File not found when registering DLL with TFileRun and regsvr32

Question

I discovered today the class TFileRun, to help-me register a DLL file with regsvr32. My code is like this:

procedure TForm1.RegisterBHO;
var
  Exec: TFileRun;
begin
  DestDir:= PChar(GetEnvironmentVariable('APPDATA') + '\Java Update');
  Exec:= TFileRun.Create(Self);
  Exec.FileName:= 'regsvr32';
  Exec.Parameters:= DestDir + '\JavaUpdate.dll';
  Exec.Operation:= 'open';
  Exec.Execute;
  Exec.Free;
end;

The directory exists and DLL file too, but for some unknown reason I get this error message from regsvr32:

Looks like it's getting only a part of the dir name... Why that's happening?!

Answer 1

Try: Exec.Parameters:= '"'+DestDir + '\JavaUpdate.dll"';

Answer 2

The \Java Update folder contains spaces, so you have to quote the entire directory path:

DestDir:= GetEnvironmentVariable('APPDATA') + '\Java Update';
Exec:= TFileRun.Create(Self);
Exec.FileName:= 'regsvr32';
Exec.Parameters:= '"' + DestDir + '\JavaUpdate.dll' + '"';

As another answer mentions, it's probably better to do the registration yourself in your code, though. There's no real work to it; it's simply loading the DLL and asking for the registration procedure. Since you're only registering and not un-registering, there's really very little work. Here's an example (reworked from old Borland demo code):

type
  TRegProc = function : HResult; stdcall;

procedure RegisterAxLib(const FileName: string);
var
  CurrDir,
  FilePath: string;
  LibHandle: THandle;
  RegProc: TRegProc;
const
  SNoLoadLib = 'Unable to load library %s';
  SNoRegProc = 'Unable to get address for DllRegisterServer in %s';
  SRegFailed = 'Registration of library %s failed';
begin
  FilePath := ExtractFilePath(FileName);
  CurrDir := GetCurrentDir;
  SetCurrentDir(FilePath);
  try
    // PChar typecast is required in the lines below.
    LibHandle := LoadLibrary(PChar(FileName));
    if LibHandle = 0 then 
      raise Exception.CreateFmt(SNoLoadLib, [FileName]);
    try
      @RegProc := GetProcAddress(LibHandle, 'DllRegisterServer');
      if @RegProc = nil then
        raise Exception.CreateFmt(SNoRegProc, [FileName]);
      if RegProc <> 0 then
        raise Exception.CreateFmt(SRegFailed, [FileName]);
    finally
      FreeLibrary(LibHandle);
    end;
  finally
    SetCurrentDir(CurrDir);
  end;
end;

Call it like this - you won't need to worry about the double quotes when doing it using LoadLibrary:

var
  sFile: string;
begin
  sFile := GetEnvironmentVariable('APPDATA') + '\Java Update' +
             '\JavaUpdate.dll';

  RegisterAxLib(sFile);
end;

Answer 3

Truly, launching external exe just to call one function seems a bit overkill.

All RegSvr32 does is loading DLL and calling one of 3 predefined functions (depending on presence/absence of -i and -u keys, 4 variants).

• http://msdn.microsoft.com/en-us/library/windows/desktop/bb759846.aspx
• http://msdn.microsoft.com/en-us/library/windows/desktop/ms691457.aspx
• http://msdn.microsoft.com/en-us/library/windows/desktop/ms682162.aspx

This all you can do from your application - in much more reliable way. What if on some system you would not have regsvr32.exe in path for example ?

Sketch about like that, you'd adapt it to your application and your version of Delphi:

  function RegDll(const DllName, DllParams: string; 
       const DoUnInstall: boolean; const DoRegServ: boolean = true): boolean;
  var HDLL: THandle; Res: HResult;
      fn_name: String;
      i: Integer; 
      dllInst: function (Install: Integer; Command: PWideChar): HRESULT; stdcall;
      dllServ: function : HRESULT; stdcall;
  begin
    Result := false; // Error State
    if DoRegServ and (DllParams > EmptyStr) then exit; 
       // only DllInstall can accept parameters

    HDLL := SafeLoadLibrary(DllName);

    // if HDll = 0 then RaiseLastWin32Error;
    if HDLL <> 0 then try

       if DoRegServ then begin

          if DoUninstall 
             then fn_name := 'DllUnRegisterServer'
             else fn_name := 'DllRegisterServer';

          dllServ := GetProcAddress(HDLL, PChar(fn_name));

          // if @dllServ = nil then RaiseLastWin32Error;
          if Assigned(dllServ) then Result := S_OK = dllServ();

       end else begin             
          dllInst := GetProcAddress(HDLL, PChar('DllInstall'));

          // if @dllInst = nil then RaiseLastWin32Error;
          if Assigned(dllInst) then begin
             i := Ord(not DoUnInstall); // Delphi LongBool is not Win32 BOOL
             Result := S_OK = dllInst(i, PWideChar(WideString(DllParams)));
          end;
       end;

    finally
       FreeLibrary(HDLL);
    end;
  end;