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  * Fixmes:
  24  *  -Most functions need better parameter checking.
  25  *  -I do not know how to handle exceptions within an exception handler.
  26  *   or what is done when ExceptionNestedException is returned from an
  27  *   exception handler
  28  *  -Real exceptions are not yet implemented. only the exception functions
  29  *   are implemented. A real implementation needs some new code in
  30  *   loader/signal.c. There would also be a need for showing debugging
  31  *   information in UnhandledExceptionFilter.
  32  *
  33  */
  34
  35 #include <assert.h>
  36 #include "winuser.h"
  37 #include "winerror.h"
  38 #include "ldt.h"
  39 #include "process.h"
  40 #include "thread.h"
  41 #include "debugtools.h"
  42 #include "except.h"
  43 #include "stackframe.h"
  44
  45 DEFAULT_DEBUG_CHANNEL(seh)
  46
  47
  48 /*******************************************************************
  49  *         RaiseException  (KERNEL32.418)
  50  */
  51 void WINAPI RaiseException( DWORD code, DWORD flags, DWORD nbargs, const LPDWORD args )
  52 {
  53     EXCEPTION_RECORD record;
  54
  55     /* Compose an exception record */
  56
  57     record.ExceptionCode    = code;
  58     record.ExceptionFlags   = flags & EH_NONCONTINUABLE;
  59     record.ExceptionRecord  = NULL;
  60     record.ExceptionAddress = RaiseException;
  61     if (nbargs && args)
  62     {
  63         if (nbargs > EXCEPTION_MAXIMUM_PARAMETERS) nbargs = EXCEPTION_MAXIMUM_PARAMETERS;
  64         record.NumberParameters = nbargs;
  65         memcpy( record.ExceptionInformation, args, nbargs * sizeof(*args) );
  66     }
  67     else record.NumberParameters = 0;
  68
  69     RtlRaiseException( &record );
  70 }
  71
  72
  73 /*******************************************************************
  74  *         UnhandledExceptionFilter   (KERNEL32.537)
  75  */
  76 DWORD WINAPI UnhandledExceptionFilter(PEXCEPTION_POINTERS epointers)
  77 {
  78     char message[80];
  79     PDB *pdb = PROCESS_Current();
  80
  81     /* FIXME: Should check if the process is being debugged */
  82
  83     if (pdb->top_filter)
  84     {
  85         DWORD ret = pdb->top_filter( epointers );
  86         if (ret != EXCEPTION_CONTINUE_SEARCH) return ret;
  87     }
  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 }