dist/ntp/sntp/timing.c

   1 /*      $NetBSD: timing.c,v 1.3 2006/05/10 21:53:14 mrg Exp $   */
   2
   3 /*  Copyright (C) 1996 N.M. Maclaren
   4     Copyright (C) 1996 The University of Cambridge
   5
   6 This includes all of the code needed to handle the time.  It assumes rather
   7 more than is defined by POSIX, unfortunately.  Systems that do not have the
   8 'X/Open' extensions may need changes. */
   9
  10
  11
  12 #include "header.h"
  13
  14 #include <sys/types.h>
  15 #include <sys/time.h>
  16
  17 #define TIMING
  18 #include "kludges.h"
  19 #undef TIMING
  20
  21
  22
  23 #define MILLION_L    1000000l          /* For conversion to/from timeval */
  24 #define MILLION_D       1.0e6          /* Must be equal to MILLION_L */
  25
  26
  27
  28 double current_time (double offset) {
  29
  30 /* Get the current UTC time in seconds since the Epoch plus an offset (usually
  31 the time from the beginning of the century to the Epoch!) */
  32
  33     struct timeval current;
  34
  35     errno = 0;
  36     if (gettimeofday(&current,NULL))
  37         fatal(1,"unable to read current machine/system time",NULL);
  38     return offset+current.tv_sec+1.0e-6*current.tv_usec;
  39 }
  40
  41
  42
  43 time_t convert_time (double value, int *millisecs) {
  44
  45 /* Convert the time to the ANSI C form. */
  46
  47     time_t result = (time_t)value;
  48
  49     if ((*millisecs = (int)(1000.0*(value-result))) >= 1000) {
  50         *millisecs = 0;
  51         ++result;
  52     }
  53     return result;
  54 }
  55
  56
  57
  58 void adjust_time (double difference, int immediate, double ignore) {
  59
  60 /* Adjust the current UTC time.  This is portable, even if struct timeval uses
  61 an unsigned long for tv_sec. */
  62
  63     struct timeval old, new, adjust, previous;
  64     char text[40];
  65     long n;
  66
  67 /* Start by converting to timeval format. Note that we have to cater for
  68 negative, unsigned values. */
  69
  70     previous.tv_sec = 0;        /* XXX gcc */
  71     previous.tv_usec = 0;       /* XXX gcc */
  72
  73     if ((n = (long)difference) > difference) --n;
  74     adjust.tv_sec = n;
  75     adjust.tv_usec = (long)(MILLION_D*(difference-n));
  76     errno = 0;
  77     if (gettimeofday(&old,NULL))
  78         fatal(1,"unable to read machine/system time",NULL);
  79     new.tv_sec = old.tv_sec+adjust.tv_sec;
  80     new.tv_usec = (n = (long)old.tv_usec+(long)adjust.tv_usec);
  81     if (n < 0) {
  82         new.tv_usec += MILLION_L;
  83         --new.tv_sec;
  84     } else if (n >= MILLION_L) {
  85         new.tv_usec -= MILLION_L;
  86         ++new.tv_sec;
  87     }
  88
  89 /* Now diagnose the situation if necessary, and perform the dirty deed. */
  90
  91     if (verbose > 2)
  92         fprintf(stderr,
  93             "Times: old=(%ld,%.6ld) new=(%ld,%.6ld) adjust=(%ld,%.6ld)\n",
  94             (long)old.tv_sec,(long)old.tv_usec,
  95             (long)new.tv_sec,(long)new.tv_usec,
  96             (long)adjust.tv_sec,(long)adjust.tv_usec);
  97     if (immediate) {
  98         errno = 0;
  99         if (settimeofday(&new,NULL))
 100             fatal(1,"unable to reset current system time",NULL);
 101     } else {
 102         previous.tv_sec  = 0;
 103         previous.tv_usec = 0;
 104         errno = 0;
 105         if (adjtime(&adjust,&previous))
 106             fatal(1,"unable to adjust current system time",NULL);
 107         if (previous.tv_sec != 0 || previous.tv_usec != 0) {
 108             sprintf(text,"(%ld,%.6ld)",
 109                 (long)previous.tv_sec,(long)previous.tv_usec);
 110             if (previous.tv_sec+1.0e-6*previous.tv_usec > ignore)
 111                 fatal(0,"outstanding time adjustment %s",text);
 112             else if (verbose)
 113                 fprintf(stderr,"%s: outstanding time adjustment %s\n",
 114                     argv0,text);
 115         }
 116     }
 117 }