tools/xenstore: add command line handling for live update

Updating an instance of Xenstore via live update needs to hand over
the command line parameters to the updated instance. Those can be
either the parameters used by the updated instance or new ones when
supplied when starting the live update.

So when supplied store the new command line parameters in lu_status.

As it is related add a new option -U (or --live-update") to the command
line of xenstored which will be added when starting the new instance.
This enables to perform slightly different initializations when
started as a result of live update.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Wei Liu <wl@xen.org>

tools/xenstore/xenstored_control.c

@@ -42,6 +42,8 @@ struct live_update {
 #else
 	char *filename;
 #endif
+
+	char *cmdline;
 };
 
 static struct live_update *lu_status;
@@ -211,6 +213,10 @@ static const char *lu_cmdline(const void *ctx, struct connection *conn,
 	if (!lu_status || lu_status->conn != conn)
 		return "Not in live-update session.";
 
+	lu_status->cmdline = talloc_strdup(lu_status, cmdline);
+	if (!lu_status->cmdline)
+		return "Allocation failure.";
+
 	return NULL;
 }
 

tools/xenstore/xenstored_core.c

@@ -1969,6 +1969,7 @@ static struct option options[] = {
 	{ "internal-db", 0, NULL, 'I' },
 	{ "verbose", 0, NULL, 'V' },
 	{ "watch-nb", 1, NULL, 'W' },
+	{ "live-update", 0, NULL, 'U' },
 	{ NULL, 0, NULL, 0 } };
 
 extern void dump_conn(struct connection *conn); 
@@ -1983,11 +1984,12 @@ int main(int argc, char *argv[])
 	bool dofork = true;
 	bool outputpid = false;
 	bool no_domain_init = false;
+	bool live_update = false;
 	const char *pidfile = NULL;
 	int timeout;
 
 
-	while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:A:M:T:RVW:", options,
+	while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:A:M:T:RVW:U", options,
 				  NULL)) != -1) {
 		switch (opt) {
 		case 'D':
@@ -2045,6 +2047,9 @@ int main(int argc, char *argv[])
 		case 'p':
 			priv_domid = strtol(optarg, NULL, 10);
 			break;
+		case 'U':
+			live_update = true;
+			break;
 		}
 	}
 	if (optind != argc)