1 /* 2 3 Copyright (c) 2007-2008 Michael G Schwern 4 5 This software originally derived from Paul Sheer's pivotal_gmtime_r.c. 6 7 The MIT License: 8 9 Permission is hereby granted, free of charge, to any person obtaining a copy 10 of this software and associated documentation files (the "Software"), to deal 11 in the Software without restriction, including without limitation the rights 12 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 13 copies of the Software, and to permit persons to whom the Software is 14 furnished to do so, subject to the following conditions: 15 16 The above copyright notice and this permission notice shall be included in 17 all copies or substantial portions of the Software. 18 19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 20 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 21 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 22 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 23 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 24 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 25 THE SOFTWARE. 26 27 */ 28 29 /* 30 31 Programmers who have available to them 64-bit time values as a 'long 32 long' type can use localtime64_r() and gmtime64_r() which correctly 33 converts the time even on 32-bit systems. Whether you have 64-bit time 34 values will depend on the operating system. 35 36 Perl_localtime64_r() is a 64-bit equivalent of localtime_r(). 37 38 Perl_gmtime64_r() is a 64-bit equivalent of gmtime_r(). 39 40 */ 41 42 #include "EXTERN.h" 43 #define PERL_IN_TIME64_C 44 #include "perl.h" 45 #include "time64.h" 46 47 static const char days_in_month[2][12] = { 48 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, 49 {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, 50 }; 51 52 static const short julian_days_by_month[2][12] = { 53 {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334}, 54 {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335}, 55 }; 56 57 static const short length_of_year[2] = { 365, 366 }; 58 59 /* Number of days in a 400 year Gregorian cycle */ 60 static const Year years_in_gregorian_cycle = 400; 61 static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1; 62 63 /* 28 year calendar cycle between 2010 and 2037 */ 64 #define SOLAR_CYCLE_LENGTH 28 65 static const short safe_years[SOLAR_CYCLE_LENGTH] = { 66 2016, 2017, 2018, 2019, 67 2020, 2021, 2022, 2023, 68 2024, 2025, 2026, 2027, 69 2028, 2029, 2030, 2031, 70 2032, 2033, 2034, 2035, 71 2036, 2037, 2010, 2011, 72 2012, 2013, 2014, 2015 73 }; 74 75 /* Let's assume people are going to be looking for dates in the future. 76 Let's provide some cheats so you can skip ahead. 77 This has a 4x speed boost when near 2008. 78 */ 79 /* Number of days since epoch on Jan 1st, 2008 GMT */ 80 #define CHEAT_DAYS (1199145600 / 24 / 60 / 60) 81 #define CHEAT_YEARS 108 82 83 #define IS_LEAP(n) ((!(((n) + 1900) % 400) || (!(((n) + 1900) % 4) && (((n) + 1900) % 100))) != 0) 84 #undef WRAP /* some <termios.h> define this */ 85 #define WRAP(a,b,m) ((a) = ((a) < 0 ) ? ((b)--, (a) + (m)) : (a)) 86 87 #ifdef USE_SYSTEM_LOCALTIME 88 # define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \ 89 (a) <= SYSTEM_LOCALTIME_MAX && \ 90 (a) >= SYSTEM_LOCALTIME_MIN \ 91 ) 92 #else 93 # define SHOULD_USE_SYSTEM_LOCALTIME(a) (0) 94 #endif 95 96 #ifdef USE_SYSTEM_GMTIME 97 # define SHOULD_USE_SYSTEM_GMTIME(a) ( \ 98 (a) <= SYSTEM_GMTIME_MAX && \ 99 (a) >= SYSTEM_GMTIME_MIN \ 100 ) 101 #else 102 # define SHOULD_USE_SYSTEM_GMTIME(a) (0) 103 #endif 104 105 /* Multi varadic macros are a C99 thing, alas */ 106 #ifdef TIME_64_DEBUG 107 # define TIME64_TRACE(format) (fprintf(stderr, format)) 108 # define TIME64_TRACE1(format, var1) (fprintf(stderr, format, var1)) 109 # define TIME64_TRACE2(format, var1, var2) (fprintf(stderr, format, var1, var2)) 110 # define TIME64_TRACE3(format, var1, var2, var3) (fprintf(stderr, format, var1, var2, var3)) 111 #else 112 # define TIME64_TRACE(format) ((void)0) 113 # define TIME64_TRACE1(format, var1) ((void)0) 114 # define TIME64_TRACE2(format, var1, var2) ((void)0) 115 # define TIME64_TRACE3(format, var1, var2, var3) ((void)0) 116 #endif 117 118 static int S_is_exception_century(Year year) 119 { 120 int is_exception = ((year % 100 == 0) && !(year % 400 == 0)); 121 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no"); 122 123 return(is_exception); 124 } 125 126 127 static Time64_T S_timegm64(struct TM *date) { 128 int days = 0; 129 Time64_T seconds = 0; 130 Year year; 131 132 if( date->tm_year > 70 ) { 133 year = 70; 134 while( year < date->tm_year ) { 135 days += length_of_year[IS_LEAP(year)]; 136 year++; 137 } 138 } 139 else if ( date->tm_year < 70 ) { 140 year = 69; 141 do { 142 days -= length_of_year[IS_LEAP(year)]; 143 year--; 144 } while( year >= date->tm_year ); 145 } 146 147 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon]; 148 days += date->tm_mday - 1; 149 150 /* Avoid overflowing the days integer */ 151 seconds = days; 152 seconds = seconds * 60 * 60 * 24; 153 154 seconds += date->tm_hour * 60 * 60; 155 seconds += date->tm_min * 60; 156 seconds += date->tm_sec; 157 158 return(seconds); 159 } 160 161 162 #ifdef DEBUGGING 163 static int S_check_tm(struct TM *tm) 164 { 165 /* Don't forget leap seconds */ 166 assert(tm->tm_sec >= 0); 167 assert(tm->tm_sec <= 61); 168 169 assert(tm->tm_min >= 0); 170 assert(tm->tm_min <= 59); 171 172 assert(tm->tm_hour >= 0); 173 assert(tm->tm_hour <= 23); 174 175 assert(tm->tm_mday >= 1); 176 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); 177 178 assert(tm->tm_mon >= 0); 179 assert(tm->tm_mon <= 11); 180 181 assert(tm->tm_wday >= 0); 182 assert(tm->tm_wday <= 6); 183 184 assert(tm->tm_yday >= 0); 185 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); 186 187 #ifdef HAS_TM_TM_GMTOFF 188 assert(tm->tm_gmtoff >= -24 * 60 * 60); 189 assert(tm->tm_gmtoff <= 24 * 60 * 60); 190 #endif 191 192 return 1; 193 } 194 #endif 195 196 197 /* The exceptional centuries without leap years cause the cycle to 198 shift by 16 199 */ 200 static Year S_cycle_offset(Year year) 201 { 202 const Year start_year = 2000; 203 Year year_diff = year - start_year; 204 Year exceptions; 205 206 if( year > start_year ) 207 year_diff--; 208 209 exceptions = year_diff / 100; 210 exceptions -= year_diff / 400; 211 212 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n", 213 year, exceptions, year_diff); 214 215 return exceptions * 16; 216 } 217 218 /* For a given year after 2038, pick the latest possible matching 219 year in the 28 year calendar cycle. 220 221 A matching year... 222 1) Starts on the same day of the week. 223 2) Has the same leap year status. 224 225 This is so the calendars match up. 226 227 Also the previous year must match. When doing Jan 1st you might 228 wind up on Dec 31st the previous year when doing a -UTC time zone. 229 230 Finally, the next year must have the same start day of week. This 231 is for Dec 31st with a +UTC time zone. 232 It doesn't need the same leap year status since we only care about 233 January 1st. 234 */ 235 static int S_safe_year(Year year) 236 { 237 int safe_year; 238 Year year_cycle = year + S_cycle_offset(year); 239 240 /* Change non-leap xx00 years to an equivalent */ 241 if( S_is_exception_century(year) ) 242 year_cycle += 11; 243 244 /* Also xx01 years, since the previous year will be wrong */ 245 if( S_is_exception_century(year - 1) ) 246 year_cycle += 17; 247 248 year_cycle %= SOLAR_CYCLE_LENGTH; 249 if( year_cycle < 0 ) 250 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle; 251 252 assert( year_cycle >= 0 ); 253 assert( year_cycle < SOLAR_CYCLE_LENGTH ); 254 safe_year = safe_years[year_cycle]; 255 256 assert(safe_year <= 2037 && safe_year >= 2010); 257 258 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n", 259 year, year_cycle, safe_year); 260 261 return safe_year; 262 } 263 264 265 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) { 266 assert(src); 267 assert(dest); 268 #ifdef USE_TM64 269 dest->tm_sec = src->tm_sec; 270 dest->tm_min = src->tm_min; 271 dest->tm_hour = src->tm_hour; 272 dest->tm_mday = src->tm_mday; 273 dest->tm_mon = src->tm_mon; 274 dest->tm_year = (Year)src->tm_year; 275 dest->tm_wday = src->tm_wday; 276 dest->tm_yday = src->tm_yday; 277 dest->tm_isdst = src->tm_isdst; 278 279 # ifdef HAS_TM_TM_GMTOFF 280 dest->tm_gmtoff = src->tm_gmtoff; 281 # endif 282 283 # ifdef HAS_TM_TM_ZONE 284 dest->tm_zone = src->tm_zone; 285 # endif 286 287 #else 288 /* They're the same type */ 289 memcpy(dest, src, sizeof(*dest)); 290 #endif 291 } 292 293 294 #ifndef HAS_LOCALTIME_R 295 /* Simulate localtime_r() to the best of our ability */ 296 static struct tm * S_localtime_r(const time_t *clock, struct tm *result) { 297 #ifdef __VMS 298 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */ 299 #endif 300 const struct tm *static_result = localtime(clock); 301 302 assert(result != NULL); 303 304 if( static_result == NULL ) { 305 memset(result, 0, sizeof(*result)); 306 return NULL; 307 } 308 else { 309 memcpy(result, static_result, sizeof(*result)); 310 return result; 311 } 312 } 313 #endif 314 315 #ifndef HAS_GMTIME_R 316 /* Simulate gmtime_r() to the best of our ability */ 317 static struct tm * S_gmtime_r(const time_t *clock, struct tm *result) { 318 #ifdef __VMS 319 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */ 320 #endif 321 const struct tm *static_result = gmtime(clock); 322 323 assert(result != NULL); 324 325 if( static_result == NULL ) { 326 memset(result, 0, sizeof(*result)); 327 return NULL; 328 } 329 else { 330 memcpy(result, static_result, sizeof(*result)); 331 return result; 332 } 333 } 334 #endif 335 336 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p) 337 { 338 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; 339 Time64_T v_tm_tday; 340 int leap; 341 Time64_T m; 342 Time64_T time = *in_time; 343 Year year = 70; 344 int cycles = 0; 345 346 assert(p != NULL); 347 348 /* Use the system gmtime() if time_t is small enough */ 349 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { 350 time_t safe_time = (time_t)*in_time; 351 struct tm safe_date; 352 GMTIME_R(&safe_time, &safe_date); 353 354 S_copy_little_tm_to_big_TM(&safe_date, p); 355 assert(S_check_tm(p)); 356 357 return p; 358 } 359 360 #ifdef HAS_TM_TM_GMTOFF 361 p->tm_gmtoff = 0; 362 #endif 363 p->tm_isdst = 0; 364 365 #ifdef HAS_TM_TM_ZONE 366 p->tm_zone = (char *)"UTC"; 367 #endif 368 369 v_tm_sec = (int)Perl_fmod(time, 60.0); 370 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 371 v_tm_min = (int)Perl_fmod(time, 60.0); 372 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 373 v_tm_hour = (int)Perl_fmod(time, 24.0); 374 time = time >= 0 ? Perl_floor(time / 24.0) : Perl_ceil(time / 24.0); 375 v_tm_tday = time; 376 377 WRAP (v_tm_sec, v_tm_min, 60); 378 WRAP (v_tm_min, v_tm_hour, 60); 379 WRAP (v_tm_hour, v_tm_tday, 24); 380 381 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0); 382 if (v_tm_wday < 0) 383 v_tm_wday += 7; 384 m = v_tm_tday; 385 386 if (m >= CHEAT_DAYS) { 387 year = CHEAT_YEARS; 388 m -= CHEAT_DAYS; 389 } 390 391 if (m >= 0) { 392 /* Gregorian cycles, this is huge optimization for distant times */ 393 cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle); 394 if( cycles ) { 395 m -= (cycles * (Time64_T) days_in_gregorian_cycle); 396 year += (cycles * years_in_gregorian_cycle); 397 } 398 399 /* Years */ 400 leap = IS_LEAP (year); 401 while (m >= (Time64_T) length_of_year[leap]) { 402 m -= (Time64_T) length_of_year[leap]; 403 year++; 404 leap = IS_LEAP (year); 405 } 406 407 /* Months */ 408 v_tm_mon = 0; 409 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { 410 m -= (Time64_T) days_in_month[leap][v_tm_mon]; 411 v_tm_mon++; 412 } 413 } else { 414 year--; 415 416 /* Gregorian cycles */ 417 cycles = (int)Perl_ceil((m / (Time64_T) days_in_gregorian_cycle) + 1); 418 if( cycles ) { 419 m -= (cycles * (Time64_T) days_in_gregorian_cycle); 420 year += (cycles * years_in_gregorian_cycle); 421 } 422 423 /* Years */ 424 leap = IS_LEAP (year); 425 while (m < (Time64_T) -length_of_year[leap]) { 426 m += (Time64_T) length_of_year[leap]; 427 year--; 428 leap = IS_LEAP (year); 429 } 430 431 /* Months */ 432 v_tm_mon = 11; 433 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) { 434 m += (Time64_T) days_in_month[leap][v_tm_mon]; 435 v_tm_mon--; 436 } 437 m += (Time64_T) days_in_month[leap][v_tm_mon]; 438 } 439 440 p->tm_year = year; 441 if( p->tm_year != year ) { 442 #ifdef EOVERFLOW 443 errno = EOVERFLOW; 444 #endif 445 return NULL; 446 } 447 448 /* At this point m is less than a year so casting to an int is safe */ 449 p->tm_mday = (int) m + 1; 450 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m; 451 p->tm_sec = v_tm_sec; 452 p->tm_min = v_tm_min; 453 p->tm_hour = v_tm_hour; 454 p->tm_mon = v_tm_mon; 455 p->tm_wday = v_tm_wday; 456 457 assert(S_check_tm(p)); 458 459 return p; 460 } 461 462 463 struct TM *Perl_localtime64_r (const Time64_T *time, struct TM *local_tm) 464 { 465 time_t safe_time; 466 struct tm safe_date; 467 struct TM gm_tm; 468 Year orig_year; 469 int month_diff; 470 471 assert(local_tm != NULL); 472 473 /* Use the system localtime() if time_t is small enough */ 474 if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) { 475 safe_time = (time_t)*time; 476 477 TIME64_TRACE1("Using system localtime for %lld\n", *time); 478 479 LOCALTIME_R(&safe_time, &safe_date); 480 481 S_copy_little_tm_to_big_TM(&safe_date, local_tm); 482 assert(S_check_tm(local_tm)); 483 484 return local_tm; 485 } 486 487 if( Perl_gmtime64_r(time, &gm_tm) == NULL ) { 488 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time); 489 return NULL; 490 } 491 492 orig_year = gm_tm.tm_year; 493 494 if (gm_tm.tm_year > (2037 - 1900) || 495 gm_tm.tm_year < (1970 - 1900) 496 ) 497 { 498 TIME64_TRACE1("Mapping tm_year %lld to safe_year\n", (Year)gm_tm.tm_year); 499 gm_tm.tm_year = S_safe_year((Year)(gm_tm.tm_year + 1900)) - 1900; 500 } 501 502 safe_time = (time_t)S_timegm64(&gm_tm); 503 if( LOCALTIME_R(&safe_time, &safe_date) == NULL ) { 504 TIME64_TRACE1("localtime_r(%d) returned NULL\n", (int)safe_time); 505 return NULL; 506 } 507 508 S_copy_little_tm_to_big_TM(&safe_date, local_tm); 509 510 local_tm->tm_year = orig_year; 511 if( local_tm->tm_year != orig_year ) { 512 TIME64_TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n", 513 (Year)local_tm->tm_year, (Year)orig_year); 514 515 #ifdef EOVERFLOW 516 errno = EOVERFLOW; 517 #endif 518 return NULL; 519 } 520 521 522 month_diff = local_tm->tm_mon - gm_tm.tm_mon; 523 524 /* When localtime is Dec 31st previous year and 525 gmtime is Jan 1st next year. 526 */ 527 if( month_diff == 11 ) { 528 local_tm->tm_year--; 529 } 530 531 /* When localtime is Jan 1st, next year and 532 gmtime is Dec 31st, previous year. 533 */ 534 if( month_diff == -11 ) { 535 local_tm->tm_year++; 536 } 537 538 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st 539 in a non-leap xx00. There is one point in the cycle 540 we can't account for which the safe xx00 year is a leap 541 year. So we need to correct for Dec 31st coming out as 542 the 366th day of the year. 543 */ 544 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 ) 545 local_tm->tm_yday--; 546 547 assert(S_check_tm(local_tm)); 548 549 return local_tm; 550 } 551