Hook all exceptions
lazarus / 62-General

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DevilDevil · 2020-10-13 17:06

Starting from Delphi 2009, it became possible to catch all exceptions
through the RaiseExceptObjProc callback, for example, for analysis
purposes.

In FreePascal, when an exception is raised, the fpc_RaiseException
function is called:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Procedure
fpc_RaiseException (Obj : TObject; AnAddr : CodePointer; AFrame :
Pointer);[Public, Alias : 'FPC_RAISEEXCEPTION']; compilerproc;var 
_ExceptObjectStack : PExceptObject;  _ExceptAddrstack :
PExceptAddr;begin{$ifdef excdebug}  writeln ('In
RaiseException');{$endif}  if ExceptTryLevel<>0 then    Halt(217); 
ExceptTryLevel:=1;  PushExceptObject(Obj,AnAddr,AFrame);  { if
PushExceptObject causes another exception, the following won't be
executed,    causing halt upon entering this routine recursively. } 
ExceptTryLevel:=0;  _ExceptAddrstack:=ExceptAddrStack;  If
_ExceptAddrStack=Nil then    DoUnhandledException; 
_ExceptObjectStack:=ExceptObjectStack;  if (RaiseProc <> nil) and
(_ExceptObjectStack <> nil) then    with _ExceptObjectStack^ do     
RaiseProc(FObject,Addr,FrameCount,Frames); 
longjmp(_ExceptAddrStack^.Buf^,FPC_Exception);end;
I am trying to override RaiseProc function, but the given code is not
being called. How to catch all exceptions by analogy with Delphi?

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
Project1; {$APPTYPE CONSOLE} uses  SysUtils; procedure
MyRaiseProc(Obj: TObject; Addr: CodePointer; FrameCount: Longint;
Frame: PCodePointer);begin  Writeln(Obj.ClassName);end; begin 
System.RaiseProc := @MyRaiseProc;   try    raise
Exception.Create('Message');  except    on E: Exception do    begin  
  Writeln('Except part');    end;  end;   Write('Press Enter to
quit');  Readln;end.

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jamie · 2020-10-13 19:34

The Tapplication has the OnException you can redirect..

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rvk · 2020-10-13 20:27

Quote from: DevilDevil on October 13, 2020, 07:06:44 pmI am trying to
override RaiseProc function, but the given code is not being called.
How to catch all exceptions by analogy with Delphi?
Does it also catch handled exception in Delphi or only unhandled
exception.

In your code you handle the exception yourself.
What happens if you don't handle the exception or reraise it?

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ASerge · 2020-10-13 22:12

And System.RaiseProc for raise. For catch System.ExceptProc.

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DevilDevil · 2020-10-14 06:40

Quote from: ASerge on October 14, 2020, 12:12:19 amAnd
System.RaiseProc for raise. For catch System.ExceptProc.

ExceptProc only works if the exception is not caught at all (without
try/except). RaiseProc never works.

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PascalDragon · 2020-10-14 09:59

Quote from: DevilDevil on October 13, 2020, 07:06:44 pmI am trying to
override RaiseProc function, but the given code is not being called.
How to catch all exceptions by analogy with Delphi?
Are you per chance testing this on i386-win32 (on 3.2.0+) or
x86_64-win64 (on 3.0.0+)? If so then due to the switch to Structured
Exception Handling, this is currently not supported and the
fpc_RaiseException you showed is not used there.

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DevilDevil · 2020-10-14 11:57

PascalDragon,

Very sorry. Thanks