SetUnhandledExceptionFilter

Overview

Group

Quick Info

Windows NT
Yes
Win95
Yes
Win32s
Yes
Import Library
kernel32.lib
Header File
winbase.h
Unicode
No
Platform Notes
None

The SetUnhandledExceptionFilter function lets an application supersede the top-level exception handler that Win32 places at the top of each thread and process.

After calling this function, if an exception occurs in a process that is not being debugged, and the exception makes it to the Win32 unhandled exception filter, that filter will call the exception filter function specified by the lpTopLevelExceptionFilter parameter.

LPTOP_LEVEL_EXCEPTION_FILTER SetUnhandledExceptionFilter(

LPTOP_LEVEL_EXCEPTION_FILTER lpTopLevelExceptionFilter	// exception filter function
);

Parameters
lpTopLevelExceptionFilter

Supplies the address of a top-level exception filter function that will be called whenever the UnhandledExceptionFilter function gets control, and the process is not being debugged. A value of NULL for this parameter specifies default handling within UnhandledExceptionFilter.

The filter function has syntax congruent to that of UnhandledExceptionFilter: It takes a single parameter of type LPEXCEPTION_POINTERS, and returns a value of type LONG. The filter function should return one of the following values:

Value	Meaning
EXCEPTION_EXECUTE_HANDLER	Return from UnhandledExceptionFilter and execute the associated exception handler. This usually results in process termination.
EXCEPTION_CONTINUE_EXECUTION	Return from UnhandledExceptionFilter and continue execution from the point of the exception. Note that the filter function is free to modify the continuation state by modifying the exception information supplied through its LPEXCEPTION_POINTERS parameter.
EXCEPTION_CONTINUE_SEARCH	Proceed with normal execution of UnhandledExceptionFilter . That means obeying the SetErrorMod flags, or invoking the Application Error pop-up message box.

Return Values
The SetUnhandledExceptionFilter function returns the address of the previous exception filter established with the function. A NULL return value means that there is no current top-level exception handler.

Remarks
Issuing SetUnhandledExceptionFilter replaces the existing top-level exception filter for all existing and all future threads in the calling process.

The exception handler specified by lpTopLevelExceptionFilter is executed in the context of the thread that caused the fault. This can affect the exception handler's ability to recover from certain exceptions, such as an invalid stack.