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 "debugger.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     char message[80];
  74     PDB *pdb = PROCESS_Current();
  75
  76     if (pdb->flags & PDB32_DEBUGGED) return EXCEPTION_CONTINUE_SEARCH;
  77
  78     if (pdb->top_filter)
  79     {
  80         DWORD ret = pdb->top_filter( epointers );
  81         if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
  82     }
  83
  84     /* FIXME: does not belong here */
  85     if (wine_debugger( epointers->ExceptionRecord,
  86                        epointers->ContextRecord, FALSE ) == DBG_CONTINUE)
  87         return EXCEPTION_CONTINUE_EXECUTION;
  88
  89     /* FIXME: Should check the current error mode */
  90
  91     sprintf( message, "Unhandled exception 0x%08lx at address 0x%08lx.",
  92              epointers->ExceptionRecord->ExceptionCode,
  93              (DWORD)epointers->ExceptionRecord->ExceptionAddress );
  94     MessageBoxA( 0, message, "Error", MB_OK | MB_ICONHAND );
  95     return EXCEPTION_EXECUTE_HANDLER;
  96 }
  97
  98
  99 /*************************************************************
 100  *            SetUnhandledExceptionFilter   (KERNEL32.516)
 101  */
 102 LPTOP_LEVEL_EXCEPTION_FILTER WINAPI SetUnhandledExceptionFilter(
 103                                           LPTOP_LEVEL_EXCEPTION_FILTER filter )
 104 {
 105     PDB *pdb = PROCESS_Current();
 106     LPTOP_LEVEL_EXCEPTION_FILTER old = pdb->top_filter;
 107     pdb->top_filter = filter;
 108     return old;
 109 }
 110
 111
 112 /*************************************************************
 113  *            WINE_exception_handler
 114  *
 115  * Exception handler for exception blocks declared in Wine code.
 116  */
 117 DWORD WINE_exception_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 118                               CONTEXT *context, LPVOID pdispatcher )
 119 {
 120     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 121
 122     if (record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND | EH_NESTED_CALL))
 123         return ExceptionContinueSearch;
 124     if (wine_frame->u.filter)
 125     {
 126         EXCEPTION_POINTERS ptrs;
 127         ptrs.ExceptionRecord = record;
 128         ptrs.ContextRecord = context;
 129         switch(wine_frame->u.filter( &ptrs ))
 130         {
 131         case EXCEPTION_CONTINUE_SEARCH:
 132             return ExceptionContinueSearch;
 133         case EXCEPTION_CONTINUE_EXECUTION:
 134             return ExceptionContinueExecution;
 135         case EXCEPTION_EXECUTE_HANDLER:
 136             break;
 137         default:
 138             MESSAGE( "Invalid return value from exception filter\n" );
 139             assert( FALSE );
 140         }
 141     }
 142     /* hack to make GetExceptionCode() work in handler */
 143     wine_frame->ExceptionCode   = record->ExceptionCode;
 144     wine_frame->ExceptionRecord = wine_frame;
 145
 146     RtlUnwind( frame, 0, record, 0 );
 147     EXC_pop_frame( frame );
 148     longjmp( wine_frame->jmp, 1 );
 149 }
 150
 151
 152 /*************************************************************
 153  *            WINE_finally_handler
 154  *
 155  * Exception handler for try/finally blocks declared in Wine code.
 156  */
 157 DWORD WINE_finally_handler( EXCEPTION_RECORD *record, EXCEPTION_FRAME *frame,
 158                             CONTEXT *context, LPVOID pdispatcher )
 159 {
 160     __WINE_FRAME *wine_frame = (__WINE_FRAME *)frame;
 161
 162     if (!(record->ExceptionFlags & (EH_UNWINDING | EH_EXIT_UNWIND)))
 163         return ExceptionContinueSearch;
 164     wine_frame->u.finally_func( FALSE );
 165     return ExceptionContinueSearch;
 166 }