how to start a the BTAGService with Windbg

Question

Hi，

I need starting a service with Windbg, though i know we can start or stop a service with services.msc. I am analying a issue which need add a break when the BTAGService is starting.

How Should i do ?

Thanks

Answer 1

Hello

Thank you for posting in Q&A forum.

To debug a service

1. Build your service in the Debug configuration.
2. Install your service. For more information, see How to: Install and Uninstall Services.
3. Start your service, either from Services Control Manager, Server Explorer, or from code. For more information, see How to: Start Services.
4. Start Visual Studio with administrative credentials so you can attach to system processes.
5. (Optional) On the Visual Studio menu bar, choose Tools, Options. In the Options dialog box, choose Debugging, Symbols, select the Microsoft Symbol Servers check box, and then choose the OK button.
6. On the menu bar, choose Attach to Process from the Debug or Tools menu. (Keyboard: Ctrl+Alt+P)

The Processes dialog box appears.

1. Select the Show processes from all users check box.
2. In the Available Processes section, choose the process for your service, and then choose Attach.

Tip

The process will have the same name as the executable file for your service.

The Attach to Process dialog box appears.

Choose the appropriate options and then choose OK to close the dialog box.

Note

You are now in debug mode.

1. Set any breakpoints you want to use in your code.
2. Access the Services Control Manager and manipulate your service, sending stop, pause, and continue commands to hit your breakpoints. For more information about running the Services Control Manager, see How to: Start Services. Also, see Troubleshooting: Debugging Windows Services.

Reference：

How to: Debug Windows Service Applications - .NET Framework | Microsoft Learn

I hope the information above is helpful.

If you have any questions or concerns, please feel free to let us know.

Best Regards,

Daisy Zhou

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Answer 2

Hi,

Thank you for your answer. But it seems that this method cannot solve my needs。

1、The BTAGService is an service which provided by Microsoft, So I don't have the source code to build.

2、 I need to analysis the start up of the BTAGService and add a break before it call ServiceMain Function, so the method of attaching to the process cannot meet my requirements.

Thanks

Answer 3

You cannot debug the startup code of a service. This is one of the known issues with building services.

The earliest you can break into a service is when the service is started. Hence any code that runs before that such as the process startup code (which is different than the service startup code) or any initialization that happens before the service's start function is called cannot be debugged.

The general workaround to this is to have a service, which by definition are console apps, also accept a command line argument that tells it to run as a normal console app instead of as a service. Within the console app's main entry point it detects this command line argument and effectively starts the service like the SCM would normally do. This allows you to run, and hence debug, the startup code when it runs as a regular console app. Of course anything that is specific to the service runtime, such as security, won't generally replicate here but if the code works as a console app and not as a service then that drastically narrows things down.

Since you mentioned that the service isn't yours and therefore you don't have the source code then you cannot really debug it can you. Even if you have the debug symbol files, which you'll likely only get by downloading the Windows symbols for the OS you're running on and even then the service may not be included, then the best you'll get is a more accurate callstack. That doesn't really help you any in most cases. This is especially true for startup code since there is no way to inject yourself into the startup of a service.

I think you're asking for something that isn't doable. I'm more interested in knowing why you need to debug this code? Are you seeing errors? If so then provide the details of what is going on and the error logs. This would be far easier to do and more likely to produce a potential solution than trying to debug a service that you don't have the code for.