113 lines
3.1 KiB
C
113 lines
3.1 KiB
C
/* Copyright (C) 1996 N.M. Maclaren
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Copyright (C) 1996 The University of Cambridge
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This includes all of the code needed to handle the time. It assumes rather
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more than is defined by POSIX, unfortunately. Systems that do not have the
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'X/Open' extensions may need changes. */
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#include "header.h"
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#include <sys/types.h>
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#include <sys/time.h>
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#define TIMING
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#include "kludges.h"
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#undef TIMING
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#define MILLION_L 1000000l /* For conversion to/from timeval */
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#define MILLION_D 1.0e6 /* Must be equal to MILLION_L */
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double current_time (double offset) {
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/* Get the current UTC time in seconds since the Epoch plus an offset (usually
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the time from the beginning of the century to the Epoch!) */
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struct timeval current;
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errno = 0;
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if (gettimeofday(¤t,NULL))
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fatal(1,"unable to read current machine/system time",NULL);
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return offset+current.tv_sec+1.0e-6*current.tv_usec;
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}
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time_t convert_time (double value, int *millisecs) {
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/* Convert the time to the ANSI C form. */
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time_t result = (time_t)value;
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if ((*millisecs = (int)(1000.0*(value-result))) >= 1000) {
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*millisecs = 0;
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++result;
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}
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return result;
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}
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void adjust_time (double difference, int immediate, double ignore) {
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/* Adjust the current UTC time. This is portable, even if struct timeval uses
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an unsigned long for tv_sec. */
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struct timeval old, new, adjust, previous;
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char text[40];
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long n;
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/* Start by converting to timeval format. Note that we have to cater for
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negative, unsigned values. */
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if ((n = (long)difference) > difference) --n;
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adjust.tv_sec = n;
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adjust.tv_usec = (long)(MILLION_D*(difference-n));
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errno = 0;
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if (gettimeofday(&old,NULL))
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fatal(1,"unable to read machine/system time",NULL);
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new.tv_sec = old.tv_sec+adjust.tv_sec;
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new.tv_usec = (n = (long)old.tv_usec+(long)adjust.tv_usec);
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if (n < 0) {
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new.tv_usec += MILLION_L;
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--new.tv_sec;
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} else if (n >= MILLION_L) {
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new.tv_usec -= MILLION_L;
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++new.tv_sec;
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}
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/* Now diagnose the situation if necessary, and perform the dirty deed. */
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if (verbose > 2)
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fprintf(stderr,
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"Times: old=(%ld,%.6ld) new=(%ld,%.6ld) adjust=(%ld,%.6ld)\n",
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(long)old.tv_sec,(long)old.tv_usec,
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(long)new.tv_sec,(long)new.tv_usec,
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(long)adjust.tv_sec,(long)adjust.tv_usec);
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if (immediate) {
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errno = 0;
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if (settimeofday(&new,NULL))
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fatal(1,"unable to reset current system time",NULL);
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} else {
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previous.tv_sec = 0;
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previous.tv_usec = 0;
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errno = 0;
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if (adjtime(&adjust,&previous))
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fatal(1,"unable to adjust current system time",NULL);
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if (previous.tv_sec != 0 || previous.tv_usec != 0) {
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sprintf(text,"(%ld,%.6ld)",
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(long)previous.tv_sec,(long)previous.tv_usec);
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if (previous.tv_sec+1.0e-6*previous.tv_usec > ignore)
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fatal(0,"outstanding time adjustment %s",text);
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else if (verbose)
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fprintf(stderr,"%s: outstanding time adjustment %s\n",
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argv0,text);
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}
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}
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}
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