delphi - 如何判断CoInitialize被调用了多少层？

Question

我正在对一个困惑的项目进行一些调试，我发现以前的开发人员不知道他们在做什么，主要问题是尝试多线程应用程序失败。我现在正在清理困惑并试图找出问题出在哪里。问题之一是为了使用 ADO 组件而对 CoInitialize 的调用不一致。

继续我的previous question ，如何确定已调用多少层 CoInitialize ？

例如，考虑以下代码:

CoInitialize(nil);
try
  CoInitialize(nil);
  try
    //2 levels have been called, how to programatically check this?
  finally
    CoUninitialize;
  end;
finally
  CoUninitialize;
end;

Answer 1

如果我必须解决这个问题，我会通过检测对 CoInitialize、CoInitializeEx 和 CoUninitialize 的调用来解决它。我会将调用 Hook 到这些函数并使用线程局部变量来计算调用次数。

您可以通过将以下单元添加到您的项目中来实现此目的。

unit InstrumentCOMinit;

interface

uses
  SysUtils, Windows, ComObj, ActiveX;

threadvar
  COMinitCount: Integer;

implementation

function CoInitialize(pvReserved: Pointer): HResult; stdcall; external 'ole32.dll';
function CoInitializeEx(pvReserved: Pointer; coInit: Longint): HResult; stdcall; external 'ole32.dll';
procedure CoUninitialize; stdcall; external 'ole32.dll';

function InstrumentedCoInitialize(pvReserved: Pointer): HResult; stdcall;
begin
  Result := CoInitialize(pvReserved);
  if Succeeded(Result) then
    inc(COMinitCount);
end;

function InstrumentedCoInitializeEx(pvReserved: Pointer; coInit: Longint): HResult; stdcall;
begin
  Result := CoInitializeEx(pvReserved, coInit);
  if Succeeded(Result) then
    inc(COMinitCount);
end;

procedure InstrumentedCoUninitialize; stdcall;
begin
  CoUninitialize;
  dec(COMinitCount);
end;

procedure Fail;
begin
  raise EAssertionFailed.Create('Fixup failed.');
end;

procedure PatchCode(Address: Pointer; const NewCode; Size: Integer);
var
  OldProtect: DWORD;
begin
  if not VirtualProtect(Address, Size, PAGE_EXECUTE_READWRITE, OldProtect) then begin
    Fail;
  end;
  Move(NewCode, Address^, Size);
  FlushInstructionCache(GetCurrentProcess, nil, 0);
  if not VirtualProtect(Address, Size, OldProtect, @OldProtect) then begin
    Fail;
  end;
end;

type
  PInstruction = ^TInstruction;
  TInstruction = packed record
    Opcode: Byte;
    Offset: Integer;
  end;

procedure RedirectProcedure(OldAddress, NewAddress: Pointer);
var
  NewCode: TInstruction;
begin
  NewCode.Opcode := $E9;//jump relative
  NewCode.Offset := NativeInt(NewAddress)-NativeInt(OldAddress)-SizeOf(NewCode);
  PatchCode(OldAddress, NewCode, SizeOf(NewCode));
end;

initialization
  RedirectProcedure(@ActiveX.CoInitialize, @InstrumentedCoInitialize);
  RedirectProcedure(@ActiveX.CoInitializeEx, @InstrumentedCoInitializeEx);
  RedirectProcedure(@ActiveX.CoUninitialize, @InstrumentedCoUninitialize);
  ComObj.CoInitializeEx := InstrumentedCoInitializeEx;

end.

与 Serg 的方法不同，此技术不会改变程序的语义。