qga/vss-win32.c

   1 /*
   2  * QEMU Guest Agent VSS utility functions
   3  *
   4  * Copyright Hitachi Data Systems Corp. 2013
   5  *
   6  * Authors:
   7  *  Tomoki Sekiyama   <tomoki.sekiyama@hds.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include <windows.h>
  15 #include "qemu/error-report.h"
  16 #include "qga/guest-agent-core.h"
  17 #include "qga/vss-win32.h"
  18 #include "qga/vss-win32/requester.h"
  19
  20 #define QGA_VSS_DLL "qga-vss.dll"
  21
  22 static HMODULE provider_lib;
  23
  24 /* Call a function in qga-vss.dll with the specified name */
  25 static HRESULT call_vss_provider_func(const char *func_name)
  26 {
  27     FARPROC WINAPI func;
  28
  29     g_assert(provider_lib);
  30
  31     func = GetProcAddress(provider_lib, func_name);
  32     if (!func) {
  33         char *msg;
  34         FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
  35                       FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
  36                       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  37                       (char *)&msg, 0, NULL);
  38         fprintf(stderr, "failed to load %s from %s: %s",
  39                 func_name, QGA_VSS_DLL, msg);
  40         LocalFree(msg);
  41         return E_FAIL;
  42     }
  43
  44     return func();
  45 }
  46
  47 /* Check whether this OS version supports VSS providers */
  48 static bool vss_check_os_version(void)
  49 {
  50     OSVERSIONINFO OSver;
  51
  52     OSver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  53     GetVersionEx(&OSver);
  54     if ((OSver.dwMajorVersion == 5 && OSver.dwMinorVersion >= 2) ||
  55        OSver.dwMajorVersion > 5) {
  56         BOOL wow64 = false;
  57 #ifndef _WIN64
  58         /* Provider doesn't work under WOW64 (32bit agent on 64bit OS) */
  59         if (!IsWow64Process(GetCurrentProcess(), &wow64)) {
  60             fprintf(stderr, "failed to IsWow64Process (Error: %lx\n)\n",
  61                     GetLastError());
  62             return false;
  63         }
  64         if (wow64) {
  65             warn_report("Running under WOW64");
  66         }
  67 #endif
  68         return !wow64;
  69     }
  70     return false;
  71 }
  72
  73 /* Load qga-vss.dll */
  74 bool vss_init(bool init_requester)
  75 {
  76     if (!vss_check_os_version()) {
  77         /* Do nothing if OS doesn't support providers. */
  78         fprintf(stderr, "VSS provider is not supported in this OS version: "
  79                 "fsfreeze is disabled.\n");
  80         return false;
  81     }
  82
  83     provider_lib = LoadLibraryA(QGA_VSS_DLL);
  84     if (!provider_lib) {
  85         char *msg;
  86         FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
  87                       FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
  88                       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  89                       (char *)&msg, 0, NULL);
  90         fprintf(stderr, "failed to load %s: %sfsfreeze is disabled\n",
  91                 QGA_VSS_DLL, msg);
  92         LocalFree(msg);
  93         return false;
  94     }
  95
  96     if (init_requester) {
  97         HRESULT hr = call_vss_provider_func("requester_init");
  98         if (FAILED(hr)) {
  99             fprintf(stderr, "fsfreeze is disabled.\n");
 100             vss_deinit(false);
 101             return false;
 102         }
 103     }
 104
 105     return true;
 106 }
 107
 108 /* Unload qga-provider.dll */
 109 void vss_deinit(bool deinit_requester)
 110 {
 111     if (deinit_requester) {
 112         call_vss_provider_func("requester_deinit");
 113     }
 114     FreeLibrary(provider_lib);
 115     provider_lib = NULL;
 116 }
 117
 118 bool vss_initialized(void)
 119 {
 120     return !!provider_lib;
 121 }
 122
 123 int ga_install_vss_provider(void)
 124 {
 125     HRESULT hr;
 126
 127     if (!vss_init(false)) {
 128         fprintf(stderr, "Installation of VSS provider is skipped. "
 129                 "fsfreeze will be disabled.\n");
 130         return 0;
 131     }
 132     hr = call_vss_provider_func("COMRegister");
 133     vss_deinit(false);
 134
 135     return SUCCEEDED(hr) ? 0 : EXIT_FAILURE;
 136 }
 137
 138 void ga_uninstall_vss_provider(void)
 139 {
 140     if (!vss_init(false)) {
 141         fprintf(stderr, "Removal of VSS provider is skipped.\n");
 142         return;
 143     }
 144     call_vss_provider_func("COMUnregister");
 145     vss_deinit(false);
 146 }
 147
 148 /* Call VSS requester and freeze/thaw filesystems and applications */
 149 void qga_vss_fsfreeze(int *nr_volume, bool freeze, Error **errp)
 150 {
 151     const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
 152     QGAVSSRequesterFunc func;
 153     ErrorSet errset = {
 154         .error_setg_win32_wrapper = error_setg_win32_internal,
 155         .errp = errp,
 156     };
 157
 158     g_assert(errp);             /* requester.cpp requires it */
 159     func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
 160     if (!func) {
 161         error_setg_win32(errp, GetLastError(), "failed to load %s from %s",
 162                          func_name, QGA_VSS_DLL);
 163         return;
 164     }
 165
 166     func(nr_volume, &errset);
 167 }