qemu-ga: Install Windows VSS provider on `qemu-ga -s install'

Register QGA VSS provider library into Windows when qemu-ga is installed as
Windows service ('-s install' option). It is deregistered when the service
is uninstalled ('-s uninstall' option).
Signed-off-by: NTomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

qga/main.c

@@ -34,6 +34,7 @@
 #include "qemu/bswap.h"
 #ifdef _WIN32
 #include "qga/service-win32.h"
+#include "qga/vss-win32.h"
 #include <windows.h>
 #endif
 #ifdef __linux__
@@ -1031,8 +1032,15 @@ int main(int argc, char **argv)
                 fixed_state_dir = (state_dir == dfl_pathnames.state_dir) ?
                                   NULL :
                                   state_dir;
-                return ga_install_service(path, log_filepath, fixed_state_dir);
+                if (ga_install_vss_provider()) {
+                    return EXIT_FAILURE;
+                }
+                if (ga_install_service(path, log_filepath, fixed_state_dir)) {
+                    return EXIT_FAILURE;
+                }
+                return 0;
             } else if (strcmp(service, "uninstall") == 0) {
+                ga_uninstall_vss_provider();
                 return ga_uninstall_service();
             } else {
                 printf("Unknown service command.\n");

qga/vss-win32.c

@@ -119,6 +119,31 @@ 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)
 {

qga/vss-win32.h

@@ -19,6 +19,9 @@ bool vss_init(bool init_requester);
 void vss_deinit(bool deinit_requester);
 bool vss_initialized(void);
 
+int ga_install_vss_provider(void);
+void ga_uninstall_vss_provider(void);
+
 void qga_vss_fsfreeze(int *nr_volume, Error **err, bool freeze);
 
 #endif