GetProcessFileNameFromPID

function GetProcessFileNameFromPID(
  dwProcessID: DWORD): WideString;
var
  Handle: THandle;
begin
  Result := EmptyStr;
  Handle := OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ, False,
    dwProcessID);
  try
    SetLength(Result, MAX_PATH);
    if Handle <> 0 then begin
      if GetModuleFileNameEx(Handle, 0, {$IFDEF UNICODE}PWideChar{$ELSE}PAnsiChar{$ENDIF}(Result), MAX_PATH) >= 0 then
        SetLength(Result, StrLen( {$IFDEF UNICODE}PWideChar{$ELSE}PAnsiChar{$ENDIF}(Result) ))
      else
        Result := EmptyStr;
    end else begin// if Handle <> 0 then begin
       if GetModuleFileNameEx(Handle, 0, {$IFDEF UNICODE}PWideChar{$ELSE}PAnsiChar{$ENDIF}(Result), MAX_PATH) >= 0 then
        SetLength(Result, StrLen( {$IFDEF UNICODE}PWideChar{$ELSE}PAnsiChar{$ENDIF}(Result) ))
       else
        Result := EmptyStr;
    end;// if Handle <> 0 then begin
  finally
    CloseHandle(Handle);
  end;// try
end;