win32/except.c

   1 /*
   2  * Win32 exception functions
   3  *
   4  * Copyright (c) 1996 Onno Hovers, (onno@stack.urc.tue.nl)
   5  *
   6  * Notes:
   7  *  What really happens behind the scenes of those new
   8  *  __try{...}__except(..){....}  and
   9  *  __try{...}__finally{...}
  10  *  statements is simply not documented by Microsoft. There could be different
  11  *  reasons for this:
  12  *  One reason could be that they try to hide the fact that exception
  13  *  handling in Win32 looks almost the same as in OS/2 2.x.
  14  *  Another reason could be that Microsoft does not want others to write
  15  *  binary compatible implementations of the Win32 API (like us).
  16  *
  17  *  Whatever the reason, THIS SUCKS!! Ensuring portabilty or future
  18  *  compatability may be valid reasons to keep some things undocumented.
  19  *  But exception handling is so basic to Win32 that it should be
  20  *  documented!
  21  *
  22  * Fixmes:
  23  *  -Most functions need better parameter checking.
  24  *  -I do not know how to handle exceptions within an exception handler.
  25  *   or what is done when ExceptionNestedException is returned from an
  26  *   exception handler
  27  *  -Real exceptions are not yet implemented. only the exception functions
  28  *   are implemented. A real implementation needs some new code in
  29  *   loader/signal.c. There would also be a need for showing debugging
  30  *   information in UnhandledExceptionFilter.
  31  *
  32  */
  33
  34 #include <assert.h>
  35 #include <stdio.h>
  36 #include "windows.h"
  37 #include "winerror.h"
  38 #include "ldt.h"
  39 #include "process.h"
  40 #include "thread.h"
  41 #include "stddebug.h"
  42 #include "debug.h"
  43 #include "except.h"
  44
  45 #define TEB_EXCEPTION_FRAME(pcontext) \
  46     ((PEXCEPTION_FRAME)((TEB *)GET_SEL_BASE((pcontext)->SegFs))->except)
  47
  48 /*******************************************************************
  49  *         _local_unwind2  (CRTDLL)
  50  */
  51 void WINAPI CRTDLL__local_unwind2(PEXCEPTION_FRAME endframe,DWORD nr,
  52                                   PCONTEXT pcontext)
  53 {
  54         fprintf(stderr,"CRTDLL__local_unwind2(%p,%ld)\n",endframe,nr);
  55         return;
  56 }
  57
  58 /*******************************************************************
  59  *         _global_unwind2  (CRTDLL)
  60  */
  61 void WINAPI CRTDLL__global_unwind2(PEXCEPTION_FRAME endframe,PCONTEXT pcontext)
  62 {
  63         RtlUnwind(endframe,NULL/*should point to the return;*/,NULL,0,pcontext);
  64         return;
  65 }
  66
  67 /*******************************************************************
  68  *         RtlUnwind  (KERNEL32.443)
  69  *
  70  *  This function is undocumented. This is the general idea of
  71  *  RtlUnwind, though. Note that error handling is not yet implemented.
  72  */
  73 void WINAPI RtlUnwind( PEXCEPTION_FRAME pEndFrame, LPVOID unusedEip,
  74                        PEXCEPTION_RECORD pRecord, DWORD returnEax,
  75                        PCONTEXT pcontext /* Wine additional parameter */ )
  76 {
  77    EXCEPTION_RECORD record;
  78    DWORD            dispatch;
  79    int              retval;
  80
  81    pcontext->Eax=returnEax;
  82
  83    /* build an exception record, if we do not have one */
  84    if(!pRecord)
  85    {
  86      record.ExceptionCode    = STATUS_INVALID_DISPOSITION;
  87      record.ExceptionFlags   = 0;
  88      record.ExceptionRecord  = NULL;
  89      record.ExceptionAddress = (LPVOID)pcontext->Eip;
  90      record.NumberParameters = 0;
  91      pRecord = &record;
  92    }
  93
  94    if(pEndFrame)
  95      pRecord->ExceptionFlags|=EH_UNWINDING;
  96    else
  97      pRecord->ExceptionFlags|=EH_UNWINDING | EH_EXIT_UNWIND;
  98
  99    /* get chain of exception frames */
 100    while ((TEB_EXCEPTION_FRAME(pcontext) != NULL) &&
 101           (TEB_EXCEPTION_FRAME(pcontext) != ((void *)0xffffffff)) &&
 102           (TEB_EXCEPTION_FRAME(pcontext) != pEndFrame))
 103    {
 104        dprintf_win32( stddeb, "calling exception handler at 0x%x\n",
 105                       (int)TEB_EXCEPTION_FRAME(pcontext)->Handler );
 106
 107        dispatch=0;
 108        retval = TEB_EXCEPTION_FRAME(pcontext)->Handler( pRecord,
 109                                                 TEB_EXCEPTION_FRAME(pcontext),
 110                                                 pcontext, &dispatch);
 111
 112        dprintf_win32(stddeb,"exception handler returns 0x%x, dispatch=0x%x\n",
 113                               retval, (int) dispatch);
 114
 115        if (     (retval == ExceptionCollidedUnwind) &&
 116                 (TEB_EXCEPTION_FRAME(pcontext) != (LPVOID)dispatch)
 117        )
 118            TEB_EXCEPTION_FRAME(pcontext) = (LPVOID)dispatch;
 119        else if (        (TEB_EXCEPTION_FRAME(pcontext) != pEndFrame) &&
 120                         (TEB_EXCEPTION_FRAME(pcontext) != TEB_EXCEPTION_FRAME(pcontext)->Prev)
 121        )
 122            TEB_EXCEPTION_FRAME(pcontext) = TEB_EXCEPTION_FRAME(pcontext)->Prev;
 123        else
 124           break;
 125    }
 126 }
 127
 128
 129 /*******************************************************************
 130  *         RaiseException  (KERNEL32.418)
 131  */
 132 void WINAPI RaiseException(DWORD dwExceptionCode,
 133                            DWORD dwExceptionFlags,
 134                            DWORD cArguments,
 135                            const LPDWORD lpArguments,
 136                            PCONTEXT pcontext /* Wine additional parameter */ )
 137 {
 138     PEXCEPTION_FRAME    pframe;
 139     EXCEPTION_RECORD    record;
 140     DWORD               dispatch; /* is this used in raising exceptions ?? */
 141     int                 retval;
 142     int                 i;
 143
 144     /* compose an exception record */
 145
 146     record.ExceptionCode       = dwExceptionCode;
 147     record.ExceptionFlags      = dwExceptionFlags;
 148     record.ExceptionRecord     = NULL;
 149     record.NumberParameters    = cArguments;
 150     record.ExceptionAddress    = (LPVOID) pcontext->Eip;
 151
 152     if (lpArguments) for( i = 0; i < cArguments; i++)
 153         record.ExceptionInformation[i] = lpArguments[i];
 154
 155     /* get chain of exception frames */
 156
 157     retval = ExceptionContinueSearch;
 158     pframe = TEB_EXCEPTION_FRAME( pcontext );
 159
 160     while((pframe!=NULL)&&(pframe!=((void *)0xFFFFFFFF)))
 161     {
 162        dprintf_win32(stddeb,"calling exception handler at 0x%x\n",
 163                                                 (int) pframe->Handler);
 164        dispatch=0;
 165        retval=pframe->Handler(&record,pframe,pcontext,&dispatch);
 166
 167        dprintf_win32(stddeb,"exception handler returns 0x%x, dispatch=0x%x\n",
 168                               retval, (int) dispatch);
 169
 170        if(retval==ExceptionContinueExecution)
 171           break;
 172        pframe=pframe->Prev;
 173    }
 174
 175    if (retval!=ExceptionContinueExecution)
 176    {
 177        /* FIXME: what should we do here? */
 178        dprintf_win32(stddeb,"no handler wanted to handle the exception, exiting\n");
 179        ExitProcess(dwExceptionCode); /* what status should be used here ? */
 180    }
 181 }
 182
 183
 184 /*******************************************************************
 185  *         UnhandledExceptionFilter   (KERNEL32.537)
 186  */
 187 DWORD WINAPI UnhandledExceptionFilter(PEXCEPTION_POINTERS epointers)
 188 {
 189     char message[80];
 190
 191     /* FIXME: Should check if the process is being debugged */
 192
 193     if (pCurrentProcess && pCurrentProcess->top_filter)
 194     {
 195         DWORD ret = pCurrentProcess->top_filter( epointers );
 196         if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
 197     }
 198
 199     /* FIXME: Should check the current error mode */
 200
 201     sprintf( message, "Unhandled exception 0x%08lx at address 0x%08lx.",
 202              epointers->ExceptionRecord->ExceptionCode,
 203              (DWORD)epointers->ExceptionRecord->ExceptionAddress );
 204     MessageBox32A( 0, message, "Error", MB_OK | MB_ICONHAND );
 205     return EXCEPTION_EXECUTE_HANDLER;
 206 }
 207
 208
 209 /*************************************************************
 210  *            SetUnhandledExceptionFilter   (KERNEL32.516)
 211  */
 212 LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
 213                                           LPTOP_LEVEL_EXCEPTION_FILTER filter )
 214 {
 215     LPTOP_LEVEL_EXCEPTION_FILTER old = pCurrentProcess->top_filter;
 216     pCurrentProcess->top_filter = filter;
 217     return old;
 218 }