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/*

 * 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 <stdio.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, Error **err, bool freeze)

{

    const char *func_name = freeze ? "requester_freeze" : "requester_thaw";

    QGAVSSRequesterFunc func;

    ErrorSet errset = {

        .error_set = (ErrorSetFunc)error_set_win32,

        .errp = (void **)err,

        .err_class = ERROR_CLASS_GENERIC_ERROR

    };

    func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);

    if (!func) {

        error_setg_win32(err, GetLastError(), "failed to load %s from %s",

                         func_name, QGA_VSS_DLL);

        return;

    }

    func(nr_volume, &errset);

}