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nagios-plugins  1.4.16
Defines | Functions | Variables
mktime.c File Reference
#include <config.h>
#include <time.h>
#include <limits.h>
#include <string.h>
#include "mktime-internal.h"

Go to the source code of this file.

Defines

#define LEAP_SECONDS_POSSIBLE   1
#define SHR(a, b)
#define TYPE_IS_INTEGER(t)   ((t) 1.5 == 1)
#define TYPE_TWOS_COMPLEMENT(t)   ((t) ~ (t) 0 == (t) -1)
#define TYPE_ONES_COMPLEMENT(t)   ((t) ~ (t) 0 == 0)
#define TYPE_SIGNED_MAGNITUDE(t)   ((t) ~ (t) 0 < (t) -1)
#define TYPE_SIGNED(t)   (! ((t) 0 < (t) -1))
#define TYPE_MINIMUM(t)
#define TYPE_MAXIMUM(t)
#define TIME_T_MIN   TYPE_MINIMUM (time_t)
#define TIME_T_MAX   TYPE_MAXIMUM (time_t)
#define TIME_T_MIDPOINT   (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
#define verify(name, assertion)   struct name { char a[(assertion) ? 1 : -1]; }
#define EPOCH_YEAR   1970
#define TM_YEAR_BASE   1900
#define __localtime_r   localtime_r
#define __mktime_internal   mktime_internal

Functions

 verify (time_t_is_integer, TYPE_IS_INTEGER(time_t))
 verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT(int))
 verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE% 100==0)
static int leapyear (long int year)
static time_t ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1, int year0, int yday0, int hour0, int min0, int sec0)
static time_t guess_time_tm (long int year, long int yday, int hour, int min, int sec, const time_t *t, const struct tm *tp)
static struct tm * ranged_convert (struct tm *(*convert)(const time_t *, struct tm *), time_t *t, struct tm *tp)
time_t __mktime_internal (struct tm *tp, struct tm *(*convert)(const time_t *, struct tm *), time_t *offset)
time_t mktime (struct tm *tp)

Variables

static const unsigned short int __mon_yday [2][13]
static time_t localtime_offset

Define Documentation

#define __localtime_r   localtime_r

Definition at line 148 of file mktime.c.

Definition at line 149 of file mktime.c.

#define EPOCH_YEAR   1970

Definition at line 113 of file mktime.c.

#define LEAP_SECONDS_POSSIBLE   1

Definition at line 32 of file mktime.c.

#define SHR (   a,
 
)
Value:
(-1 >> 1 == -1        \
   ? (a) >> (b)         \
   : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))

Definition at line 58 of file mktime.c.

#define TIME_T_MAX   TYPE_MAXIMUM (time_t)

Definition at line 100 of file mktime.c.

#define TIME_T_MIDPOINT   (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)

Definition at line 102 of file mktime.c.

#define TIME_T_MIN   TYPE_MINIMUM (time_t)

Definition at line 97 of file mktime.c.

#define TM_YEAR_BASE   1900

Definition at line 114 of file mktime.c.

#define TYPE_IS_INTEGER (   t)    ((t) 1.5 == 1)

Definition at line 68 of file mktime.c.

#define TYPE_MAXIMUM (   t)
Value:
((t) (! TYPE_SIGNED (t) \
        ? (t) -1 \
        : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))

Definition at line 91 of file mktime.c.

#define TYPE_MINIMUM (   t)
Value:
((t) (! TYPE_SIGNED (t) \
        ? (t) 0 \
        : TYPE_SIGNED_MAGNITUDE (t) \
        ? ~ (t) 0 \
        : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))

Definition at line 85 of file mktime.c.

#define TYPE_ONES_COMPLEMENT (   t)    ((t) ~ (t) 0 == 0)

Definition at line 75 of file mktime.c.

#define TYPE_SIGNED (   t)    (! ((t) 0 < (t) -1))

Definition at line 79 of file mktime.c.

#define TYPE_SIGNED_MAGNITUDE (   t)    ((t) ~ (t) 0 < (t) -1)

Definition at line 76 of file mktime.c.

#define TYPE_TWOS_COMPLEMENT (   t)    ((t) ~ (t) 0 == (t) -1)

Definition at line 74 of file mktime.c.

#define verify (   name,
  assertion 
)    struct name { char a[(assertion) ? 1 : -1]; }

Definition at line 105 of file mktime.c.


Function Documentation

time_t __mktime_internal ( struct tm *  tp,
struct tm *(*)(const time_t *, struct tm *)  convert,
time_t *  offset 
)

Definition at line 276 of file mktime.c.

{
  time_t t, gt, t0, t1, t2;
  struct tm tm;

  /* The maximum number of probes (calls to CONVERT) should be enough
     to handle any combinations of time zone rule changes, solar time,
     leap seconds, and oscillations around a spring-forward gap.
     POSIX.1 prohibits leap seconds, but some hosts have them anyway.  */
  int remaining_probes = 6;

  /* Time requested.  Copy it in case CONVERT modifies *TP; this can
     occur if TP is localtime's returned value and CONVERT is localtime.  */
  int sec = tp->tm_sec;
  int min = tp->tm_min;
  int hour = tp->tm_hour;
  int mday = tp->tm_mday;
  int mon = tp->tm_mon;
  int year_requested = tp->tm_year;
  /* Normalize the value.  */
  int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1))
               | (tp->tm_isdst != 0));

  /* 1 if the previous probe was DST.  */
  int dst2;

  /* Ensure that mon is in range, and set year accordingly.  */
  int mon_remainder = mon % 12;
  int negative_mon_remainder = mon_remainder < 0;
  int mon_years = mon / 12 - negative_mon_remainder;
  long int lyear_requested = year_requested;
  long int year = lyear_requested + mon_years;

  /* The other values need not be in range:
     the remaining code handles minor overflows correctly,
     assuming int and time_t arithmetic wraps around.
     Major overflows are caught at the end.  */

  /* Calculate day of year from year, month, and day of month.
     The result need not be in range.  */
  int mon_yday = ((__mon_yday[leapyear (year)]
                   [mon_remainder + 12 * negative_mon_remainder])
                  - 1);
  long int lmday = mday;
  long int yday = mon_yday + lmday;

  time_t guessed_offset = *offset;

  int sec_requested = sec;

  if (LEAP_SECONDS_POSSIBLE)
    {
      /* Handle out-of-range seconds specially,
         since ydhms_tm_diff assumes every minute has 60 seconds.  */
      if (sec < 0)
        sec = 0;
      if (59 < sec)
        sec = 59;
    }

  /* Invert CONVERT by probing.  First assume the same offset as last
     time.  */

  t0 = ydhms_diff (year, yday, hour, min, sec,
                   EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);

  if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
    {
      /* time_t isn't large enough to rule out overflows, so check
         for major overflows.  A gross check suffices, since if t0
         has overflowed, it is off by a multiple of TIME_T_MAX -
         TIME_T_MIN + 1.  So ignore any component of the difference
         that is bounded by a small value.  */

      /* Approximate log base 2 of the number of time units per
         biennium.  A biennium is 2 years; use this unit instead of
         years to avoid integer overflow.  For example, 2 average
         Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
         which is 63113904 seconds, and rint (log2 (63113904)) is
         26.  */
      int ALOG2_SECONDS_PER_BIENNIUM = 26;
      int ALOG2_MINUTES_PER_BIENNIUM = 20;
      int ALOG2_HOURS_PER_BIENNIUM = 14;
      int ALOG2_DAYS_PER_BIENNIUM = 10;
      int LOG2_YEARS_PER_BIENNIUM = 1;

      int approx_requested_biennia =
        (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
         - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
         + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
         + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
         + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
         + (LEAP_SECONDS_POSSIBLE
            ? 0
            : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));

      int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
      int diff = approx_biennia - approx_requested_biennia;
      int abs_diff = diff < 0 ? - diff : diff;

      /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
         gives a positive value of 715827882.  Setting a variable
         first then doing math on it seems to work.
         (ghazi@caip.rutgers.edu) */
      time_t time_t_max = TIME_T_MAX;
      time_t time_t_min = TIME_T_MIN;
      time_t overflow_threshold =
        (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;

      if (overflow_threshold < abs_diff)
        {
          /* Overflow occurred.  Try repairing it; this might work if
             the time zone offset is enough to undo the overflow.  */
          time_t repaired_t0 = -1 - t0;
          approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
          diff = approx_biennia - approx_requested_biennia;
          abs_diff = diff < 0 ? - diff : diff;
          if (overflow_threshold < abs_diff)
            return -1;
          guessed_offset += repaired_t0 - t0;
          t0 = repaired_t0;
        }
    }

  /* Repeatedly use the error to improve the guess.  */

  for (t = t1 = t2 = t0, dst2 = 0;
       (gt = guess_time_tm (year, yday, hour, min, sec, &t,
                            ranged_convert (convert, &t, &tm)),
        t != gt);
       t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
    if (t == t1 && t != t2
        && (tm.tm_isdst < 0
            || (isdst < 0
                ? dst2 <= (tm.tm_isdst != 0)
                : (isdst != 0) != (tm.tm_isdst != 0))))
      /* We can't possibly find a match, as we are oscillating
         between two values.  The requested time probably falls
         within a spring-forward gap of size GT - T.  Follow the common
         practice in this case, which is to return a time that is GT - T
         away from the requested time, preferring a time whose
         tm_isdst differs from the requested value.  (If no tm_isdst
         was requested and only one of the two values has a nonzero
         tm_isdst, prefer that value.)  In practice, this is more
         useful than returning -1.  */
      goto offset_found;
    else if (--remaining_probes == 0)
      return -1;

  /* We have a match.  Check whether tm.tm_isdst has the requested
     value, if any.  */
  if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
    {
      /* tm.tm_isdst has the wrong value.  Look for a neighboring
         time with the right value, and use its UTC offset.

         Heuristic: probe the adjacent timestamps in both directions,
         looking for the desired isdst.  This should work for all real
         time zone histories in the tz database.  */

      /* Distance between probes when looking for a DST boundary.  In
         tzdata2003a, the shortest period of DST is 601200 seconds
         (e.g., America/Recife starting 2000-10-08 01:00), and the
         shortest period of non-DST surrounded by DST is 694800
         seconds (Africa/Tunis starting 1943-04-17 01:00).  Use the
         minimum of these two values, so we don't miss these short
         periods when probing.  */
      int stride = 601200;

      /* The longest period of DST in tzdata2003a is 536454000 seconds
         (e.g., America/Jujuy starting 1946-10-01 01:00).  The longest
         period of non-DST is much longer, but it makes no real sense
         to search for more than a year of non-DST, so use the DST
         max.  */
      int duration_max = 536454000;

      /* Search in both directions, so the maximum distance is half
         the duration; add the stride to avoid off-by-1 problems.  */
      int delta_bound = duration_max / 2 + stride;

      int delta, direction;

      for (delta = stride; delta < delta_bound; delta += stride)
        for (direction = -1; direction <= 1; direction += 2)
          {
            time_t ot = t + delta * direction;
            if ((ot < t) == (direction < 0))
              {
                struct tm otm;
                ranged_convert (convert, &ot, &otm);
                if (otm.tm_isdst == isdst)
                  {
                    /* We found the desired tm_isdst.
                       Extrapolate back to the desired time.  */
                    t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
                    ranged_convert (convert, &t, &tm);
                    goto offset_found;
                  }
              }
          }
    }

 offset_found:
  *offset = guessed_offset + t - t0;

  if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
    {
      /* Adjust time to reflect the tm_sec requested, not the normalized value.
         Also, repair any damage from a false match due to a leap second.  */
      int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
      t1 = t + sec_requested;
      t2 = t1 + sec_adjustment;
      if (((t1 < t) != (sec_requested < 0))
          | ((t2 < t1) != (sec_adjustment < 0))
          | ! convert (&t2, &tm))
        return -1;
      t = t2;
    }

  *tp = tm;
  return t;
}

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static time_t guess_time_tm ( long int  year,
long int  yday,
int  hour,
int  min,
int  sec,
const time_t *  t,
const struct tm *  tp 
) [static]

Definition at line 204 of file mktime.c.

{
  if (tp)
    {
      time_t d = ydhms_diff (year, yday, hour, min, sec,
                             tp->tm_year, tp->tm_yday,
                             tp->tm_hour, tp->tm_min, tp->tm_sec);
      time_t t1 = *t + d;
      if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
        return t1;
    }

  /* Overflow occurred one way or another.  Return the nearest result
     that is actually in range, except don't report a zero difference
     if the actual difference is nonzero, as that would cause a false
     match; and don't oscillate between two values, as that would
     confuse the spring-forward gap detector.  */
  return (*t < TIME_T_MIDPOINT
          ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
          : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
}

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static int leapyear ( long int  year) [inline, static]

Definition at line 119 of file mktime.c.

{
  /* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
     Also, work even if YEAR is negative.  */
  return
    ((year & 3) == 0
     && (year % 100 != 0
         || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
}

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time_t mktime ( struct tm *  tp)

Definition at line 510 of file mktime.c.

{
#ifdef _LIBC
  /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
     time zone names contained in the external variable `tzname' shall
     be set as if the tzset() function had been called.  */
  __tzset ();
#endif

  return __mktime_internal (tp, __localtime_r, &localtime_offset);
}

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static struct tm* ranged_convert ( struct tm *(*)(const time_t *, struct tm *)  convert,
time_t *  t,
struct tm *  tp 
) [static, read]

Definition at line 231 of file mktime.c.

{
  struct tm *r = convert (t, tp);

  if (!r && *t)
    {
      time_t bad = *t;
      time_t ok = 0;

      /* BAD is a known unconvertible time_t, and OK is a known good one.
         Use binary search to narrow the range between BAD and OK until
         they differ by 1.  */
      while (bad != ok + (bad < 0 ? -1 : 1))
        {
          time_t mid = *t = (bad < 0
                             ? bad + ((ok - bad) >> 1)
                             : ok + ((bad - ok) >> 1));
          r = convert (t, tp);
          if (r)
            ok = mid;
          else
            bad = mid;
        }

      if (!r && ok)
        {
          /* The last conversion attempt failed;
             revert to the most recent successful attempt.  */
          *t = ok;
          r = convert (t, tp);
        }
    }

  return r;
}

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verify ( time_t_is_integer  ,
TYPE_IS_INTEGER(time_t)   
)
verify ( twos_complement_arithmetic  ,
TYPE_TWOS_COMPLEMENT(int)   
)
verify ( base_year_is_a_multiple_of_100  ,
TM_YEAR_BASE 100 = =0 
)
static time_t ydhms_diff ( long int  year1,
long int  yday1,
int  hour1,
int  min1,
int  sec1,
int  year0,
int  yday0,
int  hour0,
int  min0,
int  sec0 
) [inline, static]

Definition at line 165 of file mktime.c.

{
  verify (C99_integer_division, -1 / 2 == 0);
#if 0 /* This assertion fails on 32-bit systems with 64-bit time_t, such as
         NetBSD 5 on i386.  */
  verify (long_int_year_and_yday_are_wide_enough,
          INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
#endif

  /* Compute intervening leap days correctly even if year is negative.
     Take care to avoid integer overflow here.  */
  int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
  int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 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);

  /* Compute the desired time in time_t precision.  Overflow might
     occur here.  */
  time_t tyear1 = year1;
  time_t years = tyear1 - year0;
  time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
  time_t hours = 24 * days + hour1 - hour0;
  time_t minutes = 60 * hours + min1 - min0;
  time_t seconds = 60 * minutes + sec1 - sec0;
  return seconds;
}

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Variable Documentation

const unsigned short int __mon_yday[2][13] [static]
Initial value:
  {
    
    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
    
    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
  }

Definition at line 133 of file mktime.c.

time_t localtime_offset [static]

Definition at line 506 of file mktime.c.