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 /*static char *rcsid = "mktime.c,v 1.1.1.3 1998/11/15 19:23:34 kardel RELEASE_19990228_A";*/ 38 39 /* 40 * This implementation of mktime is lifted straight from the NetBSD (BSD 4.4) 41 * version. I modified it slightly to divorce it from the internals of the 42 * ctime library. Thus this version can't use details of the internal 43 * timezone state file to figure out strange unnormalized struct tm values, 44 * as might result from someone doing date math on the tm struct then passing 45 * it to mktime. 46 * 47 * It just does as well as it can at normalizing the tm input, then does a 48 * binary search of the time space using the system's localtime() function. 49 * 50 * The original binary search was defective in that it didn't consider the 51 * setting of tm_isdst when comparing tm values, causing the search to be 52 * flubbed for times near the dst/standard time changeover. The original 53 * code seems to make up for this by grubbing through the timezone info 54 * whenever the binary search barfed. Since I don't have that luxury in 55 * portable code, I have to take care of tm_isdst in the comparison routine. 56 * This requires knowing how many minutes offset dst is from standard time. 57 * 58 * So, if you live somewhere in the world where dst is not 60 minutes offset, 59 * and your vendor doesn't supply mktime(), you'll have to edit this variable 60 * by hand. Sorry about that. 61 */ 62 63 #include "ntp_machine.h" 64 65 #ifndef DSTMINUTES 66 #define DSTMINUTES 60 67 #endif 68 69 #define FALSE 0 70 #define TRUE 1 71 72 /* some constants from tzfile.h */ 73 #define SECSPERMIN 60 74 #define MINSPERHOUR 60 75 #define HOURSPERDAY 24 76 #define DAYSPERWEEK 7 77 #define DAYSPERNYEAR 365 78 #define DAYSPERLYEAR 366 79 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) 80 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY) 81 #define MONSPERYEAR 12 82 #define TM_YEAR_BASE 1900 83 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 84 85 extern time_t time(); 86 87 static int mon_lengths[2][MONSPERYEAR] = { 88 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, 89 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } 90 }; 91 92 static int year_lengths[2] = { 93 DAYSPERNYEAR, DAYSPERLYEAR 94 }; 95 96 /* 97 ** Adapted from code provided by Robert Elz, who writes: 98 ** The "best" way to do mktime I think is based on an idea of Bob 99 ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). 100 ** It does a binary search of the time_t space. Since time_t's are 101 ** just 32 bits, its a max of 32 iterations (even at 64 bits it 102 ** would still be very reasonable). 103 */ 104 105 #ifndef WRONG 106 #define WRONG (-1) 107 #endif /* !defined WRONG */ 108 109 static void 110 normalize( 111 int * tensptr, 112 int * unitsptr, 113 int base 114 ) 115 { 116 if (*unitsptr >= base) { 117 *tensptr += *unitsptr / base; 118 *unitsptr %= base; 119 } else if (*unitsptr < 0) { 120 --*tensptr; 121 *unitsptr += base; 122 if (*unitsptr < 0) { 123 *tensptr -= 1 + (-*unitsptr) / base; 124 *unitsptr = base - (-*unitsptr) % base; 125 } 126 } 127 } 128 129 static struct tm * 130 mkdst( 131 struct tm * tmp 132 ) 133 { 134 /* jds */ 135 static struct tm tmbuf; 136 137 tmbuf = *tmp; 138 tmbuf.tm_isdst = 1; 139 tmbuf.tm_min += DSTMINUTES; 140 normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR); 141 return &tmbuf; 142 } 143 144 static int 145 tmcomp( 146 register struct tm * atmp, 147 register struct tm * btmp 148 ) 149 { 150 register int result; 151 152 /* compare down to the same day */ 153 154 if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && 155 (result = (atmp->tm_mon - btmp->tm_mon)) == 0) 156 result = (atmp->tm_mday - btmp->tm_mday); 157 158 if(result != 0) 159 return result; 160 161 /* get rid of one-sided dst bias */ 162 163 if(atmp->tm_isdst == 1 && !btmp->tm_isdst) 164 btmp = mkdst(btmp); 165 else if(btmp->tm_isdst == 1 && !atmp->tm_isdst) 166 atmp = mkdst(atmp); 167 168 /* compare the rest of the way */ 169 170 if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 && 171 (result = (atmp->tm_min - btmp->tm_min)) == 0) 172 result = atmp->tm_sec - btmp->tm_sec; 173 return result; 174 } 175 176 177 static time_t 178 time2( 179 struct tm * tmp, 180 int * okayp 181 ) 182 { 183 register int dir; 184 register int bits; 185 register int i; 186 register int saved_seconds; 187 time_t t; 188 struct tm yourtm, mytm; 189 190 *okayp = FALSE; 191 yourtm = *tmp; 192 if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0) 193 normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN); 194 normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR); 195 normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY); 196 normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR); 197 while (yourtm.tm_mday <= 0) { 198 --yourtm.tm_year; 199 yourtm.tm_mday += 200 year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)]; 201 } 202 for ( ; ; ) { 203 i = mon_lengths[isleap(yourtm.tm_year + 204 TM_YEAR_BASE)][yourtm.tm_mon]; 205 if (yourtm.tm_mday <= i) 206 break; 207 yourtm.tm_mday -= i; 208 if (++yourtm.tm_mon >= MONSPERYEAR) { 209 yourtm.tm_mon = 0; 210 ++yourtm.tm_year; 211 } 212 } 213 saved_seconds = yourtm.tm_sec; 214 yourtm.tm_sec = 0; 215 /* 216 ** Calculate the number of magnitude bits in a time_t 217 ** (this works regardless of whether time_t is 218 ** signed or unsigned, though lint complains if unsigned). 219 */ 220 for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) 221 ; 222 /* 223 ** If time_t is signed, then 0 is the median value, 224 ** if time_t is unsigned, then 1 << bits is median. 225 */ 226 t = (t < 0) ? 0 : ((time_t) 1 << bits); 227 for ( ; ; ) { 228 mytm = *localtime(&t); 229 dir = tmcomp(&mytm, &yourtm); 230 if (dir != 0) { 231 if (bits-- < 0) 232 return WRONG; 233 if (bits < 0) 234 --t; 235 else if (dir > 0) 236 t -= (time_t) 1 << bits; 237 else t += (time_t) 1 << bits; 238 continue; 239 } 240 if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst) 241 break; 242 243 return WRONG; 244 } 245 t += saved_seconds; 246 *tmp = *localtime(&t); 247 *okayp = TRUE; 248 return t; 249 } 250 251 static time_t 252 time1( 253 struct tm * tmp 254 ) 255 { 256 register time_t t; 257 int okay; 258 259 if (tmp->tm_isdst > 1) 260 tmp->tm_isdst = 1; 261 t = time2(tmp, &okay); 262 if (okay || tmp->tm_isdst < 0) 263 return t; 264 265 return WRONG; 266 } 267 268 time_t 269 mktime( 270 struct tm * tmp 271 ) 272 { 273 return time1(tmp); 274 } 275