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Groups > comp.protocols.time.ntp > #164284

Re: ntpd does not start daemon control: got EOF

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In message <d3493e70-2276-4c63-a4a4-7de5e6518cc0@ntp.org>, "Harlan Stenn" 
write
s:
> On 4/27/2026 4:33 PM, Cy Schubert wrote:
> > In message <c125bd87-a762-4468-b214-5ead5147b82c@ntp.org>, "Harlan Stenn"
> > write
> > s:
> >> On 4/27/2026 12:59 PM, Cy Schubert wrote:
> >>> In message <CAMbSiYD=phHqGb=DjmYoZmYOjXWvv1r+TLex=ZjiyZHfaPYBAA@mail.gmai
> l.
> >> c
> >>> om>
> >>> , Dave Hart writes:
> >>>>
> >>>> On Mon, Apr 27, 2026 at 14:11=E2=80=AFUTC Cy Schubert wrote:
> >>>>
> >>>>> The issue with ntpd is that it forks a subprocess, with a pipe between
> >>>>> both
> >>>>> processes. The child process write "R\n" to the pipe. If the parent doe
> s
> >>>>> not read two bytes it exits with an error. Just a guess here that monit
> >>>>> might have its fingers in the pipe.
> >>>>>
> >>>>
> >>>> ntpd does have --nofork/-n to avoid forking to daemonize.  I have not
> >>>> tested, but intuitively it seems like a better solution for FreeBSD's rc
> .d
> >>>> script.
> >>>>
> >>>
> >>> I suppose users of monit could use that. rcng uses the .pid file to manag
> e
> >>> services. I don't see any benefit of changing the FreeBSD rc file to
> >>> support an esoteric process monitoring application. Applications should
> >>> conform to and work within the O/S, not the other way around. Though not
> >>> posix pidfiles are a common UNIX-like management tool.
> >>
> >> We believe we provide a robust mechanism for ntpd startup.  If there is
> >> missing functionality here, please open a bug report.
> >>
> >> There are a staggering number of systems out there that use a myriad of
> >> different startup schemes.  Any given system can undergo spontaneous
> >> changes in its startup framework.
> >>
> >> It seems unreasonable to me to expect *any* application project
> >> (including NTP) to conform to an OS.
> >>
> >> But it *is* perfectly reasonable to expect an application project to
> >> offer command-line and configuration options that are sufficiently
> >> robust to allow an arbitrary OS to reliably start/stop the application.
> >>
> >> Are we agreed on this?
> > 
> > In this regard ntp (and sendmail) are working correctly. The issue only
> > occurs when run under monit. Monit might be inserting itself between the
> > parent and the child in order to cause the parent not to read "R\n" on the
> > pipe.
>
> Cool, thanks!
>
> > I have confirmed, in a jail on a 16-CURRENT system, that the problem only
> > occurs under monit. This is why I suggested the O/P open a bugzilla bug for
> > the problem. It's one of the following:
> > 
> > - a monit bug, or
> > - a bug uncovered by monit in the FreeBSD kernel or libc.
> > 
> > What ntpd is doing by opening a pipe so the child can notify the parent it
> > can terminate itself looks reasonable.
> > 
> > 
> >>
> >> -- 
> >> Harlan Stenn <stenn@ntp.org>
> >> NTP Project Lead.  The NTP Project is part of:
> >> https://www.nwtime.org/ - be a member!
> > 
> > 
>
> -- 
> Harlan Stenn <stenn@ntp.org>
> NTP Project Lead.  The NTP Project is part of:
> https://www.nwtime.org/ - be a member!

I'll try to nail this down this week. Just to rule out whether the child is 
terminating the following DTrace probes will, hopefully, point me in a 
direction to better understand this.

diff --git a/contrib/ntp/ntpd/ntpd.c b/contrib/ntp/ntpd/ntpd.c
index b64caae06da1..6095e2144925 100644
--- a/contrib/ntp/ntpd/ntpd.c
+++ b/contrib/ntp/ntpd/ntpd.c
@@ -134,6 +134,9 @@
 # include <sys/resource.h>
 # include <seccomp.h>
 #endif /* LIBSECCOMP and KERN_SECCOMP */
+#if defined(__FreeBSD__)
+#include <sys.sdt.h>
+#endif
 
 #if defined(__FreeBSD__) &&  __FreeBSD_version < 1400037 && 
defined(HAVE_SYS_PROCCTL_H)
 # include <sys/procctl.h>
@@ -1444,7 +1447,15 @@ int scmp_sc[] = {
 	if (daemon_pipe[1] != -1 && 0 == wait_sync) {
 		if (2 != write(daemon_pipe[1], "R\n", 2)) {
 			msyslog(LOG_ERR, "daemon failed to notify parent ntpd after init");
+#if defined(__FreeBSD__)
+			DTRACE_PROBE(ntpd, child_notify_parent_fail)
+#endif
 		}
+#if defined(__FreeBSD__)
+		else {
+			DTRACE_PROBE(ntpd, child_notify_success)
+		}
+#endif
 		close(daemon_pipe[1]);
 		daemon_pipe[1] = -1;
 	}
@@ -1694,16 +1705,25 @@ wait_child_sync_if(
 		if (rc == 0) {
 			/* DPRINTF is useless here as -d/-D disable forking */
 			fprintf(stderr, "daemon control: got EOF\n");
+#if defined(__FreeBSD__)
+			DTRACE_PROBE(ntpd, parent_got_eof)
+#endif
 			return -1;	/* unexpected EOF, check daemon */
 		} else if (rc == 1) {
 			if (   ('S' == ch && wait_sync > 0)
 			    || ('R' == ch && 0 == wait_sync)) {
+#if defined(__FreeBSD__)
+				DTRACE_PROBE(ntpd, parent_got_char)
+#endif
 				return 0;
 			}
 		} else {
 			mfprintf(stderr, "%s: daemon control: read 1 char failed: %m\n",
 				 progname);
 			msyslog(LOG_ERR, "daemon control: read 1 char failed: %m");
+#if defined(__FreeBSD__)
+			DTRACE_PROBE(ntpd, parent_pipe_read_fail)
+#endif
 			return EX_IOERR;
 		}
 	} while (wait_rem > 0);


-- 
Cheers,
Cy Schubert <Cy.Schubert@cschubert.com>
FreeBSD UNIX:  <cy@FreeBSD.org>   Web:  https://FreeBSD.org
NTP:           <cy@nwtime.org>    Web:  https://nwtime.org

			e**(i*pi)+1=0

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ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-21 21:08 +0200
  Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-21 19:58 +0000
    Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-21 22:08 +0200
      Re: ntpd does not start daemon control: got EOF "Dave Hart via questions Mailing List" <questions@lists.ntp.org> - 2026-04-21 20:58 +0000
      Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-22 19:43 +0200
        Re: ntpd does not start daemon control: got EOF "Dave Hart" <davehart@gmail.com> - 2026-04-27 19:43 +0000
          Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-27 20:03 +0000
        Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-27 21:38 +0000
          Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-28 04:38 +0000
      Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-22 22:03 +0000
        Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-23 06:51 +0200
          Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-25 05:28 +0000
          Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-28 00:08 +0000
      Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-22 22:13 +0000
    Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-21 20:43 +0000
      Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-22 05:25 +0200
    Re: ntpd does not start daemon control: got EOF "Harlan Stenn via questions Mailing List" <questions@lists.ntp.org> - 2026-04-21 21:03 +0000
      Re: ntpd does not start daemon control: got EOF "Alexander Ziaee" <ziaee@FreeBSD.org> - 2026-04-22 10:03 +0000
        Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-22 12:37 +0200
          Re: ntpd does not start daemon control: got EOF "Alexander Ziaee" <ziaee@FreeBSD.org> - 2026-04-22 14:33 +0000
            Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-22 14:58 +0000
              Re: ntpd does not start daemon control: got EOF "Marco Moock" <mm@dorfdsl.de> - 2026-04-22 16:18 +0000
    Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-27 15:13 +0000
      Re: ntpd does not start daemon control: got EOF "Marco Moock" <mm@dorfdsl.de> - 2026-04-27 16:13 +0000
      Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-28 04:33 +0000
  Re: ntpd does not start daemon control: got EOF "Dave Hart" <davehart@gmail.com> - 2026-04-22 18:33 +0000
    Re: ntpd does not start daemon control: got EOF Marco Moock <mm@dorfdsl.de> - 2026-04-22 20:54 +0200
      Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-23 04:13 +0000
  Re: ntpd does not start daemon control: got EOF "Marco Moock" <mm@dorfdsl.de> - 2026-04-25 09:38 +0000
  Re: ntpd does not start daemon control: got EOF "Ralph Blach" <chip.from.nc@gmail.com> - 2026-04-27 20:08 +0000
  Re: ntpd does not start daemon control: got EOF "Cy Schubert" <Cy.Schubert@cschubert.com> - 2026-04-27 23:38 +0000

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