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[libc] Add mktime() function

Signed-off-by: Michael Brown <mcb30@ipxe.org>
tags/v1.20.1
Michael Brown 12 lat temu
rodzic
commit
bd6805a8c1
3 zmienionych plików z 173 dodań i 25 usunięć
  1. 137
    0
      src/core/time.c
  2. 11
    13
      src/include/sys/time.h
  3. 25
    12
      src/include/time.h

+ 137
- 0
src/core/time.c Wyświetl plik

@@ -0,0 +1,137 @@
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+/*
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+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License as
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+ * published by the Free Software Foundation; either version 2 of the
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+ * License, or any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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+ */
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+
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+FILE_LICENCE ( GPL2_OR_LATER );
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+
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+#include <time.h>
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+
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+/** @file
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+ *
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+ * Date and time
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+ *
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+ * POSIX:2008 section 4.15 defines "seconds since the Epoch" as an
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+ * abstract measure approximating the number of seconds that have
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+ * elapsed since the Epoch, excluding leap seconds.  The formula given
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+ * is
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+ *
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+ *    tm_sec + tm_min*60 + tm_hour*3600 + tm_yday*86400 +
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+ *    (tm_year-70)*31536000 + ((tm_year-69)/4)*86400 -
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+ *    ((tm_year-1)/100)*86400 + ((tm_year+299)/400)*86400
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+ *
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+ * This calculation assumes that leap years occur in each year that is
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+ * either divisible by 4 but not divisible by 100, or is divisible by
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+ * 400.
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+ */
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+
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+/** Days of week (for debugging) */
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+static const char *weekdays[] = {
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+	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
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+};
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+
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+/**
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+ * Determine whether or not year is a leap year
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+ *
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+ * @v tm_year		Years since 1900
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+ * @v is_leap_year	Year is a leap year
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+ */
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+static int is_leap_year ( int tm_year ) {
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+	int leap_year = 0;
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+
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+	if ( ( tm_year % 4 ) == 0 )
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+		leap_year = 1;
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+	if ( ( tm_year % 100 ) == 0 )
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+		leap_year = 0;
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+	if ( ( tm_year % 400 ) == 100 )
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+		leap_year = 1;
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+
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+	return leap_year;
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+}
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+
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+/**
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+ * Calculate number of leap years since 1900
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+ *
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+ * @v tm_year		Years since 1900
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+ * @v num_leap_years	Number of leap years
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+ */
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+static int leap_years_to_end ( int tm_year ) {
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+	int leap_years = 0;
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+
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+	leap_years += ( tm_year / 4 );
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+	leap_years -= ( tm_year / 100 );
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+	leap_years += ( ( tm_year + 300 ) / 400 );
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+
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+	return leap_years;
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+}
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+
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+/**
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+ * Calculate day of week
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+ *
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+ * @v tm_year		Years since 1900
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+ * @v tm_mon		Month of year [0,11]
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+ * @v tm_day		Day of month [1,31]
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+ */
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+static int day_of_week ( int tm_year, int tm_mon, int tm_mday ) {
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+	static const uint8_t offset[12] =
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+		{ 1, 4, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5 };
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+	int pseudo_year = tm_year;
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+
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+	if ( tm_mon < 2 )
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+		pseudo_year--;
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+	return ( ( pseudo_year + leap_years_to_end ( pseudo_year ) +
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+		   offset[tm_mon] + tm_mday ) % 7 );
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+}
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+
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+/** Days from start of year until start of months (in non-leap years) */
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+static const uint16_t days_to_month_start[] =
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+	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
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+
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+/**
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+ * Calculate seconds since the Epoch
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+ *
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+ * @v tm		Broken-down time
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+ * @ret time		Seconds since the Epoch
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+ */
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+time_t mktime ( struct tm *tm ) {
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+	int days_since_epoch;
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+	int seconds_since_day;
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+	time_t seconds;
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+
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+	/* Calculate day of year */
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+	tm->tm_yday = ( ( tm->tm_mday - 1 ) +
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+			days_to_month_start[ tm->tm_mon ] );
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+	if ( ( tm->tm_mon >= 2 ) && is_leap_year ( tm->tm_year ) )
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+		tm->tm_yday++;
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+
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+	/* Calculate day of week */
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+	tm->tm_wday = day_of_week ( tm->tm_year, tm->tm_mon, tm->tm_mday );
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+
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+	/* Calculate seconds since the Epoch */
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+	days_since_epoch = ( tm->tm_yday + ( 365 * tm->tm_year ) - 25567 +
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+			     leap_years_to_end ( tm->tm_year - 1 ) );
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+	seconds_since_day =
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+		( ( ( ( tm->tm_hour * 60 ) + tm->tm_min ) * 60 ) + tm->tm_sec );
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+	seconds = ( ( ( ( time_t ) days_since_epoch ) * ( ( time_t ) 86400 ) ) +
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+		    seconds_since_day );
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+
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+	DBGC ( &weekdays, "TIME %04d-%02d-%02d %02d:%02d:%02d => %lld (%s, "
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+	       "day %d)\n", ( tm->tm_year + 1900 ), ( tm->tm_mon + 1 ),
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+	       tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec, seconds,
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+	       weekdays[ tm->tm_wday ], tm->tm_yday );
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+
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+	return seconds;
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+}

+ 11
- 13
src/include/sys/time.h Wyświetl plik

@@ -1,20 +1,18 @@
1 1
 #ifndef _SYS_TIME_H
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 #define _SYS_TIME_H
3 3
 
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-#include <time.h>
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+/** @file
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+ *
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+ * Date and time
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+ */
5 8
 
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-typedef unsigned long suseconds_t;
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+#include <stdint.h>
7 10
 
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-struct timeval {
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-	time_t tv_sec;		/* seconds */
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-	suseconds_t tv_usec;	/* microseconds */
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-};
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-
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-struct timezone {
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-	int tz_minuteswest;	/* minutes W of Greenwich */
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-	int tz_dsttime;		/* type of dst correction */
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-};
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-
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-extern int gettimeofday ( struct timeval *tv, struct timezone *tz );
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+/** Seconds since the Epoch
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+ *
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+ * We use a 64-bit type to avoid Y2K38 issues, since we may have to
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+ * handle distant future dates (e.g. X.509 certificate expiry dates).
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+ */
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+typedef int64_t time_t;
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 #endif /* _SYS_TIME_H */

+ 25
- 12
src/include/time.h Wyświetl plik

@@ -1,22 +1,35 @@
1 1
 #ifndef _TIME_H
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 #define _TIME_H
3 3
 
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-typedef unsigned long time_t;
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+/** @file
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+ *
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+ * Date and time
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+ */
5 8
 
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+#include <sys/time.h>
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+
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+/** Broken-down time */
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 struct tm {
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-	int tm_sec;	/* seconds */
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-	int tm_min;	/* minutes */
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-	int tm_hour;	/* hours */
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-	int tm_mday;	/* day of the month */
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-	int tm_mon;	/* month */
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-	int tm_year;	/* year */
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-	int tm_wday;	/* day of the week */
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-	int tm_yday;	/* day in the year */
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-	int tm_isdst;	/* daylight saving time */
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+	/** Seconds [0,60] */
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+	int tm_sec;
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+	/** Minutes [0,59] */
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+	int tm_min;
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+	/** Hour [0,23] */
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+	int tm_hour;
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+	/** Day of month [1,31] */
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+	int tm_mday;
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+	/** Month of year [0,11] */
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+	int tm_mon;
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+	/** Years since 1900 */
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+	int tm_year;
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+	/** Day of week [0,6] (Sunday=0) */
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+	int tm_wday;
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+	/** Day of year [0,365] */
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+	int tm_yday;
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+	/** Daylight savings flag */
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+	int tm_isdst;
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 };
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-extern time_t time ( time_t *t );
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-
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 extern time_t mktime ( struct tm *tm );
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 #endif /* _TIME_H */

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