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 const 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(const struct TM *date) { 128 int days = 0; 129 Time64_T seconds = 0; 130 131 if( date->tm_year > 70 ) { 132 Year year = 70; 133 while( year < date->tm_year ) { 134 days += length_of_year[IS_LEAP(year)]; 135 year++; 136 } 137 } 138 else if ( date->tm_year < 70 ) { 139 Year year = 69; 140 do { 141 days -= length_of_year[IS_LEAP(year)]; 142 year--; 143 } while( year >= date->tm_year ); 144 } 145 146 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon]; 147 days += date->tm_mday - 1; 148 149 /* Avoid overflowing the days integer */ 150 seconds = days; 151 seconds = seconds * 60 * 60 * 24; 152 153 seconds += date->tm_hour * 60 * 60; 154 seconds += date->tm_min * 60; 155 seconds += date->tm_sec; 156 157 return(seconds); 158 } 159 160 161 #ifdef DEBUGGING 162 static int S_check_tm(const struct TM *tm) 163 { 164 /* Don't forget leap seconds */ 165 assert(tm->tm_sec >= 0); 166 assert(tm->tm_sec <= 61); 167 168 assert(tm->tm_min >= 0); 169 assert(tm->tm_min <= 59); 170 171 assert(tm->tm_hour >= 0); 172 assert(tm->tm_hour <= 23); 173 174 assert(tm->tm_mday >= 1); 175 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); 176 177 assert(tm->tm_mon >= 0); 178 assert(tm->tm_mon <= 11); 179 180 assert(tm->tm_wday >= 0); 181 assert(tm->tm_wday <= 6); 182 183 assert(tm->tm_yday >= 0); 184 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); 185 186 #ifdef HAS_TM_TM_GMTOFF 187 assert(tm->tm_gmtoff >= -24 * 60 * 60); 188 assert(tm->tm_gmtoff <= 24 * 60 * 60); 189 #endif 190 191 return 1; 192 } 193 #endif 194 195 196 /* The exceptional centuries without leap years cause the cycle to 197 shift by 16 198 */ 199 static Year S_cycle_offset(Year year) 200 { 201 const Year start_year = 2000; 202 Year year_diff = year - start_year; 203 Year exceptions; 204 205 if( year > start_year ) 206 year_diff--; 207 208 exceptions = year_diff / 100; 209 exceptions -= year_diff / 400; 210 211 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n", 212 year, exceptions, year_diff); 213 214 return exceptions * 16; 215 } 216 217 /* For a given year after 2038, pick the latest possible matching 218 year in the 28 year calendar cycle. 219 220 A matching year... 221 1) Starts on the same day of the week. 222 2) Has the same leap year status. 223 224 This is so the calendars match up. 225 226 Also the previous year must match. When doing Jan 1st you might 227 wind up on Dec 31st the previous year when doing a -UTC time zone. 228 229 Finally, the next year must have the same start day of week. This 230 is for Dec 31st with a +UTC time zone. 231 It doesn't need the same leap year status since we only care about 232 January 1st. 233 */ 234 static int S_safe_year(Year year) 235 { 236 int safe_year; 237 Year year_cycle = year + S_cycle_offset(year); 238 239 /* Change non-leap xx00 years to an equivalent */ 240 if( S_is_exception_century(year) ) 241 year_cycle += 11; 242 243 /* Also xx01 years, since the previous year will be wrong */ 244 if( S_is_exception_century(year - 1) ) 245 year_cycle += 17; 246 247 year_cycle %= SOLAR_CYCLE_LENGTH; 248 if( year_cycle < 0 ) 249 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle; 250 251 assert( year_cycle >= 0 ); 252 assert( year_cycle < SOLAR_CYCLE_LENGTH ); 253 safe_year = safe_years[year_cycle]; 254 255 assert(safe_year <= 2037 && safe_year >= 2010); 256 257 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n", 258 year, year_cycle, safe_year); 259 260 return safe_year; 261 } 262 263 264 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) { 265 assert(src); 266 assert(dest); 267 #ifdef USE_TM64 268 dest->tm_sec = src->tm_sec; 269 dest->tm_min = src->tm_min; 270 dest->tm_hour = src->tm_hour; 271 dest->tm_mday = src->tm_mday; 272 dest->tm_mon = src->tm_mon; 273 dest->tm_year = (Year)src->tm_year; 274 dest->tm_wday = src->tm_wday; 275 dest->tm_yday = src->tm_yday; 276 dest->tm_isdst = src->tm_isdst; 277 278 # ifdef HAS_TM_TM_GMTOFF 279 dest->tm_gmtoff = src->tm_gmtoff; 280 # endif 281 282 # ifdef HAS_TM_TM_ZONE 283 dest->tm_zone = src->tm_zone; 284 # endif 285 286 #else 287 /* They're the same type */ 288 memcpy(dest, src, sizeof(*dest)); 289 #endif 290 } 291 292 293 #ifndef HAS_LOCALTIME_R 294 /* Simulate localtime_r() to the best of our ability */ 295 static struct tm * S_localtime_r(const time_t *clock, struct tm *result) { 296 #ifdef __VMS 297 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */ 298 #endif 299 const struct tm * const static_result = localtime(clock); 300 301 assert(result != NULL); 302 303 if( static_result == NULL ) { 304 memset(result, 0, sizeof(*result)); 305 return NULL; 306 } 307 else { 308 memcpy(result, static_result, sizeof(*result)); 309 return result; 310 } 311 } 312 #endif 313 314 #ifndef HAS_GMTIME_R 315 /* Simulate gmtime_r() to the best of our ability */ 316 static struct tm * S_gmtime_r(const time_t *clock, struct tm *result) { 317 #ifdef __VMS 318 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */ 319 #endif 320 const struct tm * const static_result = gmtime(clock); 321 322 assert(result != NULL); 323 324 if( static_result == NULL ) { 325 memset(result, 0, sizeof(*result)); 326 return NULL; 327 } 328 else { 329 memcpy(result, static_result, sizeof(*result)); 330 return result; 331 } 332 } 333 #endif 334 335 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p) 336 { 337 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; 338 Time64_T v_tm_tday; 339 int leap; 340 Time64_T m; 341 Time64_T time = *in_time; 342 Year year = 70; 343 344 assert(p != NULL); 345 346 /* Use the system gmtime() if time_t is small enough */ 347 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { 348 time_t safe_time = (time_t)*in_time; 349 struct tm safe_date; 350 GMTIME_R(&safe_time, &safe_date); 351 352 S_copy_little_tm_to_big_TM(&safe_date, p); 353 assert(S_check_tm(p)); 354 355 return p; 356 } 357 358 #ifdef HAS_TM_TM_GMTOFF 359 p->tm_gmtoff = 0; 360 #endif 361 p->tm_isdst = 0; 362 363 #ifdef HAS_TM_TM_ZONE 364 p->tm_zone = (char *)"UTC"; 365 #endif 366 367 v_tm_sec = (int)Perl_fmod(time, 60.0); 368 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 369 v_tm_min = (int)Perl_fmod(time, 60.0); 370 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0); 371 v_tm_hour = (int)Perl_fmod(time, 24.0); 372 time = time >= 0 ? Perl_floor(time / 24.0) : Perl_ceil(time / 24.0); 373 v_tm_tday = time; 374 375 WRAP (v_tm_sec, v_tm_min, 60); 376 WRAP (v_tm_min, v_tm_hour, 60); 377 WRAP (v_tm_hour, v_tm_tday, 24); 378 379 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0); 380 if (v_tm_wday < 0) 381 v_tm_wday += 7; 382 m = v_tm_tday; 383 384 if (m >= CHEAT_DAYS) { 385 year = CHEAT_YEARS; 386 m -= CHEAT_DAYS; 387 } 388 389 if (m >= 0) { 390 /* Gregorian cycles, this is huge optimization for distant times */ 391 const int cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle); 392 if( cycles ) { 393 m -= (cycles * (Time64_T) days_in_gregorian_cycle); 394 year += (cycles * years_in_gregorian_cycle); 395 } 396 397 /* Years */ 398 leap = IS_LEAP (year); 399 while (m >= (Time64_T) length_of_year[leap]) { 400 m -= (Time64_T) length_of_year[leap]; 401 year++; 402 leap = IS_LEAP (year); 403 } 404 405 /* Months */ 406 v_tm_mon = 0; 407 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { 408 m -= (Time64_T) days_in_month[leap][v_tm_mon]; 409 v_tm_mon++; 410 } 411 } else { 412 int cycles; 413 414 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