Adding upstream version 2.36.1.upstream/2.36.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1629 insertions, 0 deletions

diff --git a/sys-utils/hwclock-parse-date.y b/sys-utils/hwclock-parse-date.y
new file mode 100644
index 0000000..35669fd
--- /dev/null
+++ b/sys-utils/hwclock-parse-date.y
@@ -0,0 +1,1629 @@
+%{
+/**
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Parse a string into an internal timestamp.
+ *
+ * This file is based on gnulib parse-datetime.y-dd7a871 with
+ * the other gnulib dependencies removed for use in util-linux.
+ *
+ * Copyright (C) 1999-2000, 2002-2017 Free Software Foundation, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Originally written by Steven M. Bellovin <smb@research.att.com> while
+ * at the University of North Carolina at Chapel Hill.  Later tweaked by
+ * a couple of people on Usenet.  Completely overhauled by Rich $alz
+ * <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
+ *
+ * Modified by Paul Eggert <eggert@twinsun.com> in August 1999 to do
+ * the right thing about local DST.  Also modified by Paul Eggert
+ * <eggert@cs.ucla.edu> in February 2004 to support
+ * nanosecond-resolution timestamps, and in October 2004 to support
+ * TZ strings in dates.
+ */
+
+/**
+ * FIXME: Check for arithmetic overflow in all cases, not just
+ * some of them.
+ */
+
+#include <sys/time.h>
+#include <time.h>
+
+#include "c.h"
+#include "timeutils.h"
+#include "hwclock.h"
+
+/**
+ * There's no need to extend the stack, so there's no need to involve
+ * alloca.
+ */
+#define YYSTACK_USE_ALLOCA 0
+
+/**
+ * Tell Bison how much stack space is needed.  20 should be plenty for
+ * this grammar, which is not right recursive.  Beware setting it too
+ * high, since that might cause problems on machines whose
+ * implementations have lame stack-overflow checking.
+ */
+#define YYMAXDEPTH 20
+#define YYINITDEPTH YYMAXDEPTH
+
+/**
+ * Since the code of parse-datetime.y is not included in the Emacs executable
+ * itself, there is no need to #define static in this file.  Even if
+ * the code were included in the Emacs executable, it probably
+ * wouldn't do any harm to #undef it here; this will only cause
+ * problems if we try to write to a static variable, which I don't
+ * think this code needs to do.
+ */
+#ifdef emacs
+# undef static
+#endif
+
+#include <inttypes.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+#include <stdarg.h>
+#include "cctype.h"
+#include "nls.h"
+
+/**
+ * Bison's skeleton tests _STDLIB_H, while some stdlib.h headers
+ * use _STDLIB_H_ as witness.  Map the latter to the one bison uses.
+ * FIXME: this is temporary.  Remove when we have a mechanism to ensure
+ * that the version we're using is fixed, too.
+ */
+#ifdef _STDLIB_H_
+# undef _STDLIB_H
+# define _STDLIB_H 1
+#endif
+
+/**
+ * Shift A right by B bits portably, by dividing A by 2**B and
+ * truncating towards minus infinity.  A and B should be free of side
+ * effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
+ * INT_BITS is the number of useful bits in an int.  GNU code can
+ * assume that INT_BITS is at least 32.
+ *
+ * ISO C99 says that A >> B is implementation-defined if A < 0.  Some
+ * implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
+ * right in the usual way when A < 0, so SHR falls back on division if
+ * ordinary A >> B doesn't seem to be the usual signed shift.
+ */
+#define SHR(a, b) \
+	(-1 >> 1 == -1 \
+	 ? (a) >> (b) \
+	 : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
+
+#define TM_YEAR_BASE 1900
+
+#define HOUR(x) ((x) * 60)
+
+#define STREQ(a, b) (strcmp (a, b) == 0)
+
+/**
+ * Convert a possibly-signed character to an unsigned character.  This is
+ * a bit safer than casting to unsigned char, since it catches some type
+ * errors that the cast doesn't.
+ */
+static unsigned char to_uchar (char ch) { return ch; }
+
+/**
+ * FIXME: It also assumes that signed integer overflow silently wraps around,
+ * but this is not true any more with recent versions of GCC 4.
+ */
+
+/**
+ * An integer value, and the number of digits in its textual
+ * representation.
+ */
+typedef struct {
+	int negative;
+	intmax_t value;
+	size_t digits;
+} textint;
+
+/* An entry in the lexical lookup table. */
+typedef struct {
+	char const *name;
+	int type;
+	int value;
+} table;
+
+/* Meridian: am, pm, or 24-hour style. */
+enum { MERam, MERpm, MER24 };
+
+enum { BILLION = 1000000000, LOG10_BILLION = 9 };
+
+/* Relative year, month, day, hour, minutes, seconds, and nanoseconds. */
+typedef struct {
+	intmax_t year;
+	intmax_t month;
+	intmax_t day;
+	intmax_t hour;
+	intmax_t minutes;
+	time_t seconds;
+	int ns;
+} relative_time;
+
+#if HAVE_COMPOUND_LITERALS
+# define RELATIVE_TIME_0 ((relative_time) { 0, 0, 0, 0, 0, 0, 0 })
+#else
+static relative_time const RELATIVE_TIME_0;
+#endif
+
+/* Information passed to and from the parser. */
+typedef struct {
+	/* The input string remaining to be parsed. */
+	const char *input;
+
+	/* N, if this is the Nth Tuesday. */
+	intmax_t day_ordinal;
+
+	/* Day of week; Sunday is 0. */
+	int day_number;
+
+	/* tm_isdst flag for the local zone. */
+	int local_isdst;
+
+	/* Time zone, in minutes east of UTC. */
+	int time_zone;
+
+	/* Style used for time. */
+	int meridian;
+
+	/* Gregorian year, month, day, hour, minutes, seconds, and ns. */
+	textint year;
+	intmax_t month;
+	intmax_t day;
+	intmax_t hour;
+	intmax_t minutes;
+	struct timespec seconds; /* includes nanoseconds */
+
+	/* Relative year, month, day, hour, minutes, seconds, and ns. */
+	relative_time rel;
+
+	/* Presence or counts of some nonterminals parsed so far. */
+	int timespec_seen;
+	int rels_seen;
+	size_t dates_seen;
+	size_t days_seen;
+	size_t local_zones_seen;
+	size_t dsts_seen;
+	size_t times_seen;
+	size_t zones_seen;
+
+	/* Table of local time zone abbreviations, null terminated. */
+	table local_time_zone_table[3];
+} parser_control;
+
+union YYSTYPE;
+static int yylex (union YYSTYPE *, parser_control *);
+static int yyerror (parser_control const *, char const *);
+static int time_zone_hhmm (parser_control *, textint, textint);
+
+/**
+ * Extract into *PC any date and time info from a string of digits
+ * of the form e.g., YYYYMMDD, YYMMDD, HHMM, HH (and sometimes YYY,
+ * YYYY, ...).
+ */
+static void digits_to_date_time(parser_control *pc, textint text_int)
+{
+	if (pc->dates_seen && ! pc->year.digits
+	    && ! pc->rels_seen && (pc->times_seen || 2 < text_int.digits)) {
+		pc->year = text_int;
+	} else {
+		if (4 < text_int.digits) {
+			pc->dates_seen++;
+			pc->day = text_int.value % 100;
+			pc->month = (text_int.value / 100) % 100;
+			pc->year.value = text_int.value / 10000;
+			pc->year.digits = text_int.digits - 4;
+		} else {
+			pc->times_seen++;
+			if (text_int.digits <= 2) {
+				pc->hour = text_int.value;
+				pc->minutes = 0;
+			}
+			else {
+				pc->hour = text_int.value / 100;
+				pc->minutes = text_int.value % 100;
+			}
+			pc->seconds.tv_sec = 0;
+			pc->seconds.tv_nsec = 0;
+			pc->meridian = MER24;
+		}
+	}
+}
+
+/* Increment PC->rel by FACTOR * REL (FACTOR is 1 or -1). */
+static void apply_relative_time(parser_control *pc, relative_time rel,
+				int factor)
+{
+	pc->rel.ns += factor * rel.ns;
+	pc->rel.seconds += factor * rel.seconds;
+	pc->rel.minutes += factor * rel.minutes;
+	pc->rel.hour += factor * rel.hour;
+	pc->rel.day += factor * rel.day;
+	pc->rel.month += factor * rel.month;
+	pc->rel.year += factor * rel.year;
+	pc->rels_seen = 1;
+}
+
+/* Set PC-> hour, minutes, seconds and nanoseconds members from arguments. */
+static void
+set_hhmmss(parser_control *pc, intmax_t hour, intmax_t minutes,
+	   time_t sec, int nsec)
+{
+	pc->hour = hour;
+	pc->minutes = minutes;
+	pc->seconds.tv_sec = sec;
+	pc->seconds.tv_nsec = nsec;
+}
+
+%}
+
+/**
+ * We want a reentrant parser, even if the TZ manipulation and the calls to
+ * localtime and gmtime are not reentrant.
+ */
+%define api.pure
+%parse-param { parser_control *pc }
+%lex-param { parser_control *pc }
+
+/* This grammar has 31 shift/reduce conflicts. */
+%expect 31
+
+%union {
+	intmax_t intval;
+	textint textintval;
+	struct timespec timespec;
+	relative_time rel;
+}
+
+%token <intval> tAGO
+%token tDST
+
+%token tYEAR_UNIT tMONTH_UNIT tHOUR_UNIT tMINUTE_UNIT tSEC_UNIT
+%token <intval> tDAY_UNIT tDAY_SHIFT
+
+%token <intval> tDAY tDAYZONE tLOCAL_ZONE tMERIDIAN
+%token <intval> tMONTH tORDINAL tZONE
+
+%token <textintval> tSNUMBER tUNUMBER
+%token <timespec> tSDECIMAL_NUMBER tUDECIMAL_NUMBER
+
+%type <textintval> o_colon_minutes
+%type <timespec> seconds signed_seconds unsigned_seconds
+
+%type <rel> relunit relunit_snumber dayshift
+
+%%
+
+spec:
+	  timespec
+	| items
+;
+
+timespec:
+	  '@' seconds {
+		pc->seconds = $2;
+		pc->timespec_seen = 1;
+	  }
+;
+
+items:
+	  /* empty */
+	| items item
+;
+
+item:
+	  datetime {
+		pc->times_seen++; pc->dates_seen++;
+	  }
+	| time {
+		pc->times_seen++;
+	  }
+	| local_zone {
+		pc->local_zones_seen++;
+	  }
+	| zone {
+		pc->zones_seen++;
+	  }
+	| date {
+		pc->dates_seen++;
+	  }
+	| day {
+		pc->days_seen++;
+	  }
+	| rel
+	| number
+	| hybrid
+;
+
+datetime:
+	  iso_8601_datetime
+;
+
+iso_8601_datetime:
+	  iso_8601_date 'T' iso_8601_time
+;
+
+time:
+	  tUNUMBER tMERIDIAN {
+		set_hhmmss (pc, $1.value, 0, 0, 0);
+		pc->meridian = $2;
+	  }
+	| tUNUMBER ':' tUNUMBER tMERIDIAN {
+		set_hhmmss (pc, $1.value, $3.value, 0, 0);
+		pc->meridian = $4;
+	  }
+	| tUNUMBER ':' tUNUMBER ':' unsigned_seconds tMERIDIAN {
+		set_hhmmss (pc, $1.value, $3.value, $5.tv_sec, $5.tv_nsec);
+		pc->meridian = $6;
+	  }
+	| iso_8601_time
+;
+
+iso_8601_time:
+	  tUNUMBER zone_offset {
+		set_hhmmss (pc, $1.value, 0, 0, 0);
+		pc->meridian = MER24;
+	  }
+	| tUNUMBER ':' tUNUMBER o_zone_offset {
+		set_hhmmss (pc, $1.value, $3.value, 0, 0);
+		pc->meridian = MER24;
+	  }
+	| tUNUMBER ':' tUNUMBER ':' unsigned_seconds o_zone_offset {
+		set_hhmmss (pc, $1.value, $3.value, $5.tv_sec, $5.tv_nsec);
+		pc->meridian = MER24;
+	  }
+;
+
+o_zone_offset:
+	/* empty */
+	| zone_offset
+;
+
+zone_offset:
+	  tSNUMBER o_colon_minutes {
+		pc->zones_seen++;
+		if (! time_zone_hhmm (pc, $1, $2)) YYABORT;
+	  }
+;
+
+/**
+ * Local zone strings only affect DST setting,
+ * and only take affect if the current TZ setting is relevant.
+ *
+ * Example 1:
+ * 'EEST' is parsed as tLOCAL_ZONE, as it relates to the effective TZ:
+ *      TZ=Europe/Helsinki date -d '2016-12-30 EEST'
+ *
+ * Example 2:
+ * 'EEST' is parsed as 'zone' (TZ=+03:00):
+ *       TZ=Asia/Tokyo ./src/date --debug -d '2011-06-11 EEST'
+ *
+ * This is implemented by probing the next three calendar quarters
+ * of the effective timezone and looking for DST changes -
+ * if found, the timezone name (EEST) is inserted into
+ * the lexical lookup table with type tLOCAL_ZONE.
+ * (Search for 'quarter' comment in  'parse_date').
+ */
+local_zone:
+	  tLOCAL_ZONE {
+		pc->local_isdst = $1;
+		pc->dsts_seen += (0 < $1);
+	  }
+	| tLOCAL_ZONE tDST {
+		pc->local_isdst = 1;
+		pc->dsts_seen += (0 < $1) + 1;
+	  }
+;
+
+/**
+ * Note 'T' is a special case, as it is used as the separator in ISO
+ * 8601 date and time of day representation.
+ */
+zone:
+	  tZONE {
+		pc->time_zone = $1;
+	  }
+	| 'T' {
+		pc->time_zone = HOUR(7);
+	  }
+	| tZONE relunit_snumber {
+		pc->time_zone = $1;
+		apply_relative_time (pc, $2, 1);
+	  }
+	| 'T' relunit_snumber {
+		pc->time_zone = HOUR(7);
+		apply_relative_time (pc, $2, 1);
+	  }
+	| tZONE tSNUMBER o_colon_minutes {
+		if (! time_zone_hhmm (pc, $2, $3)) YYABORT;
+		pc->time_zone += $1;
+	  }
+	| tDAYZONE {
+		pc->time_zone = $1 + 60;
+	  }
+	| tZONE tDST {
+		pc->time_zone = $1 + 60;
+	  }
+;
+
+day:
+	  tDAY {
+		pc->day_ordinal = 0;
+		pc->day_number = $1;
+	  }
+	| tDAY ',' {
+		pc->day_ordinal = 0;
+		pc->day_number = $1;
+	  }
+	| tORDINAL tDAY {
+		pc->day_ordinal = $1;
+		pc->day_number = $2;
+	  }
+	| tUNUMBER tDAY {
+		pc->day_ordinal = $1.value;
+		pc->day_number = $2;
+	  }
+;
+
+date:
+	  tUNUMBER '/' tUNUMBER {
+		pc->month = $1.value;
+		pc->day = $3.value;
+	  }
+	| tUNUMBER '/' tUNUMBER '/' tUNUMBER {
+	/**
+	 * Interpret as YYYY/MM/DD if the first value has 4 or more digits,
+	 * otherwise as MM/DD/YY.
+	 * The goal in recognizing YYYY/MM/DD is solely to support legacy
+	 * machine-generated dates like those in an RCS log listing.  If
+	 * you want portability, use the ISO 8601 format.
+	 */
+		if (4 <= $1.digits) {
+			pc->year = $1;
+			pc->month = $3.value;
+			pc->day = $5.value;
+		} else {
+			pc->month = $1.value;
+			pc->day = $3.value;
+			pc->year = $5;
+		}
+	  }
+	| tUNUMBER tMONTH tSNUMBER {
+		/* e.g. 17-JUN-1992. */
+		pc->day = $1.value;
+		pc->month = $2;
+		pc->year.value = -$3.value;
+		pc->year.digits = $3.digits;
+	  }
+	| tMONTH tSNUMBER tSNUMBER {
+		/* e.g. JUN-17-1992. */
+		pc->month = $1;
+		pc->day = -$2.value;
+		pc->year.value = -$3.value;
+		pc->year.digits = $3.digits;
+	  }
+	| tMONTH tUNUMBER {
+		pc->month = $1;
+		pc->day = $2.value;
+	  }
+	| tMONTH tUNUMBER ',' tUNUMBER {
+		pc->month = $1;
+		pc->day = $2.value;
+		pc->year = $4;
+	  }
+	| tUNUMBER tMONTH {
+		pc->day = $1.value;
+		pc->month = $2;
+	  }
+	| tUNUMBER tMONTH tUNUMBER {
+		pc->day = $1.value;
+		pc->month = $2;
+		pc->year = $3;
+	  }
+	| iso_8601_date
+;
+
+iso_8601_date:
+	  tUNUMBER tSNUMBER tSNUMBER {
+		/* ISO 8601 format.YYYY-MM-DD. */
+		pc->year = $1;
+		pc->month = -$2.value;
+		pc->day = -$3.value;
+	  }
+;
+
+rel:
+	  relunit tAGO
+		{ apply_relative_time (pc, $1, $2); }
+	| relunit
+		{ apply_relative_time (pc, $1, 1); }
+	| dayshift
+		{ apply_relative_time (pc, $1, 1); }
+;
+
+relunit:
+	  tORDINAL tYEAR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.year = $1; }
+	| tUNUMBER tYEAR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.year = $1.value; }
+	| tYEAR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.year = 1; }
+	| tORDINAL tMONTH_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.month = $1; }
+	| tUNUMBER tMONTH_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.month = $1.value; }
+	| tMONTH_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.month = 1; }
+	| tORDINAL tDAY_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.day = $1 * $2; }
+	| tUNUMBER tDAY_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.day = $1.value * $2; }
+	| tDAY_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.day = $1; }
+	| tORDINAL tHOUR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.hour = $1; }
+	| tUNUMBER tHOUR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.hour = $1.value; }
+	| tHOUR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.hour = 1; }
+	| tORDINAL tMINUTE_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.minutes = $1; }
+	| tUNUMBER tMINUTE_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.minutes = $1.value; }
+	| tMINUTE_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.minutes = 1; }
+	| tORDINAL tSEC_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.seconds = $1; }
+	| tUNUMBER tSEC_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.seconds = $1.value; }
+	| tSDECIMAL_NUMBER tSEC_UNIT {
+		$$ = RELATIVE_TIME_0;
+		$$.seconds = $1.tv_sec;
+		$$.ns = $1.tv_nsec;
+	  }
+	| tUDECIMAL_NUMBER tSEC_UNIT {
+		$$ = RELATIVE_TIME_0;
+		$$.seconds = $1.tv_sec;
+		$$.ns = $1.tv_nsec;
+	  }
+	| tSEC_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.seconds = 1; }
+	| relunit_snumber
+;
+
+relunit_snumber:
+	  tSNUMBER tYEAR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.year = $1.value; }
+	| tSNUMBER tMONTH_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.month = $1.value; }
+	| tSNUMBER tDAY_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.day = $1.value * $2; }
+	| tSNUMBER tHOUR_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.hour = $1.value; }
+	| tSNUMBER tMINUTE_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.minutes = $1.value; }
+	| tSNUMBER tSEC_UNIT
+		{ $$ = RELATIVE_TIME_0; $$.seconds = $1.value; }
+;
+
+dayshift:
+	  tDAY_SHIFT
+		{ $$ = RELATIVE_TIME_0; $$.day = $1; }
+;
+
+seconds: signed_seconds | unsigned_seconds;
+
+signed_seconds:
+	  tSDECIMAL_NUMBER
+	| tSNUMBER
+		{ $$.tv_sec = $1.value; $$.tv_nsec = 0; }
+;
+
+unsigned_seconds:
+	  tUDECIMAL_NUMBER
+	| tUNUMBER
+		{ $$.tv_sec = $1.value; $$.tv_nsec = 0; }
+;
+
+number:
+	  tUNUMBER
+		{ digits_to_date_time (pc, $1); }
+;
+
+hybrid:
+	  tUNUMBER relunit_snumber {
+		/**
+		 * Hybrid all-digit and relative offset, so that we accept e.g.,
+		 * "YYYYMMDD +N days" as well as "YYYYMMDD N days".
+		 */
+		digits_to_date_time (pc, $1);
+		apply_relative_time (pc, $2, 1);
+	  }
+;
+
+o_colon_minutes:
+	  /* empty */
+		{ $$.value = $$.digits = 0; }
+	| ':' tUNUMBER {
+		$$ = $2;
+	  }
+;
+
+%%
+
+static table const meridian_table[] = {
+	{ "AM",   tMERIDIAN, MERam },
+	{ "A.M.", tMERIDIAN, MERam },
+	{ "PM",   tMERIDIAN, MERpm },
+	{ "P.M.", tMERIDIAN, MERpm },
+	{ NULL, 0, 0 }
+};
+
+static table const dst_table[] = {
+	{ "DST", tDST, 0 }
+};
+
+static table const month_and_day_table[] = {
+	{ "JANUARY",  tMONTH,  1 },
+	{ "FEBRUARY", tMONTH,  2 },
+	{ "MARCH",    tMONTH,  3 },
+	{ "APRIL",    tMONTH,  4 },
+	{ "MAY",      tMONTH,  5 },
+	{ "JUNE",     tMONTH,  6 },
+	{ "JULY",     tMONTH,  7 },
+	{ "AUGUST",   tMONTH,  8 },
+	{ "SEPTEMBER",tMONTH,  9 },
+	{ "SEPT",     tMONTH,  9 },
+	{ "OCTOBER",  tMONTH, 10 },
+	{ "NOVEMBER", tMONTH, 11 },
+	{ "DECEMBER", tMONTH, 12 },
+	{ "SUNDAY",   tDAY,    0 },
+	{ "MONDAY",   tDAY,    1 },
+	{ "TUESDAY",  tDAY,    2 },
+	{ "TUES",     tDAY,    2 },
+	{ "WEDNESDAY",tDAY,    3 },
+	{ "WEDNES",   tDAY,    3 },
+	{ "THURSDAY", tDAY,    4 },
+	{ "THUR",     tDAY,    4 },
+	{ "THURS",    tDAY,    4 },
+	{ "FRIDAY",   tDAY,    5 },
+	{ "SATURDAY", tDAY,    6 },
+	{ NULL, 0, 0 }
+};
+
+static table const time_units_table[] = {
+	{ "YEAR",     tYEAR_UNIT,      1 },
+	{ "MONTH",    tMONTH_UNIT,     1 },
+	{ "FORTNIGHT",tDAY_UNIT,      14 },
+	{ "WEEK",     tDAY_UNIT,       7 },
+	{ "DAY",      tDAY_UNIT,       1 },
+	{ "HOUR",     tHOUR_UNIT,      1 },
+	{ "MINUTE",   tMINUTE_UNIT,    1 },
+	{ "MIN",      tMINUTE_UNIT,    1 },
+	{ "SECOND",   tSEC_UNIT,       1 },
+	{ "SEC",      tSEC_UNIT,       1 },
+	{ NULL, 0, 0 }
+};
+
+/* Assorted relative-time words. */
+static table const relative_time_table[] = {
+	{ "TOMORROW", tDAY_SHIFT,      1 },
+	{ "YESTERDAY",tDAY_SHIFT,     -1 },
+	{ "TODAY",    tDAY_SHIFT,      0 },
+	{ "NOW",      tDAY_SHIFT,      0 },
+	{ "LAST",     tORDINAL,       -1 },
+	{ "THIS",     tORDINAL,        0 },
+	{ "NEXT",     tORDINAL,        1 },
+	{ "FIRST",    tORDINAL,        1 },
+      /*{ "SECOND",   tORDINAL,        2 }, */
+	{ "THIRD",    tORDINAL,        3 },
+	{ "FOURTH",   tORDINAL,        4 },
+	{ "FIFTH",    tORDINAL,        5 },
+	{ "SIXTH",    tORDINAL,        6 },
+	{ "SEVENTH",  tORDINAL,        7 },
+	{ "EIGHTH",   tORDINAL,        8 },
+	{ "NINTH",    tORDINAL,        9 },
+	{ "TENTH",    tORDINAL,       10 },
+	{ "ELEVENTH", tORDINAL,       11 },
+	{ "TWELFTH",  tORDINAL,       12 },
+	{ "AGO",      tAGO,           -1 },
+	{ "HENCE",    tAGO,            1 },
+	{ NULL, 0, 0 }
+};
+
+/**
+ * The universal time zone table.  These labels can be used even for
+ * timestamps that would not otherwise be valid, e.g., GMT timestamps
+ * in London during summer.
+ */
+static table const universal_time_zone_table[] = {
+	{ "GMT",      tZONE,     HOUR ( 0) }, /* Greenwich Mean */
+	{ "UT",       tZONE,     HOUR ( 0) }, /* Universal (Coordinated) */
+	{ "UTC",      tZONE,     HOUR ( 0) },
+	{ NULL, 0, 0 }
+};
+
+/**
+ * The time zone table.  This table is necessarily incomplete, as time
+ * zone abbreviations are ambiguous; e.g. Australians interpret "EST"
+ * as Eastern time in Australia, not as US Eastern Standard Time.
+ * You cannot rely on parse_date to handle arbitrary time zone
+ * abbreviations; use numeric abbreviations like "-0500" instead.
+ */
+static table const time_zone_table[] = {
+	{ "WET",      tZONE,     HOUR ( 0) }, /* Western European */
+	{ "WEST",     tDAYZONE,  HOUR ( 0) }, /* Western European Summer */
+	{ "BST",      tDAYZONE,  HOUR ( 0) }, /* British Summer */
+	{ "ART",      tZONE,    -HOUR ( 3) }, /* Argentina */
+	{ "BRT",      tZONE,    -HOUR ( 3) }, /* Brazil */
+	{ "BRST",     tDAYZONE, -HOUR ( 3) }, /* Brazil Summer */
+	{ "NST",      tZONE,   -(HOUR ( 3) + 30) },   /* Newfoundland Standard */
+	{ "NDT",      tDAYZONE,-(HOUR ( 3) + 30) },   /* Newfoundland Daylight */
+	{ "AST",      tZONE,    -HOUR ( 4) }, /* Atlantic Standard */
+	{ "ADT",      tDAYZONE, -HOUR ( 4) }, /* Atlantic Daylight */
+	{ "CLT",      tZONE,    -HOUR ( 4) }, /* Chile */
+	{ "CLST",     tDAYZONE, -HOUR ( 4) }, /* Chile Summer */
+	{ "EST",      tZONE,    -HOUR ( 5) }, /* Eastern Standard */
+	{ "EDT",      tDAYZONE, -HOUR ( 5) }, /* Eastern Daylight */
+	{ "CST",      tZONE,    -HOUR ( 6) }, /* Central Standard */
+	{ "CDT",      tDAYZONE, -HOUR ( 6) }, /* Central Daylight */
+	{ "MST",      tZONE,    -HOUR ( 7) }, /* Mountain Standard */
+	{ "MDT",      tDAYZONE, -HOUR ( 7) }, /* Mountain Daylight */
+	{ "PST",      tZONE,    -HOUR ( 8) }, /* Pacific Standard */
+	{ "PDT",      tDAYZONE, -HOUR ( 8) }, /* Pacific Daylight */
+	{ "AKST",     tZONE,    -HOUR ( 9) }, /* Alaska Standard */
+	{ "AKDT",     tDAYZONE, -HOUR ( 9) }, /* Alaska Daylight */
+	{ "HST",      tZONE,    -HOUR (10) }, /* Hawaii Standard */
+	{ "HAST",     tZONE,    -HOUR (10) }, /* Hawaii-Aleutian Standard */
+	{ "HADT",     tDAYZONE, -HOUR (10) }, /* Hawaii-Aleutian Daylight */
+	{ "SST",      tZONE,    -HOUR (12) }, /* Samoa Standard */
+	{ "WAT",      tZONE,     HOUR ( 1) }, /* West Africa */
+	{ "CET",      tZONE,     HOUR ( 1) }, /* Central European */
+	{ "CEST",     tDAYZONE,  HOUR ( 1) }, /* Central European Summer */
+	{ "MET",      tZONE,     HOUR ( 1) }, /* Middle European */
+	{ "MEZ",      tZONE,     HOUR ( 1) }, /* Middle European */
+	{ "MEST",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
+	{ "MESZ",     tDAYZONE,  HOUR ( 1) }, /* Middle European Summer */
+	{ "EET",      tZONE,     HOUR ( 2) }, /* Eastern European */
+	{ "EEST",     tDAYZONE,  HOUR ( 2) }, /* Eastern European Summer */
+	{ "CAT",      tZONE,     HOUR ( 2) }, /* Central Africa */
+	{ "SAST",     tZONE,     HOUR ( 2) }, /* South Africa Standard */
+	{ "EAT",      tZONE,     HOUR ( 3) }, /* East Africa */
+	{ "MSK",      tZONE,     HOUR ( 3) }, /* Moscow */
+	{ "MSD",      tDAYZONE,  HOUR ( 3) }, /* Moscow Daylight */
+	{ "IST",      tZONE,    (HOUR ( 5) + 30) },   /* India Standard */
+	{ "SGT",      tZONE,     HOUR ( 8) }, /* Singapore */
+	{ "KST",      tZONE,     HOUR ( 9) }, /* Korea Standard */
+	{ "JST",      tZONE,     HOUR ( 9) }, /* Japan Standard */
+	{ "GST",      tZONE,     HOUR (10) }, /* Guam Standard */
+	{ "NZST",     tZONE,     HOUR (12) }, /* New Zealand Standard */
+	{ "NZDT",     tDAYZONE,  HOUR (12) }, /* New Zealand Daylight */
+	{ NULL, 0, 0 }
+};
+
+/**
+ * Military time zone table.
+ *
+ * Note 'T' is a special case, as it is used as the separator in ISO
+ * 8601 date and time of day representation.
+ */
+static table const military_table[] = {
+	{ "A", tZONE, -HOUR ( 1) },
+	{ "B", tZONE, -HOUR ( 2) },
+	{ "C", tZONE, -HOUR ( 3) },
+	{ "D", tZONE, -HOUR ( 4) },
+	{ "E", tZONE, -HOUR ( 5) },
+	{ "F", tZONE, -HOUR ( 6) },
+	{ "G", tZONE, -HOUR ( 7) },
+	{ "H", tZONE, -HOUR ( 8) },
+	{ "I", tZONE, -HOUR ( 9) },
+	{ "K", tZONE, -HOUR (10) },
+	{ "L", tZONE, -HOUR (11) },
+	{ "M", tZONE, -HOUR (12) },
+	{ "N", tZONE,  HOUR ( 1) },
+	{ "O", tZONE,  HOUR ( 2) },
+	{ "P", tZONE,  HOUR ( 3) },
+	{ "Q", tZONE,  HOUR ( 4) },
+	{ "R", tZONE,  HOUR ( 5) },
+	{ "S", tZONE,  HOUR ( 6) },
+	{ "T", 'T',    0 },
+	{ "U", tZONE,  HOUR ( 8) },
+	{ "V", tZONE,  HOUR ( 9) },
+	{ "W", tZONE,  HOUR (10) },
+	{ "X", tZONE,  HOUR (11) },
+	{ "Y", tZONE,  HOUR (12) },
+	{ "Z", tZONE,  HOUR ( 0) },
+	{ NULL, 0, 0 }
+};
+
+/**
+ * Convert a time offset expressed as HH:MM or HHMM into an integer count of
+ * minutes.  If hh is more than 2 digits then it is of the form HHMM and must be
+ * delimited; in that case 'mm' is required to be absent.  Otherwise, hh and mm
+ * are used ('mm' contains digits that were prefixed with a colon).
+ *
+ * POSIX TZ and ISO 8601 both define the maximum offset as 24:59. POSIX also
+ * allows seconds, but currently the parser rejects them. Both require minutes
+ * to be zero padded (2 digits). ISO requires hours to be zero padded, POSIX
+ * does not, either is accepted; which means an invalid ISO offset could pass.
+ */
+
+static int time_zone_hhmm(parser_control *pc, textint hh, textint mm)
+{
+	int h, m;
+
+	if (hh.digits > 2 && hh.digits < 5 && mm.digits == 0) {
+		h = hh.value / 100;
+		m = hh.value % 100;
+	} else if (hh.digits < 3 && (mm.digits == 0 || mm.digits == 2)) {
+		h = hh.value;
+		m = hh.negative ? -mm.value : mm.value;
+	} else
+		return 0;
+
+	if (abs(h) > 24 || abs(m) > 59)
+		return 0;
+
+	pc->time_zone =  h * 60 + m;
+	return 1;
+}
+
+static int to_hour(intmax_t hours, int meridian)
+{
+	switch (meridian) {
+	default: /* Pacify GCC. */
+	case MER24:
+		return 0 <= hours && hours < 24 ? hours : -1;
+	case MERam:
+		return 0 < hours && hours < 12 ? hours : hours == 12 ? 0 : -1;
+	case MERpm:
+		return 0 < hours && hours < 12 ? hours + 12 : hours == 12 ? 12 : -1;
+	}
+}
+
+static long int to_year(textint textyear)
+{
+	intmax_t year = textyear.value;
+
+	if (year < 0)
+		year = -year;
+
+	/**
+	 * XPG4 suggests that years 00-68 map to 2000-2068, and
+	 * years 69-99 map to 1969-1999.
+	 */
+	else if (textyear.digits == 2)
+			year += year < 69 ? 2000 : 1900;
+
+	return year;
+}
+
+static table const * lookup_zone(parser_control const *pc, char const *name)
+{
+	table const *tp;
+
+	for (tp = universal_time_zone_table; tp->name; tp++)
+		if (strcmp (name, tp->name) == 0)
+			return tp;
+
+	/**
+	 * Try local zone abbreviations before those in time_zone_table, as
+	 * the local ones are more likely to be right.
+	 */
+	for (tp = pc->local_time_zone_table; tp->name; tp++)
+		if (strcmp (name, tp->name) == 0)
+			return tp;
+
+	for (tp = time_zone_table; tp->name; tp++)
+		if (strcmp (name, tp->name) == 0)
+			return tp;
+
+	return NULL;
+}
+
+#if ! HAVE_TM_GMTOFF
+/**
+ * Yield the difference between *A and *B,
+ * measured in seconds, ignoring leap seconds.
+ * The body of this function is taken directly from the GNU C Library;
+ * see src/strftime.c.
+ */
+static int tm_diff(struct tm const *a, struct tm const *b)
+{
+	/**
+	 * Compute intervening leap days correctly even if year is negative.
+	 * Take care to avoid int overflow in leap day calculations.
+	 */
+	int a4 = SHR (a->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (a->tm_year & 3);
+	int b4 = SHR (b->tm_year, 2) + SHR (TM_YEAR_BASE, 2) - ! (b->tm_year & 3);
+	int a100 = a4 / 25 - (a4 % 25 < 0);
+	int b100 = b4 / 25 - (b4 % 25 < 0);
+	int a400 = SHR (a100, 2);
+	int b400 = SHR (b100, 2);
+	int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
+	int years = a->tm_year - b->tm_year;
+	int days = (365 * years + intervening_leap_days
+			 + (a->tm_yday - b->tm_yday));
+	return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+		+ (a->tm_sec - b->tm_sec));
+}
+#endif /* ! HAVE_TM_GMTOFF */
+
+static table const * lookup_word(parser_control const *pc, char *word)
+{
+	char *p;
+	char *q;
+	size_t wordlen;
+	table const *tp;
+	int period_found;
+	int abbrev;
+
+	/* Make it uppercase. */
+	for (p = word; *p; p++)
+		*p = c_toupper (to_uchar (*p));
+
+	for (tp = meridian_table; tp->name; tp++)
+		if (strcmp (word, tp->name) == 0)
+			return tp;
+
+	/* See if we have an abbreviation for a month. */
+	wordlen = strlen (word);
+	abbrev = wordlen == 3 || (wordlen == 4 && word[3] == '.');
+
+	for (tp = month_and_day_table; tp->name; tp++)
+		if ((abbrev ? strncmp (word, tp->name, 3) :
+		     strcmp (word, tp->name)) == 0)
+			return tp;
+
+	if ((tp = lookup_zone (pc, word)))
+		return tp;
+
+	if (strcmp (word, dst_table[0].name) == 0)
+		return dst_table;
+
+	for (tp = time_units_table; tp->name; tp++)
+		if (strcmp (word, tp->name) == 0)
+			return tp;
+
+	/* Strip off any plural and try the units table again. */
+	if (word[wordlen - 1] == 'S') {
+		word[wordlen - 1] = '\0';
+		for (tp = time_units_table; tp->name; tp++)
+			if (strcmp (word, tp->name) == 0)
+				return tp;
+		word[wordlen - 1] = 'S'; /* For "this" in relative_time_table. */
+	}
+
+	for (tp = relative_time_table; tp->name; tp++)
+		if (strcmp (word, tp->name) == 0)
+			return tp;
+
+	/* Military time zones. */
+	if (wordlen == 1)
+		for (tp = military_table; tp->name; tp++)
+			if (word[0] == tp->name[0])
+				return tp;
+
+	/* Drop out any periods and try the time zone table again. */
+	for (period_found = 0, p = q = word; (*p = *q); q++)
+		if (*q == '.')
+			period_found = 1;
+		else
+			p++;
+	if (period_found && (tp = lookup_zone (pc, word)))
+		return tp;
+
+	return NULL;
+}
+
+static int yylex (union YYSTYPE *lvalp, parser_control *pc)
+{
+	unsigned char c;
+	size_t count;
+
+	for (;;) {
+		while (c = *pc->input, c_isspace (c))
+			pc->input++;
+
+		if (c_isdigit (c) || c == '-' || c == '+') {
+			char const *p;
+			int sign;
+			uintmax_t value;
+			if (c == '-' || c == '+') {
+				sign = c == '-' ? -1 : 1;
+				while (c = *++pc->input, c_isspace (c))
+					continue;
+				if (! c_isdigit (c))
+					/* skip the '-' sign */
+					continue;
+			} else
+				sign = 0;
+			p = pc->input;
+			for (value = 0; ; value *= 10) {
+				uintmax_t value1 = value + (c - '0');
+				if (value1 < value)
+					return '?';
+				value = value1;
+				c = *++p;
+				if (! c_isdigit (c))
+					break;
+				if (UINTMAX_MAX / 10 < value)
+					return '?';
+			}
+			if ((c == '.' || c == ',') && c_isdigit (p[1])) {
+				time_t s;
+				int ns;
+				int digits;
+				uintmax_t value1;
+
+				/* Check for overflow when converting value to
+				 * time_t.
+				 */
+				if (sign < 0) {
+					s = - value;
+					if (0 < s)
+						return '?';
+					value1 = -s;
+				} else {
+					s = value;
+					if (s < 0)
+						return '?';
+					value1 = s;
+				}
+				if (value != value1)
+					return '?';
+
+				/* Accumulate fraction, to ns precision. */
+				p++;
+				ns = *p++ - '0';
+				for (digits = 2;
+				     digits <= LOG10_BILLION; digits++) {
+					ns *= 10;
+					if (c_isdigit (*p))
+						ns += *p++ - '0';
+				}
+
+				/* Skip excess digits, truncating toward
+				 * -Infinity.
+				 */
+				if (sign < 0)
+					for (; c_isdigit (*p); p++)
+						if (*p != '0') {
+							ns++;
+							break;
+						}
+				while (c_isdigit (*p))
+					p++;
+
+				/* Adjust to the timespec convention, which is
+				 * that tv_nsec is always a positive offset even
+				 * if tv_sec is negative.
+				 */
+				if (sign < 0 && ns) {
+					s--;
+					if (! (s < 0))
+						return '?';
+					ns = BILLION - ns;
+				}
+
+				lvalp->timespec.tv_sec = s;
+				lvalp->timespec.tv_nsec = ns;
+				pc->input = p;
+				return
+				  sign ? tSDECIMAL_NUMBER : tUDECIMAL_NUMBER;
+			} else {
+				lvalp->textintval.negative = sign < 0;
+				if (sign < 0) {
+					lvalp->textintval.value = - value;
+					if (0 < lvalp->textintval.value)
+						return '?';
+				} else {
+					lvalp->textintval.value = value;
+					if (lvalp->textintval.value < 0)
+						return '?';
+				}
+				lvalp->textintval.digits = p - pc->input;
+				pc->input = p;
+				return sign ? tSNUMBER : tUNUMBER;
+			}
+		}
+
+		if (c_isalpha (c)) {
+			char buff[20];
+			char *p = buff;
+			table const *tp;
+
+			do {
+				if (p < buff + sizeof buff - 1)
+				*p++ = c;
+				c = *++pc->input;
+			}
+			while (c_isalpha (c) || c == '.');
+
+			*p = '\0';
+			tp = lookup_word (pc, buff);
+			if (! tp) {
+				return '?';
+			}
+			lvalp->intval = tp->value;
+			return tp->type;
+		}
+
+		if (c != '(')
+			return to_uchar (*pc->input++);
+
+		count = 0;
+		do {
+			c = *pc->input++;
+			if (c == '\0')
+				return c;
+			if (c == '(')
+				count++;
+			else if (c == ')')
+				count--;
+		}
+		while (count != 0);
+	}
+}
+
+/* Do nothing if the parser reports an error. */
+static int yyerror(parser_control const *pc __attribute__((__unused__)),
+		   char const *s __attribute__((__unused__)))
+{
+	return 0;
+}
+
+/**
+ * If *TM0 is the old and *TM1 is the new value of a struct tm after
+ * passing it to mktime, return 1 if it's OK that mktime returned T.
+ * It's not OK if *TM0 has out-of-range members.
+ */
+
+static int mktime_ok(struct tm const *tm0, struct tm const *tm1, time_t t)
+{
+	if (t == (time_t) -1) {
+		/**
+		 * Guard against falsely reporting an error when parsing a
+		 * timestamp that happens to equal (time_t) -1, on a host that
+		 * supports such a timestamp.
+		 */
+		tm1 = localtime (&t);
+		if (!tm1)
+			return 0;
+	}
+
+	return ! ((tm0->tm_sec ^ tm1->tm_sec)
+		  | (tm0->tm_min ^ tm1->tm_min)
+		  | (tm0->tm_hour ^ tm1->tm_hour)
+		  | (tm0->tm_mday ^ tm1->tm_mday)
+		  | (tm0->tm_mon ^ tm1->tm_mon)
+		  | (tm0->tm_year ^ tm1->tm_year));
+}
+
+/**
+ * A reasonable upper bound for the size of ordinary TZ strings.
+ * Use heap allocation if TZ's length exceeds this.
+ */
+enum { TZBUFSIZE = 100 };
+
+/**
+ * Return a copy of TZ, stored in TZBUF if it fits, and heap-allocated
+ * otherwise.
+ */
+static char * get_tz(char tzbuf[TZBUFSIZE])
+{
+	char *tz = getenv ("TZ");
+	if (tz) {
+		size_t tzsize = strlen (tz) + 1;
+		tz = (tzsize <= TZBUFSIZE
+		      ? memcpy (tzbuf, tz, tzsize)
+		      : strdup (tz));
+	}
+	return tz;
+}
+
+/**
+ * Parse a date/time string, storing the resulting time value into *result.
+ * The string itself is pointed to by *p.  Return 1 if successful.
+ * *p can be an incomplete or relative time specification; if so, use
+ * *now as the basis for the returned time.
+ */
+int parse_date(struct timespec *result, char const *p,
+		   struct timespec const *now)
+{
+	time_t Start;
+	intmax_t Start_ns;
+	struct tm const *tmp;
+	struct tm tm;
+	struct tm tm0;
+	parser_control pc;
+	struct timespec gettime_buffer;
+	unsigned char c;
+	int tz_was_altered = 0;
+	char *tz0 = NULL;
+	char tz0buf[TZBUFSIZE];
+	int ok = 1;
+	struct timeval tv;
+
+	if (! now) {
+		gettimeofday (&tv, NULL);
+		gettime_buffer.tv_sec = tv.tv_sec;
+		gettime_buffer.tv_nsec = tv.tv_usec * 1000;
+		now = &gettime_buffer;
+	}
+
+	Start = now->tv_sec;
+	Start_ns = now->tv_nsec;
+
+	tmp = localtime (&now->tv_sec);
+	if (! tmp)
+		return 0;
+
+	while (c = *p, c_isspace (c))
+		p++;
+
+	if (strncmp (p, "TZ=\"", 4) == 0) {
+		char const *tzbase = p + 4;
+		size_t tzsize = 1;
+		char const *s;
+
+		for (s = tzbase; *s; s++, tzsize++)
+			if (*s == '\\') {
+				s++;
+				if (! (*s == '\\' || *s == '"'))
+					break;
+			} else if (*s == '"') {
+				char *z;
+				char *tz1;
+				char tz1buf[TZBUFSIZE];
+				int large_tz = TZBUFSIZE < tzsize;
+				int setenv_ok;
+
+				tz0 = get_tz (tz0buf);
+				if (!tz0)
+					goto fail;
+
+				if (large_tz) {
+					z = tz1 = malloc (tzsize);
+					if (!tz1)
+						goto fail;
+				} else
+					z = tz1 = tz1buf;
+
+				for (s = tzbase; *s != '"'; s++)
+					*z++ = *(s += *s == '\\');
+				*z = '\0';
+				setenv_ok = setenv ("TZ", tz1, 1) == 0;
+				if (large_tz)
+					free (tz1);
+				if (!setenv_ok)
+					goto fail;
+				tz_was_altered = 1;
+
+				p = s + 1;
+				while (c = *p, c_isspace (c))
+					p++;
+
+				break;
+			}
+	}
+
+	/**
+	 * As documented, be careful to treat the empty string just like
+	 * a date string of "0".  Without this, an empty string would be
+	 * declared invalid when parsed during a DST transition.
+	 */
+	if (*p == '\0')
+		p = "0";
+
+	pc.input = p;
+	pc.year.value = tmp->tm_year;
+	pc.year.value += TM_YEAR_BASE;
+	pc.year.digits = 0;
+	pc.month = tmp->tm_mon + 1;
+	pc.day = tmp->tm_mday;
+	pc.hour = tmp->tm_hour;
+	pc.minutes = tmp->tm_min;
+	pc.seconds.tv_sec = tmp->tm_sec;
+	pc.seconds.tv_nsec = Start_ns;
+	tm.tm_isdst = tmp->tm_isdst;
+
+	pc.meridian = MER24;
+	pc.rel = RELATIVE_TIME_0;
+	pc.timespec_seen = 0;
+	pc.rels_seen = 0;
+	pc.dates_seen = 0;
+	pc.days_seen = 0;
+	pc.times_seen = 0;
+	pc.local_zones_seen = 0;
+	pc.dsts_seen = 0;
+	pc.zones_seen = 0;
+
+#if HAVE_STRUCT_TM_TM_ZONE
+	pc.local_time_zone_table[0].name = tmp->tm_zone;
+	pc.local_time_zone_table[0].type = tLOCAL_ZONE;
+	pc.local_time_zone_table[0].value = tmp->tm_isdst;
+	pc.local_time_zone_table[1].name = NULL;
+
+	/**
+	 * Probe the names used in the next three calendar quarters, looking
+	 * for a tm_isdst different from the one we already have.
+	 */
+	{
+		int quarter;
+		for (quarter = 1; quarter <= 3; quarter++) {
+			time_t probe = Start + quarter * (90 * 24 * 60 * 60);
+			struct tm const *probe_tm = localtime (&probe);
+			if (probe_tm && probe_tm->tm_zone
+				&& probe_tm->tm_isdst
+				!= pc.local_time_zone_table[0].value) {
+					{
+					  pc.local_time_zone_table[1].name
+					  = probe_tm->tm_zone;
+					  pc.local_time_zone_table[1].type
+					  = tLOCAL_ZONE;
+					  pc.local_time_zone_table[1].value
+					  = probe_tm->tm_isdst;
+					  pc.local_time_zone_table[2].name
+					  = NULL;
+					}
+				break;
+			}
+		}
+	}
+#else
+#if HAVE_TZNAME
+	{
+# if !HAVE_DECL_TZNAME
+		extern char *tzname[];
+# endif
+		int i;
+		for (i = 0; i < 2; i++) {
+			pc.local_time_zone_table[i].name = tzname[i];
+			pc.local_time_zone_table[i].type = tLOCAL_ZONE;
+			pc.local_time_zone_table[i].value = i;
+		}
+		pc.local_time_zone_table[i].name = NULL;
+	}
+#else
+	pc.local_time_zone_table[0].name = NULL;
+#endif
+#endif
+
+	if (pc.local_time_zone_table[0].name && pc.local_time_zone_table[1].name
+	    && ! strcmp (pc.local_time_zone_table[0].name,
+			 pc.local_time_zone_table[1].name)) {
+		/**
+		 * This locale uses the same abbreviation for standard and
+		 * daylight times.  So if we see that abbreviation, we don't
+		 * know whether it's daylight time.
+		 */
+		pc.local_time_zone_table[0].value = -1;
+		pc.local_time_zone_table[1].name = NULL;
+	}
+
+	if (yyparse (&pc) != 0) {
+		goto fail;
+	}
+
+	if (pc.timespec_seen)
+		*result = pc.seconds;
+	else {
+		if (1 < (pc.times_seen | pc.dates_seen | pc.days_seen
+			 | pc.dsts_seen
+			 | (pc.local_zones_seen + pc.zones_seen))) {
+			goto fail;
+		}
+
+		tm.tm_year = to_year (pc.year) - TM_YEAR_BASE;
+		tm.tm_mon = pc.month - 1;
+		tm.tm_mday = pc.day;
+		if (pc.times_seen || (pc.rels_seen &&
+				      ! pc.dates_seen && ! pc.days_seen)) {
+			tm.tm_hour = to_hour (pc.hour, pc.meridian);
+			if (tm.tm_hour < 0) {
+				goto fail;
+			}
+			tm.tm_min = pc.minutes;
+			tm.tm_sec = pc.seconds.tv_sec;
+		} else {
+			tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+			pc.seconds.tv_nsec = 0;
+		}
+
+		/**
+		 * Let mktime deduce tm_isdst if we have an absolute timestamp.
+		 */
+		if (pc.dates_seen | pc.days_seen | pc.times_seen)
+			tm.tm_isdst = -1;
+
+		/**
+		 * But if the input explicitly specifies local time with or
+		 * without DST, give mktime that information.
+		 */
+		if (pc.local_zones_seen)
+			tm.tm_isdst = pc.local_isdst;
+
+		tm0 = tm;
+
+		Start = mktime (&tm);
+
+		if (! mktime_ok (&tm0, &tm, Start)) {
+			if (! pc.zones_seen) {
+				goto fail;
+			} else {
+				/** Guard against falsely reporting errors near
+				 * the time_t boundaries when parsing times in
+				 * other time zones.  For example, suppose the
+				 * input string "1969-12-31 23:00:00 -0100", the
+				 * current time zone is 8 hours ahead of UTC,
+				 * and the min time_t value is 1970-01-01
+				 * 00:00:00 UTC.  Then the min localtime value
+				 * is 1970-01-01 08:00:00, and mktime will
+				 * therefore fail on 1969-12-31 23:00:00.  To
+				 * work around the problem, set the time zone to
+				 * 1 hour behind UTC temporarily by setting
+				 * TZ="XXX1:00" and try mktime again.
+				 */
+
+				intmax_t time_zone = pc.time_zone;
+
+				intmax_t abs_time_zone = time_zone < 0
+					 ? - time_zone : time_zone;
+
+				intmax_t abs_time_zone_hour
+					 = abs_time_zone / 60;
+
+				int abs_time_zone_min = abs_time_zone % 60;
+
+				char tz1buf[sizeof "XXX+0:00"
+					    + sizeof pc.time_zone
+					    * CHAR_BIT / 3];
+
+				if (!tz_was_altered)
+					tz0 = get_tz (tz0buf);
+				sprintf (tz1buf, "XXX%s%jd:%02d",
+					 &"-"[time_zone < 0],
+					 abs_time_zone_hour,
+					 abs_time_zone_min);
+				if (setenv ("TZ", tz1buf, 1) != 0) {
+					goto fail;
+				}
+				tz_was_altered = 1;
+				tm = tm0;
+				Start = mktime (&tm);
+				if (! mktime_ok (&tm0, &tm, Start)) {
+					goto fail;
+				}
+			}
+		}
+
+		if (pc.days_seen && ! pc.dates_seen) {
+			tm.tm_mday += ((pc.day_number - tm.tm_wday + 7) % 7 + 7
+				       * (pc.day_ordinal
+					  - (0 < pc.day_ordinal
+					     && tm.tm_wday != pc.day_number)));
+			tm.tm_isdst = -1;
+			Start = mktime (&tm);
+			if (Start == (time_t) -1) {
+				goto fail;
+			}
+		}
+		/* Add relative date. */
+		if (pc.rel.year | pc.rel.month | pc.rel.day) {
+			int year = tm.tm_year + pc.rel.year;
+			int month = tm.tm_mon + pc.rel.month;
+			int day = tm.tm_mday + pc.rel.day;
+			if (((year < tm.tm_year) ^ (pc.rel.year < 0))
+				| ((month < tm.tm_mon) ^ (pc.rel.month < 0))
+				| ((day < tm.tm_mday) ^ (pc.rel.day < 0))) {
+				goto fail;
+			}
+			tm.tm_year = year;
+			tm.tm_mon = month;
+			tm.tm_mday = day;
+			tm.tm_hour = tm0.tm_hour;
+			tm.tm_min = tm0.tm_min;
+			tm.tm_sec = tm0.tm_sec;
+			tm.tm_isdst = tm0.tm_isdst;
+			Start = mktime (&tm);
+			if (Start == (time_t) -1) {
+				goto fail;
+			}
+		}
+
+		/**
+		 * The only "output" of this if-block is an updated Start value,
+		 * so this block must follow others that clobber Start.
+		 */
+		if (pc.zones_seen) {
+			intmax_t delta = pc.time_zone * 60;
+			time_t t1;
+#ifdef HAVE_TM_GMTOFF
+			delta -= tm.tm_gmtoff;
+#else
+			time_t t = Start;
+			struct tm const *gmt = gmtime (&t);
+			if (! gmt) {
+				goto fail;
+			}
+			delta -= tm_diff (&tm, gmt);
+#endif
+			t1 = Start - delta;
+			if ((Start < t1) != (delta < 0)) {
+				goto fail;  /* time_t overflow */
+			}
+			Start = t1;
+		}
+
+		/**
+		 * Add relative hours, minutes, and seconds.  On hosts that
+		 * support leap seconds, ignore the possibility of leap seconds;
+		 * e.g., "+ 10 minutes" adds 600 seconds, even if one of them is
+		 * a leap second.  Typically this is not what the user wants,
+		 * but it's too hard to do it the other way, because the time
+		 * zone indicator must be applied before relative times, and if
+		 * mktime is applied again the time zone will be lost.
+		 */
+		intmax_t sum_ns = pc.seconds.tv_nsec + pc.rel.ns;
+		intmax_t normalized_ns = (sum_ns % BILLION + BILLION) % BILLION;
+		time_t t0 = Start;
+		intmax_t d1 = 60 * 60 * pc.rel.hour;
+		time_t t1 = t0 + d1;
+		intmax_t d2 = 60 * pc.rel.minutes;
+		time_t t2 = t1 + d2;
+		time_t d3 = pc.rel.seconds;
+		time_t t3 = t2 + d3;
+		intmax_t d4 = (sum_ns - normalized_ns) / BILLION;
+		time_t t4 = t3 + d4;
+		time_t t5 = t4;
+
+		if ((d1 / (60 * 60) ^ pc.rel.hour)
+		    | (d2 / 60 ^ pc.rel.minutes)
+		    | ((t1 < t0) ^ (d1 < 0))
+		    | ((t2 < t1) ^ (d2 < 0))
+		    | ((t3 < t2) ^ (d3 < 0))
+		    | ((t4 < t3) ^ (d4 < 0))
+		    | (t5 != t4)) {
+			goto fail;
+		}
+		result->tv_sec = t5;
+		result->tv_nsec = normalized_ns;
+	}
+
+	goto done;
+
+	fail:
+		ok = 0;
+	done:
+		if (tz_was_altered)
+			ok &= (tz0 ? setenv ("TZ", tz0, 1)
+				   : unsetenv ("TZ")) == 0;
+		if (tz0 != tz0buf)
+			free (tz0);
+		return ok;
+}