{**************************************************************************************************}
{                                                                                                  }
{ Project JEDI Code Library (JCL)                                                                  }
{                                                                                                  }
{ The contents of this file are subject to the Mozilla Public License Version 1.1 (the "License"); }
{ you may not use this file except in compliance with the License. You may obtain a copy of the    }
{ License at http://www.mozilla.org/MPL/                                                           }
{                                                                                                  }
{ Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF   }
{ ANY KIND, either express or implied. See the License for the specific language governing rights  }
{ and limitations under the License.                                                               }
{                                                                                                  }
{ The Original Code is JclHookExcept.pas.                                                          }
{                                                                                                  }
{ The Initial Developer of the Original Code is Petr Vones. Portions created by Petr Vones are     }
{ Copyright (C) Petr Vones. All Rights Reserved.                                                   }
{                                                                                                  }
{ Contributor(s):                                                                                  }
{   Petr Vones (pvones)                                                                            }
{   Robert Marquardt (marquardt)                                                                   }
{   Andreas Hausladen (ahuser)                                                                     }
{                                                                                                  }
{**************************************************************************************************}
{                                                                                                  }
{ Exception hooking routines                                                                       }
{                                                                                                  }
{**************************************************************************************************}
{                                                                                                  }
{ Last modified: $Date:: 2008-09-09 21:32:17 +0200 (mar., 09 sept. 2008)                         $ }
{ Revision:      $Rev:: 2461                                                                     $ }
{ Author:        $Author:: outchy                                                                $ }
{                                                                                                  }
{**************************************************************************************************}

unit JclHookExcept;

interface

{$I jcl.inc}

{$IFDEF COMPILER5}
{ The Delphi 5 compiler crashes with the internal compiler error L1496 if the Y+
  option is missing for this file. Without this Y+ line the compiler can BUILD the
  JCL package but cannot MAKE it without failing with an internal error.
  Furthermore the JVCL Installer cannot be compiled without the compiler internal
  error L1496. }
{$Y+}
{$ENDIF COMPILER5}

uses
  {$IFDEF UNITVERSIONING}
  JclUnitVersioning,
  {$ENDIF UNITVERSIONING}
  Windows, SysUtils;

type
  // Exception hooking notifiers routines
  TJclExceptNotifyProc = procedure(ExceptObj: TObject; ExceptAddr: Pointer; OSException: Boolean);
  TJclExceptNotifyProcEx = procedure(ExceptObj: TObject; ExceptAddr: Pointer; OSException: Boolean; ESP: Pointer);
  TJclExceptNotifyMethod = procedure(ExceptObj: TObject; ExceptAddr: Pointer; OSException: Boolean) of object;

  TJclExceptNotifyPriority = (npNormal, npFirstChain);

function JclAddExceptNotifier(const NotifyProc: TJclExceptNotifyProc; Priority: TJclExceptNotifyPriority = npNormal): Boolean; overload;
function JclAddExceptNotifier(const NotifyProc: TJclExceptNotifyProcEx; Priority: TJclExceptNotifyPriority = npNormal): Boolean; overload;
function JclAddExceptNotifier(const NotifyMethod: TJclExceptNotifyMethod; Priority: TJclExceptNotifyPriority = npNormal): Boolean; overload;

function JclRemoveExceptNotifier(const NotifyProc: TJclExceptNotifyProc): Boolean; overload;
function JclRemoveExceptNotifier(const NotifyProc: TJclExceptNotifyProcEx): Boolean; overload;
function JclRemoveExceptNotifier(const NotifyMethod: TJclExceptNotifyMethod): Boolean;  overload;

procedure JclReplaceExceptObj(NewExceptObj: Exception);

// Exception hooking routines
function JclHookExceptions: Boolean;
function JclUnhookExceptions: Boolean;
function JclExceptionsHooked: Boolean;

function JclHookExceptionsInModule(Module: HMODULE): Boolean;
function JclUnkookExceptionsInModule(Module: HMODULE): Boolean;

// Exceptions hooking in libraries
type
  TJclModuleArray = array of HMODULE;

function JclInitializeLibrariesHookExcept: Boolean;
function JclHookedExceptModulesList(var ModulesList: TJclModuleArray): Boolean;

// Hooking routines location info helper
function JclBelongsHookedCode(Address: Pointer): Boolean;

{$IFDEF UNITVERSIONING}
const
  UnitVersioning: TUnitVersionInfo = (
    RCSfile: '$URL: https://jcl.svn.sourceforge.net/svnroot/jcl/tags/JCL-1.104-Build3248/jcl/source/windows/JclHookExcept.pas $';
    Revision: '$Revision: 2461 $';
    Date: '$Date: 2008-09-09 21:32:17 +0200 (mar., 09 sept. 2008) $';
    LogPath: 'JCL\source\windows'
    );
{$ENDIF UNITVERSIONING}

implementation

uses
  Classes,
  JclBase, JclPeImage, JclSysInfo, JclSysUtils;

type
  PExceptionArguments = ^TExceptionArguments;
  TExceptionArguments = record
    ExceptAddr: Pointer;
    ExceptObj: Exception;
  end;

  TNotifierItem = class(TObject)
  private
    FNotifyMethod: TJclExceptNotifyMethod;
    FNotifyProc: TJclExceptNotifyProc;
    FNotifyProcEx: TJclExceptNotifyProcEx;
    FPriority: TJclExceptNotifyPriority;
  public
    constructor Create(const NotifyProc: TJclExceptNotifyProc; Priority: TJclExceptNotifyPriority); overload;
    constructor Create(const NotifyProc: TJclExceptNotifyProcEx; Priority: TJclExceptNotifyPriority); overload;
    constructor Create(const NotifyMethod: TJclExceptNotifyMethod; Priority: TJclExceptNotifyPriority); overload;
    procedure DoNotify(ExceptObj: TObject; ExceptAddr: Pointer; OSException: Boolean; ESP: Pointer);
    property Priority: TJclExceptNotifyPriority read FPriority;
  end;

var
  ExceptionsHooked: Boolean;
  Kernel32_RaiseException: procedure (dwExceptionCode, dwExceptionFlags,
    nNumberOfArguments: DWORD; lpArguments: PDWORD); stdcall;
  SysUtils_ExceptObjProc: function (P: PExceptionRecord): Exception;
  Notifiers: TThreadList;

{$IFDEF HOOK_DLL_EXCEPTIONS}
const
  JclHookExceptDebugHookName = '__JclHookExcept';

type
  TJclHookExceptDebugHook = procedure(Module: HMODULE; Hook: Boolean); stdcall;

  TJclHookExceptModuleList = class(TObject)
  private
    FModules: TThreadList;
  protected
    procedure HookStaticModules;
  public
    constructor Create;
    destructor Destroy; override;
    class function JclHookExceptDebugHookAddr: Pointer;
    procedure HookModule(Module: HMODULE);
    procedure List(var ModulesList: TJclModuleArray);
    procedure UnhookModule(Module: HMODULE);
  end;

var
  HookExceptModuleList: TJclHookExceptModuleList;
  JclHookExceptDebugHook: Pointer;

exports
  JclHookExceptDebugHook name JclHookExceptDebugHookName;
{$ENDIF HOOK_DLL_EXCEPTIONS}

{$STACKFRAMES OFF}

threadvar
  Recursive: Boolean;
  NewResultExc: Exception;

//=== Helper routines ========================================================

function RaiseExceptionAddress: Pointer;
begin
  Result := GetProcAddress(GetModuleHandle(kernel32), 'RaiseException');
  Assert(Result <> nil);
end;

procedure FreeNotifiers;
var
  I: Integer;
begin
  with Notifiers.LockList do
    try
      for I := 0 to Count - 1 do
        TObject(Items[I]).Free;
    finally
      Notifiers.UnlockList;
    end;
  FreeAndNil(Notifiers);
end;

//=== { TNotifierItem } ======================================================

constructor TNotifierItem.Create(const NotifyProc: TJclExceptNotifyProc; Priority: TJclExceptNotifyPriority);
begin
  inherited Create;
  FNotifyProc := NotifyProc;
  FPriority := Priority;
end;

constructor TNotifierItem.Create(const NotifyProc: TJclExceptNotifyProcEx; Priority: TJclExceptNotifyPriority);
begin
  inherited Create;
  FNotifyProcEx := NotifyProc;
  FPriority := Priority;
end;

constructor TNotifierItem.Create(const NotifyMethod: TJclExceptNotifyMethod; Priority: TJclExceptNotifyPriority);
begin
  inherited Create;
  FNotifyMethod := NotifyMethod;
  FPriority := Priority;
end;

procedure TNotifierItem.DoNotify(ExceptObj: TObject; ExceptAddr: Pointer;
  OSException: Boolean; ESP: Pointer);
begin
  if Assigned(FNotifyProc) then
    FNotifyProc(ExceptObj, ExceptAddr, OSException)
  else
  if Assigned(FNotifyProcEx) then
    FNotifyProcEx(ExceptObj, ExceptAddr, OSException, ESP)
  else
  if Assigned(FNotifyMethod) then
    FNotifyMethod(ExceptObj, ExceptAddr, OSException);
end;

function GetEBP: Pointer;
asm
        MOV     EAX, EBP
end;

{$STACKFRAMES ON}

procedure DoExceptNotify(ExceptObj: Exception; ExceptAddr: Pointer; OSException: Boolean; ESP: Pointer);
var
  Priorities: TJclExceptNotifyPriority;
  I: Integer;
begin
  if Recursive then
    Exit;
  if Assigned(Notifiers) then
  begin
    Recursive := True;
    NewResultExc := nil;
    try
      with Notifiers.LockList do
      try
        if Count = 1 then
        begin
          with TNotifierItem(Items[0]) do
            DoNotify(ExceptObj, ExceptAddr, OSException, ESP);
        end
        else
        begin
          for Priorities := High(Priorities) downto Low(Priorities) do
            for I := 0 to Count - 1 do
              with TNotifierItem(Items[I]) do
                if Priority = Priorities then
                  DoNotify(ExceptObj, ExceptAddr, OSException, ESP);
        end;
      finally
        Notifiers.UnlockList;
      end;
    finally
      Recursive := False;
    end;
  end;
end;

procedure HookedRaiseException(ExceptionCode, ExceptionFlags, NumberOfArguments: DWORD;
  Arguments: PExceptionArguments); stdcall;
const
  {$IFDEF DELPHI2}
  cDelphiException = $0EEDFACE;
  {$ELSE}
  cDelphiException = $0EEDFADE;
  {$ENDIF DELPHI2}
  cNonContinuable = 1;
begin
  if (ExceptionFlags = cNonContinuable) and (ExceptionCode = cDelphiException) and
    (NumberOfArguments = 7) and (DWORD_PTR(Arguments) = DWORD_PTR(@Arguments) + 4) then
  begin
    DoExceptNotify(Arguments.ExceptObj, Arguments.ExceptAddr, False, GetEBP);
  end;
  Kernel32_RaiseException(ExceptionCode, ExceptionFlags, NumberOfArguments, PDWORD(Arguments));
end;

function HookedExceptObjProc(P: PExceptionRecord): Exception;
var
  NewResultExcCache: Exception; // TLS optimization
begin
  Result := SysUtils_ExceptObjProc(P);
  DoExceptNotify(Result, P^.ExceptionAddress, True, GetEBP);
  NewResultExcCache := NewResultExc;
  if NewResultExcCache <> nil then
    Result := NewResultExcCache;
end;

{$IFNDEF STACKFRAMES_ON}
{$STACKFRAMES OFF}
{$ENDIF ~STACKFRAMES_ON}

// Do not change ordering of HookedRaiseException, HookedExceptObjProc and JclBelongsHookedCode routines

function JclBelongsHookedCode(Address: Pointer): Boolean;
begin
  Result := (Cardinal(@HookedRaiseException) < Cardinal(@JclBelongsHookedCode)) and
    (Cardinal(@HookedRaiseException) <= Cardinal(Address)) and
    (Cardinal(@JclBelongsHookedCode) > Cardinal(Address));
end;

function JclAddExceptNotifier(const NotifyProc: TJclExceptNotifyProc; Priority: TJclExceptNotifyPriority): Boolean;
begin
  Result := Assigned(NotifyProc);
  if Result then
    with Notifiers.LockList do
    try
      Add(TNotifierItem.Create(NotifyProc, Priority));
    finally
      Notifiers.UnlockList;
    end;
end;

function JclAddExceptNotifier(const NotifyProc: TJclExceptNotifyProcEx; Priority: TJclExceptNotifyPriority): Boolean;
begin
  Result := Assigned(NotifyProc);
  if Result then
    with Notifiers.LockList do
    try
      Add(TNotifierItem.Create(NotifyProc, Priority));
    finally
      Notifiers.UnlockList;
    end;
end;

function JclAddExceptNotifier(const NotifyMethod: TJclExceptNotifyMethod; Priority: TJclExceptNotifyPriority): Boolean;
begin
  Result := Assigned(NotifyMethod);
  if Result then
    with Notifiers.LockList do
    try
      Add(TNotifierItem.Create(NotifyMethod, Priority));
    finally
      Notifiers.UnlockList;
    end;
end;

function JclRemoveExceptNotifier(const NotifyProc: TJclExceptNotifyProc): Boolean;
var
  O: TNotifierItem;
  I: Integer;
begin
  Result := Assigned(NotifyProc);
  if Result then
    with Notifiers.LockList do
    try
      for I := 0 to Count - 1 do
      begin
        O := TNotifierItem(Items[I]);
        if @O.FNotifyProc = @NotifyProc then
        begin
          O.Free;
          Items[I] := nil;
        end;
      end;
      Pack;
    finally
      Notifiers.UnlockList;
    end;
end;

function JclRemoveExceptNotifier(const NotifyProc: TJclExceptNotifyProcEx): Boolean;
var
  O: TNotifierItem;
  I: Integer;
begin
  Result := Assigned(NotifyProc);
  if Result then
    with Notifiers.LockList do
    try
      for I := 0 to Count - 1 do
      begin
        O := TNotifierItem(Items[I]);
        if @O.FNotifyProcEx = @NotifyProc then
        begin
          O.Free;
          Items[I] := nil;
        end;
      end;
      Pack;
    finally
      Notifiers.UnlockList;
    end;
end;

function JclRemoveExceptNotifier(const NotifyMethod: TJclExceptNotifyMethod): Boolean;
var
  O: TNotifierItem;
  I: Integer;
begin
  Result := Assigned(NotifyMethod);
  if Result then
    with Notifiers.LockList do
    try
      for I := 0 to Count - 1 do
      begin
        O := TNotifierItem(Items[I]);
        if (TMethod(O.FNotifyMethod).Code = TMethod(NotifyMethod).Code) and
          (TMethod(O.FNotifyMethod).Data = TMethod(NotifyMethod).Data) then
        begin
          O.Free;
          Items[I] := nil;
        end;
      end;
      Pack;
    finally
      Notifiers.UnlockList;
    end;
end;

procedure JclReplaceExceptObj(NewExceptObj: Exception);
begin
  Assert(Recursive);
  NewResultExc := NewExceptObj;
end;

function JclHookExceptions: Boolean;
var
  RaiseExceptionAddressCache: Pointer;
begin
  if not ExceptionsHooked then
  begin
    Recursive := False;
    RaiseExceptionAddressCache := RaiseExceptionAddress;
    with TJclPeMapImgHooks do
      Result := ReplaceImport(SystemBase, kernel32, RaiseExceptionAddressCache, @HookedRaiseException);
    if Result then
    begin
      @Kernel32_RaiseException := RaiseExceptionAddressCache;
      SysUtils_ExceptObjProc := System.ExceptObjProc;
      System.ExceptObjProc := @HookedExceptObjProc;
    end;
    ExceptionsHooked := Result;
  end
  else
    Result := True;
end;

function JclUnhookExceptions: Boolean;
begin
  if ExceptionsHooked then
  begin
    with TJclPeMapImgHooks do
      ReplaceImport(SystemBase, kernel32, @HookedRaiseException, @Kernel32_RaiseException);
    System.ExceptObjProc := @SysUtils_ExceptObjProc;
    @SysUtils_ExceptObjProc := nil;
    @Kernel32_RaiseException := nil;
    Result := True;
    ExceptionsHooked := False;
  end
  else
    Result := True;
end;

function JclExceptionsHooked: Boolean;
begin
  Result := ExceptionsHooked;
end;

function JclHookExceptionsInModule(Module: HMODULE): Boolean;
begin
  Result := ExceptionsHooked and
    TJclPeMapImgHooks.ReplaceImport(Pointer(Module), kernel32, RaiseExceptionAddress, @HookedRaiseException);
end;

function JclUnkookExceptionsInModule(Module: HMODULE): Boolean;
begin
  Result := ExceptionsHooked and
    TJclPeMapImgHooks.ReplaceImport(Pointer(Module), kernel32, @HookedRaiseException, @Kernel32_RaiseException);
end;

{$IFDEF HOOK_DLL_EXCEPTIONS}
// Exceptions hooking in libraries

procedure JclHookExceptDebugHookProc(Module: HMODULE; Hook: Boolean); stdcall;
begin
  if Hook then
    HookExceptModuleList.HookModule(Module)
  else
    HookExceptModuleList.UnhookModule(Module);
end;

function CallExportedHookExceptProc(Module: HMODULE; Hook: Boolean): Boolean;
var
  HookExceptProcPtr: PPointer;
  HookExceptProc: TJclHookExceptDebugHook;
begin
  HookExceptProcPtr := TJclHookExceptModuleList.JclHookExceptDebugHookAddr;
  Result := Assigned(HookExceptProcPtr);
  if Result then
  begin
    @HookExceptProc := HookExceptProcPtr^;
    if Assigned(HookExceptProc) then
      HookExceptProc(Module, True);
  end;
end;
{$ENDIF HOOK_DLL_EXCEPTIONS}

function JclInitializeLibrariesHookExcept: Boolean;
begin
  {$IFDEF HOOK_DLL_EXCEPTIONS}
  if IsLibrary then
    Result := CallExportedHookExceptProc(SystemTObjectInstance, True)
  else
  begin
    if not Assigned(HookExceptModuleList) then
      HookExceptModuleList := TJclHookExceptModuleList.Create;
    Result := True;
  end;
  {$ELSE HOOK_DLL_EXCEPTIONS}
  Result := True;
  {$ENDIF HOOK_DLL_EXCEPTIONS}
end;

function JclHookedExceptModulesList(var ModulesList: TJclModuleArray): Boolean;
begin
  {$IFDEF HOOK_DLL_EXCEPTIONS}
  Result := Assigned(HookExceptModuleList);
  if Result then
    HookExceptModuleList.List(ModulesList);
  {$ELSE HOOK_DLL_EXCEPTIONS}
  Result := False;
  {$ENDIF HOOK_DLL_EXCEPTIONS}
end;

{$IFDEF HOOK_DLL_EXCEPTIONS}
procedure FinalizeLibrariesHookExcept;
begin
  FreeAndNil(HookExceptModuleList);
  if IsLibrary then
    CallExportedHookExceptProc(SystemTObjectInstance, False);
end;

//=== { TJclHookExceptModuleList } ===========================================

constructor TJclHookExceptModuleList.Create;
begin
  inherited Create;
  FModules := TThreadList.Create;
  HookStaticModules;
  JclHookExceptDebugHook := @JclHookExceptDebugHookProc;
end;

destructor TJclHookExceptModuleList.Destroy;
begin
  JclHookExceptDebugHook := nil;
  FreeAndNil(FModules);
  inherited Destroy;
end;

procedure TJclHookExceptModuleList.HookModule(Module: HMODULE);
begin
  with FModules.LockList do
  try
    if IndexOf(Pointer(Module)) = -1 then
    begin
      Add(Pointer(Module));
      JclHookExceptionsInModule(Module);
    end;
  finally
    FModules.UnlockList;
  end;
end;

procedure TJclHookExceptModuleList.HookStaticModules;
var
  ModulesList: TStringList;
  I: Integer;
  Module: HMODULE;
begin
  ModulesList := nil;
  with FModules.LockList do
  try
    ModulesList := TStringList.Create;
    if LoadedModulesList(ModulesList, GetCurrentProcessId, True) then
      for I := 0 to ModulesList.Count - 1 do
      begin
        Module := HMODULE(ModulesList.Objects[I]);
        if GetProcAddress(Module, JclHookExceptDebugHookName) <> nil then
          HookModule(Module);
      end;    
  finally
    FModules.UnlockList;
    ModulesList.Free;
  end;
end;

class function TJclHookExceptModuleList.JclHookExceptDebugHookAddr: Pointer;
var
  HostModule: HMODULE;
begin
  HostModule := GetModuleHandle(nil);
  Result := GetProcAddress(HostModule, JclHookExceptDebugHookName);
end;

procedure TJclHookExceptModuleList.List(var ModulesList: TJclModuleArray);
var
  I: Integer;
begin
  with FModules.LockList do
  try
    SetLength(ModulesList, Count);
    for I := 0 to Count - 1 do
      ModulesList[I] := HMODULE(Items[I]);
  finally
    FModules.UnlockList;
  end;
end;

procedure TJclHookExceptModuleList.UnhookModule(Module: HMODULE);
begin
  with FModules.LockList do
  try
    Remove(Pointer(Module));
  finally
    FModules.UnlockList;
  end;
end;
{$ENDIF HOOK_DLL_EXCEPTIONS}

initialization
  Notifiers := TThreadList.Create;
  {$IFDEF UNITVERSIONING}
  RegisterUnitVersion(HInstance, UnitVersioning);
  {$ENDIF UNITVERSIONING}

finalization
  {$IFDEF UNITVERSIONING}
  UnregisterUnitVersion(HInstance);
  {$ENDIF UNITVERSIONING}
  {$IFDEF HOOK_DLL_EXCEPTIONS}
  FinalizeLibrariesHookExcept;
  {$ENDIF HOOK_DLL_EXCEPTIONS}
  FreeNotifiers;

end.