SetUnhandledExceptionFilter function

Enables an application to supersede the top-level exception handler of each thread of a process.

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

Syntax

LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
  _In_ LPTOP_LEVEL_EXCEPTION_FILTER lpTopLevelExceptionFilter
);

Parameters

lpTopLevelExceptionFilter [in]

A pointer to 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 similar to that of UnhandledExceptionFilter: It takes a single parameter of type LPEXCEPTION_POINTERS, has a WINAPI calling convention, and returns a value of type LONG. The filter function should return one of the following values.

Value	Meaning
EXCEPTION_EXECUTE_HANDLER 0x1	Return from UnhandledExceptionFilter and execute the associated exception handler. This usually results in process termination.
EXCEPTION_CONTINUE_EXECUTION 0xffffffff	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 0x0	Proceed with normal execution of UnhandledExceptionFilter. That means obeying the SetErrorMode flags, or invoking the Application Error pop-up message box.

 

Return value

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.

Requirements

See also

Structured Exception Handling Functions

Structured Exception Handling Overview

UnhandledExceptionFilter