/*
 * Win32 exception functions
 *
 * Copyright (c) 1996 Onno Hovers, (onno@stack.urc.tue.nl)
 * Copyright (c) 1999 Alexandre Julliard
 *
 * Notes:
 *  What really happens behind the scenes of those new
 *  __try{...}__except(..){....}  and
 *  __try{...}__finally{...}
 *  statements is simply not documented by Microsoft. There could be different
 *  reasons for this: 
 *  One reason could be that they try to hide the fact that exception 
 *  handling in Win32 looks almost the same as in OS/2 2.x.  
 *  Another reason could be that Microsoft does not want others to write
 *  binary compatible implementations of the Win32 API (like us).  
 *
 *  Whatever the reason, THIS SUCKS!! Ensuring portability or future 
 *  compatibility may be valid reasons to keep some things undocumented. 
 *  But exception handling is so basic to Win32 that it should be 
 *  documented!
 *
 */

#include <stdio.h>
#include "windef.h"
#include "winerror.h"
#include "ntddk.h"
#include "wingdi.h"
#include "winuser.h"
#include "wine/exception.h"
#include "thread.h"
#include "stackframe.h"
#include "wine/server.h"
#include "debugtools.h"

DEFAULT_DEBUG_CHANNEL(seh);

static PTOP_LEVEL_EXCEPTION_FILTER top_filter;

typedef INT (WINAPI *MessageBoxA_funcptr)(HWND,LPCSTR,LPCSTR,UINT);
typedef INT (WINAPI *MessageBoxW_funcptr)(HWND,LPCWSTR,LPCWSTR,UINT);

/*******************************************************************
 *         RaiseException  (KERNEL32.@)
 */
void WINAPI RaiseException( DWORD code, DWORD flags, DWORD nbargs, const LPDWORD args )
{
    EXCEPTION_RECORD record;

    /* Compose an exception record */ 
    
    record.ExceptionCode    = code;
    record.ExceptionFlags   = flags & EH_NONCONTINUABLE;
    record.ExceptionRecord  = NULL;
    record.ExceptionAddress = RaiseException;
    if (nbargs && args)
    {
        if (nbargs > EXCEPTION_MAXIMUM_PARAMETERS) nbargs = EXCEPTION_MAXIMUM_PARAMETERS;
        record.NumberParameters = nbargs;
        memcpy( record.ExceptionInformation, args, nbargs * sizeof(*args) );
    }
    else record.NumberParameters = 0;

    RtlRaiseException( &record );
}


/*******************************************************************
 *         format_exception_msg
 */
static int format_exception_msg( const EXCEPTION_POINTERS *ptr, char *buffer, int size )
{
    const EXCEPTION_RECORD *rec = ptr->ExceptionRecord;
    int len,len2;

    switch(rec->ExceptionCode)
    {
    case EXCEPTION_INT_DIVIDE_BY_ZERO:
        len = snprintf( buffer, size, "Unhandled division by zero" );
        break;
    case EXCEPTION_INT_OVERFLOW:
        len = snprintf( buffer, size, "Unhandled overflow" );
        break;
    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
        len = snprintf( buffer, size, "Unhandled array bounds" );
        break;
    case EXCEPTION_ILLEGAL_INSTRUCTION:
        len = snprintf( buffer, size, "Unhandled illegal instruction" );
        break;
    case EXCEPTION_STACK_OVERFLOW:
        len = snprintf( buffer, size, "Unhandled stack overflow" );
        break;
    case EXCEPTION_PRIV_INSTRUCTION:
        len = snprintf( buffer, size, "Unhandled priviledged instruction" );
        break;
    case EXCEPTION_ACCESS_VIOLATION:
        if (rec->NumberParameters == 2)
            len = snprintf( buffer, size, "Unhandled page fault on %s access to 0x%08lx",
                     rec->ExceptionInformation[0] ? "write" : "read",
                     rec->ExceptionInformation[1]);
        else
            len = snprintf( buffer, size, "Unhandled page fault");
        break;
    case EXCEPTION_DATATYPE_MISALIGNMENT:
        len = snprintf( buffer, size, "Unhandled alignment" );
        break;
    case CONTROL_C_EXIT:
        len = snprintf( buffer, size, "Unhandled ^C");
        break;
    case EXCEPTION_CRITICAL_SECTION_WAIT:
        len = snprintf( buffer, size, "Critical section %08lx wait failed",
                 rec->ExceptionInformation[0]);
        break;
    case EXCEPTION_WINE_STUB:
        len = snprintf( buffer, size, "Unimplemented function %s.%s called",
                 (char *)rec->ExceptionInformation[0], (char *)rec->ExceptionInformation[1] );
        break;
    case EXCEPTION_VM86_INTx:
        len = snprintf( buffer, size, "Unhandled interrupt %02lx in vm86 mode",
                 rec->ExceptionInformation[0]);
        break;
    case EXCEPTION_VM86_STI:
        len = snprintf( buffer, size, "Unhandled sti in vm86 mode");
        break;
    case EXCEPTION_VM86_PICRETURN:
        len = snprintf( buffer, size, "Unhandled PIC return in vm86 mode");
        break;
    default:
        len = snprintf( buffer, size, "Unhandled exception 0x%08lx", rec->ExceptionCode);
        break;
    }
    if ((len<0) || (len>=size))
        return -1;
#ifdef __i386__
    if (ptr->ContextRecord->SegCs != __get_cs())
        len2 = snprintf(buffer+len, size-len,
                        " at address 0x%04lx:0x%08lx.\nDo you wish to debug it ?",
                        ptr->ContextRecord->SegCs,
                        (DWORD)ptr->ExceptionRecord->ExceptionAddress);
    else
#endif
        len2 = snprintf(buffer+len, size-len,
                        " at address 0x%08lx.\nDo you wish to debug it ?",
                        (DWORD)ptr->ExceptionRecord->ExceptionAddress);
    if ((len2<0) || (len>=size-len))
        return -1;
    return len+len2;
}


/**********************************************************************
 *           send_debug_event
 *
 * Send an EXCEPTION_DEBUG_EVENT event to the debugger.
 */
static int send_debug_event( EXCEPTION_RECORD *rec, int first_chance, CONTEXT *context )
{
    int ret;
    HANDLE handle = 0;

    SERVER_START_VAR_REQ( queue_exception_event, 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()) handle = req->handle;
    }
    SERVER_END_VAR_REQ;
    if (!handle) return 0;  /* no debugger present or other error */

    /* No need to wait on the handle since the process gets suspended
     * once the event is passed to the debugger, so when we get back
     * here the event has been continued already.
     */
    SERVER_START_VAR_REQ( get_exception_status, sizeof(*context) )
    {
        req->handle = handle;
        if (!SERVER_CALL()) *context = *(CONTEXT *)server_data_ptr(req);
        ret = req->status;
    }
    SERVER_END_VAR_REQ;
    NtClose( handle );
    return ret;
}

/******************************************************************
 *		start_debugger
 *
 * Does the effective debugger startup according to 'format'
 */
static BOOL	start_debugger(PEXCEPTION_POINTERS epointers, HANDLE hEvent)
{
    HKEY		hDbgConf;
    DWORD		bAuto = FALSE;
    PROCESS_INFORMATION	info;
    STARTUPINFOA	startup;
    char		buffer[256];
    char 		format[256];

    if (!RegOpenKeyA(HKEY_LOCAL_MACHINE, 
		     "Software\\Microsoft\\Windows NT\\CurrentVersion\\AeDebug", &hDbgConf)) {
       DWORD 	type;
       DWORD 	count;

       count = sizeof(format);
       if (RegQueryValueExA(hDbgConf, "Debugger", 0, &type, format, &count))
	  format[0] = 0;

       count = sizeof(bAuto);
       if (RegQueryValueExA(hDbgConf, "Auto", 0, &type, (char*)&bAuto, &count))
	  bAuto = TRUE;
       else if (type == REG_SZ)
       {
           char autostr[10];
           count = sizeof(autostr);
           if (!RegQueryValueExA(hDbgConf, "Auto", 0, &type, autostr, &count))
               bAuto = atoi(autostr);
       }
       RegCloseKey(hDbgConf);
    } else {
	/* try a default setup... */
	strcpy( format, "debugger/winedbg %ld %ld" );
    }

    if (!bAuto)
    {
	HMODULE			mod = GetModuleHandleA( "user32.dll" );
	MessageBoxA_funcptr	pMessageBoxA = NULL;

	if (mod) pMessageBoxA = (MessageBoxA_funcptr)GetProcAddress( mod, "MessageBoxA" );
	if (pMessageBoxA)
	{
	    format_exception_msg( epointers, buffer, sizeof(buffer) );
	    if (pMessageBoxA( 0, buffer, "Exception raised", MB_YESNO | MB_ICONHAND ) == IDNO)
	    {
		TRACE("Killing process\n");
		return FALSE;
	    }
	}
    }

    TRACE("Starting debugger (fmt=%s)\n", format);
    sprintf(buffer, format, GetCurrentProcessId(), hEvent);
    memset(&startup, 0, sizeof(startup));
    startup.cb = sizeof(startup);
    startup.dwFlags = STARTF_USESHOWWINDOW;
    startup.wShowWindow = SW_SHOWNORMAL;
    if (CreateProcessA(NULL, buffer, NULL, NULL, TRUE, 0, NULL, NULL, &startup, &info)) {
	/* wait for debugger to come up... */
	WaitForSingleObject(hEvent, INFINITE);
	return TRUE;
    }
    ERR("Couldn't start debugger (%s) (%ld)\n"
	"Read the Wine Developers Guide on how to set up winedbg or another debugger\n",
	buffer, GetLastError());
    return FALSE;
}

/******************************************************************
 *		start_debugger_atomic
 *
 * starts the debugger is an atomic way:
 *	- either the debugger is not started and it is started
 *	- either the debugger has already been started by an other thread
 *	- either the debugger couldn't be started
 *
 * returns TRUE for the two first condition, FALSE for the last
 */
static	int	start_debugger_atomic(PEXCEPTION_POINTERS epointers)
{
    static HANDLE	hRunOnce /* = 0 */;

    if (hRunOnce == 0)
    {
	OBJECT_ATTRIBUTES	attr;
	HANDLE			hEvent;

	attr.Length                   = sizeof(attr);
	attr.RootDirectory            = 0;
	attr.Attributes               = OBJ_INHERIT;
	attr.ObjectName               = NULL;
	attr.SecurityDescriptor       = NULL;
	attr.SecurityQualityOfService = NULL;

	/* ask for manual reset, so that once the debugger is started, every thread will be
	 * know it
	 */
	NtCreateEvent( &hEvent, EVENT_ALL_ACCESS, &attr, TRUE, FALSE );
	if (InterlockedCompareExchange( (LPLONG)&hRunOnce, hEvent, 0 ) == 0)
	{
	    /* ok, our event has been set... we're the winning thread */
	    BOOL	ret = start_debugger( epointers, hRunOnce );
	    DWORD	tmp;

	    if (!ret)
	    {
		/* so that the other threads won't be stuck */
		NtSetEvent( hRunOnce, &tmp );
	    }
	    return ret;
	}
	
	/* someone beat us here... */
	CloseHandle( hEvent );
    }
	
    /* and wait for the winner to have actually created the debugger */
    WaitForSingleObject( hRunOnce, INFINITE );
    /* in fact, here, we only know that someone has tried to start the debugger, we'll know
     * by reposting the exception if it has actually attached to the current process
     */
    return TRUE;
}


/*******************************************************************
 *         UnhandledExceptionFilter   (KERNEL32.@)
 */
DWORD WINAPI UnhandledExceptionFilter(PEXCEPTION_POINTERS epointers)
{
    int 		status;
    int			loop = 0;

    for (loop = 0; loop <= 1; loop++)
    {
	/* send a last chance event to the debugger */
	status = send_debug_event( epointers->ExceptionRecord, FALSE, epointers->ContextRecord );
	switch (status)
	{
	case DBG_CONTINUE: 
	    return EXCEPTION_CONTINUE_EXECUTION;
	case DBG_EXCEPTION_NOT_HANDLED: 
	    TerminateProcess( GetCurrentProcess(), epointers->ExceptionRecord->ExceptionCode );
	    break; /* not reached */
	case 0: /* no debugger is present */
	    if (epointers->ExceptionRecord->ExceptionCode == CONTROL_C_EXIT)
	    {
		/* do not launch the debugger on ^C, simply terminate the process */
		TerminateProcess( GetCurrentProcess(), 1 );
	    }
	    /* second try, the debugger isn't present... */
	    if (loop == 1) return EXCEPTION_EXECUTE_HANDLER;
	    break;
	default: 	
	    FIXME("Unsupported yet debug continue value %d (please report)\n", status);
	    return EXCEPTION_EXECUTE_HANDLER;
	}

	/* should only be there when loop == 0 */

	if (top_filter)
	{
	    DWORD ret = top_filter( epointers );
	    if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
	}
	
	/* FIXME: Should check the current error mode */
	
	if (!start_debugger_atomic( epointers ))
	    return EXCEPTION_EXECUTE_HANDLER;
	/* now that we should have a debugger attached, try to resend event */
    }	
	
    return EXCEPTION_EXECUTE_HANDLER;
}


/***********************************************************************
 *            SetUnhandledExceptionFilter   (KERNEL32.@)
 */
LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
                                          LPTOP_LEVEL_EXCEPTION_FILTER filter )
{
    LPTOP_LEVEL_EXCEPTION_FILTER old = top_filter;
    top_filter = filter;
    return old;
}


/**************************************************************************
 *           FatalAppExitA   (KERNEL32.@)
 */
void WINAPI FatalAppExitA( UINT action, LPCSTR str )
{
    HMODULE mod = GetModuleHandleA( "user32.dll" );
    MessageBoxA_funcptr pMessageBoxA = NULL;

    WARN("AppExit\n");

    if (mod) pMessageBoxA = (MessageBoxA_funcptr)GetProcAddress( mod, "MessageBoxA" );
    if (pMessageBoxA) pMessageBoxA( 0, str, NULL, MB_SYSTEMMODAL | MB_OK );
    else ERR( "%s\n", debugstr_a(str) );
    ExitProcess(0);
}


/**************************************************************************
 *           FatalAppExitW   (KERNEL32.@)
 */
void WINAPI FatalAppExitW( UINT action, LPCWSTR str )
{
    HMODULE mod = GetModuleHandleA( "user32.dll" );
    MessageBoxW_funcptr pMessageBoxW = NULL;

    WARN("AppExit\n");

    if (mod) pMessageBoxW = (MessageBoxW_funcptr)GetProcAddress( mod, "MessageBoxW" );
    if (pMessageBoxW) pMessageBoxW( 0, str, NULL, MB_SYSTEMMODAL | MB_OK );
    else ERR( "%s\n", debugstr_w(str) );
    ExitProcess(0);
}