1 /* 2 * Copyright (c) 1987, 1989 Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Arthur David Olson of the National Cancer Institute. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. */ 35 36 /*static char *sccsid = "from: @(#)ctime.c 5.26 (Berkeley) 2/23/91";*/ 37 38 /* 39 * This implementation of mktime is lifted straight from the NetBSD (BSD 4.4) 40 * version. I modified it slightly to divorce it from the internals of the 41 * ctime library. Thus this version can't use details of the internal 42 * timezone state file to figure out strange unnormalized struct tm values, 43 * as might result from someone doing date math on the tm struct then passing 44 * it to mktime. 45 * 46 * It just does as well as it can at normalizing the tm input, then does a 47 * binary search of the time space using the system's localtime() function. 48 * 49 * The original binary search was defective in that it didn't consider the 50 * setting of tm_isdst when comparing tm values, causing the search to be 51 * flubbed for times near the dst/standard time changeover. The original 52 * code seems to make up for this by grubbing through the timezone info 53 * whenever the binary search barfed. Since I don't have that luxury in 54 * portable code, I have to take care of tm_isdst in the comparison routine. 55 * This requires knowing how many minutes offset dst is from standard time. 56 * 57 * So, if you live somewhere in the world where dst is not 60 minutes offset, 58 * and your vendor doesn't supply mktime(), you'll have to edit this variable 59 * by hand. Sorry about that. 60 */ 61 62 #include <config.h> 63 #include "ntp_machine.h" 64 65 #if !defined(HAVE_MKTIME) || ( !defined(HAVE_TIMEGM) && defined(WANT_TIMEGM) ) 66 67 #if SIZEOF_TIME_T >= 8 68 #error libntp supplied mktime()/timegm() do not support 64-bit time_t 69 #endif 70 71 #ifndef DSTMINUTES 72 #define DSTMINUTES 60 73 #endif 74 75 #define FALSE 0 76 #define TRUE 1 77 78 /* some constants from tzfile.h */ 79 #define SECSPERMIN 60 80 #define MINSPERHOUR 60 81 #define HOURSPERDAY 24 82 #define DAYSPERWEEK 7 83 #define DAYSPERNYEAR 365 84 #define DAYSPERLYEAR 366 85 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) 86 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY) 87 #define MONSPERYEAR 12 88 #define TM_YEAR_BASE 1900 89 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 90 91 static int mon_lengths[2][MONSPERYEAR] = { 92 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, 93 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } 94 }; 95 96 static int year_lengths[2] = { 97 DAYSPERNYEAR, DAYSPERLYEAR 98 }; 99 100 /* 101 ** Adapted from code provided by Robert Elz, who writes: 102 ** The "best" way to do mktime I think is based on an idea of Bob 103 ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). 104 ** It does a binary search of the time_t space. Since time_t's are 105 ** just 32 bits, its a max of 32 iterations (even at 64 bits it 106 ** would still be very reasonable). 107 */ 108 109 #ifndef WRONG 110 #define WRONG (-1) 111 #endif /* !defined WRONG */ 112 113 static void 114 normalize( 115 int * tensptr, 116 int * unitsptr, 117 int base 118 ) 119 { 120 if (*unitsptr >= base) { 121 *tensptr += *unitsptr / base; 122 *unitsptr %= base; 123 } else if (*unitsptr < 0) { 124 --*tensptr; 125 *unitsptr += base; 126 if (*unitsptr < 0) { 127 *tensptr -= 1 + (-*unitsptr) / base; 128 *unitsptr = base - (-*unitsptr) % base; 129 } 130 } 131 } 132 133 static struct tm * 134 mkdst( 135 struct tm * tmp 136 ) 137 { 138 /* jds */ 139 static struct tm tmbuf; 140 141 tmbuf = *tmp; 142 tmbuf.tm_isdst = 1; 143 tmbuf.tm_min += DSTMINUTES; 144 normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR); 145 return &tmbuf; 146 } 147 148 static int 149 tmcomp( 150 register struct tm * atmp, 151 register struct tm * btmp 152 ) 153 { 154 register int result; 155 156 /* compare down to the same day */ 157 158 if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && 159 (result = (atmp->tm_mon - btmp->tm_mon)) == 0) 160 result = (atmp->tm_mday - btmp->tm_mday); 161 162 if(result != 0) 163 return result; 164 165 /* get rid of one-sided dst bias */ 166 167 if(atmp->tm_isdst == 1 && !btmp->tm_isdst) 168 btmp = mkdst(btmp); 169 else if(btmp->tm_isdst == 1 && !atmp->tm_isdst) 170 atmp = mkdst(atmp); 171 172 /* compare the rest of the way */ 173 174 if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 && 175 (result = (atmp->tm_min - btmp->tm_min)) == 0) 176 result = atmp->tm_sec - btmp->tm_sec; 177 return result; 178 } 179 180 181 static time_t 182 time2( 183 struct tm * tmp, 184 int * okayp, 185 int usezn 186 ) 187 { 188 register int dir; 189 register int bits; 190 register int i; 191 register int saved_seconds; 192 time_t t; 193 struct tm yourtm, mytm; 194 195 *okayp = FALSE; 196 yourtm = *tmp; 197 if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0) 198 normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN); 199 normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR); 200 normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY); 201 normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR); 202 while (yourtm.tm_mday <= 0) { 203 --yourtm.tm_year; 204 yourtm.tm_mday += 205 year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)]; 206 } 207 for ( ; ; ) { 208 i = mon_lengths[isleap(yourtm.tm_year + 209 TM_YEAR_BASE)][yourtm.tm_mon]; 210 if (yourtm.tm_mday <= i) 211 break; 212 yourtm.tm_mday -= i; 213 if (++yourtm.tm_mon >= MONSPERYEAR) { 214 yourtm.tm_mon = 0; 215 ++yourtm.tm_year; 216 } 217 } 218 saved_seconds = yourtm.tm_sec; 219 yourtm.tm_sec = 0; 220 /* 221 ** Calculate the number of magnitude bits in a time_t 222 ** (this works regardless of whether time_t is 223 ** signed or unsigned, though lint complains if unsigned). 224 */ 225 for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) 226 ; 227 /* 228 ** If time_t is signed, then 0 is the median value, 229 ** if time_t is unsigned, then 1 << bits is median. 230 */ 231 t = (t < 0) ? 0 : ((time_t) 1 << bits); 232 for ( ; ; ) { 233 if (usezn) 234 mytm = *localtime(&t); 235 else 236 mytm = *gmtime(&t); 237 dir = tmcomp(&mytm, &yourtm); 238 if (dir != 0) { 239 if (bits-- < 0) 240 return WRONG; 241 if (bits < 0) 242 --t; 243 else if (dir > 0) 244 t -= (time_t) 1 << bits; 245 else t += (time_t) 1 << bits; 246 continue; 247 } 248 if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst) 249 break; 250 251 return WRONG; 252 } 253 t += saved_seconds; 254 if (usezn) 255 *tmp = *localtime(&t); 256 else 257 *tmp = *gmtime(&t); 258 *okayp = TRUE; 259 return t; 260 } 261 #else 262 int mktime_bs; 263 #endif /* !HAVE_MKTIME || !HAVE_TIMEGM */ 264 265 #ifndef HAVE_MKTIME 266 static time_t 267 time1( 268 struct tm * tmp 269 ) 270 { 271 register time_t t; 272 int okay; 273 274 if (tmp->tm_isdst > 1) 275 tmp->tm_isdst = 1; 276 t = time2(tmp, &okay, 1); 277 if (okay || tmp->tm_isdst < 0) 278 return t; 279 280 return WRONG; 281 } 282 283 time_t 284 mktime( 285 struct tm * tmp 286 ) 287 { 288 return time1(tmp); 289 } 290 #endif /* !HAVE_MKTIME */ 291 292 #ifdef WANT_TIMEGM 293 #ifndef HAVE_TIMEGM 294 time_t 295 timegm( 296 struct tm * tmp 297 ) 298 { 299 register time_t t; 300 int okay; 301 302 tmp->tm_isdst = 0; 303 t = time2(tmp, &okay, 0); 304 if (okay || tmp->tm_isdst < 0) 305 return t; 306 307 return WRONG; 308 } 309 #endif /* !HAVE_TIMEGM */ 310 #endif /* WANT_TIMEGM */ 311