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