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 #ifdef HAVE_CONFIG_H 64 #include <config.h> 65 #endif 66 67 #ifndef DSTMINUTES 68 #define DSTMINUTES 60 69 #endif 70 71 #define FALSE 0 72 #define TRUE 1 73 74 /* some constants from tzfile.h */ 75 #define SECSPERMIN 60 76 #define MINSPERHOUR 60 77 #define HOURSPERDAY 24 78 #define DAYSPERWEEK 7 79 #define DAYSPERNYEAR 365 80 #define DAYSPERLYEAR 366 81 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) 82 #define SECSPERDAY ((long) SECSPERHOUR * HOURSPERDAY) 83 #define MONSPERYEAR 12 84 #define TM_YEAR_BASE 1900 85 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0) 86 87 #ifdef HAVE_SYS_TYPES_H 88 # include <sys/types.h> 89 #endif 90 91 #include <time.h> 92 93 extern time_t time(); 94 95 static int mon_lengths[2][MONSPERYEAR] = { 96 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, 97 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 } 98 }; 99 100 static int year_lengths[2] = { 101 DAYSPERNYEAR, DAYSPERLYEAR 102 }; 103 104 /* 105 ** Adapted from code provided by Robert Elz, who writes: 106 ** The "best" way to do mktime I think is based on an idea of Bob 107 ** Kridle's (so its said...) from a long time ago. (mtxinu!kridle now). 108 ** It does a binary search of the time_t space. Since time_t's are 109 ** just 32 bits, its a max of 32 iterations (even at 64 bits it 110 ** would still be very reasonable). 111 */ 112 113 #ifndef WRONG 114 #define WRONG (-1) 115 #endif /* !defined WRONG */ 116 117 static void 118 normalize( 119 int * tensptr, 120 int * unitsptr, 121 int base 122 ) 123 { 124 if (*unitsptr >= base) { 125 *tensptr += *unitsptr / base; 126 *unitsptr %= base; 127 } else if (*unitsptr < 0) { 128 --*tensptr; 129 *unitsptr += base; 130 if (*unitsptr < 0) { 131 *tensptr -= 1 + (-*unitsptr) / base; 132 *unitsptr = base - (-*unitsptr) % base; 133 } 134 } 135 } 136 137 static struct tm * 138 mkdst( 139 struct tm * tmp 140 ) 141 { 142 /* jds */ 143 static struct tm tmbuf; 144 145 tmbuf = *tmp; 146 tmbuf.tm_isdst = 1; 147 tmbuf.tm_min += DSTMINUTES; 148 normalize(&tmbuf.tm_hour, &tmbuf.tm_min, MINSPERHOUR); 149 return &tmbuf; 150 } 151 152 static int 153 tmcomp( 154 register struct tm * atmp, 155 register struct tm * btmp 156 ) 157 { 158 register int result; 159 160 /* compare down to the same day */ 161 162 if ((result = (atmp->tm_year - btmp->tm_year)) == 0 && 163 (result = (atmp->tm_mon - btmp->tm_mon)) == 0) 164 result = (atmp->tm_mday - btmp->tm_mday); 165 166 if(result != 0) 167 return result; 168 169 /* get rid of one-sided dst bias */ 170 171 if(atmp->tm_isdst == 1 && !btmp->tm_isdst) 172 btmp = mkdst(btmp); 173 else if(btmp->tm_isdst == 1 && !atmp->tm_isdst) 174 atmp = mkdst(atmp); 175 176 /* compare the rest of the way */ 177 178 if ((result = (atmp->tm_hour - btmp->tm_hour)) == 0 && 179 (result = (atmp->tm_min - btmp->tm_min)) == 0) 180 result = atmp->tm_sec - btmp->tm_sec; 181 return result; 182 } 183 184 185 static time_t 186 time2( 187 struct tm * tmp, 188 int * okayp 189 ) 190 { 191 register int dir; 192 register int bits; 193 register int i; 194 register int saved_seconds; 195 time_t t; 196 struct tm yourtm, mytm; 197 198 *okayp = FALSE; 199 yourtm = *tmp; 200 if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0) 201 normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN); 202 normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR); 203 normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY); 204 normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR); 205 while (yourtm.tm_mday <= 0) { 206 --yourtm.tm_year; 207 yourtm.tm_mday += 208 year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)]; 209 } 210 for ( ; ; ) { 211 i = mon_lengths[isleap(yourtm.tm_year + 212 TM_YEAR_BASE)][yourtm.tm_mon]; 213 if (yourtm.tm_mday <= i) 214 break; 215 yourtm.tm_mday -= i; 216 if (++yourtm.tm_mon >= MONSPERYEAR) { 217 yourtm.tm_mon = 0; 218 ++yourtm.tm_year; 219 } 220 } 221 saved_seconds = yourtm.tm_sec; 222 yourtm.tm_sec = 0; 223 /* 224 ** Calculate the number of magnitude bits in a time_t 225 ** (this works regardless of whether time_t is 226 ** signed or unsigned, though lint complains if unsigned). 227 */ 228 for (bits = 0, t = 1; t > 0; ++bits, t <<= 1) 229 ; 230 /* 231 ** If time_t is signed, then 0 is the median value, 232 ** if time_t is unsigned, then 1 << bits is median. 233 */ 234 t = (t < 0) ? 0 : ((time_t) 1 << bits); 235 for ( ; ; ) { 236 mytm = *localtime(&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 *tmp = *localtime(&t); 255 *okayp = TRUE; 256 return t; 257 } 258 259 static time_t 260 time1( 261 struct tm * tmp 262 ) 263 { 264 register time_t t; 265 int okay; 266 267 if (tmp->tm_isdst > 1) 268 tmp->tm_isdst = 1; 269 t = time2(tmp, &okay); 270 if (okay || tmp->tm_isdst < 0) 271 return t; 272 273 return WRONG; 274 } 275 276 time_t 277 mktime( 278 struct tm * tmp 279 ) 280 { 281 return time1(tmp); 282 } 283