Delphi修改窗口类名(Hookapi)修改版/知识点:指针

program Project1;

uses
Forms,
Windows,
Messages,
SysUtils,
Variants,
Classes,
Graphics,
Controls,
Dialogs,
Unit1 in 'Unit1.pas' {Form1};

function GetClassInfoA1(x: Integer;y:Integer;j:Integer): Integer;
stdcall; external 'user32.dll' name 'GetClassInfoA';

function RtlMoveMemory1(x: Integer;y:Pointer;j:Integer): Integer;
stdcall; external 'kernel32.dll' name 'RtlMoveMemory';

var j_apidizhi,j_old:Pointer;
jmt: array[1..8] of Byte;
ent: array[1..8] of Byte;
j_ls:LongWord;

{$R *.res}
function MyGetClassInfoA(hWnd:Integer;lpText: Integer;uType:Integer): Integer; stdcall;
var myclassname:array[0..254] of char;
jack:Integer;
begin
CopyMemory(j_apidizhi, @ent, 8);
CopyMemory(@myclassname,Pointer(lptext),6);
if myclassname='TForm1' then
begin
myclassname:='hgorj3';
RtlMoveMemory1(lpText,@myclassname,6);
end;
jack:=GetClassInfoA1(hWnd,lpText,uType);

//asm
//   pushad
//  mov eax,j_apidizhi
//  mov byte [eax],$B8
//  add eax,1
//  mov ebx,j_ls
//   mov [eax],ebx
//   add eax,4
//   mov byte [eax],$FF
//   add eax,1
//  mov byte [eax],$E0
//  popad
//end;
CopyMemory(j_apidizhi, @jmt, 8);
Result:=jack;
end;

begin
j_apidizhi:=GetProcAddress(GetModuleHandle('user32.dll'),'GetClassInfoA');
VirtualProtect(j_apidizhi,8,64,j_old);
CopyMemory(@ent, j_apidizhi, 8); //保存原指令
j_ls:=LongWord(@MyGetClassInfoA);
jmt[1]:=$b8;
Pinteger(@jmt[2])^:=LongWord(@MyGetClassInfoA);
jmt[6]:=$FF;
jmt[7]:=$E0;
CopyMemory(j_apidizhi, @jmt, 8); //修改API头
//asm
//  pushad
//  mov eax,j_apidizhi
//  mov byte [eax],$B8
//  add eax,1
//  mov ebx,j_ls
//   mov [eax],ebx
//  add eax,4
//  mov byte [eax],$FF
//  add eax,1
//  mov byte [eax],$E0
//   popad
// end;

Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.

Pinteger(@jmt[2])^:=LongWord(@MyGetClassInfoA);

重点在这一句

首先@jmt[2]表示jmt第二个元素的地址

比如 00400000 01

00400001 02

00400002 03

00400003 04

00400004 05

00400005 06

00400007 08

00400002 03

@jmt[2]=00400001

然后把地址转成Pinteger类型 也就是还是00400001 转成整型指针 让编译器识别

那么Pinteger(@jmt[2])的值就是Pinteger(@jmt[2])^

把00400001里的值赋值等于MyGetClassInfoA子程序的的地址

就是这句 Pinteger(@jmt[2])^:=LongWord(@MyGetClassInfoA);