PATCH: OutputDebugString() Without \n May GP Fault in MSVC.EXE

ID: Q123493

The information in this article applies to:

SYMPTOMS

If character strings passed as arguments to the OutputDebugString() API do not end with a newline character \n, corrupt output appears in the Integrated Debugger's Output Window. In addition, a general protection fault (GP) fault can occur in MSVC.EXE.


CAUSE

The Microsoft Foundation Classes (MFC) TRACE() macro and CDumpContext class both use the OutputDebugString() API to send information to the Integrated Debugger's Output window. Therefore, using a character string without a newline character with the MFC TRACE() macro or CDumpContext class, will also cause this problem.


RESOLUTION

Avoid passing strings that do not have an appended newline character to OutputDebugString(), TRACE(), and CDumpContext objects.


STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was not reproducible in Microsoft Visual C++, 32-bit Edition, version 4.0.

NOTE: Microsoft has released a patch to Visual C++ version 1.5 that will fix this problem. This patch will modify the Visual Workbench 1.50, the new one will be version 1.50.01.

The following file is available for download from the Microsoft Software Library:

VC1501.exe
For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services


MORE INFORMATION

Steps to Reproduce Problem

  1. Add the following code to an executable portion of your application: 
    
      int i;
      for (i=0; i<500; i++)
         OutputDebugString( "This is a test!!!" );


  2. Rebuild the application, and run it (press the F5 key) such that the Debug Output window is hidden.


  3. While the loop of code is executing, switch to the Debug Output window, and scroll through the text. Or attempt to select a portion of the text using the mouse. You'll see garbage in the Output Window. Prolonged scrolling will occasionally generate a GP fault in MSVC.EXE.


Additional query words: GPF 


Keywords          : kbfile kbpatch kbDebug kbide 
Version           : 2.00
Platform          : NT WINDOWS 
Issue type        :

Last Reviewed: July 30, 1999