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 "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
  23static HMODULE provider_lib;
  24
  25/* Call a function in qga-vss.dll with the specified name */
  26static 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 */
  49static 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 */
  75bool 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 */
 110void 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
 119bool vss_initialized(void)
 120{
 121    return !!provider_lib;
 122}
 123
 124int 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
 139void 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 */
 150void qga_vss_fsfreeze(int *nr_volume, bool freeze,
 151                      strList *mountpoints, Error **errp)
 152{
 153    const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
 154    QGAVSSRequesterFunc func;
 155    ErrorSet errset = {
 156        .error_setg_win32_wrapper = error_setg_win32_internal,
 157        .errp = errp,
 158    };
 159
 160    g_assert(errp);             /* requester.cpp requires it */
 161    func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
 162    if (!func) {
 163        error_setg_win32(errp, GetLastError(), "failed to load %s from %s",
 164                         func_name, QGA_VSS_DLL);
 165        return;
 166    }
 167
 168    func(nr_volume, mountpoints, &errset);
 169}
 170