/* 
   Unix SMB/CIFS implementation.
   time handling functions
   Copyright (C) Andrew Tridgell 		1992-1998
   Copyright (C) Stefan (metze) Metzmacher	2002   
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

/*
  This stuff was largely rewritten by Paul Eggert <eggert@twinsun.com>
  in May 1996 
  */

int extra_time_offset = 0;

#ifndef CHAR_BIT
#define CHAR_BIT 8
#endif

#ifndef TIME_T_MIN
#define TIME_T_MIN ((time_t)0 < (time_t) -1 ? (time_t) 0 \
		    : ~ (time_t) 0 << (sizeof (time_t) * CHAR_BIT - 1))
#endif
#ifndef TIME_T_MAX
#define TIME_T_MAX (~ (time_t) 0 - TIME_T_MIN)
#endif

void get_nttime_max(NTTIME *t)
{
	/* FIXME: This is incorrect */
	unix_to_nt_time(t, get_time_t_max());
}

/*******************************************************************
 External access to time_t_min and time_t_max.
********************************************************************/

time_t get_time_t_max(void)
{
	return TIME_T_MAX;
}

/*******************************************************************
 A gettimeofday wrapper.
********************************************************************/

void GetTimeOfDay(struct timeval *tval)
{
#ifdef HAVE_GETTIMEOFDAY_TZ
	gettimeofday(tval,NULL);
#else
	gettimeofday(tval);
#endif
}

#define TM_YEAR_BASE 1900

/*******************************************************************
 Yield the difference between *A and *B, in seconds, ignoring leap seconds.
********************************************************************/

static int tm_diff(struct tm *a, struct tm *b)
{
	int ay = a->tm_year + (TM_YEAR_BASE - 1);
	int by = b->tm_year + (TM_YEAR_BASE - 1);
	int intervening_leap_days = (ay/4 - by/4) - (ay/100 - by/100) + (ay/400 - by/400);
	int years = ay - by;
	int days = 365*years + intervening_leap_days + (a->tm_yday - b->tm_yday);
	int hours = 24*days + (a->tm_hour - b->tm_hour);
	int minutes = 60*hours + (a->tm_min - b->tm_min);
	int seconds = 60*minutes + (a->tm_sec - b->tm_sec);

	return seconds;
}

/*******************************************************************
 Return the UTC offset in seconds west of UTC, or 0 if it cannot be determined.
******************************************************************/

int get_time_zone(time_t t)
{
	struct tm *tm = gmtime(&t);
	struct tm tm_utc;

	if (!tm) {
		return 0;
	}
	tm_utc = *tm;
	tm = localtime(&t);
	if (!tm) {
		return 0;
	}
	return tm_diff(&tm_utc,tm) + 60*extra_time_offset;
}

/*******************************************************************
 Accessor function for the server time zone offset.
 set_server_zone_offset() must have been called first.
******************************************************************/

static int server_zone_offset;

int get_server_zone_offset(void)
{
	return server_zone_offset;
}

/*******************************************************************
 Initialize the server time zone offset. Called when a client connects.
******************************************************************/

int set_server_zone_offset(time_t t)
{
	server_zone_offset = get_time_zone(t);
	return server_zone_offset;
}

/*******************************************************************
 Re-read the smb serverzone value.
******************************************************************/

static struct timeval start_time_hires;

void TimeInit(void)
{
	set_server_zone_offset(time(NULL));

	DEBUG(4,("TimeInit: Serverzone is %d\n", server_zone_offset));

	/* Save the start time of this process. */
	if (start_time_hires.tv_sec == 0 && start_time_hires.tv_usec == 0) {
		GetTimeOfDay(&start_time_hires);
	}
}

/**********************************************************************
 Return a timeval struct of the uptime of this process. As TimeInit is
 done before a daemon fork then this is the start time from the parent
 daemon start. JRA.
***********************************************************************/

void get_process_uptime(struct timeval *ret_time)
{
	struct timeval time_now_hires;

	GetTimeOfDay(&time_now_hires);
	ret_time->tv_sec = time_now_hires.tv_sec - start_time_hires.tv_sec;
	ret_time->tv_usec = time_now_hires.tv_usec - start_time_hires.tv_usec;
	if (time_now_hires.tv_usec < start_time_hires.tv_usec) {
		ret_time->tv_sec -= 1;
		ret_time->tv_usec = 1000000 + (time_now_hires.tv_usec - start_time_hires.tv_usec);
	} else {
		ret_time->tv_usec = time_now_hires.tv_usec - start_time_hires.tv_usec;
	}
}

#if 0
/****************************************************************************
 Return the UTC offset in seconds west of UTC, adjusted for extra time offset.
**************************************************************************/

int TimeDiff(time_t t)
{
	return get_time_zone(t);
}
#endif

#define TIME_FIXUP_CONSTANT (369.0*365.25*24*60*60-(3.0*24*60*60+6.0*60*60))

/****************************************************************************
 Interpret an 8 byte "filetime" structure to a time_t
 It's originally in "100ns units since jan 1st 1601"

 An 8 byte value of 0xffffffffffffffff will be returned as (time_t)0.

 Returns GMT.
****************************************************************************/

time_t nt_time_to_unix(NTTIME *nt)
{
	double d;
	time_t ret;
	/* The next two lines are a fix needed for the 
		broken SCO compiler. JRA. */
	time_t l_time_min = TIME_T_MIN;
	time_t l_time_max = TIME_T_MAX;

	if (nt->high == 0 || (nt->high == 0xffffffff && nt->low == 0xffffffff)) {
		return(0);
	}

	d = ((double)nt->high)*4.0*(double)(1<<30);
	d += (nt->low&0xFFF00000);
	d *= 1.0e-7;
 
	/* now adjust by 369 years to make the secs since 1970 */
	d -= TIME_FIXUP_CONSTANT;

	if (d <= l_time_min) {
		return (l_time_min);
	}

	if (d >= l_time_max) {
		return (l_time_max);
	}

	ret = (time_t)(d+0.5);
	return(ret);
}

/****************************************************************************
 Convert a NTTIME structure to a time_t.
 It's originally in "100ns units".

 This is an absolute version of the one above.
 By absolute I mean, it doesn't adjust from 1/1/1601 to 1/1/1970
 if the NTTIME was 5 seconds, the time_t is 5 seconds. JFM
****************************************************************************/

time_t nt_time_to_unix_abs(const NTTIME *nt)
{
	double d;
	time_t ret;
	/* The next two lines are a fix needed for the 
	   broken SCO compiler. JRA. */
	time_t l_time_min = TIME_T_MIN;
	time_t l_time_max = TIME_T_MAX;
	NTTIME neg_nt;

	if (nt->high == 0) {
		return(0);
	}

	if (nt->high==0x80000000 && nt->low==0) {
		return (time_t)-1;
	}

	/* reverse the time */
	/* it's a negative value, turn it to positive */
	neg_nt.high=~nt->high;
	neg_nt.low=~nt->low;

	d = ((double)neg_nt.high)*4.0*(double)(1<<30);
	d += (neg_nt.low&0xFFF00000);
	d *= 1.0e-7;
  
	if (!(l_time_min <= d && d <= l_time_max)) {
		return(0);
	}

	ret = (time_t)(d+0.5);

	return(ret);
}

/****************************************************************************
 Interprets an nt time into a unix time_t.
 Differs from nt_time_to_unix in that an 8 byte value of 0xffffffffffffffff
 will be returned as (time_t)-1, whereas nt_time_to_unix returns 0 in this case.
****************************************************************************/

time_t interpret_long_date(char *p)
{
	NTTIME nt;
	nt.low = IVAL(p,0);
	nt.high = IVAL(p,4);
	if (nt.low == 0xFFFFFFFF && nt.high == 0xFFFFFFFF) {
		return (time_t)-1;
	}
	return nt_time_to_unix(&nt);
}

/****************************************************************************
 Put a 8 byte filetime from a time_t. Uses GMT.
****************************************************************************/

void unix_to_nt_time(NTTIME *nt, time_t t)
{
	double d;

	if (t==0) {
		nt->low = 0;
		nt->high = 0;
		return;
	}
	if (t == TIME_T_MAX) {
		nt->low = 0xffffffff;
		nt->high = 0x7fffffff;
		return;
	}		
	if (t == (time_t)-1) {
		nt->low = 0xffffffff;
		nt->high = 0xffffffff;
		return;
	}		

	d = (double)(t);
	d += TIME_FIXUP_CONSTANT;
	d *= 1.0e7;

	nt->high = (uint32)(d * (1.0/(4.0*(double)(1<<30))));
	nt->low  = (uint32)(d - ((double)nt->high)*4.0*(double)(1<<30));
}

/****************************************************************************
 Convert a time_t to a NTTIME structure

 This is an absolute version of the one above.
 By absolute I mean, it doesn't adjust from 1/1/1970 to 1/1/1601
 If the nttime_t was 5 seconds, the NTTIME is 5 seconds. JFM
****************************************************************************/

void unix_to_nt_time_abs(NTTIME *nt, time_t t)
{
	double d;

	if (t==0) {
		nt->low = 0;
		nt->high = 0;
		return;
	}

	if (t == TIME_T_MAX) {
		nt->low = 0xffffffff;
		nt->high = 0x7fffffff;
		return;
	}
		
	if (t == (time_t)-1) {
		/* that's what NT uses for infinite */
		nt->low = 0x0;
		nt->high = 0x80000000;
		return;
	}		

	d = (double)(t);
	d *= 1.0e7;

	nt->high = (uint32)(d * (1.0/(4.0*(double)(1<<30))));
	nt->low  = (uint32)(d - ((double)nt->high)*4.0*(double)(1<<30));

	/* convert to a negative value */
	nt->high=~nt->high;
	nt->low=~nt->low;
}

/****************************************************************************
 Take a Unix time and convert to an NTTIME structure and place in buffer 
 pointed to by p.
****************************************************************************/

void put_long_date(char *p, time_t t)
{
	NTTIME nt;
	unix_to_nt_time(&nt, t);
	SIVAL(p, 0, nt.low);
	SIVAL(p, 4, nt.high);
}

/****************************************************************************
 Check if it's a null mtime.
****************************************************************************/

BOOL null_mtime(time_t mtime)
{
	if (mtime == 0 || mtime == (time_t)0xFFFFFFFF || mtime == (time_t)-1)
		return(True);
	return(False);
}

/*******************************************************************
 Create a 16 bit dos packed date.
********************************************************************/

static uint16 make_dos_date1(struct tm *t)
{
	uint16 ret=0;
	ret = (((unsigned)(t->tm_mon+1)) >> 3) | ((t->tm_year-80) << 1);
	ret = ((ret&0xFF)<<8) | (t->tm_mday | (((t->tm_mon+1) & 0x7) << 5));
	return(ret);
}

/*******************************************************************
 Create a 16 bit dos packed time.
********************************************************************/

static uint16 make_dos_time1(struct tm *t)
{
	uint16 ret=0;
	ret = ((((unsigned)t->tm_min >> 3)&0x7) | (((unsigned)t->tm_hour) << 3));
	ret = ((ret&0xFF)<<8) | ((t->tm_sec/2) | ((t->tm_min & 0x7) << 5));
	return(ret);
}

/*******************************************************************
 Create a 32 bit dos packed date/time from some parameters.
 This takes a GMT time and returns a packed localtime structure.
********************************************************************/

static uint32 make_dos_date(time_t unixdate, int zone_offset)
{
	struct tm *t;
	uint32 ret=0;

	if (unixdate == 0) {
		return 0;
	}

	unixdate -= zone_offset;
	t = gmtime(&unixdate);
	if (!t) {
		return 0xFFFFFFFF;
	}

	ret = make_dos_date1(t);
	ret = ((ret&0xFFFF)<<16) | make_dos_time1(t);

	return(ret);
}

/*******************************************************************
 Put a dos date into a buffer (time/date format).
 This takes GMT time and puts local time in the buffer.
********************************************************************/

static void put_dos_date(char *buf,int offset,time_t unixdate, int zone_offset)
{
	uint32 x = make_dos_date(unixdate, zone_offset);
	SIVAL(buf,offset,x);
}

/*******************************************************************
 Put a dos date into a buffer (date/time format).
 This takes GMT time and puts local time in the buffer.
********************************************************************/

static void put_dos_date2(char *buf,int offset,time_t unixdate, int zone_offset)
{
	uint32 x = make_dos_date(unixdate, zone_offset);
	x = ((x&0xFFFF)<<16) | ((x&0xFFFF0000)>>16);
	SIVAL(buf,offset,x);
}

/*******************************************************************
 Put a dos 32 bit "unix like" date into a buffer. This routine takes
 GMT and converts it to LOCAL time before putting it (most SMBs assume
 localtime for this sort of date)
********************************************************************/

static void put_dos_date3(char *buf,int offset,time_t unixdate, int zone_offset)
{
	if (!null_mtime(unixdate)) {
		unixdate -= zone_offset;
	}
	SIVAL(buf,offset,unixdate);
}

/*******************************************************************
 Interpret a 32 bit dos packed date/time to some parameters.
********************************************************************/

static void interpret_dos_date(uint32 date,int *year,int *month,int *day,int *hour,int *minute,int *second)
{
	uint32 p0,p1,p2,p3;

	p0=date&0xFF; p1=((date&0xFF00)>>8)&0xFF; 
	p2=((date&0xFF0000)>>16)&0xFF; p3=((date&0xFF000000)>>24)&0xFF;

	*second = 2*(p0 & 0x1F);
	*minute = ((p0>>5)&0xFF) + ((p1&0x7)<<3);
	*hour = (p1>>3)&0xFF;
	*day = (p2&0x1F);
	*month = ((p2>>5)&0xFF) + ((p3&0x1)<<3) - 1;
	*year = ((p3>>1)&0xFF) + 80;
}

/*******************************************************************
 Create a unix date (int GMT) from a dos date (which is actually in
 localtime).
********************************************************************/

static time_t make_unix_date(void *date_ptr, int zone_offset)
{
	uint32 dos_date=0;
	struct tm t;
	time_t ret;

	dos_date = IVAL(date_ptr,0);

	if (dos_date == 0) {
		return 0;
	}
  
	interpret_dos_date(dos_date,&t.tm_year,&t.tm_mon,
			&t.tm_mday,&t.tm_hour,&t.tm_min,&t.tm_sec);
	t.tm_isdst = -1;
  
	ret = timegm(&t);

	ret += zone_offset;

	return(ret);
}

/*******************************************************************
 Like make_unix_date() but the words are reversed.
********************************************************************/

static time_t make_unix_date2(void *date_ptr, int zone_offset)
{
	uint32 x,x2;

	x = IVAL(date_ptr,0);
	x2 = ((x&0xFFFF)<<16) | ((x&0xFFFF0000)>>16);
	SIVAL(&x,0,x2);

	return(make_unix_date((void *)&x, zone_offset));
}

/*******************************************************************
 Create a unix GMT date from a dos date in 32 bit "unix like" format
 these generally arrive as localtimes, with corresponding DST.
******************************************************************/

static time_t make_unix_date3(void *date_ptr, int zone_offset)
{
	time_t t = (time_t)IVAL(date_ptr,0);
	if (!null_mtime(t)) {
		t += zone_offset;
	}
	return(t);
}

/***************************************************************************
 Server versions of the above functions.
***************************************************************************/

void srv_put_dos_date(char *buf,int offset,time_t unixdate)
{
	put_dos_date(buf, offset, unixdate, server_zone_offset);
}

void srv_put_dos_date2(char *buf,int offset, time_t unixdate)
{
	put_dos_date2(buf, offset, unixdate, server_zone_offset);
}

void srv_put_dos_date3(char *buf,int offset,time_t unixdate)
{
	put_dos_date3(buf, offset, unixdate, server_zone_offset);
}

time_t srv_make_unix_date(void *date_ptr)
{
	return make_unix_date(date_ptr, server_zone_offset);
}

time_t srv_make_unix_date2(void *date_ptr)
{
	return make_unix_date2(date_ptr, server_zone_offset);
}

time_t srv_make_unix_date3(void *date_ptr)
{
	return make_unix_date3(date_ptr, server_zone_offset);
}

/***************************************************************************
 Client versions of the above functions.
***************************************************************************/

void cli_put_dos_date(struct cli_state *cli, char *buf, int offset, time_t unixdate)
{
	put_dos_date(buf, offset, unixdate, cli->serverzone);
}

void cli_put_dos_date2(struct cli_state *cli, char *buf, int offset, time_t unixdate)
{
	put_dos_date2(buf, offset, unixdate, cli->serverzone);
}

void cli_put_dos_date3(struct cli_state *cli, char *buf, int offset, time_t unixdate)
{
	put_dos_date3(buf, offset, unixdate, cli->serverzone);
}

time_t cli_make_unix_date(struct cli_state *cli, void *date_ptr)
{
	return make_unix_date(date_ptr, cli->serverzone);
}

time_t cli_make_unix_date2(struct cli_state *cli, void *date_ptr)
{
	return make_unix_date2(date_ptr, cli->serverzone);
}

time_t cli_make_unix_date3(struct cli_state *cli, void *date_ptr)
{
	return make_unix_date3(date_ptr, cli->serverzone);
}

/***************************************************************************
 Return a HTTP/1.0 time string.
***************************************************************************/

char *http_timestring(time_t t)
{
	static fstring buf;
	struct tm *tm = localtime(&t);

	if (!tm)
		slprintf(buf,sizeof(buf)-1,"%ld seconds since the Epoch",(long)t);
	else
#ifndef HAVE_STRFTIME
		fstrcpy(buf, asctime(tm));
	if(buf[strlen(buf)-1] == '\n')
		buf[strlen(buf)-1] = 0;
#else /* !HAVE_STRFTIME */
		strftime(buf, sizeof(buf)-1, "%a, %d %b %Y %H:%M:%S %Z", tm);
#endif /* !HAVE_STRFTIME */
	return buf;
}

/****************************************************************************
 Return the date and time as a string
****************************************************************************/

char *timestring(BOOL hires)
{
	static fstring TimeBuf;
	struct timeval tp;
	time_t t;
	struct tm *tm;

	if (hires) {
		GetTimeOfDay(&tp);
		t = (time_t)tp.tv_sec;
	} else {
		t = time(NULL);
	}
	tm = localtime(&t);
	if (!tm) {
		if (hires) {
			slprintf(TimeBuf,
				 sizeof(TimeBuf)-1,
				 "%ld.%06ld seconds since the Epoch",
				 (long)tp.tv_sec, 
				 (long)tp.tv_usec);
		} else {
			slprintf(TimeBuf,
				 sizeof(TimeBuf)-1,
				 "%ld seconds since the Epoch",
				 (long)t);
		}
	} else {
#ifdef HAVE_STRFTIME
		if (hires) {
			strftime(TimeBuf,sizeof(TimeBuf)-1,"%Y/%m/%d %H:%M:%S",tm);
			slprintf(TimeBuf+strlen(TimeBuf),
				 sizeof(TimeBuf)-1 - strlen(TimeBuf), 
				 ".%06ld", 
				 (long)tp.tv_usec);
		} else {
			strftime(TimeBuf,sizeof(TimeBuf)-1,"%Y/%m/%d %H:%M:%S",tm);
		}
#else
		if (hires) {
			slprintf(TimeBuf, 
				 sizeof(TimeBuf)-1, 
				 "%s.%06ld", 
				 asctime(tm), 
				 (long)tp.tv_usec);
		} else {
			fstrcpy(TimeBuf, asctime(tm));
		}
#endif
	}
	return(TimeBuf);
}

/****************************************************************************
 Return the best approximation to a 'create time' under UNIX from a stat
 structure.
****************************************************************************/

time_t get_create_time(SMB_STRUCT_STAT *st,BOOL fake_dirs)
{
	time_t ret, ret1;

	if(S_ISDIR(st->st_mode) && fake_dirs) {
		return (time_t)315493200L;          /* 1/1/1980 */
	}
    
	ret = MIN(st->st_ctime, st->st_mtime);
	ret1 = MIN(ret, st->st_atime);

	if(ret1 != (time_t)0) {
		return ret1;
	}

	/*
	 * One of ctime, mtime or atime was zero (probably atime).
	 * Just return MIN(ctime, mtime).
	 */
	return ret;
}

/****************************************************************************
 Initialise an NTTIME to -1, which means "unknown" or "don't expire".
****************************************************************************/

void init_nt_time(NTTIME *nt)
{
	nt->high = 0x7FFFFFFF;
	nt->low = 0xFFFFFFFF;
}

BOOL nt_time_is_set(const NTTIME *nt)
{
	if ((nt->high == 0x7FFFFFFF) && (nt->low == 0xFFFFFFFF)) {
		return False;
	}

	if ((nt->high == 0x80000000) && (nt->low == 0)) {
		return False;
	}

	return True;
}

/****************************************************************************
 Check if NTTIME is 0.
****************************************************************************/

BOOL nt_time_is_zero(const NTTIME *nt)
{
	if(nt->high==0) {
		return True;
	}
	return False;
}

/****************************************************************************
 Check if two NTTIMEs are the same.
****************************************************************************/

BOOL nt_time_equals(const NTTIME *nt1, const NTTIME *nt2)
{
	return (nt1->high == nt2->high && nt1->low == nt2->low);
}

/****************************************************************************
 Return a timeval difference in usec.
****************************************************************************/

SMB_BIG_INT usec_time_diff(const struct timeval *larget, const struct timeval *smallt)
{
	SMB_BIG_INT sec_diff = larget->tv_sec - smallt->tv_sec;
	return (sec_diff * 1000000) + (SMB_BIG_INT)(larget->tv_usec - smallt->tv_usec);
}

/****************************************************************************
 Return a timeval struct with the given elements.
****************************************************************************/

struct timeval timeval_set(uint32_t secs, uint32_t usecs)
{
	struct timeval tv;
	tv.tv_sec = secs;
	tv.tv_usec = usecs;
	return tv;
}

/****************************************************************************
 Return a zero timeval.
****************************************************************************/

struct timeval timeval_zero(void)
{
	return timeval_set(0,0);
}

/****************************************************************************
 Return True if a timeval is zero.
****************************************************************************/

BOOL timeval_is_zero(const struct timeval *tv)
{
	return tv->tv_sec == 0 && tv->tv_usec == 0;
}

/****************************************************************************
 Return a timeval for the current time.
****************************************************************************/

struct timeval timeval_current(void)
{
	struct timeval tv;
	GetTimeOfDay(&tv);
	return tv;
}

/****************************************************************************
 Return a timeval ofs microseconds after tv.
****************************************************************************/

struct timeval timeval_add(const struct timeval *tv,
			   uint32_t secs, uint32_t usecs)
{
	struct timeval tv2 = *tv;
	tv2.tv_sec += secs;
	tv2.tv_usec += usecs;
	tv2.tv_sec += tv2.tv_usec / 1000000;
	tv2.tv_usec = tv2.tv_usec % 1000000;
	return tv2;
}

/****************************************************************************
 Return the sum of two timeval structures.
****************************************************************************/

struct timeval timeval_sum(const struct timeval *tv1,
			   const struct timeval *tv2)
{
	return timeval_add(tv1, tv2->tv_sec, tv2->tv_usec);
}

/****************************************************************************
 Return a timeval secs/usecs into the future.
****************************************************************************/

struct timeval timeval_current_ofs(uint32_t secs, uint32_t usecs)
{
	struct timeval tv = timeval_current();
	return timeval_add(&tv, secs, usecs);
}

/****************************************************************************
 Compare two timeval structures. 
 Return -1 if tv1 < tv2
 Return 0 if tv1 == tv2
 Return 1 if tv1 > tv2
****************************************************************************/

int timeval_compare(const struct timeval *tv1, const struct timeval *tv2)
{
	if (tv1->tv_sec  > tv2->tv_sec) {
		return 1;
	}
	if (tv1->tv_sec  < tv2->tv_sec) {
		return -1;
	}
	if (tv1->tv_usec > tv2->tv_usec) {
		return 1;
	}
	if (tv1->tv_usec < tv2->tv_usec) {
		return -1;
	}
	return 0;
}

/****************************************************************************
 Return the difference between two timevals as a timeval.
 If tv1 comes after tv2, then return a zero timeval
 (this is *tv2 - *tv1).
****************************************************************************/

struct timeval timeval_until(const struct timeval *tv1,
			     const struct timeval *tv2)
{
	struct timeval t;
	if (timeval_compare(tv1, tv2) >= 0) {
		return timeval_zero();
	}
	t.tv_sec = tv2->tv_sec - tv1->tv_sec;
	if (tv1->tv_usec > tv2->tv_usec) {
		t.tv_sec--;
		t.tv_usec = 1000000 - (tv1->tv_usec - tv2->tv_usec);
	} else {
		t.tv_usec = tv2->tv_usec - tv1->tv_usec;
	}
	return t;
}

/****************************************************************************
 Return the lesser of two timevals.
****************************************************************************/

struct timeval timeval_min(const struct timeval *tv1,
			   const struct timeval *tv2)
{
	if (tv1->tv_sec < tv2->tv_sec) {
		return *tv1;
	}
	if (tv1->tv_sec > tv2->tv_sec) {
		return *tv2;
	}
	if (tv1->tv_usec < tv2->tv_usec) {
		return *tv1;
	}
	return *tv2;
}

/****************************************************************************
 Return the greater of two timevals.
****************************************************************************/

struct timeval timeval_max(const struct timeval *tv1,
			   const struct timeval *tv2)
{
	if (tv1->tv_sec > tv2->tv_sec) {
		return *tv1;
	}
	if (tv1->tv_sec < tv2->tv_sec) {
		return *tv2;
	}
	if (tv1->tv_usec > tv2->tv_usec) {
		return *tv1;
	}
	return *tv2;
}

/****************************************************************************
 Convert ASN.1 GeneralizedTime string to unix-time.
 Returns 0 on failure; Currently ignores timezone. 
****************************************************************************/

time_t generalized_to_unix_time(const char *str)
{ 
	struct tm tm;

	ZERO_STRUCT(tm);

	if (sscanf(str, "%4d%2d%2d%2d%2d%2d", 
		   &tm.tm_year, &tm.tm_mon, &tm.tm_mday, 
		   &tm.tm_hour, &tm.tm_min, &tm.tm_sec) != 6) {
		return 0;
	}
	tm.tm_year -= 1900;
	tm.tm_mon -= 1;

	return timegm(&tm);
}