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Diffstat (limited to 'contrib/ntp/libntp/mktime.c')
| -rw-r--r-- | contrib/ntp/libntp/mktime.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/contrib/ntp/libntp/mktime.c b/contrib/ntp/libntp/mktime.c new file mode 100644 index 000000000000..c7526905b0ef --- /dev/null +++ b/contrib/ntp/libntp/mktime.c @@ -0,0 +1,282 @@ +/* + * Copyright (c) 1987, 1989 Regents of the University of California. + * All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Arthur David Olson of the National Cancer Institute. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. */ + +/*static char *sccsid = "from: @(#)ctime.c 5.26 (Berkeley) 2/23/91";*/ +/*static char *rcsid = "mktime.c,v 1.1.1.3 1998/11/15 19:23:34 kardel RELEASE_19990228_A";*/ + +/* + * This implementation of mktime is lifted straight from the NetBSD (BSD 4.4) + * version. I modified it slightly to divorce it from the internals of the + * ctime library. Thus this version can't use details of the internal + * timezone state file to figure out strange unnormalized struct tm values, + * as might result from someone doing date math on the tm struct then passing + * it to mktime. + * + * It just does as well as it can at normalizing the tm input, then does a + * binary search of the time space using the system's localtime() function. + * + * The original binary search was defective in that it didn't consider the + * setting of tm_isdst when comparing tm values, causing the search to be + * flubbed for times near the dst/standard time changeover. The original + * code seems to make up for this by grubbing through the timezone info + * whenever the binary search barfed. Since I don't have that luxury in + * portable code, I have to take care of tm_isdst in the comparison routine. + * This requires knowing how many minutes offset dst is from standard time. + * + * So, if you live somewhere in the world where dst is not 60 minutes offset, + * and your vendor doesn't supply mktime(), you'll have to edit this variable + * by hand. Sorry about that. + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#ifndef DSTMINUTES +#define DSTMINUTES 60 +#endif + +#define FALSE 0 +#define TRUE 1 + +/* some constants from tzfile.h */ +#define SECSPERMIN 60 +#define MINSPERHOUR 60 +#define HOURSPERDAY 24 +#define DAYSPERWEEK 7 +#define DAYSPERNYEAR 365 +#define DAYSPERLYEAR 366 +#define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) +#define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY) +#define MONSPERYEAR 12 +#define TM_YEAR_BASE 1900 +#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) + +#ifdef HAVE_SYS_TYPES_H +# include <sys/types.h> +#endif + +#include <time.h> + +extern time_t time(); + +static int mon_lengths[2][MONSPERYEAR] = { + { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, + { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } +}; + +static int year_lengths[2] = { + DAYSPERNYEAR, DAYSPERLYEAR +}; + +/* +** Adapted from code provided by Robert Elz, who writes: +** The "best" way to do mktime I think is based on an idea of Bob +** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). +** It does a binary search of the time_t space. Since time_t's are +** just 32 bits, its a max of 32 iterations (even at 64 bits it +** would still be very reasonable). +*/ + +#ifndef WRONG +#define WRONG (-1) +#endif /* !defined WRONG */ + +static void +normalize( + int * tensptr, + int * unitsptr, + int base + ) +{ + if (*unitsptr >= base) { + *tensptr += *unitsptr / base; + *unitsptr %= base; + } else if (*unitsptr < 0) { + --*tensptr; + *unitsptr += base; + if (*unitsptr < 0) { + *tensptr -= 1 + (-*unitsptr) / base; + *unitsptr = base - (-*unitsptr) % base; + } + } +} + +static struct tm * +mkdst( + struct tm * tmp + ) +{ + /* jds */ + static struct tm tmbuf; + + tmbuf = *tmp; + tmbuf.tm_isdst = 1; + tmbuf.tm_min += DSTMINUTES; + normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR); + return &tmbuf; +} + +static int +tmcomp( + register struct tm * atmp, + register struct tm * btmp + ) +{ + register int result; + + /* compare down to the same day */ + + if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && + (result = (atmp->tm_mon - btmp->tm_mon)) == 0) + result = (atmp->tm_mday - btmp->tm_mday); + + if(result != 0) + return result; + + /* get rid of one-sided dst bias */ + + if(atmp->tm_isdst == 1 && !btmp->tm_isdst) + btmp = mkdst(btmp); + else if(btmp->tm_isdst == 1 && !atmp->tm_isdst) + atmp = mkdst(atmp); + + /* compare the rest of the way */ + + if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 && + (result = (atmp->tm_min - btmp->tm_min)) == 0) + result = atmp->tm_sec - btmp->tm_sec; + return result; +} + + +static time_t +time2( + struct tm * tmp, + int * okayp + ) +{ + register int dir; + register int bits; + register int i; + register int saved_seconds; + time_t t; + struct tm yourtm, mytm; + + *okayp = FALSE; + yourtm = *tmp; + if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0) + normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN); + normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR); + normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY); + normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR); + while (yourtm.tm_mday <= 0) { + --yourtm.tm_year; + yourtm.tm_mday += + year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)]; + } + for ( ; ; ) { + i = mon_lengths[isleap(yourtm.tm_year + + TM_YEAR_BASE)][yourtm.tm_mon]; + if (yourtm.tm_mday <= i) + break; + yourtm.tm_mday -= i; + if (++yourtm.tm_mon >= MONSPERYEAR) { + yourtm.tm_mon = 0; + ++yourtm.tm_year; + } + } + saved_seconds = yourtm.tm_sec; + yourtm.tm_sec = 0; + /* + ** Calculate the number of magnitude bits in a time_t + ** (this works regardless of whether time_t is + ** signed or unsigned, though lint complains if unsigned). + */ + for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) + ; + /* + ** If time_t is signed, then 0 is the median value, + ** if time_t is unsigned, then 1 << bits is median. + */ + t = (t < 0) ? 0 : ((time_t) 1 << bits); + for ( ; ; ) { + mytm = *localtime(&t); + dir = tmcomp(&mytm, &yourtm); + if (dir != 0) { + if (bits-- < 0) + return WRONG; + if (bits < 0) + --t; + else if (dir > 0) + t -= (time_t) 1 << bits; + else t += (time_t) 1 << bits; + continue; + } + if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst) + break; + + return WRONG; + } + t += saved_seconds; + *tmp = *localtime(&t); + *okayp = TRUE; + return t; +} + +static time_t +time1( + struct tm * tmp + ) +{ + register time_t t; + int okay; + + if (tmp->tm_isdst > 1) + tmp->tm_isdst = 1; + t = time2(tmp, &okay); + if (okay || tmp->tm_isdst < 0) + return t; + + return WRONG; +} + +time_t +mktime( + struct tm * tmp + ) +{ + return time1(tmp); +} |