mariadb/sql-common/my_time.c

/* Copyright (C) 2004 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include <my_time.h>
#include <m_string.h>
#include <m_ctype.h>
/* Windows version of localtime_r() is declared in my_ptrhead.h */
#include <my_pthread.h>

ulonglong log_10_int[20]=
{
  1, 10, 100, 1000, 10000UL, 100000UL, 1000000UL, 10000000UL,
  ULL(100000000), ULL(1000000000), ULL(10000000000), ULL(100000000000),
  ULL(1000000000000), ULL(10000000000000), ULL(100000000000000),
  ULL(1000000000000000), ULL(10000000000000000), ULL(100000000000000000),
  ULL(1000000000000000000), ULL(10000000000000000000)
};


/* Position for YYYY-DD-MM HH-MM-DD.FFFFFF AM in default format */

static uchar internal_format_positions[]=
{0, 1, 2, 3, 4, 5, 6, (uchar) 255};

static char time_separator=':';

static ulong const days_at_timestart=719528;	/* daynr at 1970.01.01 */
uchar days_in_month[]= {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0};

/*
  Offset of system time zone from UTC in seconds used to speed up 
  work of my_system_gmt_sec() function.
*/
static long my_time_zone=0;


/* Calc days in one year. works with 0 <= year <= 99 */

uint calc_days_in_year(uint year)
{
  return ((year & 3) == 0 && (year%100 || (year%400 == 0 && year)) ?
          366 : 365);
}

/*
  check date.

  SYNOPOSIS
    bool check_date()
    time	Date to check.

  NOTES
    Here we assume that year and month is ok !
    If month is 0 we allow any date. (This only happens if we allow zero
    date parts in str_to_datetime())

  RETURN
    0  ok
    1  errro
*/

bool check_date(MYSQL_TIME *ltime)
{
  if (ltime->month && ltime->day > days_in_month[ltime->month-1])
  {
    if (ltime->month != 2 || calc_days_in_year(ltime->year) != 366 ||
        ltime->day != 29)
      return 1;
  }
  return 0;
}


/*
  Convert a timestamp string to a MYSQL_TIME value.

  SYNOPSIS
    str_to_datetime()
    str                 String to parse
    length              Length of string
    l_time              Date is stored here
    flags               Bitmap of following items
                        TIME_FUZZY_DATE    Set if we should allow partial dates
                        TIME_DATETIME_ONLY Set if we only allow full datetimes.
                        TIME_NO_ZERO_IN_DATE	Don't allow partial dates
                        TIME_NO_ZERO_DATE	Don't allow 0000-00-00 date
                        TIME_INVALID_DATES	Allow 2000-02-31
    was_cut             0	Value ok
			1       If value was cut during conversion
			2	Date part was withing ranges but date was wrong

  DESCRIPTION
    At least the following formats are recogniced (based on number of digits)
    YYMMDD, YYYYMMDD, YYMMDDHHMMSS, YYYYMMDDHHMMSS
    YY-MM-DD, YYYY-MM-DD, YY-MM-DD HH.MM.SS
    YYYYMMDDTHHMMSS  where T is a the character T (ISO8601)
    Also dates where all parts are zero are allowed

    The second part may have an optional .###### fraction part.

  NOTES
   This function should work with a format position vector as long as the
   following things holds:
   - All date are kept together and all time parts are kept together
   - Date and time parts must be separated by blank
   - Second fractions must come after second part and be separated
     by a '.'.  (The second fractions are optional)
   - AM/PM must come after second fractions (or after seconds if no fractions)
   - Year must always been specified.
   - If time is before date, then we will use datetime format only if
     the argument consist of two parts, separated by space.
     Otherwise we will assume the argument is a date.
   - The hour part must be specified in hour-minute-second order.

  RETURN VALUES
    MYSQL_TIMESTAMP_NONE        String wasn't a timestamp, like
                                [DD [HH:[MM:[SS]]]].fraction.
                                l_time is not changed.
    MYSQL_TIMESTAMP_DATE        DATE string (YY MM and DD parts ok)
    MYSQL_TIMESTAMP_DATETIME    Full timestamp
    MYSQL_TIMESTAMP_ERROR       Timestamp with wrong values.
                                All elements in l_time is set to 0
*/

#define MAX_DATE_PARTS 8

enum enum_mysql_timestamp_type
str_to_datetime(const char *str, uint length, MYSQL_TIME *l_time,
                uint flags, int *was_cut)
{
  uint field_length, year_length, digits, i, number_of_fields;
  uint date[MAX_DATE_PARTS], date_len[MAX_DATE_PARTS];
  uint add_hours= 0, start_loop;
  ulong not_zero_date, allow_space;
  bool is_internal_format;
  const char *pos, *last_field_pos;
  const char *end=str+length;
  const uchar *format_position;
  bool found_delimitier= 0, found_space= 0;
  uint frac_pos, frac_len;
  DBUG_ENTER("str_to_datetime");
  DBUG_PRINT("ENTER",("str: %.*s",length,str));

  LINT_INIT(field_length);
  LINT_INIT(year_length);
  LINT_INIT(last_field_pos);

  *was_cut= 0;

  /* Skip space at start */
  for (; str != end && my_isspace(&my_charset_latin1, *str) ; str++)
    ;
  if (str == end || ! my_isdigit(&my_charset_latin1, *str))
  {
    *was_cut= 1;
    DBUG_RETURN(MYSQL_TIMESTAMP_NONE);
  }
  if (flags & TIME_NO_ZERO_IN_DATE)
    flags&= ~TIME_FUZZY_DATE;

  is_internal_format= 0;
  /* This has to be changed if want to activate different timestamp formats */
  format_position= internal_format_positions;

  /*
    Calculate number of digits in first part.
    If length= 8 or >= 14 then year is of format YYYY.
    (YYYY-MM-DD,  YYYYMMDD, YYYYYMMDDHHMMSS)
  */
  for (pos=str; pos != end && my_isdigit(&my_charset_latin1,*pos) ; pos++)
    ;

  digits= (uint) (pos-str);
  start_loop= 0;                                /* Start of scan loop */
  date_len[format_position[0]]= 0;              /* Length of year field */
  if (pos == end)
  {
    /* Found date in internal format (only numbers like YYYYMMDD) */
    year_length= (digits == 4 || digits == 8 || digits >= 14) ? 4 : 2;
    field_length=year_length-1;
    is_internal_format= 1;
    format_position= internal_format_positions;
  }
  else
  {
    if (format_position[0] >= 3)                /* If year is after HHMMDD */
    {
      /*
        If year is not in first part then we have to determinate if we got
        a date field or a datetime field.
        We do this by checking if there is two numbers separated by
        space in the input.
      */
      while (pos < end && !my_isspace(&my_charset_latin1, *pos))
        pos++;
      while (pos < end && !my_isdigit(&my_charset_latin1, *pos))
        pos++;
      if (pos == end)
      {
        if (flags & TIME_DATETIME_ONLY)
        {
          *was_cut= 1;
          DBUG_RETURN(MYSQL_TIMESTAMP_NONE);   /* Can't be a full datetime */
        }
        /* Date field.  Set hour, minutes and seconds to 0 */
        date[0]= date[1]= date[2]= date[3]= date[4]= 0;
        start_loop= 5;                         /* Start with first date part */
      }
    }
  }

  /*
    Only allow space in the first "part" of the datetime field and:
    - after days, part seconds
    - before and after AM/PM (handled by code later)

    2003-03-03 20:00:20 AM
    20:00:20.000000 AM 03-03-2000
  */
  i= max((uint) format_position[0], (uint) format_position[1]);
  set_if_bigger(i, (uint) format_position[2]);
  allow_space= ((1 << i) | (1 << format_position[6]));
  allow_space&= (1 | 2 | 4 | 8);

  not_zero_date= 0;
  for (i = start_loop;
       i < MAX_DATE_PARTS-1 && str != end &&
         my_isdigit(&my_charset_latin1,*str);
       i++)
  {
    const char *start= str;
    ulong tmp_value= (uint) (uchar) (*str++ - '0');
    while (str != end && my_isdigit(&my_charset_latin1,str[0]) &&
           (!is_internal_format || field_length--))
    {
      tmp_value=tmp_value*10 + (ulong) (uchar) (*str - '0');
      str++;
    }
    date_len[i]= (uint) (str - start);
    if (tmp_value > 999999)                     /* Impossible date part */
    {
      *was_cut= 1;
      DBUG_RETURN(MYSQL_TIMESTAMP_NONE);
    }
    date[i]=tmp_value;
    not_zero_date|= tmp_value;

    /* Length-1 of next field */
    field_length= format_position[i+1] == 0 ? 3 : 1;

    if ((last_field_pos= str) == end)
    {
      i++;                                      /* Register last found part */
      break;
    }
    /* Allow a 'T' after day to allow CCYYMMDDT type of fields */
    if (i == format_position[2] && *str == 'T')
    {
      str++;                                    /* ISO8601:  CCYYMMDDThhmmss */
      continue;
    }
    if (i == format_position[5])                /* Seconds */
    {
      if (*str == '.')                          /* Followed by part seconds */
      {
        str++;
        field_length= 5;                        /* 5 digits after first (=6) */
      }
      continue;

      /* No part seconds */
      date[++i]= 0;
    }
    while (str != end &&
           (my_ispunct(&my_charset_latin1,*str) ||
            my_isspace(&my_charset_latin1,*str)))
    {
      if (my_isspace(&my_charset_latin1,*str))
      {
        if (!(allow_space & (1 << i)))
        {
          *was_cut= 1;
          DBUG_RETURN(MYSQL_TIMESTAMP_NONE);
        }
        found_space= 1;
      }
      str++;
      found_delimitier= 1;                      /* Should be a 'normal' date */
    }
    /* Check if next position is AM/PM */
    if (i == format_position[6])                /* Seconds, time for AM/PM */
    {
      i++;                                      /* Skip AM/PM part */
      if (format_position[7] != 255)            /* If using AM/PM */
      {
        if (str+2 <= end && (str[1] == 'M' || str[1] == 'm'))
        {
          if (str[0] == 'p' || str[0] == 'P')
            add_hours= 12;
          else if (str[0] != 'a' || str[0] != 'A')
            continue;                           /* Not AM/PM */
          str+= 2;                              /* Skip AM/PM */
          /* Skip space after AM/PM */
          while (str != end && my_isspace(&my_charset_latin1,*str))
            str++;
        }
      }
    }
    last_field_pos= str;
  }
  if (found_delimitier && !found_space && (flags & TIME_DATETIME_ONLY))
  {
    *was_cut= 1;
    DBUG_RETURN(MYSQL_TIMESTAMP_NONE);          /* Can't be a datetime */
  }

  str= last_field_pos;

  number_of_fields= i - start_loop;
  while (i < MAX_DATE_PARTS)
  {
    date_len[i]= 0;
    date[i++]= 0;
  }

  if (!is_internal_format)
  {
    year_length= date_len[(uint) format_position[0]];
    if (!year_length)                           /* Year must be specified */
    {
      *was_cut= 1;
      DBUG_RETURN(MYSQL_TIMESTAMP_NONE);
    }

    l_time->year=               date[(uint) format_position[0]];
    l_time->month=              date[(uint) format_position[1]];
    l_time->day=                date[(uint) format_position[2]];
    l_time->hour=               date[(uint) format_position[3]];
    l_time->minute=             date[(uint) format_position[4]];
    l_time->second=             date[(uint) format_position[5]];

    frac_pos= (uint) format_position[6];
    frac_len= date_len[frac_pos];
    if (frac_len < 6)
      date[frac_pos]*= (uint) log_10_int[6 - frac_len];
    l_time->second_part= date[frac_pos];

    if (format_position[7] != (uchar) 255)
    {
      if (l_time->hour > 12)
      {
        *was_cut= 1;
        goto err;
      }
      l_time->hour= l_time->hour%12 + add_hours;
    }
  }
  else
  {
    l_time->year=       date[0];
    l_time->month=      date[1];
    l_time->day=        date[2];
    l_time->hour=       date[3];
    l_time->minute=     date[4];
    l_time->second=     date[5];
    if (date_len[6] < 6)
      date[6]*= (uint) log_10_int[6 - date_len[6]];
    l_time->second_part=date[6];
  }
  l_time->neg= 0;

  if (year_length == 2 && i >= format_position[1] && i >=format_position[2] &&
      (l_time->month || l_time->day))
    l_time->year+= (l_time->year < YY_PART_YEAR ? 2000 : 1900);

  if (!not_zero_date && (flags & TIME_NO_ZERO_DATE))
  {
    /*
      We don't set *was_cut here to signal that the problem was a zero date
      and not an invalid date
    */
    goto err;
  }

  if (number_of_fields < 3 || l_time->month > 12 ||
      l_time->day > 31 || l_time->hour > 23 ||
      l_time->minute > 59 || l_time->second > 59 ||
      (!(flags & TIME_FUZZY_DATE) && (l_time->month == 0 ||
                                      l_time->day == 0) &&
       not_zero_date))
  {
    /* Only give warning for a zero date if there is some garbage after */
    if (!not_zero_date)                         /* If zero date */
    {
      for (; str != end ; str++)
      {
        if (!my_isspace(&my_charset_latin1, *str))
        {
          not_zero_date= 1;                     /* Give warning */
          break;
        }
      }
    }
    *was_cut= test(not_zero_date);
    goto err;
  }

  l_time->time_type= (number_of_fields <= 3 ?
                      MYSQL_TIMESTAMP_DATE : MYSQL_TIMESTAMP_DATETIME);

  if (not_zero_date && !(flags & TIME_INVALID_DATES) && check_date(l_time))
  {
    *was_cut= 2;                                /* Not correct date */
    goto err;
  }

  for (; str != end ; str++)
  {
    if (!my_isspace(&my_charset_latin1,*str))
    {
      *was_cut= 1;
      break;
    }
  }

  DBUG_RETURN(l_time->time_type=
              (number_of_fields <= 3 ? MYSQL_TIMESTAMP_DATE :
                                       MYSQL_TIMESTAMP_DATETIME));

err:
  bzero((char*) l_time, sizeof(*l_time));
  DBUG_RETURN(MYSQL_TIMESTAMP_ERROR);
}


/*
 Convert a time string to a TIME struct.

  SYNOPSIS
   str_to_time()
   str                  A string in full TIMESTAMP format or
                        [-] DAYS [H]H:MM:SS, [H]H:MM:SS, [M]M:SS, [H]HMMSS,
                        [M]MSS or [S]S
                        There may be an optional [.second_part] after seconds
   length               Length of str
   l_time               Store result here
   was_cut              Set to 1 if value was cut during conversion or to 0
                        otherwise.

   NOTES
     Because of the extra days argument, this function can only
     work with times where the time arguments are in the above order.

   RETURN
     0  ok
     1  error
*/

bool str_to_time(const char *str, uint length, MYSQL_TIME *l_time,
                 int *was_cut)
{
  long date[5],value;
  const char *end=str+length, *end_of_days;
  bool found_days,found_hours;
  uint state;

  l_time->neg=0;
  *was_cut= 0;
  for (; str != end && my_isspace(&my_charset_latin1,*str) ; str++)
    length--;
  if (str != end && *str == '-')
  {
    l_time->neg=1;
    str++;
    length--;
  }
  if (str == end)
    return 1;

  /* Check first if this is a full TIMESTAMP */
  if (length >= 12)
  {                                             /* Probably full timestamp */
    enum enum_mysql_timestamp_type
      res= str_to_datetime(str, length, l_time,
                           (TIME_FUZZY_DATE | TIME_DATETIME_ONLY), was_cut);
    if ((int) res >= (int) MYSQL_TIMESTAMP_ERROR)
      return res == MYSQL_TIMESTAMP_ERROR;
    /* We need to restore was_cut flag since str_to_datetime can modify it */
    *was_cut= 0;
  }

  /* Not a timestamp. Try to get this as a DAYS_TO_SECOND string */
  for (value=0; str != end && my_isdigit(&my_charset_latin1,*str) ; str++)
    value=value*10L + (long) (*str - '0');

  /* Skip all space after 'days' */
  end_of_days= str;
  for (; str != end && my_isspace(&my_charset_latin1, str[0]) ; str++)
    ;

  LINT_INIT(state);
  found_days=found_hours=0;
  if ((uint) (end-str) > 1 && str != end_of_days &&
      my_isdigit(&my_charset_latin1, *str))
  {                                             /* Found days part */
    date[0]= value;
    state= 1;                                   /* Assume next is hours */
    found_days= 1;
  }
  else if ((end-str) > 1 &&  *str == time_separator &&
           my_isdigit(&my_charset_latin1, str[1]))
  {
    date[0]=0;                                  /* Assume we found hours */
    date[1]=value;
    state=2;
    found_hours=1;
    str++;                                      /* skip ':' */
  }
  else
  {
    /* String given as one number; assume HHMMSS format */
    date[0]= 0;
    date[1]= value/10000;
    date[2]= value/100 % 100;
    date[3]= value % 100;
    state=4;
    goto fractional;
  }

  /* Read hours, minutes and seconds */
  for (;;)
  {
    for (value=0; str != end && my_isdigit(&my_charset_latin1,*str) ; str++)
      value=value*10L + (long) (*str - '0');
    date[state++]=value;
    if (state == 4 || (end-str) < 2 || *str != time_separator ||
        !my_isdigit(&my_charset_latin1,str[1]))
      break;
    str++;                                      /* Skip time_separator (':') */
  }

  if (state != 4)
  {                                             /* Not HH:MM:SS */
    /* Fix the date to assume that seconds was given */
    if (!found_hours && !found_days)
    {
      bmove_upp((char*) (date+4), (char*) (date+state),
                sizeof(long)*(state-1));
      bzero((char*) date, sizeof(long)*(4-state));
    }
    else
      bzero((char*) (date+state), sizeof(long)*(4-state));
  }

fractional:
  /* Get fractional second part */
  if ((end-str) >= 2 && *str == '.' && my_isdigit(&my_charset_latin1,str[1]))
  {
    uint field_length=5;
    str++; value=(uint) (uchar) (*str - '0');
    while (++str != end && 
           my_isdigit(&my_charset_latin1,str[0]) && 
           field_length--)
      value=value*10 + (uint) (uchar) (*str - '0');
    if (field_length)
      value*= (long) log_10_int[field_length];
    date[4]=value;
  }
  else
    date[4]=0;

  if (internal_format_positions[7] != 255)
  {
    /* Read a possible AM/PM */
    while (str != end && my_isspace(&my_charset_latin1, *str))
      str++;
    if (str+2 <= end && (str[1] == 'M' || str[1] == 'm'))
    {
      if (str[0] == 'p' || str[0] == 'P')
      {
        str+= 2;
        date[1]= date[1]%12 + 12;
      }
      else if (str[0] == 'a' || str[0] == 'A')
        str+=2;
    }
  }

  /* Some simple checks */
  if (date[2] >= 60 || date[3] >= 60)
  {
    *was_cut= 1;
    return 1;
  }
  l_time->year=         0;                      /* For protocol::store_time */
  l_time->month=        0;
  l_time->day=          date[0];
  l_time->hour=         date[1];
  l_time->minute=       date[2];
  l_time->second=       date[3];
  l_time->second_part=  date[4];
  l_time->time_type= MYSQL_TIMESTAMP_TIME;

  /* Check if there is garbage at end of the TIME specification */
  if (str != end)
  {
    do
    {
      if (!my_isspace(&my_charset_latin1,*str))
      {
        *was_cut= 1;
        break;
      }
    } while (++str != end);
  }
  return 0;
}


/*
  Prepare offset of system time zone from UTC for my_system_gmt_sec() func.

  SYNOPSIS
    init_time()
*/
void init_time(void)
{
  time_t seconds;
  struct tm *l_time,tm_tmp;
  MYSQL_TIME my_time;
  bool not_used;

  seconds= (time_t) time((time_t*) 0);
  localtime_r(&seconds,&tm_tmp);
  l_time= &tm_tmp;
  my_time_zone=		3600;		/* Comp. for -3600 in my_gmt_sec */
  my_time.year=		(uint) l_time->tm_year+1900;
  my_time.month=	(uint) l_time->tm_mon+1;
  my_time.day=		(uint) l_time->tm_mday;
  my_time.hour=		(uint) l_time->tm_hour;
  my_time.minute=	(uint) l_time->tm_min;
  my_time.second=	(uint) l_time->tm_sec;
  my_system_gmt_sec(&my_time, &my_time_zone, &not_used); /* Init my_time_zone */
}


	/* Calculate nr of day since year 0 in new date-system (from 1615) */

long calc_daynr(uint year,uint month,uint day)
{
  long delsum;
  int temp;
  DBUG_ENTER("calc_daynr");

  if (year == 0 && month == 0 && day == 0)
    DBUG_RETURN(0);				/* Skip errors */
  if (year < 200)
  {
    if ((year=year+1900) < 1900+YY_PART_YEAR)
      year+=100;
  }
  delsum= (long) (365L * year+ 31*(month-1) +day);
  if (month <= 2)
      year--;
  else
    delsum-= (long) (month*4+23)/10;
  temp=(int) ((year/100+1)*3)/4;
  DBUG_PRINT("exit",("year: %d  month: %d  day: %d -> daynr: %ld",
		     year+(month <= 2),month,day,delsum+year/4-temp));
  DBUG_RETURN(delsum+(int) year/4-temp);
} /* calc_daynr */


/*
  Convert time in MYSQL_TIME representation in system time zone to its
  my_time_t form (number of seconds in UTC since begginning of Unix Epoch).

  SYNOPSIS
    my_system_gmt_sec()
      t               - time value to be converted
      my_timezone     - pointer to long where offset of system time zone
                        from UTC will be stored for caching
      in_dst_time_gap - set to true if time falls into spring time-gap

  NOTES
    The idea is to cache the time zone offset from UTC (including daylight 
    saving time) for the next call to make things faster. But currently we 
    just calculate this offset during startup (by calling init_time() 
    function) and use it all the time.
    Time value provided should be legal time value (e.g. '2003-01-01 25:00:00'
    is not allowed).

  RETURN VALUE
    Time in UTC seconds since Unix Epoch representation.
*/
my_time_t 
my_system_gmt_sec(const MYSQL_TIME *t, long *my_timezone, bool *in_dst_time_gap)
{
  uint loop;
  time_t tmp;
  struct tm *l_time,tm_tmp;
  long diff, current_timezone;

  /*
    Calculate the gmt time based on current time and timezone
    The -1 on the end is to ensure that if have a date that exists twice
    (like 2002-10-27 02:00:0 MET), we will find the initial date.

    By doing -3600 we will have to call localtime_r() several times, but
    I couldn't come up with a better way to get a repeatable result :(

    We can't use mktime() as it's buggy on many platforms and not thread safe.
  */
  tmp=(time_t) (((calc_daynr((uint) t->year,(uint) t->month,(uint) t->day) -
		  (long) days_at_timestart)*86400L + (long) t->hour*3600L +
		 (long) (t->minute*60 + t->second)) + (time_t) my_time_zone -
		3600);
  current_timezone= my_time_zone;

  localtime_r(&tmp,&tm_tmp);
  l_time=&tm_tmp;
  for (loop=0;
       loop < 2 &&
	 (t->hour != (uint) l_time->tm_hour ||
	  t->minute != (uint) l_time->tm_min);
       loop++)
  {					/* One check should be enough ? */
    /* Get difference in days */
    int days= t->day - l_time->tm_mday;
    if (days < -1)
      days= 1;					/* Month has wrapped */
    else if (days > 1)
      days= -1;
    diff=(3600L*(long) (days*24+((int) t->hour - (int) l_time->tm_hour)) +
	  (long) (60*((int) t->minute - (int) l_time->tm_min)));
    current_timezone+= diff+3600;		/* Compensate for -3600 above */
    tmp+= (time_t) diff;
    localtime_r(&tmp,&tm_tmp);
    l_time=&tm_tmp;
  }
  /*
    Fix that if we are in the not existing daylight saving time hour
    we move the start of the next real hour
  */
  if (loop == 2 && t->hour != (uint) l_time->tm_hour)
  {
    int days= t->day - l_time->tm_mday;
    if (days < -1)
      days=1;					/* Month has wrapped */
    else if (days > 1)
      days= -1;
    diff=(3600L*(long) (days*24+((int) t->hour - (int) l_time->tm_hour))+
	  (long) (60*((int) t->minute - (int) l_time->tm_min)));
    if (diff == 3600)
      tmp+=3600 - t->minute*60 - t->second;	/* Move to next hour */
    else if (diff == -3600)
      tmp-=t->minute*60 + t->second;		/* Move to previous hour */

    *in_dst_time_gap= 1;
  }
  *my_timezone= current_timezone;
  
  return (my_time_t) tmp;
} /* my_system_gmt_sec */


/* Set MYSQL_TIME structure to 0000-00-00 00:00:00.000000 */

void set_zero_time(MYSQL_TIME *tm)
{
  bzero((void*) tm, sizeof(*tm));
  tm->time_type= MYSQL_TIMESTAMP_NONE;
}