在过去的几个月里，我一直在组装我自己的基于 QtWebKit 的浏览器( WildFox ，BSD 许可)，这是一次非常愉快的体验。然而，我注意到奇怪的崩溃，基本上是从一开始就发生的。昨天，当它无法重复加载我的个人网站 www.mayaposch.com 时，我决定深入研究这些崩溃。
事件顺序如下:我使用load()或setUrl()告诉QWebView元素加载http://www.mayaposch.com， loadFinished() 返回 false，表示在加载页面期间出现错误，然后是应用程序段错误。
我正在使用 Qt 4.8(最新的 SDK)，发布和调试库(动态)。
使用 gdb 运行调试构建时的堆栈跟踪:
0 WTF::HashTable<WTF::RefPtr<WebCore::ResourceLoader>, std::pair<WTF::RefPtr<WebCore::ResourceLoader>, WTF::RefPtr<WebCore::SubstituteResource> >, WTF::PairFirstExtractor<std::pair<WTF::RefPtr<WebCore::ResourceLoader>, WTF::RefPtr<WebCore::SubstituteResource> > >, WTF::PtrHash<WTF::RefPtr<WebCore::ResourceLoader> >, WTF::PairHashTraits<WTF::HashTraits<WTF::RefPtr<WebCore::ResourceLoader> >, WTF::HashTraits<WTF::RefPtr<WebCore::SubstituteResource> > >, WTF::HashTraits<WTF::RefPtr<WebCore::ResourceLoader> > >::isEmpty() const D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xbcd036e
1 WTF::HashMap<WTF::RefPtr<WebCore::ResourceLoader>, WTF::RefPtr<WebCore::SubstituteResource>, WTF::PtrHash<WTF::RefPtr<WebCore::ResourceLoader> >, WTF::HashTraits<WTF::RefPtr<WebCore::ResourceLoader> >, WTF::HashTraits<WTF::RefPtr<WebCore::SubstituteResource> > >::isEmpty() const D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xbcc7315
2 WebCore::DocumentLoader::cancelPendingSubstituteLoad(WebCore::ResourceLoader*) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb3cbb96
3 WebCore::ResourceLoader::didCancel(WebCore::ResourceError const&) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb62277f
4 WebCore::SubresourceLoader::didCancel(WebCore::ResourceError const&) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb75859c
5 WebCore::ResourceLoader::cancel(WebCore::ResourceError const&) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb622900
6 WebCore::ResourceLoader::cancel() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb62285a
7 WebCore::cancelAll(WTF::HashSet<WTF::RefPtr<WebCore::ResourceLoader>, WTF::PtrHash<WTF::RefPtr<WebCore::ResourceLoader> >, WTF::HashTraits<WTF::RefPtr<WebCore::ResourceLoader> > > const&) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb3c8725
8 WebCore::DocumentLoader::stopLoadingSubresources() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb3cbfa4
9 WebCore::DocumentLoader::stopLoading() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb3ca9e0
10 WebCore::FrameLoader::stopAllLoaders(WebCore::ClearProvisionalItemPolicy) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f3694
11 WebCore::FrameLoader::continueLoadAfterNavigationPolicy(WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f7d29
12 WebCore::FrameLoader::callContinueLoadAfterNavigationPolicy(void*, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f76a1
13 WebCore::PolicyCallback::call(bool) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb56e06c
14 WebCore::PolicyChecker::continueAfterNavigationPolicy(WebCore::PolicyAction) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb56ed26
15 WebCore::FrameLoaderClientQt::callPolicyFunction(void (WebCore::PolicyChecker::*)(WebCore::PolicyAction), WebCore::PolicyAction) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb141188
16 WebCore::FrameLoaderClientQt::dispatchDecidePolicyForNavigationAction(void (WebCore::PolicyChecker::*)(WebCore::PolicyAction), WebCore::NavigationAction const&, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb146959
17 WebCore::PolicyChecker::checkNavigationPolicy(WebCore::ResourceRequest const&, WebCore::DocumentLoader*, WTF::PassRefPtr<WebCore::FormState>, void (*)(void*, WebCore::ResourceRequest const&, WTF::PassRefPtr<WebCore::FormState>, bool), void*) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb56e7ef
18 WebCore::FrameLoader::loadWithDocumentLoader(WebCore::DocumentLoader*, WebCore::FrameLoadType, WTF::PassRefPtr<WebCore::FormState>) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f25e9
19 WebCore::FrameLoader::loadWithNavigationAction(WebCore::ResourceRequest const&, WebCore::NavigationAction const&, bool, WebCore::FrameLoadType, WTF::PassRefPtr<WebCore::FormState>) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f1fc5
20 WebCore::FrameLoader::loadURL(WebCore::KURL const&, WTF::String const&, WTF::String const&, bool, WebCore::FrameLoadType, WTF::PassRefPtr<WebCore::Event>, WTF::PassRefPtr<WebCore::FormState>) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f17f1
21 WebCore::FrameLoader::loadFrameRequest(WebCore::FrameLoadRequest const&, bool, bool, WTF::PassRefPtr<WebCore::Event>, WTF::PassRefPtr<WebCore::FormState>, WebCore::ReferrerPolicy) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2f1086
22 WebCore::FrameLoader::urlSelected(WebCore::FrameLoadRequest const&, WTF::PassRefPtr<WebCore::Event>, bool, bool, WebCore::ReferrerPolicy, WebCore::ShouldReplaceDocumentIfJavaScriptURL) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2ece3e
23 WebCore::FrameLoader::changeLocation(WTF::PassRefPtr<WebCore::SecurityOrigin>, WebCore::KURL const&, WTF::String const&, bool, bool, bool) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb2ec9de
24 WebCore::ScheduledURLNavigation::fire(WebCore::Frame*) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xbc30de8
25 WebCore::NavigationScheduler::timerFired(WebCore::Timer<WebCore::NavigationScheduler>*) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb3cd565
26 WebCore::Timer<WebCore::NavigationScheduler>::fired() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xbc7adb2
27 WebCore::ThreadTimers::sharedTimerFiredInternal() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb4a84e6
28 WebCore::ThreadTimers::sharedTimerFired() D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb4a8433
29 WebCore::SharedTimerQt::timerEvent(QTimerEvent*) D:\Dev\Qt\SDK\Desktop\Qt\4.8.0\mingw\bin\QtWebKitd4.dll 0 0xb686a5a
30 QObject::event qobject.cpp 1157 0x6a22499a
31 QApplicationPrivate::notify_helper qapplication.cpp 4550 0xa4c020
32 QApplication::notify qapplication.cpp 3932 0xa49973
33 QCoreApplication::notifyInternal qcoreapplication.cpp 876 0x6a213252
34 QCoreApplication::sendEvent qcoreapplication.h 231 0x6a283f54
35 QEventDispatcherWin32::event qeventdispatcher_win.cpp 1135 0x6a23ac60
36 QApplicationPrivate::notify_helper qapplication.cpp 4550 0xa4c020
37 QApplication::notify qapplication.cpp 3932 0xa49973
38 QCoreApplication::notifyInternal qcoreapplication.cpp 876 0x6a213252
39 QCoreApplication::sendEvent qcoreapplication.h 231 0x6a283f54
40 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1500 0x6a21416d
41 qt_internal_proc qeventdispatcher_win.cpp 496 0x6a238a2f
42 USER32!IsDialogMessageW C:\Windows\syswow64\user32.dll 0 0x75a46238
43 operator+ 0 0x7113ae
44 USER32!AllowForegroundActivation C:\Windows\syswow64\user32.dll 0 0x75a468ea
45 qt_fast_timer_proc qeventdispatcher_win.cpp 428 0x6a2387c8
46 USER32!GetMessageExtraInfo C:\Windows\syswow64\user32.dll 0 0x75a47d31
47 ?? 0
故障线(拆机)表示为:
0xbcd036e <+0x0006> mov 0xc(%eax),%eax
这是内部 QtWebKit 错误吗？从堆栈跟踪我会说它是，但我缺乏它的内部知识来说明出了什么问题。崩溃最常发生在我的个人网站上，但其他人报告说它在其他网站上也会崩溃，包括中断加载时(例如，在加载完成之前单击链接)。
感谢您提供的任何帮助。
最佳答案
在与 Net147 (Jonathan Liu) 在#Qt @Freenode IRC 上进行讨论后，确定这确实是由于 webkit 中的一个错误:https://bugs.webkit.org/show_bug.cgi?id=83565
The crash is caused by a null pointer dereference in Source/WebCore/loader/ResourceLoader.cpp in the function ResourceLoader::didCancel(). m_documentLoader->cancelPendingSubstituteLoad(this) is called without checking if m_documentLoader is null.
我觉得最有趣的是我的代码触发了这个错误，而 Qt 浏览器演示却没有。任何愿意弄清楚为什么会这样的人都非常欢迎:)
关于c++ - 加载特定网站时 QtWebKit 2.2 段错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10072774/