lib/parse-date.y

   1 %{
   2 /**
   3  * Parse a string into an internal timestamp.
   4  *
   5  * This file is based on gnulib parse-datetime.y-dd7a871 with
   6  * the other gnulib dependencies removed for use in util-linux.
   7  *
   8  * Copyright (C) 1999-2000, 2002-2017 Free Software Foundation, Inc.
   9  *
  10  * This program is free software: you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 3 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22  *
  23  * Originally written by Steven M. Bellovin <smb@research.att.com> while
  24  * at the University of North Carolina at Chapel Hill.  Later tweaked by
  25  * a couple of people on Usenet.  Completely overhauled by Rich $alz
  26  * <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
  27  *
  28  * Modified by Paul Eggert <eggert@twinsun.com> in August 1999 to do
  29  * the right thing about local DST.  Also modified by Paul Eggert
  30  * <eggert@cs.ucla.edu> in February 2004 to support
  31  * nanosecond-resolution timestamps, and in October 2004 to support
  32  * TZ strings in dates.
  33  */
  34
  35 /**
  36  * FIXME: Check for arithmetic overflow in all cases, not just
  37  * some of them.
  38  */
  39
  40 #include <sys/time.h>
  41 #include <time.h>
  42
  43 #include "c.h"
  44 #include "timeutils.h"
  45
  46 /**
  47  * There's no need to extend the stack, so there's no need to involve
  48  * alloca.
  49  */
  50 #define YYSTACK_USE_ALLOCA 0
  51
  52 /**
  53  * Tell Bison how much stack space is needed.  20 should be plenty for
  54  * this grammar, which is not right recursive.  Beware setting it too
  55  * high, since that might cause problems on machines whose
  56  * implementations have lame stack-overflow checking.
  57  */
  58 #define YYMAXDEPTH 20
  59 #define YYINITDEPTH YYMAXDEPTH
  60
  61 /**
  62  * Since the code of parse-datetime.y is not included in the Emacs executable
  63  * itself, there is no need to #define static in this file.  Even if
  64  * the code were included in the Emacs executable, it probably
  65  * wouldn't do any harm to #undef it here; this will only cause
  66  * problems if we try to write to a static variable, which I don't
  67  * think this code needs to do.
  68  */
  69 #ifdef emacs
  70 # undef static
  71 #endif
  72
  73 #include <inttypes.h>
  74 #include <limits.h>
  75 #include <stdio.h>
  76 #include <stdlib.h>
  77 #include <string.h>
  78
  79
  80 #include <stdarg.h>
  81 #include "cctype.h"
  82 #include "nls.h"
  83
  84 /**
  85  * Bison's skeleton tests _STDLIB_H, while some stdlib.h headers
  86  * use _STDLIB_H_ as witness.  Map the latter to the one bison uses.
  87  * FIXME: this is temporary.  Remove when we have a mechanism to ensure
  88  * that the version we're using is fixed, too.
  89  */
  90 #ifdef _STDLIB_H_
  91 # undef _STDLIB_H
  92 # define _STDLIB_H 1
  93 #endif
  94
  95 /**
  96  * Shift A right by B bits portably, by dividing A by 2**B and
  97  * truncating towards minus infinity.  A and B should be free of side
  98  * effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
  99  * INT_BITS is the number of useful bits in an int.  GNU code can
 100  * assume that INT_BITS is at least 32.
 101  *
 102  * ISO C99 says that A >> B is implementation-defined if A < 0.  Some
 103  * implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
 104  * right in the usual way when A < 0, so SHR falls back on division if
 105  * ordinary A >> B doesn't seem to be the usual signed shift.
 106  */
 107 #define SHR(a, b) \
 108         (-1 >> 1 == -1 \
 109          ? (a) >> (b) \
 110          : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
 111
 112 #define TM_YEAR_BASE 1900
 113
 114 #define HOUR(x) ((x) * 60)
 115
 116 #define STREQ(a, b) (strcmp (a, b) == 0)
 117
 118 /**
 119  * Convert a possibly-signed character to an unsigned character.  This is
 120  * a bit safer than casting to unsigned char, since it catches some type
 121  * errors that the cast doesn't.
 122  */
 123 static unsigned char to_uchar (char ch) { return ch; }
 124
 125 /**
 126  * FIXME: It also assumes that signed integer overflow silently wraps around,
 127  * but this is not true any more with recent versions of GCC 4.
 128  */
 129
 130 /**
 131  * An integer value, and the number of digits in its textual
 132  * representation.
 133  */
 134 typedef struct {
 135         int negative;
 136         intmax_t value;
 137         size_t digits;
 138 } textint;
 139
 140 /* An entry in the lexical lookup table. */
 141 typedef struct {
 142         char const *name;
 143         int type;
 144         int value;
 145 } table;
 146
 147 /* Meridian: am, pm, or 24-hour style. */
 148 enum { MERam, MERpm, MER24 };
 149
 150 enum { BILLION = 1000000000, LOG10_BILLION = 9 };
 151
 152 /* Relative year, month, day, hour, minutes, seconds, and nanoseconds. */
 153 typedef struct {
 154         intmax_t year;
 155         intmax_t month;
 156         intmax_t day;
 157         intmax_t hour;
 158         intmax_t minutes;
 159         time_t seconds;
 160         int ns;
 161 } relative_time;
 162
 163 #if HAVE_COMPOUND_LITERALS
 164 # define RELATIVE_TIME_0 ((relative_time) { 0, 0, 0, 0, 0, 0, 0 })
 165 #else
 166 static relative_time const RELATIVE_TIME_0;
 167 #endif
 168
 169 /* Information passed to and from the parser. */
 170 typedef struct {
 171         /* The input string remaining to be parsed. */
 172         const char *input;
 173
 174         /* N, if this is the Nth Tuesday. */
 175         intmax_t day_ordinal;
 176
 177         /* Day of week; Sunday is 0. */
 178         int day_number;
 179
 180         /* tm_isdst flag for the local zone. */
 181         int local_isdst;
 182
 183         /* Time zone, in minutes east of UTC. */
 184         int time_zone;
 185
 186         /* Style used for time. */
 187         int meridian;
 188
 189         /* Gregorian year, month, day, hour, minutes, seconds, and ns. */
 190         textint year;
 191         intmax_t month;
 192         intmax_t day;
 193         intmax_t hour;
 194         intmax_t minutes;
 195         struct timespec seconds; /* includes nanoseconds */
 196
 197         /* Relative year, month, day, hour, minutes, seconds, and ns. */
 198         relative_time rel;
 199
 200         /* Presence or counts of some nonterminals parsed so far. */
 201         int timespec_seen;
 202         int rels_seen;
 203         size_t dates_seen;
 204         size_t days_seen;
 205         size_t local_zones_seen;
 206         size_t dsts_seen;
 207         size_t times_seen;
 208         size_t zones_seen;
 209
 210         /* Table of local time zone abbreviations, null terminated. */
 211         table local_time_zone_table[3];
 212 } parser_control;
 213
 214 union YYSTYPE;
 215 static int yylex (union YYSTYPE *, parser_control *);
 216 static int yyerror (parser_control const *, char const *);
 217 static int time_zone_hhmm (parser_control *, textint, textint);
 218
 219 /**
 220  * Extract into *PC any date and time info from a string of digits
 221  * of the form e.g., YYYYMMDD, YYMMDD, HHMM, HH (and sometimes YYY,
 222  * YYYY, ...).
 223  */
 224 static void digits_to_date_time(parser_control *pc, textint text_int)
 225 {
 226         if (pc->dates_seen && ! pc->year.digits
 227             && ! pc->rels_seen && (pc->times_seen || 2 < text_int.digits)) {
 228                 pc->year = text_int;
 229         } else {
 230                 if (4 < text_int.digits) {
 231                         pc->dates_seen++;
 232                         pc->day = text_int.value % 100;
 233                         pc->month = (text_int.value / 100) % 100;
 234                         pc->year.value = text_int.value / 10000;
 235                         pc->year.digits = text_int.digits - 4;
 236                 } else {
 237                         pc->times_seen++;
 238                         if (text_int.digits <= 2) {
 239                                 pc->hour = text_int.value;
 240                                 pc->minutes = 0;
 241                         }
 242                         else {
 243                                 pc->hour = text_int.value / 100;
 244                                 pc->minutes = text_int.value % 100;
 245                         }
 246                         pc->seconds.tv_sec = 0;
 247                         pc->seconds.tv_nsec = 0;
 248                         pc->meridian = MER24;
 249                 }
 250         }
 251 }
 252
 253 /* Increment PC->rel by FACTOR * REL (FACTOR is 1 or -1). */
 254 static void apply_relative_time(parser_control *pc, relative_time rel,
 255                                 int factor)
 256 {
 257         pc->rel.ns += factor * rel.ns;
 258         pc->rel.seconds += factor * rel.seconds;
 259         pc->rel.minutes += factor * rel.minutes;
 260         pc->rel.hour += factor * rel.hour;
 261         pc->rel.day += factor * rel.day;
 262         pc->rel.month += factor * rel.month;
 263         pc->rel.year += factor * rel.year;
 264         pc->rels_seen = 1;
 265 }
 266
 267 /* Set PC-> hour, minutes, seconds and nanoseconds members from arguments. */
 268 static void
 269 set_hhmmss(parser_control *pc, intmax_t hour, intmax_t minutes,
 270            time_t sec, int nsec)
 271 {
 272         pc->hour = hour;
 273         pc->minutes = minutes;
 274         pc->seconds.tv_sec = sec;
 275         pc->seconds.tv_nsec = nsec;
 276 }
 277
 278 %}
 279
 280 /**
 281  * We want a reentrant parser, even if the TZ manipulation and the calls to
 282  * localtime and gmtime are not reentrant.
 283  */
 284 %pure-parser
 285 %parse-param { parser_control *pc }
 286 %lex-param { parser_control *pc }
 287
 288 /* This grammar has 31 shift/reduce conflicts. */
 289 %expect 31
 290
 291 %union {
 292         intmax_t intval;
 293         textint textintval;
 294         struct timespec timespec;
 295         relative_time rel;
 296 }
 297
 298 %token <intval> tAGO
 299 %token tDST
 300
 301 %token tYEAR_UNIT tMONTH_UNIT tHOUR_UNIT tMINUTE_UNIT tSEC_UNIT
 302 %token <intval> tDAY_UNIT tDAY_SHIFT
 303
 304 %token <intval> tDAY tDAYZONE tLOCAL_ZONE tMERIDIAN
 305 %token <intval> tMONTH tORDINAL tZONE
 306
 307 %token <textintval> tSNUMBER tUNUMBER
 308 %token <timespec> tSDECIMAL_NUMBER tUDECIMAL_NUMBER
 309
 310 %type <textintval> o_colon_minutes
 311 %type <timespec> seconds signed_seconds unsigned_seconds
 312
 313 %type <rel> relunit relunit_snumber dayshift
 314
 315 %%
 316
 317 spec:
 318           timespec
 319         | items
 320 ;
 321
 322 timespec:
 323           '@' seconds {
 324                 pc->seconds = $2;
 325                 pc->timespec_seen = 1;
 326           }
 327 ;
 328
 329 items:
 330           /* empty */
 331         | items item
 332 ;
 333
 334 item:
 335           datetime {
 336                 pc->times_seen++; pc->dates_seen++;
 337           }
 338         | time {
 339                 pc->times_seen++;
 340           }
 341         | local_zone {
 342                 pc->local_zones_seen++;
 343           }
 344         | zone {
 345                 pc->zones_seen++;
 346           }
 347         | date {
 348                 pc->dates_seen++;
 349           }
 350         | day {
 351                 pc->days_seen++;
 352           }
 353         | rel
 354         | number
 355         | hybrid
 356 ;
 357
 358 datetime:
 359           iso_8601_datetime
 360 ;
 361
 362 iso_8601_datetime:
 363           iso_8601_date 'T' iso_8601_time
 364 ;
 365
 366 time:
 367           tUNUMBER tMERIDIAN {
 368                 set_hhmmss (pc, $1.value, 0, 0, 0);
 369                 pc->meridian = $2;
 370           }
 371         | tUNUMBER ':' tUNUMBER tMERIDIAN {
 372                 set_hhmmss (pc, $1.value, $3.value, 0, 0);
 373                 pc->meridian = $4;
 374           }
 375         | tUNUMBER ':' tUNUMBER ':' unsigned_seconds tMERIDIAN {
 376                 set_hhmmss (pc, $1.value, $3.value, $5.tv_sec, $5.tv_nsec);
 377                 pc->meridian = $6;
 378           }
 379         | iso_8601_time
 380 ;
 381
 382 iso_8601_time:
 383           tUNUMBER zone_offset {
 384                 set_hhmmss (pc, $1.value, 0, 0, 0);
 385                 pc->meridian = MER24;
 386           }
 387         | tUNUMBER ':' tUNUMBER o_zone_offset {
 388                 set_hhmmss (pc, $1.value, $3.value, 0, 0);
 389                 pc->meridian = MER24;
 390           }
 391         | tUNUMBER ':' tUNUMBER ':' unsigned_seconds o_zone_offset {
 392                 set_hhmmss (pc, $1.value, $3.value, $5.tv_sec, $5.tv_nsec);
 393                 pc->meridian = MER24;
 394           }
 395 ;
 396
 397 o_zone_offset:
 398         /* empty */
 399         | zone_offset
 400 ;
 401
 402 zone_offset:
 403           tSNUMBER o_colon_minutes {
 404                 pc->zones_seen++;
 405                 if (! time_zone_hhmm (pc, $1, $2)) YYABORT;
 406           }
 407 ;
 408
 409 /**
 410  * Local zone strings only affect DST setting,
 411  * and only take affect if the current TZ setting is relevant.
 412  *
 413  * Example 1:
 414  * 'EEST' is parsed as tLOCAL_ZONE, as it relates to the effective TZ:
 415  *      TZ=Europe/Helsinki date -d '2016-12-30 EEST'
 416  *
 417  * Example 2:
 418  * 'EEST' is parsed as 'zone' (TZ=+03:00):
 419  *       TZ=Asia/Tokyo ./src/date --debug -d '2011-06-11 EEST'
 420  *
 421  * This is implemented by probing the next three calendar quarters
 422  * of the effective timezone and looking for DST changes -
 423  * if found, the timezone name (EEST) is inserted into
 424  * the lexical lookup table with type tLOCAL_ZONE.
 425  * (Search for 'quarter' comment in  'parse_date').
 426  */
 427 local_zone:
 428           tLOCAL_ZONE {
 429                 pc->local_isdst = $1;
 430                 pc->dsts_seen += (0 < $1);
 431           }
 432         | tLOCAL_ZONE tDST {
 433                 pc->local_isdst = 1;
 434                 pc->dsts_seen += (0 < $1) + 1;
 435           }
 436 ;
 437
 438 /**
 439  * Note 'T' is a special case, as it is used as the separator in ISO
 440  * 8601 date and time of day representation.
 441  */
 442 zone:
 443           tZONE {
 444                 pc->time_zone = $1;
 445           }
 446         | 'T' {
 447                 pc->time_zone = HOUR(7);
 448           }
 449         | tZONE relunit_snumber {
 450                 pc->time_zone = $1;
 451                 apply_relative_time (pc, $2, 1);
 452           }
 453         | 'T' relunit_snumber {
 454                 pc->time_zone = HOUR(7);
 455                 apply_relative_time (pc, $2, 1);
 456           }
 457         | tZONE tSNUMBER o_colon_minutes {
 458                 if (! time_zone_hhmm (pc, $2, $3)) YYABORT;
 459                 pc->time_zone += $1;
 460           }
 461         | tDAYZONE {
 462                 pc->time_zone = $1 + 60;
 463           }
 464         | tZONE tDST {
 465                 pc->time_zone = $1 + 60;
 466           }
 467 ;
 468
 469 day:
 470           tDAY {
 471                 pc->day_ordinal = 0;
 472                 pc->day_number = $1;
 473           }
 474         | tDAY ',' {
 475                 pc->day_ordinal = 0;
 476                 pc->day_number = $1;
 477           }
 478         | tORDINAL tDAY {
 479                 pc->day_ordinal = $1;
 480                 pc->day_number = $2;
 481           }
 482         | tUNUMBER tDAY {
 483                 pc->day_ordinal = $1.value;
 484                 pc->day_number = $2;
 485           }
 486 ;
 487
 488 date:
 489           tUNUMBER '/' tUNUMBER {
 490                 pc->month = $1.value;
 491                 pc->day = $3.value;
 492           }
 493         | tUNUMBER '/' tUNUMBER '/' tUNUMBER {
 494         /**
 495          * Interpret as YYYY/MM/DD if the first value has 4 or more digits,
 496          * otherwise as MM/DD/YY.
 497          * The goal in recognizing YYYY/MM/DD is solely to support legacy
 498          * machine-generated dates like those in an RCS log listing.  If
 499          * you want portability, use the ISO 8601 format.
 500          */
 501                 if (4 <= $1.digits) {
 502                         pc->year = $1;
 503                         pc->month = $3.value;
 504                         pc->day = $5.value;
 505                 } else {
 506                         pc->month = $1.value;
 507                         pc->day = $3.value;
 508                         pc->year = $5;
 509                 }
 510           }
 511         | tUNUMBER tMONTH tSNUMBER {
 512                 /* e.g. 17-JUN-1992. */
 513                 pc->day = $1.value;
 514                 pc->month = $2;
 515                 pc->year.value = -$3.value;
 516                 pc->year.digits = $3.digits;
 517           }
 518         | tMONTH tSNUMBER tSNUMBER {
 519                 /* e.g. JUN-17-1992. */
 520                 pc->month = $1;
 521                 pc->day = -$2.value;
 522                 pc->year.value = -$3.value;
 523                 pc->year.digits = $3.digits;
 524           }
 525         | tMONTH tUNUMBER {
 526                 pc->month = $1;
 527                 pc->day = $2.value;
 528           }
 529         | tMONTH tUNUMBER ',' tUNUMBER {
 530                 pc->month = $1;
 531                 pc->day = $2.value;
 532                 pc->year = $4;
 533           }
 534         | tUNUMBER tMONTH {
 535                 pc->day = $1.value;
 536                 pc->month = $2;
 537           }
 538         | tUNUMBER tMONTH tUNUMBER {
 539                 pc->day = $1.value;
 540                 pc->month = $2;
 541                 pc->year = $3;
 542           }
 543         | iso_8601_date
 544 ;
 545
 546 iso_8601_date:
 547           tUNUMBER tSNUMBER tSNUMBER {
 548                 /* ISO 8601 format.YYYY-MM-DD. */
 549                 pc->year = $1;
 550                 pc->month = -$2.value;
 551                 pc->day = -$3.value;
 552           }
 553 ;
 554
 555 rel:
 556           relunit tAGO
 557                 { apply_relative_time (pc, $1, $2); }
 558         | relunit
 559                 { apply_relative_time (pc, $1, 1); }
 560         | dayshift
 561                 { apply_relative_time (pc, $1, 1); }
 562 ;
 563
 564 relunit:
 565           tORDINAL tYEAR_UNIT
 566                 { $$ = RELATIVE_TIME_0; $$.year = $1; }
 567         | tUNUMBER tYEAR_UNIT
 568                 { $$ = RELATIVE_TIME_0; $$.year = $1.value; }
 569         | tYEAR_UNIT
 570                 { $$ = RELATIVE_TIME_0; $$.year = 1; }
 571         | tORDINAL tMONTH_UNIT
 572                 { $$ = RELATIVE_TIME_0; $$.month = $1; }
 573         | tUNUMBER tMONTH_UNIT
 574                 { $$ = RELATIVE_TIME_0; $$.month = $1.value; }
 575         | tMONTH_UNIT
 576                 { $$ = RELATIVE_TIME_0; $$.month = 1; }
 577         | tORDINAL tDAY_UNIT
 578                 { $$ = RELATIVE_TIME_0; $$.day = $1 * $2; }
 579         | tUNUMBER tDAY_UNIT
 580                 { $$ = RELATIVE_TIME_0; $$.day = $1.value * $2; }
 581         | tDAY_UNIT
 582                 { $$ = RELATIVE_TIME_0; $$.day = $1; }
 583         | tORDINAL tHOUR_UNIT
 584                 { $$ = RELATIVE_TIME_0; $$.hour = $1; }
 585         | tUNUMBER tHOUR_UNIT
 586                 { $$ = RELATIVE_TIME_0; $$.hour = $1.value; }
 587         | tHOUR_UNIT
 588                 { $$ = RELATIVE_TIME_0; $$.hour = 1; }
 589         | tORDINAL tMINUTE_UNIT
 590                 { $$ = RELATIVE_TIME_0; $$.minutes = $1; }
 591         | tUNUMBER tMINUTE_UNIT
 592                 { $$ = RELATIVE_TIME_0; $$.minutes = $1.value; }
 593         | tMINUTE_UNIT
 594                 { $$ = RELATIVE_TIME_0; $$.minutes = 1; }
 595         | tORDINAL tSEC_UNIT
 596                 { $$ = RELATIVE_TIME_0; $$.seconds = $1; }
 597         | tUNUMBER tSEC_UNIT
 598                 { $$ = RELATIVE_TIME_0; $$.seconds = $1.value; }
 599         | tSDECIMAL_NUMBER tSEC_UNIT {
 600                 $$ = RELATIVE_TIME_0;
 601                 $$.seconds = $1.tv_sec;
 602                 $$.ns = $1.tv_nsec;
 603           }
 604         | tUDECIMAL_NUMBER tSEC_UNIT {
 605                 $$ = RELATIVE_TIME_0;
 606                 $$.seconds = $1.tv_sec;
 607                 $$.ns = $1.tv_nsec;
 608           }
 609         | tSEC_UNIT
 610                 { $$ = RELATIVE_TIME_0; $$.seconds = 1; }
 611         | relunit_snumber
 612 ;
 613
 614 relunit_snumber:
 615           tSNUMBER tYEAR_UNIT
 616                 { $$ = RELATIVE_TIME_0; $$.year = $1.value; }
 617         | tSNUMBER tMONTH_UNIT
 618                 { $$ = RELATIVE_TIME_0; $$.month = $1.value; }
 619         | tSNUMBER tDAY_UNIT
 620                 { $$ = RELATIVE_TIME_0; $$.day = $1.value * $2; }
 621         | tSNUMBER tHOUR_UNIT
 622                 { $$ = RELATIVE_TIME_0; $$.hour = $1.value; }
 623         | tSNUMBER tMINUTE_UNIT
 624                 { $$ = RELATIVE_TIME_0; $$.minutes = $1.value; }
 625         | tSNUMBER tSEC_UNIT
 626                 { $$ = RELATIVE_TIME_0; $$.seconds = $1.value; }
 627 ;
 628
 629 dayshift:
 630           tDAY_SHIFT
 631                 { $$ = RELATIVE_TIME_0; $$.day = $1; }
 632 ;
 633
 634 seconds: signed_seconds | unsigned_seconds;
 635
 636 signed_seconds:
 637           tSDECIMAL_NUMBER
 638         | tSNUMBER
 639                 { $$.tv_sec = $1.value; $$.tv_nsec = 0; }
 640 ;
 641
 642 unsigned_seconds:
 643           tUDECIMAL_NUMBER
 644         | tUNUMBER
 645                 { $$.tv_sec = $1.value; $$.tv_nsec = 0; }
 646 ;
 647
 648 number:
 649           tUNUMBER
 650                 { digits_to_date_time (pc, $1); }
 651 ;
 652
 653 hybrid:
 654           tUNUMBER relunit_snumber {
 655                 /**
 656                  * Hybrid all-digit and relative offset, so that we accept e.g.,
 657                  * "YYYYMMDD +N days" as well as "YYYYMMDD N days".
 658                  */
 659                 digits_to_date_time (pc, $1);
 660                 apply_relative_time (pc, $2, 1);
 661           }
 662 ;
 663
 664 o_colon_minutes:
 665           /* empty */
 666                 { $$.value = $$.digits = 0; }
 667         | ':' tUNUMBER {
 668                 $$ = $2;
 669           }
 670 ;
 671
 672 %%
 673
 674 static table const meridian_table[] = {
 675         { "AM",   tMERIDIAN, MERam },
 676         { "A.M.", tMERIDIAN, MERam },
 677         { "PM",   tMERIDIAN, MERpm },
 678         { "P.M.", tMERIDIAN, MERpm },
 679         { NULL, 0, 0 }
 680 };
 681
 682 static table const dst_table[] = {
 683         { "DST", tDST, 0 }
 684 };
 685
 686 static table const month_and_day_table[] = {
 687         { "JANUARY",  tMONTH,  1 },
 688         { "FEBRUARY", tMONTH,  2 },
 689         { "MARCH",    tMONTH,  3 },
 690         { "APRIL",    tMONTH,  4 },
 691         { "MAY",      tMONTH,  5 },
 692         { "JUNE",     tMONTH,  6 },
 693         { "JULY",     tMONTH,  7 },
 694         { "AUGUST",   tMONTH,  8 },
 695         { "SEPTEMBER",tMONTH,  9 },
 696         { "SEPT",     tMONTH,  9 },
 697         { "OCTOBER",  tMONTH, 10 },
 698         { "NOVEMBER", tMONTH, 11 },
 699         { "DECEMBER", tMONTH, 12 },
 700         { "SUNDAY",   tDAY,    0 },
 701         { "MONDAY",   tDAY,    1 },
 702         { "TUESDAY",  tDAY,    2 },
 703         { "TUES",     tDAY,    2 },
 704         { "WEDNESDAY",tDAY,    3 },
 705         { "WEDNES",   tDAY,    3 },
 706         { "THURSDAY", tDAY,    4 },
 707         { "THUR",     tDAY,    4 },
 708         { "THURS",    tDAY,    4 },
 709         { "FRIDAY",   tDAY,    5 },
 710         { "SATURDAY", tDAY,    6 },
 711         { NULL, 0, 0 }
 712 };
 713
 714 static table const time_units_table[] = {
 715         { "YEAR",     tYEAR_UNIT,      1 },
 716         { "MONTH",    tMONTH_UNIT,     1 },
 717         { "FORTNIGHT",tDAY_UNIT,      14 },
 718         { "WEEK",     tDAY_UNIT,       7 },
 719         { "DAY",      tDAY_UNIT,       1 },
 720         { "HOUR",     tHOUR_UNIT,      1 },
 721         { "MINUTE",   tMINUTE_UNIT,    1 },
 722         { "MIN",      tMINUTE_UNIT,    1 },
 723         { "SECOND",   tSEC_UNIT,       1 },
 724         { "SEC",      tSEC_UNIT,       1 },
 725         { NULL, 0, 0 }
 726 };
 727
 728 /* Assorted relative-time words. */
 729 static table const relative_time_table[] = {
 730         { "TOMORROW", tDAY_SHIFT,      1 },
 731         { "YESTERDAY",tDAY_SHIFT,     -1 },
 732         { "TODAY",    tDAY_SHIFT,      0 },
 733         { "NOW",      tDAY_SHIFT,      0 },
 734         { "LAST",     tORDINAL,       -1 },
 735         { "THIS",     tORDINAL,        0 },
 736         { "NEXT",     tORDINAL,        1 },
 737         { "FIRST",    tORDINAL,        1 },
 738       /*{ "SECOND",   tORDINAL,        2 }, */
 739         { "THIRD",    tORDINAL,        3 },
 740         { "FOURTH",   tORDINAL,        4 },
 741         { "FIFTH",    tORDINAL,        5 },
 742         { "SIXTH",    tORDINAL,        6 },
 743         { "SEVENTH",  tORDINAL,        7 },
 744         { "EIGHTH",   tORDINAL,        8 },
 745         { "NINTH",    tORDINAL,        9 },
 746         { "TENTH",    tORDINAL,       10 },
 747         { "ELEVENTH", tORDINAL,       11 },
 748         { "TWELFTH",  tORDINAL,       12 },
 749         { "AGO",      tAGO,           -1 },
 750         { "HENCE",    tAGO,            1 },
 751         { NULL, 0, 0 }
 752 };
 753
 754 /**
 755  * The universal time zone table.  These labels can be used even for
 756  * timestamps that would not otherwise be valid, e.g., GMT timestamps
 757  * in London during summer.
 758  */
 759 static table const universal_time_zone_table[] = {
 760         { "GMT",      tZONE,     HOUR ( 0) }, /* Greenwich Mean */
 761         { "UT",       tZONE,     HOUR ( 0) }, /* Universal (Coordinated) */
 762         { "UTC",      tZONE,     HOUR ( 0) },
 763         { NULL, 0, 0 }
 764 };
 765
 766 /**
 767  * The time zone table.  This table is necessarily incomplete, as time
 768  * zone abbreviations are ambiguous; e.g. Australians interpret "EST"
 769  * as Eastern time in Australia, not as US Eastern Standard Time.
 770  * You cannot rely on parse_date to handle arbitrary time zone
 771  * abbreviations; use numeric abbreviations like "-0500" instead.
 772  */
 773 static table const time_zone_table[] = {
 774         { "WET",      tZONE,     HOUR ( 0) }, /* Western European */
 775         { "WEST",     tDAYZONE,  HOUR ( 0) }, /* Western European Summer */
 776         { "BST",      tDAYZONE,  HOUR ( 0) }, /* British Summer */
 777         { "ART",      tZONE,    -HOUR ( 3) }, /* Argentina */
 778         { "BRT",      tZONE,    -HOUR ( 3) }, /* Brazil */
 779         { "BRST",     tDAYZONE, -HOUR ( 3) }, /* Brazil Summer */
 780         { "NST",      tZONE,   -(HOUR ( 3) + 30) },   /* Newfoundland Standard */
 781         { "NDT",      tDAYZONE,-(HOUR ( 3) + 30) },   /* Newfoundland Daylight */
 782         { "AST",      tZONE,    -HOUR ( 4) }, /* Atlantic Standard */
 783         { "ADT",      tDAYZONE, -HOUR ( 4) }, /* Atlantic Daylight */
 784         { "CLT",      tZONE,    -HOUR ( 4) }, /* Chile */
 785         { "CLST",     tDAYZONE, -HOUR ( 4) }, /* Chile Summer */
 786         { "EST",      tZONE,    -HOUR ( 5) }, /* Eastern Standard */
 787         { "EDT",      tDAYZONE, -HOUR ( 5) }, /* Eastern Daylight */
 788         { "CST",      tZONE,    -HOUR ( 6) }, /* Central Standard */
 789         { "CDT",      tDAYZONE, -HOUR ( 6) }, /* Central Daylight */
 790         { "MST",      tZONE,    -HOUR ( 7) }, /* Mountain Standard */
 791         { "MDT",      tDAYZONE, -HOUR ( 7) }, /* Mountain Daylight */
 792         { "PST",      tZONE,    -HOUR ( 8) }, /* Pacific Standard */
 793         { "PDT",      tDAYZONE, -HOUR ( 8) }, /* Pacific Daylight */
 794         { "AKST",     tZONE,    -HOUR ( 9) }, /* Alaska Standard */
 795         { "AKDT",     tDAYZONE, -HOUR ( 9) }, /* Alaska Daylight */
 796         { "HST",      tZONE,    -HOUR (10) }, /* Hawaii Standard */
 797         { "HAST",     tZONE,    -HOUR (10) }, /* Hawaii-Aleutian Standard */
 798         { "HADT",     tDAYZONE, -HOUR (10) }, /* Hawaii-Aleutian Daylight */
 799         { "SST",      tZONE,    -HOUR (12) }, /* Samoa Standard */
 800         { "WAT",      tZONE,     HOUR ( 1) }, /* West Africa */
 801         { "CET",      tZONE,     HOUR ( 1) }, /* Central European */
 802         { "CEST",     tDAYZONE,  HOUR ( 1) }, /* Central European Summer */
 803         { "MET",      tZONE,     HOUR ( 1) }, /* Middle European */
 804         { "MEZ",      tZONE,     HOUR ( 1) }, /* Middle European */
 805         { "MEST",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
 806         { "MESZ",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
 807         { "EET",      tZONE,     HOUR ( 2) }, /* Eastern European */
 808         { "EEST",     tDAYZONE,  HOUR ( 2) }, /* Eastern European Summer */
 809         { "CAT",      tZONE,     HOUR ( 2) }, /* Central Africa */
 810         { "SAST",     tZONE,     HOUR ( 2) }, /* South Africa Standard */
 811         { "EAT",      tZONE,     HOUR ( 3) }, /* East Africa */
 812         { "MSK",      tZONE,     HOUR ( 3) }, /* Moscow */
 813         { "MSD",      tDAYZONE,  HOUR ( 3) }, /* Moscow Daylight */
 814         { "IST",      tZONE,    (HOUR ( 5) + 30) },   /* India Standard */
 815         { "SGT",      tZONE,     HOUR ( 8) }, /* Singapore */
 816         { "KST",      tZONE,     HOUR ( 9) }, /* Korea Standard */
 817         { "JST",      tZONE,     HOUR ( 9) }, /* Japan Standard */
 818         { "GST",      tZONE,     HOUR (10) }, /* Guam Standard */
 819         { "NZST",     tZONE,     HOUR (12) }, /* New Zealand Standard */
 820         { "NZDT",     tDAYZONE,  HOUR (12) }, /* New Zealand Daylight */
 821         { NULL, 0, 0 }
 822 };
 823
 824 /**
 825  * Military time zone table.
 826  *
 827  * Note 'T' is a special case, as it is used as the separator in ISO
 828  * 8601 date and time of day representation.
 829  */
 830 static table const military_table[] = {
 831         { "A", tZONE, -HOUR ( 1) },
 832         { "B", tZONE, -HOUR ( 2) },
 833         { "C", tZONE, -HOUR ( 3) },
 834         { "D", tZONE, -HOUR ( 4) },
 835         { "E", tZONE, -HOUR ( 5) },
 836         { "F", tZONE, -HOUR ( 6) },
 837         { "G", tZONE, -HOUR ( 7) },
 838         { "H", tZONE, -HOUR ( 8) },
 839         { "I", tZONE, -HOUR ( 9) },
 840         { "K", tZONE, -HOUR (10) },
 841         { "L", tZONE, -HOUR (11) },
 842         { "M", tZONE, -HOUR (12) },
 843         { "N", tZONE,  HOUR ( 1) },
 844         { "O", tZONE,  HOUR ( 2) },
 845         { "P", tZONE,  HOUR ( 3) },
 846         { "Q", tZONE,  HOUR ( 4) },
 847         { "R", tZONE,  HOUR ( 5) },
 848         { "S", tZONE,  HOUR ( 6) },
 849         { "T", 'T',    0 },
 850         { "U", tZONE,  HOUR ( 8) },
 851         { "V", tZONE,  HOUR ( 9) },
 852         { "W", tZONE,  HOUR (10) },
 853         { "X", tZONE,  HOUR (11) },
 854         { "Y", tZONE,  HOUR (12) },
 855         { "Z", tZONE,  HOUR ( 0) },
 856         { NULL, 0, 0 }
 857 };
 858
 859 /**
 860  * Convert a time offset expressed as HH:MM or HHMM into an integer count of
 861  * minutes.  If hh is more than 2 digits then it is of the form HHMM and must be
 862  * delimited; in that case 'mm' is required to be absent.  Otherwise, hh and mm
 863  * are used ('mm' contains digits that were prefixed with a colon).
 864  *
 865  * POSIX TZ and ISO 8601 both define the maximum offset as 24:59. POSIX also
 866  * allows seconds, but currently the parser rejects them. Both require minutes
 867  * to be zero padded (2 digits). ISO requires hours to be zero padded, POSIX
 868  * does not, either is accepted; which means an invalid ISO offset could pass.
 869  */
 870
 871 static int time_zone_hhmm(parser_control *pc, textint hh, textint mm)
 872 {
 873         int h, m;
 874
 875         if (hh.digits > 2 && hh.digits < 5 && mm.digits == 0) {
 876                 h = hh.value / 100;
 877                 m = hh.value % 100;
 878         } else if (hh.digits < 3 && (mm.digits == 0 || mm.digits == 2)) {
 879                 h = hh.value;
 880                 m = hh.negative ? -mm.value : mm.value;
 881         } else
 882                 return 0;
 883
 884         if (abs(h) > 24 || abs(m) > 59)
 885                 return 0;
 886
 887         pc->time_zone =  h * 60 + m;
 888         return 1;
 889 }
 890
 891 static int to_hour(intmax_t hours, int meridian)
 892 {
 893         switch (meridian) {
 894         default: /* Pacify GCC. */
 895         case MER24:
 896                 return 0 <= hours && hours < 24 ? hours : -1;
 897         case MERam:
 898                 return 0 < hours && hours < 12 ? hours : hours == 12 ? 0 : -1;
 899         case MERpm:
 900                 return 0 < hours && hours < 12 ? hours + 12 : hours == 12 ? 12 : -1;
 901         }
 902 }
 903
 904 static long int to_year(textint textyear)
 905 {
 906         intmax_t year = textyear.value;
 907
 908         if (year < 0)
 909                 year = -year;
 910
 911         /**
 912          * XPG4 suggests that years 00-68 map to 2000-2068, and
 913          * years 69-99 map to 1969-1999.
 914          */
 915         else if (textyear.digits == 2)
 916                         year += year < 69 ? 2000 : 1900;
 917
 918         return year;
 919 }
 920
 921 static table const * lookup_zone(parser_control const *pc, char const *name)
 922 {
 923         table const *tp;
 924
 925         for (tp = universal_time_zone_table; tp->name; tp++)
 926                 if (strcmp (name, tp->name) == 0)
 927                         return tp;
 928
 929         /**
 930          * Try local zone abbreviations before those in time_zone_table, as
 931          * the local ones are more likely to be right.
 932          */
 933         for (tp = pc->local_time_zone_table; tp->name; tp++)
 934                 if (strcmp (name, tp->name) == 0)
 935                         return tp;
 936
 937         for (tp = time_zone_table; tp->name; tp++)
 938                 if (strcmp (name, tp->name) == 0)
 939                         return tp;
 940
 941         return NULL;
 942 }
 943
 944 #if ! HAVE_TM_GMTOFF
 945 /**
 946  * Yield the difference between *A and *B,
 947  * measured in seconds, ignoring leap seconds.
 948  * The body of this function is taken directly from the GNU C Library;
 949  * see src/strftime.c.
 950  */
 951 static int tm_diff(struct tm const *a, struct tm const *b)
 952 {
 953         /**
 954          * Compute intervening leap days correctly even if year is negative.
 955          * Take care to avoid int overflow in leap day calculations.
 956          */
 957         int a4 = SHR (a->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (a->tm_year & 3);
 958         int b4 = SHR (b->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (b->tm_year & 3);
 959         int a100 = a4 / 25 - (a4 % 25 < 0);
 960         int b100 = b4 / 25 - (b4 % 25 < 0);
 961         int a400 = SHR (a100, 2);
 962         int b400 = SHR (b100, 2);
 963         int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
 964         int years = a->tm_year - b->tm_year;
 965         int days = (365 * years + intervening_leap_days
 966                          + (a->tm_yday - b->tm_yday));
 967         return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
 968                 + (a->tm_min - b->tm_min))
 969                 + (a->tm_sec - b->tm_sec));
 970 }
 971 #endif /* ! HAVE_TM_GMTOFF */
 972
 973 static table const * lookup_word(parser_control const *pc, char *word)
 974 {
 975         char *p;
 976         char *q;
 977         size_t wordlen;
 978         table const *tp;
 979         int period_found;
 980         int abbrev;
 981
 982         /* Make it uppercase. */
 983         for (p = word; *p; p++)
 984                 *p = c_toupper (to_uchar (*p));
 985
 986         for (tp = meridian_table; tp->name; tp++)
 987                 if (strcmp (word, tp->name) == 0)
 988                         return tp;
 989
 990         /* See if we have an abbreviation for a month. */
 991         wordlen = strlen (word);
 992         abbrev = wordlen == 3 || (wordlen == 4 && word[3] == '.');
 993
 994         for (tp = month_and_day_table; tp->name; tp++)
 995                 if ((abbrev ? strncmp (word, tp->name, 3) :
 996                      strcmp (word, tp->name)) == 0)
 997                         return tp;
 998
 999         if ((tp = lookup_zone (pc, word)))
1000                 return tp;
1001
1002         if (strcmp (word, dst_table[0].name) == 0)
1003                 return dst_table;
1004
1005         for (tp = time_units_table; tp->name; tp++)
1006                 if (strcmp (word, tp->name) == 0)
1007                         return tp;
1008
1009         /* Strip off any plural and try the units table again. */
1010         if (word[wordlen - 1] == 'S') {
1011                 word[wordlen - 1] = '\0';
1012                 for (tp = time_units_table; tp->name; tp++)
1013                         if (strcmp (word, tp->name) == 0)
1014                                 return tp;
1015                 word[wordlen - 1] = 'S'; /* For "this" in relative_time_table. */
1016         }
1017
1018         for (tp = relative_time_table; tp->name; tp++)
1019                 if (strcmp (word, tp->name) == 0)
1020                         return tp;
1021
1022         /* Military time zones. */
1023         if (wordlen == 1)
1024                 for (tp = military_table; tp->name; tp++)
1025                         if (word[0] == tp->name[0])
1026                                 return tp;
1027
1028         /* Drop out any periods and try the time zone table again. */
1029         for (period_found = 0, p = q = word; (*p = *q); q++)
1030                 if (*q == '.')
1031                         period_found = 1;
1032                 else
1033                         p++;
1034         if (period_found && (tp = lookup_zone (pc, word)))
1035                 return tp;
1036
1037         return NULL;
1038 }
1039
1040 static int yylex (union YYSTYPE *lvalp, parser_control *pc)
1041 {
1042         unsigned char c;
1043         size_t count;
1044
1045         for (;;) {
1046                 while (c = *pc->input, c_isspace (c))
1047                         pc->input++;
1048
1049                 if (c_isdigit (c) || c == '-' || c == '+') {
1050                         char const *p;
1051                         int sign;
1052                         uintmax_t value;
1053                         if (c == '-' || c == '+') {
1054                                 sign = c == '-' ? -1 : 1;
1055                                 while (c = *++pc->input, c_isspace (c))
1056                                         continue;
1057                                 if (! c_isdigit (c))
1058                                         /* skip the '-' sign */
1059                                         continue;
1060                         } else
1061                                 sign = 0;
1062                         p = pc->input;
1063                         for (value = 0; ; value *= 10) {
1064                                 uintmax_t value1 = value + (c - '0');
1065                                 if (value1 < value)
1066                                         return '?';
1067                                 value = value1;
1068                                 c = *++p;
1069                                 if (! c_isdigit (c))
1070                                         break;
1071                                 if (UINTMAX_MAX / 10 < value)
1072                                         return '?';
1073                         }
1074                         if ((c == '.' || c == ',') && c_isdigit (p[1])) {
1075                                 time_t s;
1076                                 int ns;
1077                                 int digits;
1078                                 uintmax_t value1;
1079
1080                                 /* Check for overflow when converting value to
1081                                  * time_t.
1082                                  */
1083                                 if (sign < 0) {
1084                                         s = - value;
1085                                         if (0 < s)
1086                                                 return '?';
1087                                         value1 = -s;
1088                                 } else {
1089                                         s = value;
1090                                         if (s < 0)
1091                                                 return '?';
1092                                         value1 = s;
1093                                 }
1094                                 if (value != value1)
1095                                         return '?';
1096
1097                                 /* Accumulate fraction, to ns precision. */
1098                                 p++;
1099                                 ns = *p++ - '0';
1100                                 for (digits = 2;
1101                                      digits <= LOG10_BILLION; digits++) {
1102                                         ns *= 10;
1103                                         if (c_isdigit (*p))
1104                                                 ns += *p++ - '0';
1105                                 }
1106
1107                                 /* Skip excess digits, truncating toward
1108                                  * -Infinity.
1109                                  */
1110                                 if (sign < 0)
1111                                         for (; c_isdigit (*p); p++)
1112                                                 if (*p != '0') {
1113                                                         ns++;
1114                                                         break;
1115                                                 }
1116                                 while (c_isdigit (*p))
1117                                         p++;
1118
1119                                 /* Adjust to the timespec convention, which is
1120                                  * that tv_nsec is always a positive offset even
1121                                  * if tv_sec is negative.
1122                                  */
1123                                 if (sign < 0 && ns) {
1124                                         s--;
1125                                         if (! (s < 0))
1126                                                 return '?';
1127                                         ns = BILLION - ns;
1128                                 }
1129
1130                                 lvalp->timespec.tv_sec = s;
1131                                 lvalp->timespec.tv_nsec = ns;
1132                                 pc->input = p;
1133                                 return
1134                                   sign ? tSDECIMAL_NUMBER : tUDECIMAL_NUMBER;
1135                         } else {
1136                                 lvalp->textintval.negative = sign < 0;
1137                                 if (sign < 0) {
1138                                         lvalp->textintval.value = - value;
1139                                         if (0 < lvalp->textintval.value)
1140                                                 return '?';
1141                                 } else {
1142                                         lvalp->textintval.value = value;
1143                                         if (lvalp->textintval.value < 0)
1144                                                 return '?';
1145                                 }
1146                                 lvalp->textintval.digits = p - pc->input;
1147                                 pc->input = p;
1148                                 return sign ? tSNUMBER : tUNUMBER;
1149                         }
1150                 }
1151
1152                 if (c_isalpha (c)) {
1153                         char buff[20];
1154                         char *p = buff;
1155                         table const *tp;
1156
1157                         do {
1158                                 if (p < buff + sizeof buff - 1)
1159                                 *p++ = c;
1160                                 c = *++pc->input;
1161                         }
1162                         while (c_isalpha (c) || c == '.');
1163
1164                         *p = '\0';
1165                         tp = lookup_word (pc, buff);
1166                         if (! tp) {
1167                                 return '?';
1168                         }
1169                         lvalp->intval = tp->value;
1170                         return tp->type;
1171                 }
1172
1173                 if (c != '(')
1174                         return to_uchar (*pc->input++);
1175
1176                 count = 0;
1177                 do {
1178                         c = *pc->input++;
1179                         if (c == '\0')
1180                                 return c;
1181                         if (c == '(')
1182                                 count++;
1183                         else if (c == ')')
1184                                 count--;
1185                 }
1186                 while (count != 0);
1187         }
1188 }
1189
1190 /* Do nothing if the parser reports an error. */
1191 static int yyerror(parser_control const *pc __attribute__((__unused__)),
1192                    char const *s __attribute__((__unused__)))
1193 {
1194         return 0;
1195 }
1196
1197 /**
1198  * If *TM0 is the old and *TM1 is the new value of a struct tm after
1199  * passing it to mktime, return 1 if it's OK that mktime returned T.
1200  * It's not OK if *TM0 has out-of-range members.
1201  */
1202
1203 static int mktime_ok(struct tm const *tm0, struct tm const *tm1, time_t t)
1204 {
1205         if (t == (time_t) -1) {
1206                 /**
1207                  * Guard against falsely reporting an error when parsing a
1208                  * timestamp that happens to equal (time_t) -1, on a host that
1209                  * supports such a timestamp.
1210                  */
1211                 tm1 = localtime (&t);
1212                 if (!tm1)
1213                         return 0;
1214         }
1215
1216         return ! ((tm0->tm_sec ^ tm1->tm_sec)
1217                   | (tm0->tm_min ^ tm1->tm_min)
1218                   | (tm0->tm_hour ^ tm1->tm_hour)
1219                   | (tm0->tm_mday ^ tm1->tm_mday)
1220                   | (tm0->tm_mon ^ tm1->tm_mon)
1221                   | (tm0->tm_year ^ tm1->tm_year));
1222 }
1223
1224 /**
1225  * A reasonable upper bound for the size of ordinary TZ strings.
1226  * Use heap allocation if TZ's length exceeds this.
1227  */
1228 enum { TZBUFSIZE = 100 };
1229
1230 /**
1231  * Return a copy of TZ, stored in TZBUF if it fits, and heap-allocated
1232  * otherwise.
1233  */
1234 static char * get_tz(char tzbuf[TZBUFSIZE])
1235 {
1236         char *tz = getenv ("TZ");
1237         if (tz) {
1238                 size_t tzsize = strlen (tz) + 1;
1239                 tz = (tzsize <= TZBUFSIZE
1240                       ? memcpy (tzbuf, tz, tzsize)
1241                       : strdup (tz));
1242         }
1243         return tz;
1244 }
1245
1246 /**
1247  * Parse a date/time string, storing the resulting time value into *result.
1248  * The string itself is pointed to by *p.  Return 1 if successful.
1249  * *p can be an incomplete or relative time specification; if so, use
1250  * *now as the basis for the returned time.
1251  */
1252 int parse_date(struct timespec *result, char const *p,
1253                    struct timespec const *now)
1254 {
1255         time_t Start;
1256         intmax_t Start_ns;
1257         struct tm const *tmp;
1258         struct tm tm;
1259         struct tm tm0;
1260         parser_control pc;
1261         struct timespec gettime_buffer;
1262         unsigned char c;
1263         int tz_was_altered = 0;
1264         char *tz0 = NULL;
1265         char tz0buf[TZBUFSIZE];
1266         int ok = 1;
1267         struct timeval tv;
1268
1269         if (! now) {
1270                 gettimeofday (&tv, NULL);
1271                 gettime_buffer.tv_sec = tv.tv_sec;
1272                 gettime_buffer.tv_nsec = tv.tv_usec * 1000;
1273                 now = &gettime_buffer;
1274         }
1275
1276         Start = now->tv_sec;
1277         Start_ns = now->tv_nsec;
1278
1279         tmp = localtime (&now->tv_sec);
1280         if (! tmp)
1281                 return 0;
1282
1283         while (c = *p, c_isspace (c))
1284                 p++;
1285
1286         if (strncmp (p, "TZ=\"", 4) == 0) {
1287                 char const *tzbase = p + 4;
1288                 size_t tzsize = 1;
1289                 char const *s;
1290
1291                 for (s = tzbase; *s; s++, tzsize++)
1292                         if (*s == '\\') {
1293                                 s++;
1294                                 if (! (*s == '\\' || *s == '"'))
1295                                         break;
1296                         } else if (*s == '"') {
1297                                 char *z;
1298                                 char *tz1;
1299                                 char tz1buf[TZBUFSIZE];
1300                                 int large_tz = TZBUFSIZE < tzsize;
1301                                 int setenv_ok;
1302
1303                                 tz0 = get_tz (tz0buf);
1304                                 if (!tz0)
1305                                         goto fail;
1306
1307                                 if (large_tz) {
1308                                         z = tz1 = malloc (tzsize);
1309                                         if (!tz1)
1310                                                 goto fail;
1311                                 } else
1312                                         z = tz1 = tz1buf;
1313
1314                                 for (s = tzbase; *s != '"'; s++)
1315                                         *z++ = *(s += *s == '\\');
1316                                 *z = '\0';
1317                                 setenv_ok = setenv ("TZ", tz1, 1) == 0;
1318                                 if (large_tz)
1319                                         free (tz1);
1320                                 if (!setenv_ok)
1321                                         goto fail;
1322                                 tz_was_altered = 1;
1323
1324                                 p = s + 1;
1325                                 while (c = *p, c_isspace (c))
1326                                         p++;
1327
1328                                 break;
1329                         }
1330         }
1331
1332         /**
1333          * As documented, be careful to treat the empty string just like
1334          * a date string of "0".  Without this, an empty string would be
1335          * declared invalid when parsed during a DST transition.
1336          */
1337         if (*p == '\0')
1338                 p = "0";
1339
1340         pc.input = p;
1341         pc.year.value = tmp->tm_year;
1342         pc.year.value += TM_YEAR_BASE;
1343         pc.year.digits = 0;
1344         pc.month = tmp->tm_mon + 1;
1345         pc.day = tmp->tm_mday;
1346         pc.hour = tmp->tm_hour;
1347         pc.minutes = tmp->tm_min;
1348         pc.seconds.tv_sec = tmp->tm_sec;
1349         pc.seconds.tv_nsec = Start_ns;
1350         tm.tm_isdst = tmp->tm_isdst;
1351
1352         pc.meridian = MER24;
1353         pc.rel = RELATIVE_TIME_0;
1354         pc.timespec_seen = 0;
1355         pc.rels_seen = 0;
1356         pc.dates_seen = 0;
1357         pc.days_seen = 0;
1358         pc.times_seen = 0;
1359         pc.local_zones_seen = 0;
1360         pc.dsts_seen = 0;
1361         pc.zones_seen = 0;
1362
1363 #if HAVE_STRUCT_TM_TM_ZONE
1364         pc.local_time_zone_table[0].name = tmp->tm_zone;
1365         pc.local_time_zone_table[0].type = tLOCAL_ZONE;
1366         pc.local_time_zone_table[0].value = tmp->tm_isdst;
1367         pc.local_time_zone_table[1].name = NULL;
1368
1369         /**
1370          * Probe the names used in the next three calendar quarters, looking
1371          * for a tm_isdst different from the one we already have.
1372          */
1373         {
1374                 int quarter;
1375                 for (quarter = 1; quarter <= 3; quarter++) {
1376                         time_t probe = Start + quarter * (90 * 24 * 60 * 60);
1377                         struct tm const *probe_tm = localtime (&probe);
1378                         if (probe_tm && probe_tm->tm_zone
1379                                 && probe_tm->tm_isdst
1380                                 != pc.local_time_zone_table[0].value) {
1381                                         {
1382                                           pc.local_time_zone_table[1].name
1383                                           = probe_tm->tm_zone;
1384                                           pc.local_time_zone_table[1].type
1385                                           = tLOCAL_ZONE;
1386                                           pc.local_time_zone_table[1].value
1387                                           = probe_tm->tm_isdst;
1388                                           pc.local_time_zone_table[2].name
1389                                           = NULL;
1390                                         }
1391                                 break;
1392                         }
1393                 }
1394         }
1395 #else
1396 #if HAVE_TZNAME
1397         {
1398 # if !HAVE_DECL_TZNAME
1399                 extern char *tzname[];
1400 # endif
1401                 int i;
1402                 for (i = 0; i < 2; i++) {
1403                         pc.local_time_zone_table[i].name = tzname[i];
1404                         pc.local_time_zone_table[i].type = tLOCAL_ZONE;
1405                         pc.local_time_zone_table[i].value = i;
1406                 }
1407                 pc.local_time_zone_table[i].name = NULL;
1408         }
1409 #else
1410         pc.local_time_zone_table[0].name = NULL;
1411 #endif
1412 #endif
1413
1414         if (pc.local_time_zone_table[0].name && pc.local_time_zone_table[1].name
1415             && ! strcmp (pc.local_time_zone_table[0].name,
1416                          pc.local_time_zone_table[1].name)) {
1417                 /**
1418                  * This locale uses the same abbreviation for standard and
1419                  * daylight times.  So if we see that abbreviation, we don't
1420                  * know whether it's daylight time.
1421                  */
1422                 pc.local_time_zone_table[0].value = -1;
1423                 pc.local_time_zone_table[1].name = NULL;
1424         }
1425
1426         if (yyparse (&pc) != 0) {
1427                 goto fail;
1428         }
1429
1430         if (pc.timespec_seen)
1431                 *result = pc.seconds;
1432         else {
1433                 if (1 < (pc.times_seen | pc.dates_seen | pc.days_seen
1434                          | pc.dsts_seen
1435                          | (pc.local_zones_seen + pc.zones_seen))) {
1436                         goto fail;
1437                 }
1438
1439                 tm.tm_year = to_year (pc.year) - TM_YEAR_BASE;
1440                 tm.tm_mon = pc.month - 1;
1441                 tm.tm_mday = pc.day;
1442                 if (pc.times_seen || (pc.rels_seen &&
1443                                       ! pc.dates_seen && ! pc.days_seen)) {
1444                         tm.tm_hour = to_hour (pc.hour, pc.meridian);
1445                         if (tm.tm_hour < 0) {
1446                                 goto fail;
1447                         }
1448                         tm.tm_min = pc.minutes;
1449                         tm.tm_sec = pc.seconds.tv_sec;
1450                 } else {
1451                         tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
1452                         pc.seconds.tv_nsec = 0;
1453                 }
1454
1455                 /**
1456                  * Let mktime deduce tm_isdst if we have an absolute timestamp.
1457                  */
1458                 if (pc.dates_seen | pc.days_seen | pc.times_seen)
1459                         tm.tm_isdst = -1;
1460
1461                 /**
1462                  * But if the input explicitly specifies local time with or
1463                  * without DST, give mktime that information.
1464                  */
1465                 if (pc.local_zones_seen)
1466                         tm.tm_isdst = pc.local_isdst;
1467
1468                 tm0 = tm;
1469
1470                 Start = mktime (&tm);
1471
1472                 if (! mktime_ok (&tm0, &tm, Start)) {
1473                         if (! pc.zones_seen) {
1474                                 goto fail;
1475                         } else {
1476                                 /** Guard against falsely reporting errors near
1477                                  * the time_t boundaries when parsing times in
1478                                  * other time zones.  For example, suppose the
1479                                  * input string "1969-12-31 23:00:00 -0100", the
1480                                  * current time zone is 8 hours ahead of UTC,
1481                                  * and the min time_t value is 1970-01-01
1482                                  * 00:00:00 UTC.  Then the min localtime value
1483                                  * is 1970-01-01 08:00:00, and mktime will
1484                                  * therefore fail on 1969-12-31 23:00:00.  To
1485                                  * work around the problem, set the time zone to
1486                                  * 1 hour behind UTC temporarily by setting
1487                                  * TZ="XXX1:00" and try mktime again.
1488                                  */
1489
1490                                 intmax_t time_zone = pc.time_zone;
1491
1492                                 intmax_t abs_time_zone = time_zone < 0
1493                                          ? - time_zone : time_zone;
1494
1495                                 intmax_t abs_time_zone_hour
1496                                          = abs_time_zone / 60;
1497
1498                                 int abs_time_zone_min = abs_time_zone % 60;
1499
1500                                 char tz1buf[sizeof "XXX+0:00"
1501                                             + sizeof pc.time_zone
1502                                             * CHAR_BIT / 3];
1503
1504                                 if (!tz_was_altered)
1505                                         tz0 = get_tz (tz0buf);
1506                                 sprintf (tz1buf, "XXX%s%jd:%02d",
1507                                          &"-"[time_zone < 0],
1508                                          abs_time_zone_hour,
1509                                          abs_time_zone_min);
1510                                 if (setenv ("TZ", tz1buf, 1) != 0) {
1511                                         goto fail;
1512                                 }
1513                                 tz_was_altered = 1;
1514                                 tm = tm0;
1515                                 Start = mktime (&tm);
1516                                 if (! mktime_ok (&tm0, &tm, Start)) {
1517                                         goto fail;
1518                                 }
1519                         }
1520                 }
1521
1522                 if (pc.days_seen && ! pc.dates_seen) {
1523                         tm.tm_mday += ((pc.day_number - tm.tm_wday + 7) % 7 + 7
1524                                        * (pc.day_ordinal
1525                                           - (0 < pc.day_ordinal
1526                                              && tm.tm_wday != pc.day_number)));
1527                         tm.tm_isdst = -1;
1528                         Start = mktime (&tm);
1529                         if (Start == (time_t) -1) {
1530                                 goto fail;
1531                         }
1532                 }
1533                 /* Add relative date. */
1534                 if (pc.rel.year | pc.rel.month | pc.rel.day) {
1535                         int year = tm.tm_year + pc.rel.year;
1536                         int month = tm.tm_mon + pc.rel.month;
1537                         int day = tm.tm_mday + pc.rel.day;
1538                         if (((year < tm.tm_year) ^ (pc.rel.year < 0))
1539                                 | ((month < tm.tm_mon) ^ (pc.rel.month < 0))
1540                                 | ((day < tm.tm_mday) ^ (pc.rel.day < 0))) {
1541                                 goto fail;
1542                         }
1543                         tm.tm_year = year;
1544                         tm.tm_mon = month;
1545                         tm.tm_mday = day;
1546                         tm.tm_hour = tm0.tm_hour;
1547                         tm.tm_min = tm0.tm_min;
1548                         tm.tm_sec = tm0.tm_sec;
1549                         tm.tm_isdst = tm0.tm_isdst;
1550                         Start = mktime (&tm);
1551                         if (Start == (time_t) -1) {
1552                                 goto fail;
1553                         }
1554                 }
1555
1556                 /**
1557                  * The only "output" of this if-block is an updated Start value,
1558                  * so this block must follow others that clobber Start.
1559                  */
1560                 if (pc.zones_seen) {
1561                         intmax_t delta = pc.time_zone * 60;
1562                         time_t t1;
1563 #ifdef HAVE_TM_GMTOFF
1564                         delta -= tm.tm_gmtoff;
1565 #else
1566                         time_t t = Start;
1567                         struct tm const *gmt = gmtime (&t);
1568                         if (! gmt) {
1569                                 goto fail;
1570                         }
1571                         delta -= tm_diff (&tm, gmt);
1572 #endif
1573                         t1 = Start - delta;
1574                         if ((Start < t1) != (delta < 0)) {
1575                                 goto fail;  /* time_t overflow */
1576                         }
1577                         Start = t1;
1578                 }
1579
1580                 /**
1581                  * Add relative hours, minutes, and seconds.  On hosts that
1582                  * support leap seconds, ignore the possibility of leap seconds;
1583                  * e.g., "+ 10 minutes" adds 600 seconds, even if one of them is
1584                  * a leap second.  Typically this is not what the user wants,
1585                  * but it's too hard to do it the other way, because the time
1586                  * zone indicator must be applied before relative times, and if
1587                  * mktime is applied again the time zone will be lost.
1588                  */
1589                 intmax_t sum_ns = pc.seconds.tv_nsec + pc.rel.ns;
1590                 intmax_t normalized_ns = (sum_ns % BILLION + BILLION) % BILLION;
1591                 time_t t0 = Start;
1592                 intmax_t d1 = 60 * 60 * pc.rel.hour;
1593                 time_t t1 = t0 + d1;
1594                 intmax_t d2 = 60 * pc.rel.minutes;
1595                 time_t t2 = t1 + d2;
1596                 time_t d3 = pc.rel.seconds;
1597                 time_t t3 = t2 + d3;
1598                 intmax_t d4 = (sum_ns - normalized_ns) / BILLION;
1599                 time_t t4 = t3 + d4;
1600                 time_t t5 = t4;
1601
1602                 if ((d1 / (60 * 60) ^ pc.rel.hour)
1603                     | (d2 / 60 ^ pc.rel.minutes)
1604                     | ((t1 < t0) ^ (d1 < 0))
1605                     | ((t2 < t1) ^ (d2 < 0))
1606                     | ((t3 < t2) ^ (d3 < 0))
1607                     | ((t4 < t3) ^ (d4 < 0))
1608                     | (t5 != t4)) {
1609                         goto fail;
1610                 }
1611                 result->tv_sec = t5;
1612                 result->tv_nsec = normalized_ns;
1613         }
1614
1615         goto done;
1616
1617         fail:
1618                 ok = 0;
1619         done:
1620                 if (tz_was_altered)
1621                         ok &= (tz0 ? setenv ("TZ", tz0, 1)
1622                                    : unsetenv ("TZ")) == 0;
1623                 if (tz0 != tz0buf)
1624                         free (tz0);
1625                 return ok;
1626 }