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From: dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi)
Newsgroups: comp.unix.questions,alt.sys.sun
Subject: adjtime(2) hints needed
Message-ID: <2119@cirrusl.UUCP>
Date: 2 Aug 90 21:31:16 GMT
Sender: news@cirrusl.UUCP
Organization: Cirrus Logic Inc.
Lines: 36

(Environment:  SunOS 4.0.3 on Sun-3 and Sun-4 machines.)

I am trying to use the adjtime(2) system call.

I get the time-of-day from a remote host into a variable "struct
timeval remote_time".  I also call gettimeofday(2) to get the local
time-of-day in the variable "struct timeval local_time".

I must supply adjtime(2) with a delta time by which the local clock
should be adjusted.  So, I want to store this delta into "struct
timeval delta_time".

QUESTION:  How should I use the values remote_time and local_time to
calculate the values in delta_time?  I am currently doing this:

   delta_time.tv_sec  = remote_time.tv_sec  - local_time.tv_sec;
   delta_time.tv_usec = remote_time.tv_usec - local_time.tv_usec;

As a result, delta_time.tv_sec and delta_time.tv_usec could have
different signs.  Is this acceptable?  If not, what should I be doing?
The problem here is that I don't know how delta time is supposed to be
represented in the two fields, and the manuals don't seem to address
the issue.

SECONDARY QUESTION:  I am using the rtime(3) function (which may be
SunOS-specific), to get time from a remote host.  I need to supply
rtime(3) the address of the remote host in a "struct sockaddr_in"
structure.  Am I supposed to place any specific value for a port number
in the sin_port field of this structure?  I find that rtime(3) seems to
work correctly regardless of the value of sin_port, but it would be
nice to know what the official intended usage is.

I will appreciate any help anybody can provide.
--
Rahul Dhesi <dhesi%cirrusl@oliveb.ATC.olivetti.com>
UUCP:  oliveb!cirrusl!dhesi