qemu/qga/vss-win32.c

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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 **errp, bool freeze)
{
const char *func_name = freeze ? "requester_freeze" : "requester_thaw";
QGAVSSRequesterFunc func;
ErrorSet errset = {
.error_setg_win32 = error_setg_win32_internal,
.errp = errp,
};
g_assert(errp); /* requester.cpp requires it */
func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name);
if (!func) {
error_setg_win32(errp, GetLastError(), "failed to load %s from %s",
func_name, QGA_VSS_DLL);
return;
}
func(nr_volume, &errset);
}