This somewhat links to my previous question. Background details here: Simple HTTP request with C++
Basically I am sending data to a server through an URL with C++. I am now using openURL() function in the CInternetSession class to do it. If the openURL connects to the server successfully, no errors or exceptions are thrown. However, sometimes, in the debugger in Visual C++ 2006, I would get this pop-up
First-chance exception in myProg.exe (KERNELBASE.DLL):
0xE06D7363: Microsoft C++ Exception.
I have set the debug exceptions to "stop always" and in the debug window it shows me
Warning: throwing CInternetException for error 12029
In addition, when I run the program by itself (without the debugger and stuff), I get a pop-up saying debug error.
I understand that this is because the openURL() couldn't make a connection to the specified URL. However, my problem now is I do not want a pop-up to inform me of this. I have put a try catch block around my code but it's still not handling the exception. Here's the code
try {
// Open HTTP file
pHttpFile =(CHttpFile *) mySession.OpenURL(test1.c_str());
}
catch (CInternetException) {
printf("Received Exception from OpenURL()");
// Handle exception
}
Am I missing something here!?
Try connecting to that IP address with another method manually with 'connect'. If you can connect to it, then the openURL won't throw an exception because you already tested that you can connect to it with that other function I just mentioned.
May you also consider looking in your code to ensure that the exception is not being thrown elsewhere?
I think you should catch CInternetException* instead. For all MFC exceptions is throwed as a pointer.
PS.
You should also use CException::Delete() in your catch block to delete the exception object you just catched if you don't need to throw it again.
Related
A library I am using (zmq) throws an exception. The debugger breaks and informs me.
How, if possible, can I see this exception. Specifically the what() message?
Without having to place try/catch around it and printing to the output stream.
It does not appear in the Autos or Locals watch lists. I have searched the stack frames around the point at which it occured.
Adding $exception to a manual watch list simply returns a value of "identifier $exception is undefined"
Using memory explorer to interrogate the exception's location does not show anything useful.
I have read this can be done when using the CLR - can I do it in regular C++?
Referencing this answer:
You'll get a window when the exception is thrown with the option to break/continue/ignore. Copy and paste the hex address this dialog reports, then click the break button. Now in a watch window, enter something like:
(std::exception*)0xXXXXXXXX
(1) Please check that whether the Exception messages was enabled in the output window under Tools->Options->Debugging->Output window.
(2)If it still no exception messages, one possible reason is that zmq really doesn't support the Exception throw feature of VS. Of course, you could write a general app like C# or VC++ which can prove it. If other apps have no this issue, we would think about the specific zmq.
Step 1. Identify the exception (it would be logged in the output window in VS)
Step 2. Put an exception breakpoint with the exception you saw from the output.
If this is ZeroMQ, I'd wager you're Sending 2 requests on a REQ socket without waiting for a reply.
your output window
(View/Output or click CTRL + ALT + O)
is where you should see the message, but you may need to check the exceptions option:
Look here for more detail
As far as I'm aware, this isn't currently possible. I've added a User Voice suggestion here but I'm not sure when, if ever, Microsoft will implement this feature.
For now, what you can do is take the Type and Location of the exception (from the message 'Exception thrown at Address in Module: Microsoft C++ exception: Type at memory location Location.', and then add to the Watch window the expression '(Type*)Location'. If Type is some internal exception type that you don't have access to, then you can hope it derives from std::exception and cast to that instead.
I am working with point cloud library and it has a handled exception which is thrown when there is no model to fit.
I do not want to see their message in my log, I cannot catch it again as it has already been caught via pcl.
is there a way in C++ to workaround this issue and stop their message?
I keep getting the following error in visual studio:
http://i.stack.imgur.com/qKyk8.png
However if I click continue my application runs perfectly fine, every time I run it it does this. As you can imagine this is incredibly annoying. I have gone through the exception settings to try and find something under runtime, error, runtime_error, std and so on. I was not able to find anything that matched the description of the error. Additionally I have no idea what is causing this to popup in the first place, as how am I supposed to know what is using that memory location?
You can disable it by properly handling the cause of the exception being thrown. Debug your code to find what is causing the exception.
Try going to exception settings, add new C++ exception: std::runtime_error and uncheck it. Or just stop breaking in any C++ exceptions at all.
I'm a beginner with the windows api so there must be something i don't understand here. In my main function i'm using a try-catch to catch all uncaught exceptions, but for some reason, exceptions i throw from somewhere else in the code are never caught. My application uses a single (main) thread.
I'm throwing like this :
throw "ClassName::methodName() - Error message";
And catching the exceptions outside of the message loop :
try {
while(GetMessage(args...)) {
TranslateMessage(args...);
DispatchMessage(args...);
}
}
catch( const char * sExc ) {
::MessageBox(args...);
}
I first thought it was a problem of types mismatching, but then i added a catch(...) with ellipsis and i still caught nothing. If you ask, yes, i'm sure the exception is thrown. Isn't it a problem related to some kind of asynchronousness or something like that ?
Thanks for your help !
It depends on the specific message that's getting dispatched. But no, not all of them allow the stack to be unwound through Windows internal code. Particularly the messages that involve the window manager, WM_CREATE for example. There's a backstop inside Windows that prevents the stack from being unwound past that critical code. There's also an issue with exceptions in 32-bit code that run on the 64-bit version of Windows 7, they can get swallowed when the message needs to traverse the Wow64 boundary several times. Fixed in Windows 8.
On later Windows versions this can also activate "self-healing" code, automatically activating an appcompat shim that swallows the exception. You'll get a notification for that, easy to dismiss. You'll then see the first-chance exception notification in the VS Output window but your program keeps running. Okayish for the user perhaps but not great while you are debugging of course. Run Regedit.exe and navigate to HKCU\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Compatibility Assistant\Persisted and check if your program is listed there. Just delete the entry.
Long story short, it is not safe to catch exceptions outside of the message loop. You have to do it inside the window procedure.
You are talking about "Windows Structured Exception Handling" (http://msdn.microsoft.com/en-us/library/windows/desktop/ms680657%28v=vs.85%29.aspx). C++ exceptions are not thrown.
If you want to go the troublesome route: _set_se_translator
See also: Can a C program handle C++ exceptions? (The windows API is not C++)
My app was running fine until I tried to debug it with the Application Verifier. After that I started getting "First-chance exception... : An invalid handle was specified" and the issue seems to be in the "bailout.c" file in Pantheios:
hFile = CreateFileA("logging-bailout.txt"
, GENERIC_WRITE
, 0
, NULL
, OPEN_ALWAYS
, 0
, NULL); <--- this is where it crashes, line 442
And message:
First-chance exception at 0x7769f8cd in myapp.exe: 0xC0000008: An invalid handle was specified.
=======================================
VERIFIER STOP 0000000000000300: pid 0x3814: Invalid handle exception for current stack trace.
00000000C0000008 : Exception code.
00000000111DE950 : Exception record. Use .exr to display it.
00000000111DE460 : Context record. Use .cxr to display it.
0000000000000000 : Not used.
=======================================
This verifier stop is continuable.
After debugging it use `go' to continue.
=======================================
Before the console just logged the exceptions that I got with Pantheios and I didnt really care too much about. However, now when the app crashes on the first occurrence of logging using Pantheios it's time for me to deal with this, but I'm not too sure sure how to.
I was following this guide when setting up my Pantheios: http://www.codeproject.com/Articles/27119/Using-Callback-Back-ends-with-the-Pantheios-Loggin
In every file I have logging I have the following lines in the source file:
#include <pantheios/pantheios.hpp>
#include <pantheios/inserters/boolean.hpp>
#include <pantheios/inserters/integer.hpp>
#include <Shared/logs.h>
logs.h contains:
#include <pantheios/implicit_link/core.h>
#include <pantheios/implicit_link/fe.simple.h>
#include <pantheios/implicit_link/be.WindowsConsole.h>
I also call pantheios::init(); before doing any logging.
I'm using Visual studio 2010 and are including the following lib-files under "Additional Dependencies":
$(PANTHEIOS_ROOT)\lib\pantheios.1.core.vc10.mt.debug.lib
$(PANTHEIOS_ROOT)\lib\pantheios.1.be.WindowsConsole.vc10.mt.debug.lib
$(PANTHEIOS_ROOT)\lib\pantheios.1.fe.simple.vc10.mt.debug.lib
$(PANTHEIOS_ROOT)\lib\pantheios.1.util.vc10.mt.debug.lib
However, all my logging looks like this:
First-chance exception at 0x750bb9bc in myapp.exe: Microsoft C++ exception: stlsoft::winstl_project::windows_exception at memory location 0x1822bda0..
20120423-104817.497: failed to write message to log file; given message follows: [myapp.Qt.Framework.13424, 23/04/2012 10:48:17.496 a.m.; Debug]: "some logging"
when calling pantheios::log(pantheios::debug, "some logging");
Then, all my logging is written to a "bailout"file in the same folder as the project. This worked before but it was a big bullet on my "To-do-list" (but a bit further down than other things).
So now my question is, how do I fix this? Followed every tutorial I can find but with no success. And why did my app decide to not accept this anymore after running the Ms Application Verifier? Makes no sense.
First chance exceptions mean only that an exception was thrown. It does not mean you have a bug in your program, just that the debugger is showing you that an exception is being thrown, so you have a chance to examine it before it is propagated up the call chain. If the exception is caught by an exception handler (e.g. for logging), your application continues, otherwise the debugger gives you a second-chance exception notification to inform you that the application will exit due to an unhandled exception.
If you do not want to receive the first-chance exception notifications, you can turn it off in your debugger. This link may help on how to turn off exception handling in Application Verifier.
To work around this problem, turn off exceptions testing in Application Verifier. To do this, follow these steps:
1.Start Application Verifier.
2.Under Applications, click the GDI+ program that you want to test.
3.Under Tests, expand Basics.
4.Click to clear the Exceptions check box.
5.Run the GDI+ program that you want to test.
You can also configure the debugging tool to make sure that you do not experience a breakpoint in the debugging tool when an access violation occurs.
The alternative (turning off exception notification in MSVS) is via "Debug->Exceptions..."
Alternatively, if it is possible, make sure the exception does not get thrown in the first place. You will need to examine the nature of the exception (e.g. file not found) and fix the condition that is preventing the intended operation.
Given the nature/purpose of Application Verifier, I would suggest the latter approach: AV is telling you that something incorrect is going on that might have been ok previously, but can cause problems later on (depending on enviornment, circumstances, etc.)