1 /* $NetBSD: mktime.c,v 1.1.1.1 2009/12/13 16:55:03 kardel Exp $ */ 2 3 /* 4 * Copyright (c) 1987, 1989 Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Arthur David Olson of the National Cancer Institute. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. */ 37 38 /*static char *sccsid = "from: @(#)ctime.c 5.26 (Berkeley) 2/23/91";*/ 39 40 /* 41 * This implementation of mktime is lifted straight from the NetBSD (BSD 4.4) 42 * version. I modified it slightly to divorce it from the internals of the 43 * ctime library. Thus this version can't use details of the internal 44 * timezone state file to figure out strange unnormalized struct tm values, 45 * as might result from someone doing date math on the tm struct then passing 46 * it to mktime. 47 * 48 * It just does as well as it can at normalizing the tm input, then does a 49 * binary search of the time space using the system's localtime() function. 50 * 51 * The original binary search was defective in that it didn't consider the 52 * setting of tm_isdst when comparing tm values, causing the search to be 53 * flubbed for times near the dst/standard time changeover. The original 54 * code seems to make up for this by grubbing through the timezone info 55 * whenever the binary search barfed. Since I don't have that luxury in 56 * portable code, I have to take care of tm_isdst in the comparison routine. 57 * This requires knowing how many minutes offset dst is from standard time. 58 * 59 * So, if you live somewhere in the world where dst is not 60 minutes offset, 60 * and your vendor doesn't supply mktime(), you'll have to edit this variable 61 * by hand. Sorry about that. 62 */ 63 64 #include "ntp_machine.h" 65 66 #if !defined(HAVE_MKTIME) || !defined(HAVE_TIMEGM) 67 68 #ifndef DSTMINUTES 69 #define DSTMINUTES 60 70 #endif 71 72 #define FALSE 0 73 #define TRUE 1 74 75 /* some constants from tzfile.h */ 76 #define SECSPERMIN 60 77 #define MINSPERHOUR 60 78 #define HOURSPERDAY 24 79 #define DAYSPERWEEK 7 80 #define DAYSPERNYEAR 365 81 #define DAYSPERLYEAR 366 82 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) 83 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY) 84 #define MONSPERYEAR 12 85 #define TM_YEAR_BASE 1900 86 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 87 88 static int mon_lengths[2][MONSPERYEAR] = { 89 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, 90 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } 91 }; 92 93 static int year_lengths[2] = { 94 DAYSPERNYEAR, DAYSPERLYEAR 95 }; 96 97 /* 98 ** Adapted from code provided by Robert Elz, who writes: 99 ** The "best" way to do mktime I think is based on an idea of Bob 100 ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). 101 ** It does a binary search of the time_t space. Since time_t's are 102 ** just 32 bits, its a max of 32 iterations (even at 64 bits it 103 ** would still be very reasonable). 104 */ 105 106 #ifndef WRONG 107 #define WRONG (-1) 108 #endif /* !defined WRONG */ 109 110 static void 111 normalize( 112 int * tensptr, 113 int * unitsptr, 114 int base 115 ) 116 { 117 if (*unitsptr >= base) { 118 *tensptr += *unitsptr / base; 119 *unitsptr %= base; 120 } else if (*unitsptr < 0) { 121 --*tensptr; 122 *unitsptr += base; 123 if (*unitsptr < 0) { 124 *tensptr -= 1 + (-*unitsptr) / base; 125 *unitsptr = base - (-*unitsptr) % base; 126 } 127 } 128 } 129 130 static struct tm * 131 mkdst( 132 struct tm * tmp 133 ) 134 { 135 /* jds */ 136 static struct tm tmbuf; 137 138 tmbuf = *tmp; 139 tmbuf.tm_isdst = 1; 140 tmbuf.tm_min += DSTMINUTES; 141 normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR); 142 return &tmbuf; 143 } 144 145 static int 146 tmcomp( 147 register struct tm * atmp, 148 register struct tm * btmp 149 ) 150 { 151 register int result; 152 153 /* compare down to the same day */ 154 155 if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && 156 (result = (atmp->tm_mon - btmp->tm_mon)) == 0) 157 result = (atmp->tm_mday - btmp->tm_mday); 158 159 if(result != 0) 160 return result; 161 162 /* get rid of one-sided dst bias */ 163 164 if(atmp->tm_isdst == 1 && !btmp->tm_isdst) 165 btmp = mkdst(btmp); 166 else if(btmp->tm_isdst == 1 && !atmp->tm_isdst) 167 atmp = mkdst(atmp); 168 169 /* compare the rest of the way */ 170 171 if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 && 172 (result = (atmp->tm_min - btmp->tm_min)) == 0) 173 result = atmp->tm_sec - btmp->tm_sec; 174 return result; 175 } 176 177 178 static time_t 179 time2( 180 struct tm * tmp, 181 int * okayp, 182 int usezn 183 ) 184 { 185 register int dir; 186 register int bits; 187 register int i; 188 register int saved_seconds; 189 time_t t; 190 struct tm yourtm, mytm; 191 192 *okayp = FALSE; 193 yourtm = *tmp; 194 if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0) 195 normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN); 196 normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR); 197 normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY); 198 normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR); 199 while (yourtm.tm_mday <= 0) { 200 --yourtm.tm_year; 201 yourtm.tm_mday += 202 year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)]; 203 } 204 for ( ; ; ) { 205 i = mon_lengths[isleap(yourtm.tm_year + 206 TM_YEAR_BASE)][yourtm.tm_mon]; 207 if (yourtm.tm_mday <= i) 208 break; 209 yourtm.tm_mday -= i; 210 if (++yourtm.tm_mon >= MONSPERYEAR) { 211 yourtm.tm_mon = 0; 212 ++yourtm.tm_year; 213 } 214 } 215 saved_seconds = yourtm.tm_sec; 216 yourtm.tm_sec = 0; 217 /* 218 ** Calculate the number of magnitude bits in a time_t 219 ** (this works regardless of whether time_t is 220 ** signed or unsigned, though lint complains if unsigned). 221 */ 222 for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) 223 ; 224 /* 225 ** If time_t is signed, then 0 is the median value, 226 ** if time_t is unsigned, then 1 << bits is median. 227 */ 228 t = (t < 0) ? 0 : ((time_t) 1 << bits); 229 for ( ; ; ) { 230 if (usezn) 231 mytm = *localtime(&t); 232 else 233 mytm = *gmtime(&t); 234 dir = tmcomp(&mytm, &yourtm); 235 if (dir != 0) { 236 if (bits-- < 0) 237 return WRONG; 238 if (bits < 0) 239 --t; 240 else if (dir > 0) 241 t -= (time_t) 1 << bits; 242 else t += (time_t) 1 << bits; 243 continue; 244 } 245 if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst) 246 break; 247 248 return WRONG; 249 } 250 t += saved_seconds; 251 if (usezn) 252 *tmp = *localtime(&t); 253 else 254 *tmp = *gmtime(&t); 255 *okayp = TRUE; 256 return t; 257 } 258 #else 259 int mktime_bs; 260 #endif /* !HAVE_MKTIME || !HAVE_TIMEGM */ 261 262 #ifndef HAVE_MKTIME 263 static time_t 264 time1( 265 struct tm * tmp 266 ) 267 { 268 register time_t t; 269 int okay; 270 271 if (tmp->tm_isdst > 1) 272 tmp->tm_isdst = 1; 273 t = time2(tmp, &okay, 1); 274 if (okay || tmp->tm_isdst < 0) 275 return t; 276 277 return WRONG; 278 } 279 280 time_t 281 mktime( 282 struct tm * tmp 283 ) 284 { 285 return time1(tmp); 286 } 287 #endif /* !HAVE_MKTIME */ 288 289 #ifndef HAVE_TIMEGM 290 time_t 291 timegm( 292 struct tm * tmp 293 ) 294 { 295 register time_t t; 296 int okay; 297 298 tmp->tm_isdst = 0; 299 t = time2(tmp, &okay, 0); 300 if (okay || tmp->tm_isdst < 0) 301 return t; 302 303 return WRONG; 304 } 305 #endif /* !HAVE_TIMEGM */ 306