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 /* Set up the mutexes for this file. There are no races possible on 119 * non-threaded perls, nor platforms that naturally don't have them. 120 * Otherwise, we need to have mutexes. If we have reentrant versions of the 121 * functions below, they automatically will be substituted for the 122 * non-reentrant ones. That solves the problem of the buffers being trashed by 123 * another thread, but not of the environment or locale changing during their 124 * execution. To do that, we only need a read lock (which prevents writing by 125 * others). However, if we don't have re-entrant functions, we can gain some 126 * measure of thread-safety by using an exclusive lock during their execution. 127 * That will protect against any other use of the functions that use the 128 * mutexes, which all of core should be using. */ 129 #ifdef USE_REENTRANT_API /* This indicates a platform where we need reentrant 130 versions if have them */ 131 # ifdef PERL_REENTR_USING_LOCALTIME_R 132 # define LOCALTIME_LOCK ENV_LOCALE_READ_LOCK 133 # define LOCALTIME_UNLOCK ENV_LOCALE_READ_UNLOCK 134 # else 135 # define LOCALTIME_LOCK ENV_LOCALE_LOCK 136 # define LOCALTIME_UNLOCK ENV_LOCALE_UNLOCK 137 # endif 138 # ifdef PERL_REENTR_USING_GMTIME_R 139 # define GMTIME_LOCK ENV_LOCALE_READ_LOCK 140 # define GMTIME_UNLOCK ENV_LOCALE_READ_UNLOCK 141 # else 142 # define GMTIME_LOCK ENV_LOCALE_LOCK 143 # define GMTIME_UNLOCK ENV_LOCALE_UNLOCK 144 # endif 145 #else /* Reentrant not needed, so races not possible */ 146 # define LOCALTIME_LOCK NOOP 147 # define LOCALTIME_UNLOCK NOOP 148 # define GMTIME_LOCK NOOP 149 # define GMTIME_UNLOCK NOOP 150 #endif 151 152 static int S_is_exception_century(Year year) 153 { 154 const int is_exception = ((year % 100 == 0) && !(year % 400 == 0)); 155 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no"); 156 157 return(is_exception); 158 } 159 160 161 static Time64_T S_timegm64(const struct TM *date) { 162 int days = 0; 163 Time64_T seconds = 0; 164 165 if( date->tm_year > 70 ) { 166 Year year = 70; 167 while( year < date->tm_year ) { 168 days += length_of_year[IS_LEAP(year)]; 169 year++; 170 } 171 } 172 else if ( date->tm_year < 70 ) { 173 Year year = 69; 174 do { 175 days -= length_of_year[IS_LEAP(year)]; 176 year--; 177 } while( year >= date->tm_year ); 178 } 179 180 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon]; 181 days += date->tm_mday - 1; 182 183 /* Avoid overflowing the days integer */ 184 seconds = days; 185 seconds = seconds * 60 * 60 * 24; 186 187 seconds += date->tm_hour * 60 * 60; 188 seconds += date->tm_min * 60; 189 seconds += date->tm_sec; 190 191 return(seconds); 192 } 193 194 195 #ifdef DEBUGGING 196 static int S_check_tm(const struct TM *tm) 197 { 198 /* Don't forget leap seconds */ 199 assert(tm->tm_sec >= 0); 200 assert(tm->tm_sec <= 61); 201 202 assert(tm->tm_min >= 0); 203 assert(tm->tm_min <= 59); 204 205 assert(tm->tm_hour >= 0); 206 assert(tm->tm_hour <= 23); 207 208 assert(tm->tm_mday >= 1); 209 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); 210 211 assert(tm->tm_mon >= 0); 212 assert(tm->tm_mon <= 11); 213 214 assert(tm->tm_wday >= 0); 215 assert(tm->tm_wday <= 6); 216 217 assert(tm->tm_yday >= 0); 218 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); 219 220 #ifdef HAS_TM_TM_GMTOFF 221 assert(tm->tm_gmtoff >= -24 * 60 * 60); 222 assert(tm->tm_gmtoff <= 24 * 60 * 60); 223 #endif 224 225 return 1; 226 } 227 #endif 228 229 230 /* The exceptional centuries without leap years cause the cycle to 231 shift by 16 232 */ 233 static Year S_cycle_offset(Year year) 234 { 235 const Year start_year = 2000; 236 Year year_diff = year - start_year; 237 Year exceptions; 238 239 if( year > start_year ) 240 year_diff--; 241 242 exceptions = year_diff / 100; 243 exceptions -= year_diff / 400; 244 245 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n", 246 year, exceptions, year_diff); 247 248 return exceptions * 16; 249 } 250 251 /* For a given year after 2038, pick the latest possible matching 252 year in the 28 year calendar cycle. 253 254 A matching year... 255 1) Starts on the same day of the week. 256 2) Has the same leap year status. 257 258 This is so the calendars match up. 259 260 Also the previous year must match. When doing Jan 1st you might 261 wind up on Dec 31st the previous year when doing a -UTC time zone. 262 263 Finally, the next year must have the same start day of week. This 264 is for Dec 31st with a +UTC time zone. 265 It doesn't need the same leap year status since we only care about 266 January 1st. 267 */ 268 static int S_safe_year(Year year) 269 { 270 int safe_year; 271 Year year_cycle = year + S_cycle_offset(year); 272 273 /* Change non-leap xx00 years to an equivalent */ 274 if( S_is_exception_century(year) ) 275 year_cycle += 11; 276 277 /* Also xx01 years, since the previous year will be wrong */ 278 if( S_is_exception_century(year - 1) ) 279 year_cycle += 17; 280 281 year_cycle %= SOLAR_CYCLE_LENGTH; 282 if( year_cycle < 0 ) 283 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle; 284 285 assert( year_cycle >= 0 ); 286 assert( year_cycle < SOLAR_CYCLE_LENGTH ); 287 safe_year = safe_years[year_cycle]; 288 289 assert(safe_year <= 2037 && safe_year >= 2010); 290 291 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n", 292 year, year_cycle, safe_year); 293 294 return safe_year; 295 } 296 297 298 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) { 299 assert(src); 300 assert(dest); 301 #ifdef USE_TM64 302 dest->tm_sec = src->tm_sec; 303 dest->tm_min = src->tm_min; 304 dest->tm_hour = src->tm_hour; 305 dest->tm_mday = src->tm_mday; 306 dest->tm_mon = src->tm_mon; 307 dest->tm_year = (Year)src->tm_year; 308 dest->tm_wday = src->tm_wday; 309 dest->tm_yday = src->tm_yday; 310 dest->tm_isdst = src->tm_isdst; 311 312 # ifdef HAS_TM_TM_GMTOFF 313 dest->tm_gmtoff = src->tm_gmtoff; 314 # endif 315 316 # ifdef HAS_TM_TM_ZONE 317 dest->tm_zone = src->tm_zone; 318 # endif 319 320 #else 321 /* They're the same type */ 322 memcpy(dest, src, sizeof(*dest)); 323 #endif 324 } 325 326 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p) 327 { 328 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; 329 Time64_T v_tm_tday; 330 int leap; 331 Time64_T m; 332 Time64_T time = *in_time; 333 Year year = 70; 334 dTHX; 335 336 assert(p != NULL); 337 338 /* Use the system gmtime() if time_t is small enough */ 339 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { 340 time_t safe_time = (time_t)*in_time; 341 struct tm safe_date; 342 struct tm * result; 343 344 GMTIME_LOCK; 345 346 /* reentr.h will automatically replace this with a call to gmtime_r() 347 * when appropriate */ 348 result = gmtime(&safe_time); 349 350 assert(result != NULL); 351 352 #if defined(HAS_GMTIME_R) && defined(USE_REENTRANT_API) 353 354 PERL_UNUSED_VAR(safe_date); 355 #else 356 /* Here, no gmtime_r() and is a threaded perl where the result can be 357 * overwritten by a call in another thread. Copy to a safe place, 358 * hopefully before another gmtime that isn't using the mutexes can 359 * jump in and trash this result. */ 360 memcpy(&safe_date, result, sizeof(safe_date)); 361 result = &safe_date; 362 #endif 363 GMTIME_UNLOCK; 364 365 S_copy_little_tm_to_big_TM(result, p); 366 assert(S_check_tm(p)); 367 368 return p; 369 } 370 371 #ifdef HAS_TM_TM_GMTOFF 372 p->tm_gmtoff = 0; 373 #endif 374 p->tm_isdst = 0; 375 376 #ifdef HAS_TM_TM_ZONE 377 p->tm_zone = "UTC"; 378 #endif 379 380 v_tm_sec = (int)Perl_fmod(time, 60.0); 381 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 382 v_tm_min = (int)Perl_fmod(time, 60.0); 383 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 384 v_tm_hour = (int)Perl_fmod(time, 24.0); 385 time = time >= 0 ? Perl_floor(time / 24.0) : Perl_ceil(time / 24.0); 386 v_tm_tday = time; 387 388 WRAP (v_tm_sec, v_tm_min, 60); 389 WRAP (v_tm_min, v_tm_hour, 60); 390 WRAP (v_tm_hour, v_tm_tday, 24); 391 392 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0); 393 if (v_tm_wday < 0) 394 v_tm_wday += 7; 395 m = v_tm_tday; 396 397 if (m >= CHEAT_DAYS) { 398 year = CHEAT_YEARS; 399 m -= CHEAT_DAYS; 400 } 401 402 if (m >= 0) { 403 /* Gregorian cycles, this is huge optimization for distant times */ 404 const int cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle); 405 if( cycles ) { 406 m -= (cycles * (Time64_T) days_in_gregorian_cycle); 407 year += (cycles * years_in_gregorian_cycle); 408 } 409 410 /* Years */ 411 leap = IS_LEAP (year); 412 while (m >= (Time64_T) length_of_year[leap]) { 413 m -= (Time64_T) length_of_year[leap]; 414 year++; 415 leap = IS_LEAP (year); 416 } 417 418 /* Months */ 419 v_tm_mon = 0; 420 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { 421 m -= (Time64_T) days_in_month[leap][v_tm_mon]; 422 v_tm_mon++; 423 } 424 } else { 425 int cycles; 426 427 year--; 428 429 /* Gregorian cycles */ 430 cycles = (int)Perl_ceil((m / (Time64_T) days_in_gregorian_cycle) + 1); 431 if( cycles ) { 432 m -= (cycles * (Time64_T) days_in_gregorian_cycle); 433 year += (cycles * years_in_gregorian_cycle); 434 } 435 436 /* Years */ 437 leap = IS_LEAP (year); 438 while (m < (Time64_T) -length_of_year[leap]) { 439 m += (Time64_T) length_of_year[leap]; 440 year--; 441 leap = IS_LEAP (year); 442 } 443 444 /* Months */ 445 v_tm_mon = 11; 446 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) { 447 m += (Time64_T) days_in_month[leap][v_tm_mon]; 448 v_tm_mon--; 449 } 450 m += (Time64_T) days_in_month[leap][v_tm_mon]; 451 } 452 453 p->tm_year = year; 454 if( p->tm_year != year ) { 455 #ifdef EOVERFLOW 456 errno = EOVERFLOW; 457 #endif 458 return NULL; 459 } 460 461 /* At this point m is less than a year so casting to an int is safe */ 462 p->tm_mday = (int) m + 1; 463 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m; 464 p->tm_sec = v_tm_sec; 465 p->tm_min = v_tm_min; 466 p->tm_hour = v_tm_hour; 467 p->tm_mon = v_tm_mon; 468 p->tm_wday = v_tm_wday; 469 470 assert(S_check_tm(p)); 471 472 return p; 473 } 474 475 476 struct TM *Perl_localtime64_r (const Time64_T *time, struct TM *local_tm) 477 { 478 time_t safe_time; 479 struct tm safe_date; 480 const struct tm * result; 481 struct TM gm_tm; 482 Year orig_year = 0; /* initialise to avoid spurious compiler warning */ 483 int month_diff; 484 const bool use_system = SHOULD_USE_SYSTEM_LOCALTIME(*time); 485 dTHX; 486 487 assert(local_tm != NULL); 488 489 /* Use the system localtime() if time_t is small enough */ 490 if (use_system) { 491 safe_time = (time_t)*time; 492 493 TIME64_TRACE1("Using system localtime for %lld\n", *time); 494 } 495 else { 496 if (Perl_gmtime64_r(time, &gm_tm) == NULL) { 497 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time); 498 return NULL; 499 } 500 501 orig_year = gm_tm.tm_year; 502 503 if (gm_tm.tm_year > (2037 - 1900) || 504 gm_tm.tm_year < (1970 - 1900) 505 ) 506 { 507 TIME64_TRACE1("Mapping tm_year %lld to safe_year\n", 508 (Year)gm_tm.tm_year); 509 gm_tm.tm_year = S_safe_year((Year)(gm_tm.tm_year + 1900)) - 1900; 510 } 511 512 safe_time = (time_t)S_timegm64(&gm_tm); 513 } 514 515 LOCALTIME_LOCK; 516 517 /* reentr.h will automatically replace this with a call to localtime_r() 518 * when appropriate */ 519 result = localtime(&safe_time); 520 521 if(UNLIKELY(result == NULL)) { 522 LOCALTIME_UNLOCK; 523 TIME64_TRACE1("localtime(%d) returned NULL\n", (int)safe_time); 524 return NULL; 525 } 526 527 #if ! defined(USE_REENTRANT_API) || defined(PERL_REENTR_USING_LOCALTIME_R) 528 529 PERL_UNUSED_VAR(safe_date); 530 531 #else 532 533 /* Here, would be using localtime_r() if it could, meaning there isn't one, 534 * and is a threaded perl where the result can be overwritten by a call in 535 * another thread. Copy to a safe place, hopefully before another 536 * localtime that isn't using the mutexes can jump in and trash this 537 * result. */ 538 memcpy(&safe_date, result, sizeof(safe_date)); 539 result = &safe_date; 540 541 #endif 542 543 LOCALTIME_UNLOCK; 544 545 S_copy_little_tm_to_big_TM(result, local_tm); 546 547 if (! use_system) { 548 549 local_tm->tm_year = orig_year; 550 if( local_tm->tm_year != orig_year ) { 551 TIME64_TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n", 552 (Year)local_tm->tm_year, (Year)orig_year); 553 554 #ifdef EOVERFLOW 555 errno = EOVERFLOW; 556 #endif 557 return NULL; 558 } 559 560 month_diff = local_tm->tm_mon - gm_tm.tm_mon; 561 562 /* When localtime is Dec 31st previous year and 563 gmtime is Jan 1st next year. 564 */ 565 if( month_diff == 11 ) { 566 local_tm->tm_year--; 567 } 568 569 /* When localtime is Jan 1st, next year and 570 gmtime is Dec 31st, previous year. 571 */ 572 if( month_diff == -11 ) { 573 local_tm->tm_year++; 574 } 575 576 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st 577 in a non-leap xx00. There is one point in the cycle 578 we can't account for which the safe xx00 year is a leap 579 year. So we need to correct for Dec 31st coming out as 580 the 366th day of the year. 581 */ 582 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 ) 583 local_tm->tm_yday--; 584 585 } 586 587 assert(S_check_tm(local_tm)); 588 589 return local_tm; 590 } 591