Coverage Report

Created: 2018-09-25 14:53

/src/mozilla-central/js/xpconnect/src/XPCJSWeakReference.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* vim: set ts=8 sts=4 et sw=4 tw=99: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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 * License, v. 2.0. If a copy of the MPL was not distributed with this
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 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "xpcprivate.h"
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#include "XPCJSWeakReference.h"
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#include "nsContentUtils.h"
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using namespace JS;
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xpcJSWeakReference::xpcJSWeakReference()
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{
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}
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NS_IMPL_ISUPPORTS(xpcJSWeakReference, xpcIJSWeakReference)
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nsresult xpcJSWeakReference::Init(JSContext* cx, const JS::Value& object)
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{
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    if (!object.isObject()) {
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        return NS_OK;
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    }
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    JS::RootedObject obj(cx, &object.toObject());
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    XPCCallContext ccx(cx);
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    // See if the object is a wrapped native that supports weak references.
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    nsCOMPtr<nsISupports> supports = xpc::UnwrapReflectorToISupports(obj);
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    nsCOMPtr<nsISupportsWeakReference> supportsWeakRef =
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        do_QueryInterface(supports);
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    if (supportsWeakRef) {
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        supportsWeakRef->GetWeakReference(getter_AddRefs(mReferent));
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        if (mReferent) {
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            return NS_OK;
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        }
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    }
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    // If it's not a wrapped native, or it is a wrapped native that does not
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    // support weak references, fall back to getting a weak ref to the object.
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    // See if object is a wrapped JSObject.
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    RefPtr<nsXPCWrappedJS> wrapped;
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    nsresult rv = nsXPCWrappedJS::GetNewOrUsed(cx, obj,
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                                               NS_GET_IID(nsISupports),
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                                               getter_AddRefs(wrapped));
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    if (!wrapped) {
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        NS_ERROR("can't get nsISupportsWeakReference wrapper for obj");
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        return rv;
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    }
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    return wrapped->GetWeakReference(getter_AddRefs(mReferent));
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}
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NS_IMETHODIMP
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xpcJSWeakReference::Get(JSContext* aCx, MutableHandleValue aRetval)
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{
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    aRetval.setNull();
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    if (!mReferent) {
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        return NS_OK;
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    }
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    nsCOMPtr<nsISupports> supports = do_QueryReferent(mReferent);
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    if (!supports) {
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        return NS_OK;
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    }
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    nsCOMPtr<nsIXPConnectWrappedJS> wrappedObj = do_QueryInterface(supports);
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    if (!wrappedObj) {
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        // We have a generic XPCOM object that supports weak references here.
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        // Wrap it and pass it out.
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        return nsContentUtils::WrapNative(aCx, supports,
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                                          &NS_GET_IID(nsISupports),
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                                          aRetval);
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    }
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    JS::RootedObject obj(aCx, wrappedObj->GetJSObject());
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    if (!obj) {
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        return NS_OK;
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    }
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    // Most users of XPCWrappedJS don't need to worry about
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    // re-wrapping because things are implicitly rewrapped by
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    // xpcconvert. However, because we're doing this directly
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    // through the native call context, we need to call
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    // JS_WrapObject().
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    if (!JS_WrapObject(aCx, &obj)) {
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        return NS_ERROR_FAILURE;
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    }
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    aRetval.setObject(*obj);
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    return NS_OK;
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}