ID: Q98890
The information in this article applies to:
The steps in this article illustrate how to debug a service under Windows NT using WinDbg and the interactive debugger included with Microsoft Visual C++ 4.x. WinDbg ships with the Win32 Software Development Kit (SDK). For illustration purposes, these procedures use the SERVICE sample, which is built with debugging information by default. This sample is located in:
Mstools\Samples\Win32\Winnt\Service
1. Build the sample.
2. Install the Simple service with the following command:
simple -install
You receive a message indicating whether you were successful.
service or you can also use:
sc start simpleservice
Sc.exe is located in Mstools\Bin.
(PID) for the Simple service. For example, if PView shows the process as
simple(0xD5), the PID is 0xD5. If you're using Microsoft Visual C++ 4.X,
convert the PID from hexadecimal to decimal. For example, 0xD5 is 213 in
decimal.
To specify Microsoft Visual C++ 4.X as your Just-in-time debugger:
1. On the tools menu, click options.
2. Click the debug tag, and select the Just-in-time debugging option.
To specify Windbg as your Just-in-time debugger, please refer to the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q103861
TITLE : Choosing the Debugger That the System Will Spawn
Runtime error!
Program: <MSDevDir\bin>\MSDEV.exe
abnormal program termination
If the spawned debugger is Windbg, the debugger will appear to have correctly attached to the service but you will notice a painting problem with the application.
If the service account does not belong to the administrator's group, the following error message appears on both Microsoft Visual C++ 4.X and Windbg:
Initialization of the dynamic link library
<system>\system32\USER32.dll failed. The process is
terminating abnormally.
The following sample code applies a NULL dacl to the interactive windowstation and desktop objects. This application should be executed before debugging the service. Once the debugging session has been completed, the DACLs for the interactive windowstation and desktop objects can be reset by logging off and then logging on again.
#include <windows.h>
#include <stdio.h>
void main(void)
{
HDESK hdesk = NULL;
HWINSTA hwinsta = NULL;
SECURITY_DESCRIPTOR sd;
SECURITY_INFORMATION si = DACL_SECURITY_INFORMATION;
__try
{
//
// Obtain a handle to the interactive windowstation.
//
hwinsta = OpenWindowStation("winsta0", FALSE, WRITE_DAC);
if (hwinsta == NULL)
__leave;
//
// Obtain a handle to the interactive desktop.
//
hdesk = OpenDesktop("default", 0, FALSE,
WRITE_DAC | DESKTOP_WRITEOBJECTS | DESKTOP_READOBJECTS);
if (hdesk == NULL)
__leave;
//
// Create a null dacl.
//
if (!InitializeSecurityDescriptor(&sd,
SECURITY_DESCRIPTOR_REVISION))
__leave;
if (!SetSecurityDescriptorDacl(&sd, TRUE, (PACL) NULL, FALSE))
__leave;
//
// Apply NULL dacl to the windowstation and desktop objects.
//
if (!SetUserObjectSecurity(hwinsta, &si, &sd))
__leave;
if (!SetUserObjectSecurity(hdesk, &si, &sd))
__leave;
}
__finally
{
if (hdesk != NULL)
CloseDesktop(hdesk);
if (hwinsta != NULL)
CloseWindowStation(hwinsta);
}
}
1. Follow steps 1-5 in the "Preparation" section of this article. Include
a DebugBreak() statement in the service's code that is before line 223
in Simple.c.
Choose the cancel button to debug the service. The system does now
spawn the debugger.
4. Follow steps 4-8 in the "Debugging a Service with WinDbg" or steps 3-6
in the "Debugging a Service with MSVC++". Note that if you are using
WinDbg step 4 will break on line 245 instead of line 256.
Debugging a Service with WinDbg:
1. Follow steps 1-5 in the "Preparation" section of this article.
2. At a command prompt, go to the directory containing the sample
executable and type:
start WinDbg
to start WinDbg in its own command shell.
.attach <PID>
(Simple.c).
6. Type "g" (a go command) in the WinDbg command window or press the F5 key
to restart after the thread that WinDbg uses to do the .attach
terminates.
client [-pipe <pipename>] [-string <string>]
For example: client -pipe \\.\pipe\simple -string "franki"
will be on line 256. Press the F5 key again to go to the next
breakpoint. Keep pressing F5 until line 223 waits again for a client to
connect. Try connecting another client and repeat the same steps.
1. Follow steps 1-5 in the "Preparation" section of this article.
2. At a command prompt, go to the directory containing the sample and type:
MSDEV /P <PID>
where <PID> is the Process ID value you retrieved in step 4.
(Simple.c).
color at this point.
client [-pipe <pipename>] [-string <string>]
For example: client -pipe \\.\pipe\simple -string "franki"
will be on line 256. Press the F5 key again to go to the next
breakpoint. Keep pressing F5 until line 223 waits again for a client to
connect. Try connecting another client and repeat the same steps.
NOTE: The "System Account" and the "LocalSystem Account" are the same account.
Keywords : kbtool kbAPI kbKernBase kbThread kbGrpKernBase
Version : 3.51 4.0
Platform : NT WINDOWS
Issue type : kbhowtoLast Reviewed: October 12, 1997