在新连接的LoadResString方法

时间：2015-05-21 08:39:24

标签： delphi winapi hook resourcestring

供参考 - 以下是我的代码，我在NewLoadResString函数中获取StackOverflow异常。这种情况就像我已经创建了两个stringlist，即RecStrNameIdMap和NewStringValueList。 这里RecStrNameIdMap是用于存储名称和字符串标识符映射的哈希字符串列表。这样我就可以将资源字符串名称称为其标识符，即ID。

NewStringValueList是一个字符串列表，其中包含少数Resourcestrings的新值。

我已经在system.LoadResString方法上连接了NewLoadResString方法。在新方法中，我正在检查我是否在NewStringValueList中为给定的resourcestring提供了新值，然后获取该值并返回new而不是旧的声明值。

Stack Overflow异常发生在第*行

上
  

如果RecStrNameIdMap.IndexOfName（IntToStr（ResStringRec ^ .Identifier））＆gt;   -1然后

* 任何人都可以请检查我收到此错误的原因。

unit UnitTest;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IniFiles, StdCtrls;

type
  TForm2 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;


type
  TMethodHook = class
  private
    aOriginal : packed array[ 0..4 ] of byte;
    pOldProc, pNewProc : pointer;
    pPosition : PByteArray;
  public
    constructor Create( pOldProc, pNewProc : pointer );
    destructor Destroy; override;
  end;


var
  Form2: TForm2;

implementation

{$R *.dfm}

ResourceString
  RS_1 = 'ABC';
  RS_2 = 'XYZ';

procedure TForm2.Button1Click(Sender: TObject);
var
  aMethodHook: TMethodHook;
  RecStrNameIdMap: THashedStringList;
  NewStringValueList: TStringList;

  {Hookup aNewProcedure on aOriginalProcedure}
  procedure RegisterProcedures(aOriginalProcedure, aNewProcedure: pointer);
  begin
    if Assigned(aOriginalProcedure) and Assigned(aNewProcedure) then
      aMethodHook := TMethodHook.Create( aOriginalProcedure, aNewProcedure);
  end;

  {Replacement for System.LoadResString}
  function NewLoadResString(ResStringRec: PResStringRec): String;
  var
    Buffer: array [0..4095] of char;
  begin
    if ResStringRec = nil then Exit;
    if ResStringRec.Identifier >= 64 * 1024 then
    begin
      Result := PChar(ResStringRec.Identifier);
    end
    else
    begin
      if RecStrNameIdMap.IndexOfName(IntToStr(ResStringRec^.Identifier)) > -1 then
      begin
        Result := NewStringValueList.Values[
          RecStrNameIdMap.Values[IntToStr(ResStringRec^.Identifier)]];
      end
      else
      begin
        SetString(Result, Buffer,
          LoadString(FindResourceHInstance(ResStringRec.Module^),
            ResStringRec.Identifier, Buffer, SizeOf(Buffer)));
      end;
    end;
  end;

  procedure CreateNameIdMapping;
  begin
    {This is done to get string name from ID}
    RecStrNameIdMap.CaseSensitive := False;
    RecStrNameIdMap.Add(Inttostr(PResStringRec(RS_2)^.Identifier)+'='+'XYZ');
  end;

begin
  aMethodHook := nil;
  try
    RecStrNameIdMap := THashedStringList.Create;
    NewStringValueList := TStringList.Create;

    CreateNameIdMapping;

    {Create new value list for ResourceStrings}
    NewStringValueList.Add('XYZ'+'='+'new value for ResourceString RS_2');
    RegisterProcedures(@System.LoadResString, @NewLoadResString);

    {This should return 'new value for ResourceString RS_2' instead of 'XYZ'}
    ShowMessage(RS_2);

    {This should return 'ABC' - no change in value}
    ShowMessage(RS_1);
  finally
    aMethodHook.Free;
    RecStrNameIdMap.Free;
    NewStringValueList.Free;
  end;
end;

{ TMethodHook }

constructor TMethodHook.Create(pOldProc, pNewProc: pointer);
var
  iOffset : integer;
  iMemProtect : cardinal;
  i : integer;
begin
  Self.pOldProc := pOldProc;
  Self.pNewProc := pNewProc;

  pPosition := pOldProc;
  iOffset := integer( pNewProc ) - integer( pointer( pPosition ) ) - 5;

  for i := 0 to 4 do aOriginal[ i ] := pPosition^[ i ];

  VirtualProtect( pointer( pPosition ), 5, PAGE_EXECUTE_READWRITE,
    @iMemProtect );

  pPosition^[ 0 ] := $E9;
  pPosition^[ 1 ] := byte( iOffset );
  pPosition^[ 2 ] := byte( iOffset shr 8 );
  pPosition^[ 3 ] := byte( iOffset shr 16 );
  pPosition^[ 4 ] := byte( iOffset shr 24 );
end;

destructor TMethodHook.Destroy;
var
  i : integer;
begin
  for i := 0 to 4 do pPosition^[ i ] := aOriginal[ i ];
  inherited;
end;

end.

1 个答案:

答案 0 :(得分：5)

似乎替换程序不能成为嵌套程序 如documentation中所述：

  

过程类型允许您将过程和函数视为可以分配给变量或传递给其他过程和函数的值。

...

  

嵌套过程和函数（在其他例程中声明的例程）不能用作过程值，也不能用作预定义的过程和函数。

程序类型是指针。虽然嵌套例程不能用作过程类型，但我假设指向嵌套例程的指针不能用作过程参数，或者此操作可能具有不可预测的结果，例如在这种情况下。
程序正确连接（你做了）;我解除了程序NewLoadResString，并且 stackoverflow 错误不再发生 弹出的resourcestring始终是旧的，但我在NewLoadResString程序中没有做任何更改。
整个编辑过的单元如下。

unit UnitTest;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IniFiles, StdCtrls;

type
  TForm2 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    RecStrNameIdMap: THashedStringList;
    NewStringValueList: TStringList;
  public
    { Public declarations }
  end;


type
  TMethodHook = class
  private
    aOriginal : packed array[ 0..4 ] of byte;
    pOldProc, pNewProc : pointer;
    pPosition : PByteArray;
  public
    constructor Create( pOldProc, pNewProc : pointer );
    destructor Destroy; override;
  end;


var
  Form2: TForm2;

implementation

{$R *.dfm}

ResourceString
  RS_1 = 'ABC';
  RS_2 = 'XYZ';


{Replacement for System.LoadResString}
function NewLoadResString(ResStringRec: PResStringRec): String;
var
  Buffer: array [0..4095] of char;
begin
  if ResStringRec = nil then Exit;
  if ResStringRec.Identifier >= 64 * 1024 then
  begin
    Result := PChar(ResStringRec.Identifier);
  end
  else
  begin
    if RecStrNameIdMap.IndexOfName(IntToStr(ResStringRec^.Identifier)) > -1 then
    begin
      Result := NewStringValueList.Values[
        RecStrNameIdMap.Values[IntToStr(ResStringRec^.Identifier)]];
    end
    else
    begin
      SetString(Result, Buffer,
        LoadString(FindResourceHInstance(ResStringRec.Module^),
          ResStringRec.Identifier, Buffer, SizeOf(Buffer)));
    end;
  end;
end;

procedure TForm2.Button1Click(Sender: TObject);
var
  aMethodHook: TMethodHook;

  {Hookup aNewProcedure on aOriginalProcedure}
  procedure RegisterProcedures(aOriginalProcedure, aNewProcedure: pointer);
  begin
    if Assigned(aOriginalProcedure) and Assigned(aNewProcedure) then
      aMethodHook := TMethodHook.Create( aOriginalProcedure, aNewProcedure);
  end;

  procedure CreateNameIdMapping;
  begin
    {This is done to get string name from ID}
    RecStrNameIdMap.CaseSensitive := False;
    RecStrNameIdMap.Add(Inttostr(PResStringRec(RS_2)^.Identifier)+'='+'XYZ');
  end;

begin
  aMethodHook := nil;
  RecStrNameIdMap := THashedStringList.Create;
  NewStringValueList := TStringList.Create;
  try
    CreateNameIdMapping;

    {Create new value list for ResourceStrings}
    NewStringValueList.Add('XYZ'+'='+'new value for ResourceString RS_2');
    RegisterProcedures(@System.LoadResString, @NewLoadResString);

    {This should return 'new value for ResourceString RS_2' instead of 'XYZ'}
    ShowMessage(RS_2);

    {This should return 'ABC' - no change in value}
    ShowMessage(RS_1);
  finally
    aMethodHook.Free;
    RecStrNameIdMap.Free;
    NewStringValueList.Free;
  end;
end;

{ TMethodHook }

constructor TMethodHook.Create(pOldProc, pNewProc: pointer);
var
  iOffset : integer;
  iMemProtect : cardinal;
  i : integer;
begin
  Self.pOldProc := pOldProc;
  Self.pNewProc := pNewProc;

  pPosition := pOldProc;
  iOffset := integer( pNewProc ) - integer( pointer( pPosition ) ) - 5;

  for i := 0 to 4 do aOriginal[ i ] := pPosition^[ i ];

  VirtualProtect( pointer( pPosition ), 5, PAGE_EXECUTE_READWRITE,
    @iMemProtect );

  pPosition^[ 0 ] := $E9;
  pPosition^[ 1 ] := byte( iOffset );
  pPosition^[ 2 ] := byte( iOffset shr 8 );
  pPosition^[ 3 ] := byte( iOffset shr 16 );
  pPosition^[ 4 ] := byte( iOffset shr 24 );
end;

destructor TMethodHook.Destroy;
var
  i : integer;
begin
  for i := 0 to 4 do pPosition^[ i ] := aOriginal[ i ];
  inherited;
end;

end.
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