1 // test the systems mktime() function
12 #ifdef HAVE_SYS_TIMEB_H
13 # include <sys/types.h>
14 # include <sys/timeb.h> // for ftime() and struct timeb
17 # include <unistd.h> // for gettimeofday()
19 #ifdef HAVE_SYS_TIME_H
20 # include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
23 #define LST_MAGIC_TIME_1998 890481600
25 // For now we assume that if daylight is not defined in
26 // /usr/include/time.h that we have a machine with a BSD behaving
28 #if !defined(HAVE_DAYLIGHT)
29 # define MK_TIME_IS_GMT 1
33 // Fix up timezone if using ftime()
34 long int fix_up_timezone( long int timezone_orig ) {
35 #if !defined( HAVE_GETTIMEOFDAY ) && defined( HAVE_FTIME )
36 // ftime() needs a little extra help finding the current timezone
39 return( current.timezone * 60 );
41 return( timezone_orig );
46 // Return time_t for Sat Mar 21 12:00:00 GMT
48 // I believe the mktime() has a SYSV vs. BSD behavior difference.
50 // The BSD style mktime() is nice because it returns its result
51 // assuming you have specified the input time in GMT
53 // The SYSV style mktime() is a pain because it returns its result
54 // assuming you have specified the input time in your local timezone.
55 // Therefore you have to go to extra trouble to convert back to GMT.
57 // If you are having problems with incorrectly positioned astronomical
58 // bodies, this is a really good place to start looking.
60 time_t get_start_gmt(int year) {
69 mt.tm_isdst = -1; // let the system determine the proper time zone
71 #if defined( HAVE_TIMEGM )
72 return ( timegm(&mt) );
73 #elif defined( MK_TIME_IS_GMT )
74 return ( mktime(&mt) );
75 #else // ! defined ( MK_TIME_IS_GMT )
77 // timezone seems to work as a proper offset for Linux & Solaris
78 # if defined( __linux__ ) || defined( __sun__ )
79 # define TIMEZONE_OFFSET_WORKS 1
82 time_t start = mktime(&mt);
84 printf("start1 = %ld\n", start);
85 printf("start2 = %s", ctime(&start));
86 printf("(tm_isdst = %d)\n", mt.tm_isdst);
88 timezone = fix_up_timezone( timezone );
90 # if defined( TIMEZONE_OFFSET_WORKS )
91 printf("start = %ld, timezone = %ld\n", start, timezone);
92 return( start - timezone );
93 # else // ! defined( TIMEZONE_OFFSET_WORKS )
95 daylight = mt.tm_isdst;
98 } else if ( daylight < 0 ) {
99 printf("OOOPS, problem in fg_time.cxx, no daylight savings info.\n");
102 long int offset = -(timezone / 3600 - daylight);
104 printf(" Raw time zone offset = %ld\n", timezone);
105 printf(" Daylight Savings = %d\n", daylight);
106 printf(" Local hours from GMT = %ld\n", offset);
108 long int start_gmt = start - timezone + (daylight * 3600);
110 printf(" March 21 noon (CST) = %ld\n", start);
112 return ( start_gmt );
113 # endif // ! defined( TIMEZONE_OFFSET_WORKS )
114 #endif // ! defined ( MK_TIME_IS_GMT )
121 start_gmt = get_start_gmt(98);
124 if ( start_gmt == LST_MAGIC_TIME_1998 ) {
125 printf("Time test = PASSED\n\n");
127 printf("You have timegm() which is just like mktime() except that\n");
128 printf("it explicitely expects input in GMT ... lucky you!\n");
130 printf("You don't seem to have timegm(), but mktime() seems to\n");
131 printf("assume input is GMT on your system ... I guess that works\n");
133 printf("mktime() assumes local time zone on your system, but we can\n");
134 printf("compensate just fine.\n");
137 printf("Time test = FAILED\n\n");
138 printf("There is likely a problem with mktime() on your system.\n");
139 printf("This will cause the sun/moon/stars/planets to be in the\n");
140 printf("wrong place in the sky and the rendered time of day will be\n");
141 printf("incorrect.\n\n");
142 printf("Please report this to curt@me.umn.edu so we can work to fix\n");
143 printf("the problem on your platform.\n");