130 lines
3.7 KiB
ObjectPascal
130 lines
3.7 KiB
ObjectPascal
{-----------------------------------------------------------------------------
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The contents of this file are subject to the Mozilla Public License
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Version 1.1 (the "License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.mozilla.org/MPL/MPL-1.1.html
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Software distributed under the License is distributed on an "AS IS" basis,
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WITHOUT WARRANTY OF ANY KIND, either expressed or implied. See the License for
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the specific language governing rights and limitations under the License.
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The Original Code is: JvHook.PAS, released on 2002-07-04.
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The Initial Developers of the Original Code are: Fedor Koshevnikov, Igor Pavluk and Serge Korolev
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Copyright (c) 1997, 1998 Fedor Koshevnikov, Igor Pavluk and Serge Korolev
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Copyright (c) 2001,2002 SGB Software
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All Rights Reserved.
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Last Modified: 2002-07-04
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You may retrieve the latest version of this file at the Project JEDI's JVCL home page,
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located at http://jvcl.sourceforge.net
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Known Issues:
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(rom) this file should definitely be merged with JclSysUtils.pas
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-----------------------------------------------------------------------------}
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{$I JVCL.INC}
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unit JvHook;
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interface
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uses
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Windows,
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SysUtils;
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{, JvComponent}
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type
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PClass = ^TClass;
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function GetVirtualMethodCount(AClass: TClass): Integer;
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function GetVirtualMethodAddress(AClass: TClass; AIndex: Integer): Pointer;
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function SetVirtualMethodAddress(AClass: TClass; AIndex: Integer;
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NewAddress: Pointer): Pointer;
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function FindVirtualMethodIndex(AClass: TClass; MethodAddr: Pointer): Integer;
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implementation
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{ SetVirtualMethodAddress procedure. Destroy destructor has index 0,
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first user defined virtual method has index 1. }
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type
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PPointer = ^Pointer;
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// (rom) copied from JCL
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function GetVirtualMethodCount(AClass: TClass): Integer;
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var
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BeginVMT: Longint;
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EndVMT: Longint;
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TablePointer: Longint;
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I: Integer;
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begin
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BeginVMT := Longint(AClass);
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// Scan the offset entries in the class table for the various fields,
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// namely vmtIntfTable, vmtAutoTable, ..., vmtDynamicTable
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// The last entry is always the vmtClassName, so stop once we got there
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// After the last virtual method there is one of these entries.
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EndVMT := PLongint(Longint(AClass) + vmtClassName)^;
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// Set iterator to first item behind VMT table pointer
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I := vmtSelfPtr + SizeOf(Pointer);
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repeat
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TablePointer := PLongint(Longint(AClass) + I)^;
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if (TablePointer <> 0) and (TablePointer >= BeginVMT) and
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(TablePointer < EndVMT) then
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EndVMT := Longint(TablePointer);
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Inc(I, SizeOf(Pointer));
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until I >= vmtClassName;
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Result := (EndVMT - BeginVMT) div SizeOf(Pointer);
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end;
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function GetVirtualMethodAddress(AClass: TClass; AIndex: Integer): Pointer;
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var
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Table: PPointer;
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begin
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Table := PPointer(AClass);
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Inc(Table, AIndex - 1);
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Result := Table^;
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end;
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function SetVirtualMethodAddress(AClass: TClass; AIndex: Integer;
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NewAddress: Pointer): Pointer;
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const
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PageSize = SizeOf(Pointer);
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var
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Table: PPointer;
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SaveFlag: DWORD;
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begin
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Table := PPointer(AClass);
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Inc(Table, AIndex - 1);
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Result := Table^;
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if VirtualProtect(Table, PageSize, PAGE_EXECUTE_READWRITE, @SaveFlag) then
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try
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Table^ := NewAddress;
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finally
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VirtualProtect(Table, PageSize, SaveFlag, @SaveFlag);
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end;
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end;
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// (rom) reimplemented using GetVirtualMethodCount
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function FindVirtualMethodIndex(AClass: TClass; MethodAddr: Pointer): Integer;
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var
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I: Integer;
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begin
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Result := -1; // (rom) API change!
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for I := 0 to GetVirtualMethodCount(AClass)-1 do
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if GetVirtualMethodAddress(AClass, Result) = MethodAddr then
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begin
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Result := I;
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Break;
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end;
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end;
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end.
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