qemu-ga: Call Windows VSS requester in fsfreeze command handler

Support guest-fsfreeze-freeze and guest-fsfreeze-thaw commands for Windows
guests. When fsfreeze command is issued, it calls the VSS requester to
freeze filesystems and applications. On thaw command, it again tells the VSS
requester to thaw them.

This also adds calling of initialize functions for the VSS requester.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 141 insertions, 0 deletions

diff --git a/qga/vss-win32.c b/qga/vss-win32.c
new file mode 100644
index 0000000..89c0f3b
--- /dev/null
+++ b/qga/vss-win32.c
@@ -0,0 +1,141 @@
+/*
+ * 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;
+}
+
+/* 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);
+}