win32/except.c

   1 /*
   2  * Win32 exception functions
   3  *
   4  * Copyright (c) 1996 Onno Hovers, (onno@stack.urc.tue.nl)
   5  * Copyright (c) 1999 Alexandre Julliard
   6  *
   7  * Notes:
   8  *  What really happens behind the scenes of those new
   9  *  __try{...}__except(..){....}  and
  10  *  __try{...}__finally{...}
  11  *  statements is simply not documented by Microsoft. There could be different
  12  *  reasons for this:
  13  *  One reason could be that they try to hide the fact that exception
  14  *  handling in Win32 looks almost the same as in OS/2 2.x.
  15  *  Another reason could be that Microsoft does not want others to write
  16  *  binary compatible implementations of the Win32 API (like us).
  17  *
  18  *  Whatever the reason, THIS SUCKS!! Ensuring portabilty or future
  19  *  compatability may be valid reasons to keep some things undocumented.
  20  *  But exception handling is so basic to Win32 that it should be
  21  *  documented!
  22  *
  23  */
  24
  25 #include <assert.h>
  26 #include "winuser.h"
  27 #include "winerror.h"
  28 #include "ntddk.h"
  29 #include "wine/exception.h"
  30 #include "ldt.h"
  31 #include "process.h"
  32 #include "thread.h"
  33 #include "stackframe.h"
  34 #include "debugtools.h"
  35
  36 DEFAULT_DEBUG_CHANNEL(seh)
  37
  38
  39 /*******************************************************************
  40  *         RaiseException  (KERNEL32.418)
  41  */
  42 void WINAPI RaiseException( DWORD code, DWORD flags, DWORD nbargs, const LPDWORD args )
  43 {
  44     EXCEPTION_RECORD record;
  45
  46     /* Compose an exception record */
  47
  48     record.ExceptionCode    = code;
  49     record.ExceptionFlags   = flags & EH_NONCONTINUABLE;
  50     record.ExceptionRecord  = NULL;
  51     record.ExceptionAddress = RaiseException;
  52     if (nbargs && args)
  53     {
  54         if (nbargs > EXCEPTION_MAXIMUM_PARAMETERS) nbargs = EXCEPTION_MAXIMUM_PARAMETERS;
  55         record.NumberParameters = nbargs;
  56         memcpy( record.ExceptionInformation, args, nbargs * sizeof(*args) );
  57     }
  58     else record.NumberParameters = 0;
  59
  60     RtlRaiseException( &record );
  61 }
  62
  63
  64 /*******************************************************************
  65  *         UnhandledExceptionFilter   (KERNEL32.537)
  66  */
  67 DWORD WINAPI UnhandledExceptionFilter(PEXCEPTION_POINTERS epointers)
  68 {
  69     char message[80];
  70     PDB *pdb = PROCESS_Current();
  71
  72     /* FIXME: Should check if the process is being debugged */
  73
  74     if (pdb->top_filter)
  75     {
  76         DWORD ret = pdb->top_filter( epointers );
  77         if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
  78     }
  79
  80     /* FIXME: Should check the current error mode */
  81
  82     sprintf( message, "Unhandled exception 0x%08lx at address 0x%08lx.",
  83              epointers->ExceptionRecord->ExceptionCode,
  84              (DWORD)epointers->ExceptionRecord->ExceptionAddress );
  85     MessageBoxA( 0, message, "Error", MB_OK | MB_ICONHAND );
  86     return EXCEPTION_EXECUTE_HANDLER;
  87 }
  88
  89
  90 /*************************************************************
  91  *            SetUnhandledExceptionFilter   (KERNEL32.516)
  92  */
  93 LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
  94                                           LPTOP_LEVEL_EXCEPTION_FILTER filter )
  95 {
  96     PDB *pdb = PROCESS_Current();
  97     LPTOP_LEVEL_EXCEPTION_FILTER old = pdb->top_filter;
  98     pdb->top_filter = filter;
  99     return old;
 100 }
 101
 102
 103 /*************************************************************
 104  *            WINE_exception_handler
 105  *
 106  * Exception handler for exception blocks declared in Wine code.
 107  */
 108 DWORD WINAPI WINE_exception_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 109                                      CONTEXT *context, LPVOID pdispatcher )
 110 {
 111     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 112
 113     if (record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND | EH_NESTED_CALL))
 114         return ExceptionContinueSearch;
 115     if (wine_frame->u.e.filter)
 116     {
 117         EXCEPTION_POINTERS ptrs;
 118         __WINE_DUMMY_FRAME dummy;
 119
 120         ptrs.ExceptionRecord = record;
 121         ptrs.ContextRecord = context;
 122         dummy.u.e.code = record->ExceptionCode;
 123         switch(wine_frame->u.e.filter( &ptrs, dummy, wine_frame->u.e.param ))
 124         {
 125         case EXCEPTION_CONTINUE_SEARCH:
 126             return ExceptionContinueSearch;
 127         case EXCEPTION_CONTINUE_EXECUTION:
 128             return ExceptionContinueExecution;
 129         case EXCEPTION_EXECUTE_HANDLER:
 130             break;
 131         default:
 132             MESSAGE( "Invalid return value from exception filter\n" );
 133             assert( FALSE );
 134         }
 135     }
 136     RtlUnwind( frame, 0, record, 0 );
 137     longjmp( wine_frame->u.e.jmp, 1 );
 138 }
 139
 140
 141 /*************************************************************
 142  *            WINE_finally_handler
 143  *
 144  * Exception handler for try/finally blocks declared in Wine code.
 145  */
 146 DWORD WINAPI WINE_finally_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 147                                    CONTEXT *context, LPVOID pdispatcher )
 148 {
 149     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 150
 151     if (!(record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
 152         return ExceptionContinueSearch;
 153     wine_frame->u.f.finally_func( FALSE, wine_frame->u.f.param );
 154     return ExceptionContinueSearch;
 155 }