Platform SDK: Debugging and Error Handling |
When a hardware or software exception occurs, the processor stops execution at the point at which the exception occurred and transfers control to the system. First, the system saves both the machine state of the current thread and information that describes the exception. The system then attempts to find an exception handler to handle the exception.
The machine state of the thread in which the exception occurred is saved in a CONTEXT structure. This information (called the context record) enables the system to continue execution at the point of the exception if the exception is successfully handled. The description of the exception (called the exception record) is saved in an EXCEPTION_RECORD structure. Because it stores the machine-dependent information of the context record separately from the machine-independent information of the exception record, the exception-handling mechanism is portable to different platforms.
The information in both the context and exception records is available by means of the GetExceptionInformation function, and can be made available to any exception handlers that are executed as a result of the exception. The exception record includes the following information.
When an exception occurs in user-mode code, the system uses the following search order to find an exception handler:
When an exception occurs in kernel-mode code, the system searches the stack frames of the kernel stack in an attempt to locate an exception handler. If a handler cannot be located or no handler handles the exception, the system is shut down as if the ExitWindows function had been called.