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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 // AdbWinApi.cpp : Implementation of DLL Exports.
     18 
     19 #include "stdafx.h"
     20 #include "adb_api.h"
     21 #include "adb_winusb_api.h"
     22 
     23 extern "C" {
     24 int _forceCRTManifest;
     25 int _forceMFCManifest;
     26 int _forceAtlDllManifest;
     27 };
     28 
     29 /// References InstantiateWinUsbInterface declared in adb_api.cpp
     30 extern PFN_INSTWINUSBINTERFACE InstantiateWinUsbInterface;
     31 
     32 class CAdbWinApiModule : public CAtlDllModuleT< CAdbWinApiModule > {
     33  public:
     34   CAdbWinApiModule()
     35       : CAtlDllModuleT< CAdbWinApiModule >(),
     36         adbwinusbapi_handle_(NULL),
     37         is_initialized_(false) {
     38   }
     39 
     40   ~CAdbWinApiModule() {
     41     // Unload AdbWinUsbApi.dll before we exit
     42     if (NULL != adbwinusbapi_handle_) {
     43       FreeLibrary(adbwinusbapi_handle_);
     44     }
     45   }
     46 
     47   /** \brief Loads AdbWinUsbApi.dll and caches its InstantiateWinUsbInterface
     48     export.
     49 
     50     This method is called from DllMain on DLL_PROCESS_ATTACH event. In this
     51     method we will check if WINUSB.DLL required by AdbWinUsbApi.dll is
     52     installed, and if it is we will load AdbWinUsbApi.dll and cache address of
     53     InstantiateWinUsbInterface routine exported from AdbWinUsbApi.dll
     54   */
     55   void AttachToAdbWinUsbApi() {
     56     // We only need to run this only once.
     57     if (is_initialized_) {
     58       return;
     59     }
     60 
     61     // Just mark that we have ran initialization.
     62     is_initialized_ = true;
     63 
     64     // Before we can load AdbWinUsbApi.dll we must make sure that WINUSB.DLL
     65     // has been installed. Build path to the file.
     66     wchar_t path_to_winusb_dll[MAX_PATH+1];
     67     if (!GetSystemDirectory(path_to_winusb_dll, MAX_PATH)) {
     68       return;
     69     }
     70     wcscat(path_to_winusb_dll, L"\\WINUSB.DLL");
     71 
     72     if (0xFFFFFFFF == GetFileAttributes(path_to_winusb_dll)) {
     73       // WINUSB.DLL is not installed. We don't (in fact, can't) load
     74       // AdbWinUsbApi.dll
     75       return;
     76     }
     77 
     78     // WINUSB.DLL is installed. Lets load AdbWinUsbApi.dll and cache its
     79     // InstantiateWinUsbInterface export.
     80     // We require that AdbWinUsbApi.dll is located in the same folder
     81     // where AdbWinApi.dll and adb.exe are located, so by Windows
     82     // conventions we can pass just module name, and not the full path.
     83     adbwinusbapi_handle_ = LoadLibrary(L"AdbWinUsbApi.dll");
     84     if (NULL != adbwinusbapi_handle_) {
     85       InstantiateWinUsbInterface = reinterpret_cast<PFN_INSTWINUSBINTERFACE>
     86           (GetProcAddress(adbwinusbapi_handle_, "InstantiateWinUsbInterface"));
     87     }
     88   }
     89 
     90  protected:
     91   /// Handle to the loaded AdbWinUsbApi.dll
     92   HINSTANCE adbwinusbapi_handle_;
     93 
     94   /// Flags whether or not this module has been initialized.
     95   bool      is_initialized_;
     96 };
     97 
     98 CAdbWinApiModule _AtlModule;
     99 
    100 // DLL Entry Point
    101 extern "C" BOOL WINAPI DllMain(HINSTANCE instance,
    102                                DWORD reason,
    103                                LPVOID reserved) {
    104   // Lets see if we need to initialize InstantiateWinUsbInterface
    105   // variable. We do that only once, on condition that this DLL is
    106   // being attached to the process and InstantiateWinUsbInterface
    107   // address has not been calculated yet.
    108   if (DLL_PROCESS_ATTACH == reason) {
    109     _AtlModule.AttachToAdbWinUsbApi();
    110   }
    111   return _AtlModule.DllMain(reason, reserved);
    112 }
    113