text: /*
   * QEMU Guest Agent VSS utility functions
   *
   * Copyright Hitachi Data Systems Corp. 2013
   *
   * Authors:
   *  Tomoki Sekiyama   <tomoki.sekiyama@hds.com>
   *
   * This work is licensed under the terms of the GNU GPL, version 2 or later.
   * See the COPYING file in the top-level directory.
   */
  
  #include "qemu/osdep.h"
  #include <windows.h>
  #include "qga/guest-agent-core.h"
  #include "qga/vss-win32.h"
  #include "qga/vss-win32/requester.h"
  
  #define QGA_VSS_DLL "qga-vss.dll"
  
  static HMODULE provider_lib;
  
  /* Call a function in qga-vss.dll with the specified name */
  static HRESULT call_vss_provider_func(const char *func_name)
  {
      FARPROC WINAPI func;
  
      g_assert(provider_lib);
  
      func = GetProcAddress(provider_lib, func_name);
      if (!func) {
          char *msg;
          FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                        FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                        (char *)&msg, 0, NULL);
          fprintf(stderr, "failed to load %s from %s: %s",
                  func_name, QGA_VSS_DLL, msg);
          LocalFree(msg);
          return E_FAIL;
      }
  
      return func();
  }
  
  /* Check whether this OS version supports VSS providers */
  static bool vss_check_os_version(void)
  {
      OSVERSIONINFO OSver;
  
      OSver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
      GetVersionEx(&OSver);
      if ((OSver.dwMajorVersion == 5 && OSver.dwMinorVersion >= 2) ||
         OSver.dwMajorVersion > 5) {
          BOOL wow64 = false;
  #ifndef _WIN64
          /* Provider doesn't work under WOW64 (32bit agent on 64bit OS) */
          if (!IsWow64Process(GetCurrentProcess(), &wow64)) {
              fprintf(stderr, "failed to IsWow64Process (Error: %lx\n)\n",
                      GetLastError());
              return false;
          }
          if (wow64) {
              fprintf(stderr, "Warning: Running under WOW64\n");
          }
  #endif
          return !wow64;
      }
      return false;
  }
  
  /* Load qga-vss.dll */
  bool vss_init(bool init_requester)
  {
      if (!vss_check_os_version()) {
          /* Do nothing if OS doesn't support providers. */
          fprintf(stderr, "VSS provider is not supported in this OS version: "
                  "fsfreeze is disabled.\n");
          return false;
      }
  
      provider_lib = LoadLibraryA(QGA_VSS_DLL);
      if (!provider_lib) {
          char *msg;
          FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                        FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                        (char *)&msg, 0, NULL);
          fprintf(stderr, "failed to load %s: %sfsfreeze is disabled\n",
                  QGA_VSS_DLL, msg);
          LocalFree(msg);
          return false;
      }
  
      if (init_requester) {
          HRESULT hr = call_vss_provider_func("requester_init");
          if (FAILED(hr)) {
              fprintf(stderr, "fsfreeze is disabled.\n");
              vss_deinit(false);
              return false;
          }
      }
  
      return true;
  }
  
  /* Unload qga-provider.dll */
  void vss_deinit(bool deinit_requester)
  {
      if (deinit_requester) {
          call_vss_provider_func("requester_deinit");
      }
      FreeLibrary(provider_lib);
      provider_lib = NULL;
  }
  
  bool vss_initialized(void)
  {
      return !!provider_lib;
  }
  
  int ga_install_vss_provider(void)
  {
      HRESULT hr;
  
      if (!vss_init(false)) {
          fprintf(stderr, "Installation of VSS provider is skipped. "
                  "fsfreeze will be disabled.\n");
          return 0;
      }
      hr = call_vss_provider_func("COMRegister");
      vss_deinit(false);
  
      return SUCCEEDED(hr) ? 0 : EXIT_FAILURE;
  }
  
  void ga_uninstall_vss_provider(void)
  {
      if (!vss_init(false)) {
          fprintf(stderr, "Removal of VSS provider is skipped.\n");
          return;
      }
      call_vss_provider_func("COMUnregister");
      vss_deinit(false);
  }
  
  /* Call VSS requester and freeze/thaw filesystems and applications */
  void qga_vss_fsfreeze(int *nr_volume, bool freeze, Error **errp)
  {
      const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
      QGAVSSRequesterFunc func;
      ErrorSet errset = {
          .error_setg_win32_wrapper = error_setg_win32_internal,
          .errp = errp,
      };
  
      g_assert(errp);             /* requester.cpp requires it */
      func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
      if (!func) {
          error_setg_win32(errp, GetLastError(), "failed to load %s from %s",
                           func_name, QGA_VSS_DLL);
          return;
      }
  
      func(nr_volume, &errset);
  }
  