From f1a6884a516a73bdba9653914aa5cc93f5280e56 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Sun, 6 Sep 2020 10:02:45 -0400
Subject: [PATCH] ntpquery: Add a -s flag to make it adjust the time

---
 Userland/ntpquery.cpp | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/Userland/ntpquery.cpp b/Userland/ntpquery.cpp
index 58a8ab2826..e87a7a2109 100644
--- a/Userland/ntpquery.cpp
+++ b/Userland/ntpquery.cpp
@@ -100,24 +100,33 @@ static String format_ntp_timestamp(NtpTimestamp ntp_timestamp)
 
 int main(int argc, char** argv)
 {
-    if (pledge("stdio inet dns", nullptr) < 0) {
+    if (pledge("stdio inet dns settime", nullptr) < 0) {
         perror("pledge");
         return 1;
     }
 
+    bool set_time = false;
     // FIXME: Change to serenityos.pool.ntp.org once https://manage.ntppool.org/manage/vendor/zone?a=km5a8h&id=vz-14154g is approved.
     const char* host = "time.google.com";
     Core::ArgsParser args_parser;
+    args_parser.add_option(set_time, "Adjust system time (requires root)", "set", 's');
     args_parser.add_positional_argument(host, "NTP server", "host", Core::ArgsParser::Required::No);
     args_parser.parse(argc, argv);
 
+    if (!set_time) {
+        if (pledge("stdio inet dns", nullptr) < 0) {
+            perror("pledge");
+            return 1;
+        }
+    }
+
     auto* hostent = gethostbyname(host);
     if (!hostent) {
         fprintf(stderr, "Lookup failed for '%s'\n", host);
         return 1;
     }
 
-    if (pledge("stdio inet", nullptr) < 0) {
+    if (pledge(set_time ? "stdio inet settime" : "stdio inet", nullptr) < 0) {
         perror("pledge");
         return 1;
     }
@@ -180,6 +189,15 @@ int main(int argc, char** argv)
     NtpTimestamp transmit_timestamp = be64toh(packet.transmit_timestamp);
     NtpTimestamp destination_timestamp = ntp_timestamp_from_timeval(t);
 
+    if (set_time) {
+        // FIXME: Do all the time filtering described in 5905, or at least correct for time of flight.
+        timeval t = timeval_from_ntp_timestamp(transmit_timestamp);
+        if (settimeofday(&t, nullptr) < 0) {
+            perror("settimeofday");
+            return 1;
+        }
+    }
+
     printf("NTP response from %s:\n", inet_ntoa(peer_address.sin_addr));
     printf("Leap Information: %d\n", packet.li_vn_mode >> 6);
     printf("Version Number: %d\n", (packet.li_vn_mode >> 3) & 7);