xref: /openbmc/qemu/qga/vss-win32.c (revision 69e2d038)
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 
23 static HMODULE provider_lib;
24 
25 /* Call a function in qga-vss.dll with the specified name */
call_vss_provider_func(const char * func_name)26 static 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 */
vss_check_os_version(void)49 static 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 */
vss_init(bool init_requester)75 bool 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 */
vss_deinit(bool deinit_requester)110 void 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 
vss_initialized(void)119 bool vss_initialized(void)
120 {
121     return !!provider_lib;
122 }
123 
ga_install_vss_provider(void)124 int 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 
ga_uninstall_vss_provider(void)139 void 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 */
qga_vss_fsfreeze(int * nr_volume,bool freeze,strList * mountpoints,Error ** errp)150 void 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