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
  21 static HMODULE provider_lib;
  22
  23 /* Call a function in qga-vss.dll with the specified name */
  24 static 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 */
  47 static 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 */
  73 bool 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 */
 108 void 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
 117 bool vss_initialized(void)
 118 {
 119     return !!provider_lib;
 120 }
 121
 122 int 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
 137 void 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 */
 148 void 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 = 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 }