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 <stdio.h>
  27 #include "windef.h"
  28 #include "wingdi.h"
  29 #include "winuser.h"
  30 #include "winerror.h"
  31 #include "ntddk.h"
  32 #include "wine/exception.h"
  33 #include "ldt.h"
  34 #include "process.h"
  35 #include "thread.h"
  36 #include "stackframe.h"
  37 #include "server.h"
  38 #include "debugtools.h"
  39
  40 DEFAULT_DEBUG_CHANNEL(seh);
  41
  42
  43 /*******************************************************************
  44  *         RaiseException  (KERNEL32.418)
  45  */
  46 void WINAPI RaiseException( DWORD code, DWORD flags, DWORD nbargs, const LPDWORD args )
  47 {
  48     EXCEPTION_RECORD record;
  49
  50     /* Compose an exception record */
  51
  52     record.ExceptionCode    = code;
  53     record.ExceptionFlags   = flags & EH_NONCONTINUABLE;
  54     record.ExceptionRecord  = NULL;
  55     record.ExceptionAddress = RaiseException;
  56     if (nbargs && args)
  57     {
  58         if (nbargs > EXCEPTION_MAXIMUM_PARAMETERS) nbargs = EXCEPTION_MAXIMUM_PARAMETERS;
  59         record.NumberParameters = nbargs;
  60         memcpy( record.ExceptionInformation, args, nbargs * sizeof(*args) );
  61     }
  62     else record.NumberParameters = 0;
  63
  64     RtlRaiseException( &record );
  65 }
  66
  67
  68 /*******************************************************************
  69  *         UnhandledExceptionFilter   (KERNEL32.537)
  70  */
  71 DWORD WINAPI UnhandledExceptionFilter(PEXCEPTION_POINTERS epointers)
  72 {
  73     struct exception_event_request *req = get_req_buffer();
  74     char message[80];
  75     PDB *pdb = PROCESS_Current();
  76
  77     /* send a last chance event to the debugger */
  78     req->record  = *epointers->ExceptionRecord;
  79     req->first   = 0;
  80     req->context = *epointers->ContextRecord;
  81     if (!server_call_noerr( REQ_EXCEPTION_EVENT )) *epointers->ContextRecord = req->context;
  82     if (req->status == DBG_CONTINUE) return EXCEPTION_CONTINUE_EXECUTION;
  83
  84     if (pdb->top_filter)
  85     {
  86         DWORD ret = pdb->top_filter( epointers );
  87         if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
  88     }
  89
  90     /* FIXME: Should check the current error mode */
  91
  92     sprintf( message, "Unhandled exception 0x%08lx at address 0x%08lx.",
  93              epointers->ExceptionRecord->ExceptionCode,
  94              (DWORD)epointers->ExceptionRecord->ExceptionAddress );
  95     MessageBoxA( 0, message, "Error", MB_OK | MB_ICONHAND );
  96     return EXCEPTION_EXECUTE_HANDLER;
  97 }
  98
  99
 100 /*************************************************************
 101  *            SetUnhandledExceptionFilter   (KERNEL32.516)
 102  */
 103 LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
 104                                           LPTOP_LEVEL_EXCEPTION_FILTER filter )
 105 {
 106     PDB *pdb = PROCESS_Current();
 107     LPTOP_LEVEL_EXCEPTION_FILTER old = pdb->top_filter;
 108     pdb->top_filter = filter;
 109     return old;
 110 }
 111
 112
 113 /*************************************************************
 114  *            WINE_exception_handler
 115  *
 116  * Exception handler for exception blocks declared in Wine code.
 117  */
 118 DWORD WINE_exception_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 119                               CONTEXT *context, LPVOID pdispatcher )
 120 {
 121     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 122
 123     if (record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND | EH_NESTED_CALL))
 124         return ExceptionContinueSearch;
 125     if (wine_frame->u.filter)
 126     {
 127         EXCEPTION_POINTERS ptrs;
 128         ptrs.ExceptionRecord = record;
 129         ptrs.ContextRecord = context;
 130         switch(wine_frame->u.filter( &ptrs ))
 131         {
 132         case EXCEPTION_CONTINUE_SEARCH:
 133             return ExceptionContinueSearch;
 134         case EXCEPTION_CONTINUE_EXECUTION:
 135             return ExceptionContinueExecution;
 136         case EXCEPTION_EXECUTE_HANDLER:
 137             break;
 138         default:
 139             MESSAGE( "Invalid return value from exception filter\n" );
 140             assert( FALSE );
 141         }
 142     }
 143     /* hack to make GetExceptionCode() work in handler */
 144     wine_frame->ExceptionCode   = record->ExceptionCode;
 145     wine_frame->ExceptionRecord = wine_frame;
 146
 147     RtlUnwind( frame, 0, record, 0 );
 148     EXC_pop_frame( frame );
 149     longjmp( wine_frame->jmp, 1 );
 150 }
 151
 152
 153 /*************************************************************
 154  *            WINE_finally_handler
 155  *
 156  * Exception handler for try/finally blocks declared in Wine code.
 157  */
 158 DWORD WINE_finally_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 159                             CONTEXT *context, LPVOID pdispatcher )
 160 {
 161     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 162
 163     if (!(record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
 164         return ExceptionContinueSearch;
 165     wine_frame->u.finally_func( FALSE );
 166     return ExceptionContinueSearch;
 167 }