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 "qapi/error.h"
  16 #include "qemu/error-report.h"
  17 #include "guest-agent-core.h"
  18 #include "vss-win32.h"
  19 #include "vss-win32/requester.h"
  20
  21 #define QGA_VSS_DLL "qga-vss.dll"
  22
  23 static HMODULE provider_lib;
  24
  25 /* Call a function in qga-vss.dll with the specified name */
  26 static HRESULT call_vss_provider_func(const char *func_name)
  27 {
  28     FARPROC WINAPI func;
  29
  30     g_assert(provider_lib);
  31
  32     func = GetProcAddress(provider_lib, func_name);
  33     if (!func) {
  34         char *msg;
  35         FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
  36                       FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
  37                       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  38                       (char *)&msg, 0, NULL);
  39         fprintf(stderr, "failed to load %s from %s: %s",
  40                 func_name, QGA_VSS_DLL, msg);
  41         LocalFree(msg);
  42         return E_FAIL;
  43     }
  44
  45     return func();
  46 }
  47
  48 /* Check whether this OS version supports VSS providers */
  49 static bool vss_check_os_version(void)
  50 {
  51     OSVERSIONINFO OSver;
  52
  53     OSver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  54     GetVersionEx(&OSver);
  55     if ((OSver.dwMajorVersion == 5 && OSver.dwMinorVersion >= 2) ||
  56        OSver.dwMajorVersion > 5) {
  57         BOOL wow64 = false;
  58 #ifndef _WIN64
  59         /* Provider doesn't work under WOW64 (32bit agent on 64bit OS) */
  60         if (!IsWow64Process(GetCurrentProcess(), &wow64)) {
  61             fprintf(stderr, "failed to IsWow64Process (Error: %lx\n)\n",
  62                     GetLastError());
  63             return false;
  64         }
  65         if (wow64) {
  66             warn_report("Running under WOW64");
  67         }
  68 #endif
  69         return !wow64;
  70     }
  71     return false;
  72 }
  73
  74 /* Load qga-vss.dll */
  75 bool vss_init(bool init_requester)
  76 {
  77     if (!vss_check_os_version()) {
  78         /* Do nothing if OS doesn't support providers. */
  79         fprintf(stderr, "VSS provider is not supported in this OS version: "
  80                 "fsfreeze is disabled.\n");
  81         return false;
  82     }
  83
  84     provider_lib = LoadLibraryA(QGA_VSS_DLL);
  85     if (!provider_lib) {
  86         char *msg;
  87         FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
  88                       FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
  89                       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  90                       (char *)&msg, 0, NULL);
  91         fprintf(stderr, "failed to load %s: %sfsfreeze is disabled\n",
  92                 QGA_VSS_DLL, msg);
  93         LocalFree(msg);
  94         return false;
  95     }
  96
  97     if (init_requester) {
  98         HRESULT hr = call_vss_provider_func("requester_init");
  99         if (FAILED(hr)) {
 100             fprintf(stderr, "fsfreeze is disabled.\n");
 101             vss_deinit(false);
 102             return false;
 103         }
 104     }
 105
 106     return true;
 107 }
 108
 109 /* Unload qga-provider.dll */
 110 void vss_deinit(bool deinit_requester)
 111 {
 112     if (deinit_requester) {
 113         call_vss_provider_func("requester_deinit");
 114     }
 115     FreeLibrary(provider_lib);
 116     provider_lib = NULL;
 117 }
 118
 119 bool vss_initialized(void)
 120 {
 121     return !!provider_lib;
 122 }
 123
 124 int ga_install_vss_provider(void)
 125 {
 126     HRESULT hr;
 127
 128     if (!vss_init(false)) {
 129         fprintf(stderr, "Installation of VSS provider is skipped. "
 130                 "fsfreeze will be disabled.\n");
 131         return 0;
 132     }
 133     hr = call_vss_provider_func("COMRegister");
 134     vss_deinit(false);
 135
 136     return SUCCEEDED(hr) ? 0 : EXIT_FAILURE;
 137 }
 138
 139 void ga_uninstall_vss_provider(void)
 140 {
 141     if (!vss_init(false)) {
 142         fprintf(stderr, "Removal of VSS provider is skipped.\n");
 143         return;
 144     }
 145     call_vss_provider_func("COMUnregister");
 146     vss_deinit(false);
 147 }
 148
 149 /* Call VSS requester and freeze/thaw filesystems and applications */
 150 void qga_vss_fsfreeze(int *nr_volume, bool freeze, Error **errp)
 151 {
 152     const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
 153     QGAVSSRequesterFunc func;
 154     ErrorSet errset = {
 155         .error_setg_win32_wrapper = error_setg_win32_internal,
 156         .errp = errp,
 157     };
 158
 159     g_assert(errp);             /* requester.cpp requires it */
 160     func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
 161     if (!func) {
 162         error_setg_win32(errp, GetLastError(), "failed to load %s from %s",
 163                          func_name, QGA_VSS_DLL);
 164         return;
 165     }
 166
 167     func(nr_volume, &errset);
 168 }