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Diffstat (limited to 'src/util/support/gmt_mktime.c')
| -rw-r--r-- | src/util/support/gmt_mktime.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/util/support/gmt_mktime.c b/src/util/support/gmt_mktime.c new file mode 100644 index 000000000000..32fef4386cd4 --- /dev/null +++ b/src/util/support/gmt_mktime.c @@ -0,0 +1,168 @@ +/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */ +/* This code placed in the public domain by Mark W. Eichin */ + +#include "autoconf.h" +#include <stdio.h> + +#ifdef HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#ifdef HAVE_SYS_TIME_H +#include <sys/time.h> +#ifdef TIME_WITH_SYS_TIME +#include <time.h> +#endif +#else +#include <time.h> +#endif + +#include "k5-gmt_mktime.h" + +#if !HAVE_TIMEGM || TEST_LEAP +static time_t gmt_mktime(struct tm *t); +#endif + +/* + * Use the nonstandard timegm() (if available) to convert broken-down + * UTC times into time_t values. Use our custom gmt_mktime() if + * timegm() is not available. + * + * We use gmtime() (or gmtime_r()) when encoding ASN.1 GeneralizedTime + * values. On systems where a "right" (leap-second-aware) time zone + * is configured, gmtime() adjusts for the presence of accumulated + * leap seconds in the input time_t value. POSIX requires that time_t + * values omit leap seconds; systems configured to include leap + * seconds in their time_t values are non-conforming and will have + * difficulties exchanging timestamp information with other systems. + * + * We use krb5int_gmt_mktime() for decoding ASN.1 GeneralizedTime + * values. If timegm() is not available, krb5int_gmt_mktime() won't + * be the inverse of gmtime() on a system that counts leap seconds. A + * system configured with a "right" time zone probably has timegm() + * available; without it, an application would have no reliable way of + * converting broken-down UTC times into time_t values. + */ +time_t +krb5int_gmt_mktime(struct tm *t) +{ +#if HAVE_TIMEGM + return timegm(t); +#else + return gmt_mktime(t); +#endif +} + +#if !HAVE_TIMEGM || TEST_LEAP + +/* take a struct tm, return seconds from GMT epoch */ +/* like mktime, this ignores tm_wday and tm_yday. */ +/* unlike mktime, this does not set them... it only passes a return value. */ + +static const int days_in_month[12] = { + 0, /* jan 31 */ + 31, /* feb 28 */ + 59, /* mar 31 */ + 90, /* apr 30 */ + 120, /* may 31 */ + 151, /* jun 30 */ + 181, /* jul 31 */ + 212, /* aug 31 */ + 243, /* sep 30 */ + 273, /* oct 31 */ + 304, /* nov 30 */ + 334 /* dec 31 */ +}; + +#define hasleapday(year) (year%400?(year%100?(year%4?0:1):0):1) + +static time_t +gmt_mktime(struct tm *t) +{ + time_t accum; + +#define assert_time(cnd) if(!(cnd)) return (time_t) -1 + + /* + * For 32-bit signed time_t centered on 1/1/1970, the range is: + * time 0x80000000 -> Fri Dec 13 16:45:52 1901 + * time 0x7fffffff -> Mon Jan 18 22:14:07 2038 + * + * So years 1901 and 2038 are allowable, but we can't encode all + * dates in those years, and we're not doing overflow/underflow + * checking for such cases. + */ + assert_time(t->tm_year>=1); + assert_time(t->tm_year<=138); + + assert_time(t->tm_mon>=0); + assert_time(t->tm_mon<=11); + assert_time(t->tm_mday>=1); + assert_time(t->tm_mday<=31); + assert_time(t->tm_hour>=0); + assert_time(t->tm_hour<=23); + assert_time(t->tm_min>=0); + assert_time(t->tm_min<=59); + assert_time(t->tm_sec>=0); + assert_time(t->tm_sec<=62); + +#undef assert_time + + + accum = t->tm_year - 70; + accum *= 365; /* 365 days/normal year */ + + /* add in leap day for all previous years */ + if (t->tm_year >= 70) + accum += (t->tm_year - 69) / 4; + else + accum -= (72 - t->tm_year) / 4; + /* add in leap day for this year */ + if(t->tm_mon >= 2) /* march or later */ + if(hasleapday((t->tm_year + 1900))) accum += 1; + + accum += days_in_month[t->tm_mon]; + accum += t->tm_mday-1; /* days of month are the only 1-based field */ + accum *= 24; /* 24 hour/day */ + accum += t->tm_hour; + accum *= 60; /* 60 minute/hour */ + accum += t->tm_min; + accum *= 60; /* 60 seconds/minute */ + accum += t->tm_sec; + + return accum; +} +#endif /* !HAVE_TIMEGM || TEST_LEAP */ + +#ifdef TEST_LEAP +int +main (int argc, char *argv[]) +{ + int yr; + time_t t; + struct tm tm = { + .tm_mon = 0, .tm_mday = 1, + .tm_hour = 0, .tm_min = 0, .tm_sec = 0, + }; + for (yr = 60; yr <= 104; yr++) + { + printf ("1/1/%d%c -> ", 1900 + yr, hasleapday((1900+yr)) ? '*' : ' '); + tm.tm_year = yr; + t = gmt_mktime (&tm); + if (t == (time_t) -1) + printf ("-1\n"); + else + { + long u; + if (t % (24 * 60 * 60)) + printf ("(not integral multiple of days) "); + u = t / (24 * 60 * 60); + printf ("%3ld*365%+ld\t0x%08lx\n", + (long) (u / 365), (long) (u % 365), + (long) t); + } + } + t = 0x80000000, printf ("time 0x%lx -> %s", t, ctime (&t)); + t = 0x7fffffff, printf ("time 0x%lx -> %s", t, ctime (&t)); + return 0; +} +#endif |