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