我的 C++在某些机器上，库无法捕获它引发的异常

Question

我有一个简单的 C#.NET Windows 窗体应用程序。 它动态加载 C++ DLL（用 RAD Studio 创建）并调用其方法。

有时，库会抛出异常并捕获它们，以便它向我的应用程序返回有意义的错误。 在某些机器上，这种行为会使整个应用程序崩溃，因为显然库没有捕获异常（我的应用程序也没有捕获异常）。这怎么可能？

应用程序和DLL都是64位架构。如果我用 32 位构建就没有问题。

它运行的机器装有 Windows Server 2008 R2 Enterprise。

它不起作用的计算机具有 Windows Server 2019 Datacenter 和 Windows 10。

这是我的应用程序：

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;

namespace TestMyLib
{
    public partial class FMain : Form
    {
        public static readonly string LIBRARY_NAME = "MyLib.dll";
        private IntPtr handle;

        private void btnMM489_Click(object sender, EventArgs ea)
        {
            try
            {
                //load library
                string libPath = Path.Combine(Directory.GetCurrentDirectory(), "lib", LIBRARY_NAME);
                handle = NativeDlls.LoadLibraryEx(libPath, IntPtr.Zero, NativeDlls.LoadLibraryFlags.LOAD_WITH_ALTERED_SEARCH_PATH);
                if (handle == IntPtr.Zero)
                    throw new Exception(string.Format("Failed to load library '{0}'. {1}", LIBRARY_NAME, Marshal.GetLastWin32Error()));

                //call some lib functions
                //...

                //call a function (_FailingFunction)
                //that we know will launch an exception inside its try/catch
                Type delegateFunType = typeof(_FailingFunction);
                IntPtr funAddr = NativeDlls.GetProcAddress(handle, delegateFunType.Name);
                dynamic fun = Convert.ChangeType(Marshal.GetDelegateForFunctionPointer(funAddr, delegateFunType), delegateFunType);

                //********* THIS LINE MAKES THE APPLICATION CRASH *************
                fun.Invoke();

                //...

                MessageBox.Show("Success!");
            }
            catch (ExternalException e) { MessageBox.Show(e.ErrorCode + Environment.NewLine + e.Message + Environment.NewLine + e.StackTrace); }
            catch (Exception e) { MessageBox.Show(e.Message + Environment.NewLine + e.StackTrace); }
        }

        //Given delegate type, return the pointer to the DLL function,
        //which can be used to invoke such function
        private dynamic GetFunctionPtr(Type delegateFunType)
        {
            IntPtr funAddr = NativeDlls.GetProcAddress(handle, delegateFunType.Name);
            if (funAddr == IntPtr.Zero)
                throw new Exception(string.Format("Failed to load function {0} from library {1}: error code {2}",
                    delegateFunType.Name, LIBRARY_NAME, Marshal.GetLastWin32Error()));
            var fun = Convert.ChangeType(Marshal.GetDelegateForFunctionPointer(funAddr, delegateFunType), delegateFunType);
            return fun;
        }

        //delegates to MyLib.dll methods
        //...
        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
        private delegate bool _FailingFunction();

        public FMain() { InitializeComponent(); }
    }

    /// <summary>
    /// Static class containing some Windows API methods for handling
    /// native (unmanaged) DLLs.
    /// </summary>
    public static class NativeDlls
    {
        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern IntPtr LoadLibraryEx(string lpFileName, IntPtr hReservedNull, LoadLibraryFlags dwFlags);

        [Flags]
        public enum LoadLibraryFlags : uint { LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008 }

        [DllImport("kernel32.dll", CharSet = CharSet.Ansi)]
        public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
    }
}

如您所见，它调用我的库的函数 _FailingFunction。这样的函数会抛出一个明显的异常，应该捕获它：

bool FailingFunction()
{
    try
    {
        //****** THROW EXCEPTION! *******
        throw Exception("An error occured!");
        return true;
    }
    catch (Exception &E)
    {
        //****** HERE WE SHOULD CATCH IT... *******
        return false;
    }
}   

在 Windows 事件查看器中，崩溃生成此事件：

Applicazione: TestMyLib.exe
Versione framework: v4.0.30319
Descrizione: il processo è stato terminato a causa di un'eccezione non gestita.
Informazioni sull'eccezione: System.AccessViolationException
   in DynamicClass.CallSite.Target(System.Runtime.CompilerServices.Closure, System.Runtime.CompilerServices.CallSite, System.Object, Int32, System.String, System.String, System.Text.StringBuilder, Int32)
   in System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid6[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]](System.Runtime.CompilerServices.CallSite, System.__Canon, Int32, System.__Canon, System.__Canon, System.__Canon, Int32)
   in TestMyLib.FMain.btnMM489_Click(System.Object, System.EventArgs)
   in System.Windows.Forms.Control.OnClick(System.EventArgs)
   in System.Windows.Forms.Button.OnClick(System.EventArgs)
   in System.Windows.Forms.Button.OnMouseUp(System.Windows.Forms.MouseEventArgs)
   in System.Windows.Forms.Control.WmMouseUp(System.Windows.Forms.Message ByRef, System.Windows.Forms.MouseButtons, Int32)
   in System.Windows.Forms.Control.WndProc(System.Windows.Forms.Message ByRef)
   in System.Windows.Forms.ButtonBase.WndProc(System.Windows.Forms.Message ByRef)
   in System.Windows.Forms.Button.WndProc(System.Windows.Forms.Message ByRef)
   in System.Windows.Forms.NativeWindow.Callback(IntPtr, Int32, IntPtr, IntPtr)
   in System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG ByRef)
   in System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr, Int32, Int32)
   in System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner(Int32, System.Windows.Forms.ApplicationContext)
   in System.Windows.Forms.Application+ThreadContext.RunMessageLoop(Int32, System.Windows.Forms.ApplicationContext)
   in TestMyLib.Program.Main()

并且此事件：

Nome dell'applicazione che ha generato l'errore: TestMyLib.exe, versione: 1.0.1.2, timestamp: 0xf5550cd3
Nome del modulo che ha generato l'errore: KERNELBASE.dll, versione: 10.0.17763.2183, timestamp: 0x8e097f91
Codice eccezione: 0xc0000005
Offset errore 0x0000000000039329
ID processo che ha generato l'errore: 0x846c
Ora di avvio dell'applicazione che ha generato l'errore: 0x01d82e13c8a73c68
Percorso dell'applicazione che ha generato l'errore: C:\Users\Me\Desktop\TestMyLib\TestMyLib.exe
Percorso del modulo che ha generato l'errore: C:\Windows\System32\KERNELBASE.dll
ID segnalazione: 250ac398-95c1-4ef7-b999-c69d50653af1
Nome completo pacchetto che ha generato l'errore: 
ID applicazione relativo al pacchetto che ha generato l'errore: 

Answer 1

错误 c0000005 是 Windows 中“访问冲突”（又名 SIGBUS）的说法，是由于尝试读取或写入无效地址而引起的。

这是我们从您的日志中看到的一件事，但也许这是一个转移注意力的事情，而且似乎与您发布的代码无关。但是您可以捕获它 - 如果您发现需要 - 但不能使用 try ... catch。相反，您需要使用 Windows 的结构化异常处理 (SEH)，您将找到详细描述 此处。基本上，您需要做的是：；

__try
{
    some_code_i_dont_trust ();
}
__except(EXCEPTION_EXECUTE_HANDLER)
{
    handle_the_low_level_exception ();     // you might `throw` here, for example
}

您还应该查阅该链接来决定要使用哪些编译器开关，因为这些开关会影响编译器在引发异常时为您（或不为您）清理资源的方式。有关更多信息，请此处。

实际上，对我来说最好的方法是什么并不明显，但是如果您将所有潜在的硬件异常包装在 __try ... __ except 中，那么，从 Hans Passant 发布的内容来看，您'最好不要使用 /EHa。

除以零实际上也是一个“低级”（也称为硬件）异常，因此可以以相同的方式捕获和处理。再说一次，try ... catch 不会看到它。