz;
    }
}

/**
 * Get the interface name and member name (for error messages).
 *
 * We could instead have each quick stub pass its name to the error-handling
 * functions, as that name is statically known.  But that would be redundant;
 * the information is handy at runtime anyway.  Also, this code often produces
 * a more specific error message, e.g. "[nsIDOMHTMLDocument.appendChild]"
 * rather than "[nsIDOMNode.appendChild]".
 */
static void
GetMemberInfo(JSObject *obj, jsid memberId, const char **ifaceName)
{
    *ifaceName = "Unknown";

    // Don't try to generate a useful name if there are security wrappers,
    // because it isn't worth the risk of something going wrong just to generate
    // an error message. Instead, only handle the simple case where we have the
    // reflector in hand.
    if (IS_WN_REFLECTOR(obj)) {
        XPCWrappedNative *wrapper = XPCWrappedNative::Get(obj);
        XPCWrappedNativeProto *proto = wrapper->GetProto();
        if (proto) {
            XPCNativeSet *set = proto->GetSet();
            if (set) {
                XPCNativeMember *member;
                XPCNativeInterface *iface;

                if (set->FindMember(memberId, &member, &iface))
                    *ifaceName = iface->GetNameString();
            }
        }
    }
}

bool
XPC_WN_Shared_Enumerate(JSContext* cx, HandleObject obj)
{
    XPCCallContext ccx(cx, obj);
    XPCWrappedNative* wrapper = ccx.GetWrapper();
    THROW_AND_RETURN_IF_BAD_WRAPPER(cx, wrapper);

    // Since we aren't going to enumerate tearoff names and the prototype
    // handles non-mutated members, we can do this potential short-circuit.
    if (!wrapper->HasMutatedSet())
        return true;

    XPCNativeSet* set = wrapper->GetSet();
    XPCNativeSet* protoSet = wrapper->HasProto() ?
                                wrapper->GetProto()->GetSet() : nullptr;

    uint16_t interface_count = set->GetInterfaceCount();
    XPCNativeInterface** interfaceArray = set->GetInterfaceArray();
    for (uint16_t i = 0; i < interface_count; i++) {
        XPCNativeInterface* iface = interfaceArray[i];
        uint16_t member_count = iface->GetMemberCount();
        for (uint16_t k = 0; k < member_count; k++) {
            XPCNativeMember* member = iface->GetMemberAt(k);
            jsid name = member->GetName();

            // Skip if this member is going to come from the proto.
            uint16_t index;
            if (protoSet &&
                protoSet->FindMember(name, nullptr, &index) && index == i)
                continue;
            if (!xpc_ForcePropertyResolve(cx, obj, name))
                return false;
        }
    }
    return true;
}

//.........这里部分代码省略.........
                // Skip this part if XPConnect is shutting down. We get into
                // bad locking problems with the thread iteration otherwise.
                if(!self->GetXPConnect()->IsShuttingDown())
                {
                    PRLock* threadLock = XPCPerThreadData::GetLock();
                    if(threadLock)
                    { // scoped lock
                        nsAutoLock lock(threadLock);

                        XPCPerThreadData* iterp = nsnull;
                        XPCPerThreadData* thread;

                        while(nsnull != (thread =
                                     XPCPerThreadData::IterateThreads(&iterp)))
                        {
                            // Mark those AutoMarkingPtr lists!
                            thread->MarkAutoRootsAfterJSFinalize();

                            XPCCallContext* ccxp = thread->GetCallContext();
                            while(ccxp)
                            {
                                // Deal with the strictness of callcontext that
                                // complains if you ask for a set when
                                // it is in a state where the set could not
                                // possibly be valid.
                                if(ccxp->CanGetSet())
                                {
                                    XPCNativeSet* set = ccxp->GetSet();
                                    if(set)
                                        set->Mark();
                                }
                                if(ccxp->CanGetInterface())
                                {
                                    XPCNativeInterface* iface = ccxp->GetInterface();
                                    if(iface)
                                        iface->Mark();
                                }
                                ccxp = ccxp->GetPrevCallContext();
                            }
                        }
                    }
                }

                // Do the sweeping...

                // We don't want to sweep the JSClasses at shutdown time.
                // At this point there may be JSObjects using them that have
                // been removed from the other maps.
                if(!self->GetXPConnect()->IsShuttingDown())
                {
                    self->mNativeScriptableSharedMap->
                        Enumerate(JSClassSweeper, nsnull);
                }

                self->mClassInfo2NativeSetMap->
                    Enumerate(NativeUnMarkedSetRemover, nsnull);

                self->mNativeSetMap->
                    Enumerate(NativeSetSweeper, nsnull);

                CX_AND_XPCRT_Data data = {cx, self};

                self->mIID2NativeInterfaceMap->
                    Enumerate(NativeInterfaceSweeper, &data);

#ifdef DEBUG