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/* -*- 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 */
#include "MMPrinter.h"
#include "jsapi.h"
#include "nsJSUtils.h"
#include "Logging.h"
#include "mozilla/Bootstrap.h"
#include "mozilla/dom/ipc/StructuredCloneData.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/RandomNum.h"
#include "nsFrameMessageManager.h"
#include "prenv.h"
namespace mozilla::dom {
LazyLogModule MMPrinter::sMMLog("MessageManager");
// You can use
// the output of the logs into logs more friendly to reading.
/* static */
void MMPrinter::PrintImpl(char const* aLocation, const nsAString& aMsg,
ClonedMessageData const& aData) {
NS_ConvertUTF16toUTF8 charMsg(aMsg);
* The topic will be skipped if the topic name appears anywhere as a substring
* of the filter.
* Example:
* MOZ_LOG_MESSAGEMANAGER_SKIP="foobar|extension"
* Will match the topics 'foobar', 'foo', 'bar', and 'ten' (even though
* you may not have intended to match the latter three) and it will not match
* the topics 'extensionresult' or 'Foo'.
if (mmSkipLog && strstr(mmSkipLog, charMsg.get())) {
uint64_t msg_id = RandomUint64OrDie();
MOZ_LOG(MMPrinter::sMMLog, LogLevel::Debug,
("%" PRIu64 " %s Message: %s in process type: %s", msg_id, aLocation,
charMsg.get(), XRE_GetProcessTypeString()));
if (!MOZ_LOG_TEST(sMMLog, LogLevel::Verbose)) {
ErrorResult rv;
AutoJSAPI jsapi;
// We're using this context to deserialize, stringify, and print a message
// manager message here. Since the messages are always sent from and to system
// scopes, we need to do this in a system scope, or attempting to deserialize
// certain privileged objects will fail.
JSContext* cx =;
ipc::StructuredCloneData data;
ipc::UnpackClonedMessageData(aData, data);
/* Read original StructuredCloneData. */
JS::Rooted<JS::Value> scdContent(cx);
data.Read(cx, &scdContent, rv);
if (rv.Failed()) {
// In testing, the only reason this would fail was if there was no data in
// the message; so it seems like this is safe-ish.
MOZ_LOG(MMPrinter::sMMLog, LogLevel::Verbose,
("%" PRIu64 " (No Data)", msg_id));
JS::Rooted<JSString*> unevalObj(cx, JS_ValueToSource(cx, scdContent));
nsAutoJSString srcString;
if (!srcString.init(cx, unevalObj)) return;
MOZ_LOG(MMPrinter::sMMLog, LogLevel::Verbose,
("%" PRIu64 " %s", msg_id, NS_ConvertUTF16toUTF8(srcString).get()));
} // namespace mozilla::dom