wanuptime: improve buffer validation (snprintf/strlcpy)

release/src-rt-6.x.4708/router/wanuptime/wanuptime.c

@@ -13,23 +13,20 @@ int main(int argc, char *argv[])
 	char prefix[] = "wanXX";
 
 	if (argc > 1)
-		strcpy(prefix, argv[1]);
+		strlcpy(prefix, argv[0], sizeof(prefix));
 	else
-		strcpy(prefix, "wan");
+		strlcpy(prefix, "wan", sizeof(prefix));
 
 	memset(wantime_file, 0, sizeof(wantime_file));
-	sprintf(wantime_file, "/var/lib/misc/%s_time", prefix);
+	snprintf(wantime_file, sizeof(wantime_file), "/var/lib/misc/%s_time", prefix);
 
-	if (sysinfo(&si) == -1) {
+	if (sysinfo(&si) == -1)
 		return 1;
-	}
 
-	if (check_wanup(prefix) && f_read(wantime_file, &uptime, sizeof(time_t)) == sizeof(uptime)) {
+	if (check_wanup(prefix) && f_read(wantime_file, &uptime, sizeof(time_t)) == sizeof(uptime))
 		printf("%ld\n", si.uptime - uptime);
-	}
-	else {
+	else
 		printf("0\n");
-	}
 
 	return 0;
 }