/*
 * NT exception handling routines
 * 
 * Copyright 1999 Turchanov Sergey
 * Copyright 1999 Alexandre Julliard
 */

#include <assert.h>
#include <signal.h>
#include "winnt.h"
#include "ntddk.h"
#include "global.h"
#include "wine/exception.h"
#include "stackframe.h"
#include "miscemu.h"
#include "server.h"
#include "debugtools.h"

DEFAULT_DEBUG_CHANNEL(seh);

/* Exception record for handling exceptions happening inside exception handlers */
typedef struct
{
    EXCEPTION_FRAME frame;
    EXCEPTION_FRAME *prevFrame;
} EXC_NESTED_FRAME;

 
/*******************************************************************
 *         EXC_RaiseHandler
 *
 * Handler for exceptions happening inside a handler.
 */
static DWORD EXC_RaiseHandler( EXCEPTION_RECORD *rec, EXCEPTION_FRAME *frame,
                               CONTEXT *context, EXCEPTION_FRAME **dispatcher )
{
    if (rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND))
        return ExceptionContinueSearch;
    /* We shouldn't get here so we store faulty frame in dispatcher */
    *dispatcher = ((EXC_NESTED_FRAME*)frame)->prevFrame;
    return ExceptionNestedException;
}


/*******************************************************************
 *         EXC_UnwindHandler
 *
 * Handler for exceptions happening inside an unwind handler.
 */
static DWORD EXC_UnwindHandler( EXCEPTION_RECORD *rec, EXCEPTION_FRAME *frame,
                                CONTEXT *context, EXCEPTION_FRAME **dispatcher )
{
    if (!(rec->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
        return ExceptionContinueSearch;
    /* We shouldn't get here so we store faulty frame in dispatcher */
    *dispatcher = ((EXC_NESTED_FRAME*)frame)->prevFrame;
    return ExceptionCollidedUnwind;
}


/*******************************************************************
 *         EXC_CallHandler
 *
 * Call an exception handler, setting up an exception frame to catch exceptions
 * happening during the handler execution.
 * Please do not change the first 4 parameters order in any way - some exceptions handlers
 * rely on Base Pointer (EBP) to have a fixed position related to the exception frame
 */
static DWORD EXC_CallHandler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
                              CONTEXT *context, EXCEPTION_FRAME **dispatcher, 
                              PEXCEPTION_HANDLER handler, PEXCEPTION_HANDLER nested_handler)
{
    EXC_NESTED_FRAME newframe;
    DWORD ret;

    newframe.frame.Handler = nested_handler;
    newframe.prevFrame     = frame;
    __wine_push_frame( &newframe.frame );
    TRACE( "calling handler at %p code=%lx flags=%lx\n",
           handler, record->ExceptionCode, record->ExceptionFlags );
    ret = handler( record, frame, context, dispatcher );
    TRACE( "handler returned %lx\n", ret );
    __wine_pop_frame( &newframe.frame );
    return ret;
}


/**********************************************************************
 *           send_debug_event
 *
 * Send an EXCEPTION_DEBUG_EVENT event to the debugger.
 */
static inline int send_debug_event( EXCEPTION_RECORD *rec, int first_chance, CONTEXT *context )
{
    int ret;
    SERVER_START_REQ
    {
        struct exception_event_request *req = server_alloc_req( sizeof(*req),
                                                                sizeof(*rec)+sizeof(*context) );
        CONTEXT *context_ptr = server_data_ptr(req);
        EXCEPTION_RECORD *rec_ptr = (EXCEPTION_RECORD *)(context_ptr + 1);
        req->first   = first_chance;
        *rec_ptr     = *rec;
        *context_ptr = *context;
        if (!server_call_noerr( REQ_EXCEPTION_EVENT )) *context = *context_ptr;
        ret = req->status;
    }
    SERVER_END_REQ;
    return ret;
}


/*******************************************************************
 *         EXC_DefaultHandling
 *
 * Default handling for exceptions. Called when we didn't find a suitable handler.
 */
static void EXC_DefaultHandling( EXCEPTION_RECORD *rec, CONTEXT *context )
{
    if (send_debug_event( rec, FALSE, context ) == DBG_CONTINUE) return;  /* continue execution */

    if (rec->ExceptionFlags & EH_STACK_INVALID)
        ERR("Exception frame is not in stack limits => unable to dispatch exception.\n");
    else if (rec->ExceptionCode == EXCEPTION_NONCONTINUABLE_EXCEPTION)
        ERR("Process attempted to continue execution after noncontinuable exception.\n");
    else
        ERR("Unhandled exception code %lx flags %lx addr %p\n",
            rec->ExceptionCode, rec->ExceptionFlags, rec->ExceptionAddress );
    NtTerminateProcess( NtCurrentProcess(), 1 );
}


/***********************************************************************
 *            EXC_RtlRaiseException / RtlRaiseException (NTDLL.464)
 */
DEFINE_REGS_ENTRYPOINT_1( RtlRaiseException, EXC_RtlRaiseException, EXCEPTION_RECORD * )
void WINAPI EXC_RtlRaiseException( EXCEPTION_RECORD *rec, CONTEXT *context )
{
    PEXCEPTION_FRAME frame, dispatch, nested_frame;
    EXCEPTION_RECORD newrec;
    DWORD res;

    TRACE( "code=%lx flags=%lx\n", rec->ExceptionCode, rec->ExceptionFlags );

    if (send_debug_event( rec, TRUE, context ) == DBG_CONTINUE) return;  /* continue execution */

    frame = NtCurrentTeb()->except;
    nested_frame = NULL;
    while (frame != (PEXCEPTION_FRAME)0xFFFFFFFF)
    {
        /* Check frame address */
        if (((void*)frame < NtCurrentTeb()->stack_low) ||
            ((void*)(frame+1) > NtCurrentTeb()->stack_top) ||
            (int)frame & 3)
        {
            rec->ExceptionFlags |= EH_STACK_INVALID;
            break;
        }

        /* Call handler */
        res = EXC_CallHandler( rec, frame, context, &dispatch, frame->Handler, EXC_RaiseHandler );
        if (frame == nested_frame)
        {
            /* no longer nested */
            nested_frame = NULL;
            rec->ExceptionFlags &= ~EH_NESTED_CALL;
        }

        switch(res)
        {
        case ExceptionContinueExecution:
            if (!(rec->ExceptionFlags & EH_NONCONTINUABLE)) return;
            newrec.ExceptionCode    = STATUS_NONCONTINUABLE_EXCEPTION;
            newrec.ExceptionFlags   = EH_NONCONTINUABLE;
            newrec.ExceptionRecord  = rec;
            newrec.NumberParameters = 0;
            RtlRaiseException( &newrec );  /* never returns */
            break;
        case ExceptionContinueSearch:
            break;
        case ExceptionNestedException:
            if (nested_frame < dispatch) nested_frame = dispatch;
            rec->ExceptionFlags |= EH_NESTED_CALL;
            break;
        default:
            newrec.ExceptionCode    = STATUS_INVALID_DISPOSITION;
            newrec.ExceptionFlags   = EH_NONCONTINUABLE;
            newrec.ExceptionRecord  = rec;
            newrec.NumberParameters = 0;
            RtlRaiseException( &newrec );  /* never returns */
            break;
        }
        frame = frame->Prev;
    }
    EXC_DefaultHandling( rec, context );
}


/*******************************************************************
 *         EXC_RtlUnwind / RtlUnwind  (KERNEL32.590) (NTDLL.518)
 */
DEFINE_REGS_ENTRYPOINT_4( RtlUnwind, EXC_RtlUnwind, 
                          PEXCEPTION_FRAME, LPVOID, PEXCEPTION_RECORD, DWORD )
void WINAPI EXC_RtlUnwind( PEXCEPTION_FRAME pEndFrame, LPVOID unusedEip, 
                           PEXCEPTION_RECORD pRecord, DWORD returnEax,
                           CONTEXT *context )
{
    EXCEPTION_RECORD record, newrec;
    PEXCEPTION_FRAME frame, dispatch;

#ifdef __i386__
    context->Eax = returnEax;
#endif

    /* build an exception record, if we do not have one */
    if (!pRecord)
    {
        record.ExceptionCode    = STATUS_UNWIND;
        record.ExceptionFlags   = 0;
        record.ExceptionRecord  = NULL;
        record.ExceptionAddress = GET_IP(context); 
        record.NumberParameters = 0;
        pRecord = &record;
    }

    pRecord->ExceptionFlags |= EH_UNWINDING | (pEndFrame ? 0 : EH_EXIT_UNWIND);

    TRACE( "code=%lx flags=%lx\n", pRecord->ExceptionCode, pRecord->ExceptionFlags );

    /* get chain of exception frames */
    frame = NtCurrentTeb()->except;
    while ((frame != (PEXCEPTION_FRAME)0xffffffff) && (frame != pEndFrame))
    {
        /* Check frame address */
        if (pEndFrame && (frame > pEndFrame))
        {
            newrec.ExceptionCode    = STATUS_INVALID_UNWIND_TARGET;
            newrec.ExceptionFlags   = EH_NONCONTINUABLE;
            newrec.ExceptionRecord  = pRecord;
            newrec.NumberParameters = 0;
            RtlRaiseException( &newrec );  /* never returns */
        }
        if (((void*)frame < NtCurrentTeb()->stack_low) ||
            ((void*)(frame+1) > NtCurrentTeb()->stack_top) ||
            (int)frame & 3)
        {
            newrec.ExceptionCode    = STATUS_BAD_STACK;
            newrec.ExceptionFlags   = EH_NONCONTINUABLE;
            newrec.ExceptionRecord  = pRecord;
            newrec.NumberParameters = 0;
            RtlRaiseException( &newrec );  /* never returns */
        }

        /* Call handler */
        switch(EXC_CallHandler( pRecord, frame, context, &dispatch,
                                frame->Handler, EXC_UnwindHandler ))
        {
        case ExceptionContinueSearch:
            break;
        case ExceptionCollidedUnwind:
            frame = dispatch;
            break;
        default:
            newrec.ExceptionCode    = STATUS_INVALID_DISPOSITION;
            newrec.ExceptionFlags   = EH_NONCONTINUABLE;
            newrec.ExceptionRecord  = pRecord;
            newrec.NumberParameters = 0;
            RtlRaiseException( &newrec );  /* never returns */
            break;
        }
        frame = __wine_pop_frame( frame );
    }
}


/*******************************************************************
 *            EXC_NtRaiseException / NtRaiseException  (NTDLL.175)
 */
DEFINE_REGS_ENTRYPOINT_3( NtRaiseException, EXC_NtRaiseException,
                          EXCEPTION_RECORD *, CONTEXT *, BOOL )
void WINAPI EXC_NtRaiseException( EXCEPTION_RECORD *rec, CONTEXT *ctx,
                                  BOOL first, CONTEXT *context )
{
    EXC_RtlRaiseException( rec, ctx );
    *context = *ctx;
}


/***********************************************************************
 *            RtlRaiseStatus  (NTDLL.465)
 *
 * Raise an exception with ExceptionCode = status
 */
void WINAPI RtlRaiseStatus( NTSTATUS status )
{
    EXCEPTION_RECORD ExceptionRec;

    ExceptionRec.ExceptionCode    = status;
    ExceptionRec.ExceptionFlags   = EH_NONCONTINUABLE;
    ExceptionRec.ExceptionRecord  = NULL;
    ExceptionRec.NumberParameters = 0;
    RtlRaiseException( &ExceptionRec );
}


/*************************************************************
 *            __wine_exception_handler
 *
 * Exception handler for exception blocks declared in Wine code.
 */
DWORD __wine_exception_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
                                CONTEXT *context, LPVOID pdispatcher )
{
    __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;

    if (record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND | EH_NESTED_CALL))
        return ExceptionContinueSearch;
    if (wine_frame->u.filter)
    {
        EXCEPTION_POINTERS ptrs;
        ptrs.ExceptionRecord = record;
        ptrs.ContextRecord = context;
        switch(wine_frame->u.filter( &ptrs ))
        {
        case EXCEPTION_CONTINUE_SEARCH:
            return ExceptionContinueSearch;
        case EXCEPTION_CONTINUE_EXECUTION:
            return ExceptionContinueExecution;
        case EXCEPTION_EXECUTE_HANDLER:
            break;
        default:
            MESSAGE( "Invalid return value from exception filter\n" );
            assert( FALSE );
        }
    }
    /* hack to make GetExceptionCode() work in handler */
    wine_frame->ExceptionCode   = record->ExceptionCode;
    wine_frame->ExceptionRecord = wine_frame;

    RtlUnwind( frame, 0, record, 0 );
    __wine_pop_frame( frame );
    longjmp( wine_frame->jmp, 1 );
}


/*************************************************************
 *            __wine_finally_handler
 *
 * Exception handler for try/finally blocks declared in Wine code.
 */
DWORD __wine_finally_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
                              CONTEXT *context, LPVOID pdispatcher )
{
    __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;

    if (!(record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
        return ExceptionContinueSearch;
    wine_frame->u.finally_func( FALSE );
    return ExceptionContinueSearch;
}