tor-browser

prtime.c (60892B)

---

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
* prtime.c --
*
*     NSPR date and time functions
*
*/

#include "prinit.h"
#include "prtime.h"
#include "prlock.h"
#include "prprf.h"
#include "prlog.h"

#include <string.h>
#include <ctype.h>
#include <errno.h> /* for EINVAL */
#include <time.h>

/*
* The COUNT_LEAPS macro counts the number of leap years passed by
* till the start of the given year Y.  At the start of the year 4
* A.D. the number of leap years passed by is 0, while at the start of
* the year 5 A.D. this count is 1. The number of years divisible by
* 100 but not divisible by 400 (the non-leap years) is deducted from
* the count to get the correct number of leap years.
*
* The COUNT_DAYS macro counts the number of days since 01/01/01 till the
* start of the given year Y. The number of days at the start of the year
* 1 is 0 while the number of days at the start of the year 2 is 365
* (which is ((2)-1) * 365) and so on. The reference point is 01/01/01
* midnight 00:00:00.
*/

#define COUNT_LEAPS(Y) (((Y) - 1) / 4 - ((Y) - 1) / 100 + ((Y) - 1) / 400)
#define COUNT_DAYS(Y) (((Y) - 1) * 365 + COUNT_LEAPS(Y))
#define DAYS_BETWEEN_YEARS(A, B) (COUNT_DAYS(B) - COUNT_DAYS(A))

/*
* Static variables used by functions in this file
*/

/*
* The following array contains the day of year for the last day of
* each month, where index 1 is January, and day 0 is January 1.
*/

static const int lastDayOfMonth[2][13] = {
   {-1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364},
   {-1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365}};

/*
* The number of days in a month
*/

static const PRInt8 nDays[2][12] = {
   {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
   {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};

/*
* Declarations for internal functions defined later in this file.
*/

static void ComputeGMT(PRTime time, PRExplodedTime* gmt);
static int IsLeapYear(PRInt16 year);
static void ApplySecOffset(PRExplodedTime* time, PRInt32 secOffset);

/*
*------------------------------------------------------------------------
*
* ComputeGMT --
*
*     Caveats:
*     - we ignore leap seconds
*
*------------------------------------------------------------------------
*/

static void ComputeGMT(PRTime time, PRExplodedTime* gmt) {
 PRInt32 tmp, rem;
 PRInt32 numDays;
 PRInt64 numDays64, rem64;
 int isLeap;
 PRInt64 sec;
 PRInt64 usec;
 PRInt64 usecPerSec;
 PRInt64 secPerDay;

 /*
  * We first do the usec, sec, min, hour thing so that we do not
  * have to do LL arithmetic.
  */

 LL_I2L(usecPerSec, 1000000L);
 LL_DIV(sec, time, usecPerSec);
 LL_MOD(usec, time, usecPerSec);
 LL_L2I(gmt->tm_usec, usec);
 /* Correct for weird mod semantics so the remainder is always positive */
 if (gmt->tm_usec < 0) {
   PRInt64 one;

   LL_I2L(one, 1L);
   LL_SUB(sec, sec, one);
   gmt->tm_usec += 1000000L;
 }

 LL_I2L(secPerDay, 86400L);
 LL_DIV(numDays64, sec, secPerDay);
 LL_MOD(rem64, sec, secPerDay);
 /* We are sure both of these numbers can fit into PRInt32 */
 LL_L2I(numDays, numDays64);
 LL_L2I(rem, rem64);
 if (rem < 0) {
   numDays--;
   rem += 86400L;
 }

 /* Compute day of week.  Epoch started on a Thursday. */

 gmt->tm_wday = (numDays + 4) % 7;
 if (gmt->tm_wday < 0) {
   gmt->tm_wday += 7;
 }

 /* Compute the time of day. */

 gmt->tm_hour = rem / 3600;
 rem %= 3600;
 gmt->tm_min = rem / 60;
 gmt->tm_sec = rem % 60;

 /*
  * Compute the year by finding the 400 year period, then working
  * down from there.
  *
  * Since numDays is originally the number of days since January 1, 1970,
  * we must change it to be the number of days from January 1, 0001.
  */

 numDays += 719162;      /* 719162 = days from year 1 up to 1970 */
 tmp = numDays / 146097; /* 146097 = days in 400 years */
 rem = numDays % 146097;
 gmt->tm_year = tmp * 400 + 1;

 /* Compute the 100 year period. */

 tmp = rem / 36524; /* 36524 = days in 100 years */
 rem %= 36524;
 if (tmp == 4) { /* the 400th year is a leap year */
   tmp = 3;
   rem = 36524;
 }
 gmt->tm_year += tmp * 100;

 /* Compute the 4 year period. */

 tmp = rem / 1461; /* 1461 = days in 4 years */
 rem %= 1461;
 gmt->tm_year += tmp * 4;

 /* Compute which year in the 4. */

 tmp = rem / 365;
 rem %= 365;
 if (tmp == 4) { /* the 4th year is a leap year */
   tmp = 3;
   rem = 365;
 }

 gmt->tm_year += tmp;
 gmt->tm_yday = rem;
 isLeap = IsLeapYear(gmt->tm_year);

 /* Compute the month and day of month. */

 for (tmp = 1; lastDayOfMonth[isLeap][tmp] < gmt->tm_yday; tmp++) {
 }
 gmt->tm_month = --tmp;
 gmt->tm_mday = gmt->tm_yday - lastDayOfMonth[isLeap][tmp];

 gmt->tm_params.tp_gmt_offset = 0;
 gmt->tm_params.tp_dst_offset = 0;
}

/*
*------------------------------------------------------------------------
*
* PR_ExplodeTime --
*
*     Cf. struct tm *gmtime(const time_t *tp) and
*         struct tm *localtime(const time_t *tp)
*
*------------------------------------------------------------------------
*/

PR_IMPLEMENT(void)
PR_ExplodeTime(PRTime usecs, PRTimeParamFn params, PRExplodedTime* exploded) {
 ComputeGMT(usecs, exploded);
 exploded->tm_params = params(exploded);
 ApplySecOffset(exploded, exploded->tm_params.tp_gmt_offset +
                              exploded->tm_params.tp_dst_offset);
}

/*
*------------------------------------------------------------------------
*
* PR_ImplodeTime --
*
*     Cf. time_t mktime(struct tm *tp)
*     Note that 1 year has < 2^25 seconds.  So an PRInt32 is large enough.
*
*------------------------------------------------------------------------
*/
PR_IMPLEMENT(PRTime)
PR_ImplodeTime(const PRExplodedTime* exploded) {
 PRExplodedTime copy;
 PRTime retVal;
 PRInt64 secPerDay, usecPerSec;
 PRInt64 temp;
 PRInt64 numSecs64;
 PRInt32 numDays;
 PRInt32 numSecs;

 /* Normalize first.  Do this on our copy */
 copy = *exploded;
 PR_NormalizeTime(&copy, PR_GMTParameters);

 numDays = DAYS_BETWEEN_YEARS(1970, copy.tm_year);

 numSecs = copy.tm_yday * 86400 + copy.tm_hour * 3600 + copy.tm_min * 60 +
           copy.tm_sec;

 LL_I2L(temp, numDays);
 LL_I2L(secPerDay, 86400);
 LL_MUL(temp, temp, secPerDay);
 LL_I2L(numSecs64, numSecs);
 LL_ADD(numSecs64, numSecs64, temp);

 /* apply the GMT and DST offsets */
 LL_I2L(temp, copy.tm_params.tp_gmt_offset);
 LL_SUB(numSecs64, numSecs64, temp);
 LL_I2L(temp, copy.tm_params.tp_dst_offset);
 LL_SUB(numSecs64, numSecs64, temp);

 LL_I2L(usecPerSec, 1000000L);
 LL_MUL(temp, numSecs64, usecPerSec);
 LL_I2L(retVal, copy.tm_usec);
 LL_ADD(retVal, retVal, temp);

 return retVal;
}

/*
*-------------------------------------------------------------------------
*
* IsLeapYear --
*
*     Returns 1 if the year is a leap year, 0 otherwise.
*
*-------------------------------------------------------------------------
*/

static int IsLeapYear(PRInt16 year) {
 if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
   return 1;
 }
 return 0;
}

/*
* 'secOffset' should be less than 86400 (i.e., a day).
* 'time' should point to a normalized PRExplodedTime.
*/

static void ApplySecOffset(PRExplodedTime* time, PRInt32 secOffset) {
 time->tm_sec += secOffset;

 /* Note that in this implementation we do not count leap seconds */
 if (time->tm_sec < 0 || time->tm_sec >= 60) {
   time->tm_min += time->tm_sec / 60;
   time->tm_sec %= 60;
   if (time->tm_sec < 0) {
     time->tm_sec += 60;
     time->tm_min--;
   }
 }

 if (time->tm_min < 0 || time->tm_min >= 60) {
   time->tm_hour += time->tm_min / 60;
   time->tm_min %= 60;
   if (time->tm_min < 0) {
     time->tm_min += 60;
     time->tm_hour--;
   }
 }

 if (time->tm_hour < 0) {
   /* Decrement mday, yday, and wday */
   time->tm_hour += 24;
   time->tm_mday--;
   time->tm_yday--;
   if (time->tm_mday < 1) {
     time->tm_month--;
     if (time->tm_month < 0) {
       time->tm_month = 11;
       time->tm_year--;
       if (IsLeapYear(time->tm_year)) {
         time->tm_yday = 365;
       } else {
         time->tm_yday = 364;
       }
     }
     time->tm_mday = nDays[IsLeapYear(time->tm_year)][time->tm_month];
   }
   time->tm_wday--;
   if (time->tm_wday < 0) {
     time->tm_wday = 6;
   }
 } else if (time->tm_hour > 23) {
   /* Increment mday, yday, and wday */
   time->tm_hour -= 24;
   time->tm_mday++;
   time->tm_yday++;
   if (time->tm_mday > nDays[IsLeapYear(time->tm_year)][time->tm_month]) {
     time->tm_mday = 1;
     time->tm_month++;
     if (time->tm_month > 11) {
       time->tm_month = 0;
       time->tm_year++;
       time->tm_yday = 0;
     }
   }
   time->tm_wday++;
   if (time->tm_wday > 6) {
     time->tm_wday = 0;
   }
 }
}

PR_IMPLEMENT(void)
PR_NormalizeTime(PRExplodedTime* time, PRTimeParamFn params) {
 int daysInMonth;
 PRInt32 numDays;

 /* Get back to GMT */
 time->tm_sec -= time->tm_params.tp_gmt_offset + time->tm_params.tp_dst_offset;
 time->tm_params.tp_gmt_offset = 0;
 time->tm_params.tp_dst_offset = 0;

 /* Now normalize GMT */

 if (time->tm_usec < 0 || time->tm_usec >= 1000000) {
   time->tm_sec += time->tm_usec / 1000000;
   time->tm_usec %= 1000000;
   if (time->tm_usec < 0) {
     time->tm_usec += 1000000;
     time->tm_sec--;
   }
 }

 /* Note that we do not count leap seconds in this implementation */
 if (time->tm_sec < 0 || time->tm_sec >= 60) {
   time->tm_min += time->tm_sec / 60;
   time->tm_sec %= 60;
   if (time->tm_sec < 0) {
     time->tm_sec += 60;
     time->tm_min--;
   }
 }

 if (time->tm_min < 0 || time->tm_min >= 60) {
   time->tm_hour += time->tm_min / 60;
   time->tm_min %= 60;
   if (time->tm_min < 0) {
     time->tm_min += 60;
     time->tm_hour--;
   }
 }

 if (time->tm_hour < 0 || time->tm_hour >= 24) {
   time->tm_mday += time->tm_hour / 24;
   time->tm_hour %= 24;
   if (time->tm_hour < 0) {
     time->tm_hour += 24;
     time->tm_mday--;
   }
 }

 /* Normalize month and year before mday */
 if (time->tm_month < 0 || time->tm_month >= 12) {
   time->tm_year += time->tm_month / 12;
   time->tm_month %= 12;
   if (time->tm_month < 0) {
     time->tm_month += 12;
     time->tm_year--;
   }
 }

 /* Now that month and year are in proper range, normalize mday */

 if (time->tm_mday < 1) {
   /* mday too small */
   do {
     /* the previous month */
     time->tm_month--;
     if (time->tm_month < 0) {
       time->tm_month = 11;
       time->tm_year--;
     }
     time->tm_mday += nDays[IsLeapYear(time->tm_year)][time->tm_month];
   } while (time->tm_mday < 1);
 } else {
   daysInMonth = nDays[IsLeapYear(time->tm_year)][time->tm_month];
   while (time->tm_mday > daysInMonth) {
     /* mday too large */
     time->tm_mday -= daysInMonth;
     time->tm_month++;
     if (time->tm_month > 11) {
       time->tm_month = 0;
       time->tm_year++;
     }
     daysInMonth = nDays[IsLeapYear(time->tm_year)][time->tm_month];
   }
 }

 /* Recompute yday and wday */
 time->tm_yday =
     time->tm_mday + lastDayOfMonth[IsLeapYear(time->tm_year)][time->tm_month];

 numDays = DAYS_BETWEEN_YEARS(1970, time->tm_year) + time->tm_yday;
 time->tm_wday = (numDays + 4) % 7;
 if (time->tm_wday < 0) {
   time->tm_wday += 7;
 }

 /* Recompute time parameters */

 time->tm_params = params(time);

 ApplySecOffset(time,
                time->tm_params.tp_gmt_offset + time->tm_params.tp_dst_offset);
}

/*
*-------------------------------------------------------------------------
*
* PR_LocalTimeParameters --
*
*     returns the time parameters for the local time zone
*
*     The following uses localtime() from the standard C library.
*     (time.h)  This is our fallback implementation.  Unix, PC, and BeOS
*     use this version.  A platform may have its own machine-dependent
*     implementation of this function.
*
*-------------------------------------------------------------------------
*/

#if defined(HAVE_INT_LOCALTIME_R)

/*
* In this case we could define the macro as
*     #define MT_safe_localtime(timer, result) \
*             (localtime_r(timer, result) == 0 ? result : NULL)
* I chose to compare the return value of localtime_r with -1 so
* that I can catch the cases where localtime_r returns a pointer
* to struct tm.  The macro definition above would not be able to
* detect such mistakes because it is legal to compare a pointer
* with 0.
*/

#  define MT_safe_localtime(timer, result) \
   (localtime_r(timer, result) == -1 ? NULL : result)

#elif defined(HAVE_POINTER_LOCALTIME_R)

#  define MT_safe_localtime localtime_r

#elif defined(_MSC_VER)

/* Visual C++ has had localtime_s() since Visual C++ 2005. */

static struct tm* MT_safe_localtime(const time_t* clock, struct tm* result) {
 errno_t err = localtime_s(result, clock);
 if (err != 0) {
   errno = err;
   return NULL;
 }
 return result;
}

#else

#  define HAVE_LOCALTIME_MONITOR                 \
   1 /* We use 'monitor' to serialize our calls \
      * to localtime(). */
static PRLock* monitor = NULL;

static struct tm* MT_safe_localtime(const time_t* clock, struct tm* result) {
 struct tm* tmPtr;
 int needLock = PR_Initialized(); /* We need to use a lock to protect
                                   * against NSPR threads only when the
                                   * NSPR thread system is activated. */

 if (needLock) {
   PR_Lock(monitor);
 }

 /*
  * Microsoft (all flavors) localtime() returns a NULL pointer if 'clock'
  * represents a time before midnight January 1, 1970.  In
  * that case, we also return a NULL pointer and the struct tm
  * object pointed to by 'result' is not modified.
  *
  */

 tmPtr = localtime(clock);

 if (tmPtr) {
   *result = *tmPtr;
 } else {
   result = NULL;
 }

 if (needLock) {
   PR_Unlock(monitor);
 }

 return result;
}

#endif /* definition of MT_safe_localtime() */

void _PR_InitTime(void) {
#ifdef HAVE_LOCALTIME_MONITOR
 monitor = PR_NewLock();
#endif
#ifdef WINCE
 _MD_InitTime();
#endif
}

void _PR_CleanupTime(void) {
#ifdef HAVE_LOCALTIME_MONITOR
 if (monitor) {
   PR_DestroyLock(monitor);
   monitor = NULL;
 }
#endif
#ifdef WINCE
 _MD_CleanupTime();
#endif
}

#if defined(XP_UNIX) || defined(XP_PC)

PR_IMPLEMENT(PRTimeParameters)
PR_LocalTimeParameters(const PRExplodedTime* gmt) {
 PRTimeParameters retVal;
 struct tm localTime;
 struct tm* localTimeResult;
 time_t secs;
 PRTime secs64;
 PRInt64 usecPerSec;
 PRInt64 usecPerSec_1;
 PRInt64 maxInt32;
 PRInt64 minInt32;
 PRInt32 dayOffset;
 PRInt32 offset2Jan1970;
 PRInt32 offsetNew;
 int isdst2Jan1970;

 /*
  * Calculate the GMT offset.  First, figure out what is
  * 00:00:00 Jan. 2, 1970 GMT (which is exactly a day, or 86400
  * seconds, since the epoch) in local time.  Then we calculate
  * the difference between local time and GMT in seconds:
  *     gmt_offset = local_time - GMT
  *
  * Caveat: the validity of this calculation depends on two
  * assumptions:
  * 1. Daylight saving time was not in effect on Jan. 2, 1970.
  * 2. The time zone of the geographic location has not changed
  *    since Jan. 2, 1970.
  */

 secs = 86400L;
 localTimeResult = MT_safe_localtime(&secs, &localTime);
 PR_ASSERT(localTimeResult != NULL);
 if (localTimeResult == NULL) {
   /* Shouldn't happen. Use safe fallback for optimized builds. */
   return PR_GMTParameters(gmt);
 }

 /* GMT is 00:00:00, 2nd of Jan. */

 offset2Jan1970 = (PRInt32)localTime.tm_sec + 60L * (PRInt32)localTime.tm_min +
                  3600L * (PRInt32)localTime.tm_hour +
                  86400L * (PRInt32)((PRInt32)localTime.tm_mday - 2L);

 isdst2Jan1970 = localTime.tm_isdst;

 /*
  * Now compute DST offset.  We calculate the overall offset
  * of local time from GMT, similar to above.  The overall
  * offset has two components: gmt offset and dst offset.
  * We subtract gmt offset from the overall offset to get
  * the dst offset.
  *     overall_offset = local_time - GMT
  *     overall_offset = gmt_offset + dst_offset
  * ==> dst_offset = local_time - GMT - gmt_offset
  */

 secs64 = PR_ImplodeTime(gmt); /* This is still in microseconds */
 LL_I2L(usecPerSec, PR_USEC_PER_SEC);
 LL_I2L(usecPerSec_1, PR_USEC_PER_SEC - 1);
 /* Convert to seconds, truncating down (3.1 -> 3 and -3.1 -> -4) */
 if (LL_GE_ZERO(secs64)) {
   LL_DIV(secs64, secs64, usecPerSec);
 } else {
   LL_NEG(secs64, secs64);
   LL_ADD(secs64, secs64, usecPerSec_1);
   LL_DIV(secs64, secs64, usecPerSec);
   LL_NEG(secs64, secs64);
 }
 LL_I2L(maxInt32, PR_INT32_MAX);
 LL_I2L(minInt32, PR_INT32_MIN);
 if (LL_CMP(secs64, >, maxInt32) || LL_CMP(secs64, <, minInt32)) {
   /* secs64 is too large or too small for time_t (32-bit integer) */
   retVal.tp_gmt_offset = offset2Jan1970;
   retVal.tp_dst_offset = 0;
   return retVal;
 }
 LL_L2I(secs, secs64);

 /*
  * On Windows, localtime() (and our MT_safe_localtime() too)
  * returns a NULL pointer for time before midnight January 1,
  * 1970 GMT.  In that case, we just use the GMT offset for
  * Jan 2, 1970 and assume that DST was not in effect.
  */

 if (MT_safe_localtime(&secs, &localTime) == NULL) {
   retVal.tp_gmt_offset = offset2Jan1970;
   retVal.tp_dst_offset = 0;
   return retVal;
 }

 /*
  * dayOffset is the offset between local time and GMT in
  * the day component, which can only be -1, 0, or 1.  We
  * use the day of the week to compute dayOffset.
  */

 dayOffset = (PRInt32)localTime.tm_wday - gmt->tm_wday;

 /*
  * Need to adjust for wrapping around of day of the week from
  * 6 back to 0.
  */

 if (dayOffset == -6) {
   /* Local time is Sunday (0) and GMT is Saturday (6) */
   dayOffset = 1;
 } else if (dayOffset == 6) {
   /* Local time is Saturday (6) and GMT is Sunday (0) */
   dayOffset = -1;
 }

 offsetNew = (PRInt32)localTime.tm_sec - gmt->tm_sec +
             60L * ((PRInt32)localTime.tm_min - gmt->tm_min) +
             3600L * ((PRInt32)localTime.tm_hour - gmt->tm_hour) +
             86400L * (PRInt32)dayOffset;

 if (localTime.tm_isdst <= 0) {
   /* DST is not in effect */
   retVal.tp_gmt_offset = offsetNew;
   retVal.tp_dst_offset = 0;
 } else {
   /* DST is in effect */
   if (isdst2Jan1970 <= 0) {
     /*
      * DST was not in effect back in 2 Jan. 1970.
      * Use the offset back then as the GMT offset,
      * assuming the time zone has not changed since then.
      */
     retVal.tp_gmt_offset = offset2Jan1970;
     retVal.tp_dst_offset = offsetNew - offset2Jan1970;
   } else {
     /*
      * DST was also in effect back in 2 Jan. 1970.
      * Then our clever trick (or rather, ugly hack) fails.
      * We will just assume DST offset is an hour.
      */
     retVal.tp_gmt_offset = offsetNew - 3600;
     retVal.tp_dst_offset = 3600;
   }
 }

 return retVal;
}

#endif /* defined(XP_UNIX) || defined(XP_PC) */

/*
*------------------------------------------------------------------------
*
* PR_USPacificTimeParameters --
*
*     The time parameters function for the US Pacific Time Zone.
*
*------------------------------------------------------------------------
*/

/*
* Returns the mday of the first sunday of the month, where
* mday and wday are for a given day in the month.
* mdays start with 1 (e.g. 1..31).
* wdays start with 0 and are in the range 0..6.  0 = Sunday.
*/
#define firstSunday(mday, wday) (((mday - wday + 7 - 1) % 7) + 1)

/*
* Returns the mday for the N'th Sunday of the month, where
* mday and wday are for a given day in the month.
* mdays start with 1 (e.g. 1..31).
* wdays start with 0 and are in the range 0..6.  0 = Sunday.
* N has the following values: 0 = first, 1 = second (etc), -1 = last.
* ndays is the number of days in that month, the same value as the
* mday of the last day of the month.
*/
static PRInt32 NthSunday(PRInt32 mday, PRInt32 wday, PRInt32 N, PRInt32 ndays) {
 PRInt32 firstSun = firstSunday(mday, wday);

 if (N < 0) {
   N = (ndays - firstSun) / 7;
 }
 return firstSun + (7 * N);
}

typedef struct DSTParams {
 PRInt8 dst_start_month;       /* 0 = January */
 PRInt8 dst_start_Nth_Sunday;  /* N as defined above */
 PRInt8 dst_start_month_ndays; /* ndays as defined above */
 PRInt8 dst_end_month;         /* 0 = January */
 PRInt8 dst_end_Nth_Sunday;    /* N as defined above */
 PRInt8 dst_end_month_ndays;   /* ndays as defined above */
} DSTParams;

static const DSTParams dstParams[2] = {
   /* year < 2007:  First April Sunday - Last October Sunday */
   {3, 0, 30, 9, -1, 31},
   /* year >= 2007: Second March Sunday - First November Sunday */
   {2, 1, 31, 10, 0, 30}};

PR_IMPLEMENT(PRTimeParameters)
PR_USPacificTimeParameters(const PRExplodedTime* gmt) {
 const DSTParams* dst;
 PRTimeParameters retVal;
 PRExplodedTime st;

 /*
  * Based on geographic location and GMT, figure out offset of
  * standard time from GMT.  In this example implementation, we
  * assume the local time zone is US Pacific Time.
  */

 retVal.tp_gmt_offset = -8L * 3600L;

 /*
  * Make a copy of GMT.  Note that the tm_params field of this copy
  * is ignored.
  */

 st.tm_usec = gmt->tm_usec;
 st.tm_sec = gmt->tm_sec;
 st.tm_min = gmt->tm_min;
 st.tm_hour = gmt->tm_hour;
 st.tm_mday = gmt->tm_mday;
 st.tm_month = gmt->tm_month;
 st.tm_year = gmt->tm_year;
 st.tm_wday = gmt->tm_wday;
 st.tm_yday = gmt->tm_yday;

 /* Apply the offset to GMT to obtain the local standard time */
 ApplySecOffset(&st, retVal.tp_gmt_offset);

 if (st.tm_year < 2007) { /* first April Sunday - Last October Sunday */
   dst = &dstParams[0];
 } else { /* Second March Sunday - First November Sunday */
   dst = &dstParams[1];
 }

 /*
  * Apply the rules on standard time or GMT to obtain daylight saving
  * time offset.  In this implementation, we use the US DST rule.
  */
 if (st.tm_month < dst->dst_start_month) {
   retVal.tp_dst_offset = 0L;
 } else if (st.tm_month == dst->dst_start_month) {
   int NthSun = NthSunday(st.tm_mday, st.tm_wday, dst->dst_start_Nth_Sunday,
                          dst->dst_start_month_ndays);
   if (st.tm_mday < NthSun) { /* Before starting Sunday */
     retVal.tp_dst_offset = 0L;
   } else if (st.tm_mday == NthSun) { /* Starting Sunday */
     /* 01:59:59 PST -> 03:00:00 PDT */
     if (st.tm_hour < 2) {
       retVal.tp_dst_offset = 0L;
     } else {
       retVal.tp_dst_offset = 3600L;
     }
   } else { /* After starting Sunday */
     retVal.tp_dst_offset = 3600L;
   }
 } else if (st.tm_month < dst->dst_end_month) {
   retVal.tp_dst_offset = 3600L;
 } else if (st.tm_month == dst->dst_end_month) {
   int NthSun = NthSunday(st.tm_mday, st.tm_wday, dst->dst_end_Nth_Sunday,
                          dst->dst_end_month_ndays);
   if (st.tm_mday < NthSun) { /* Before ending Sunday */
     retVal.tp_dst_offset = 3600L;
   } else if (st.tm_mday == NthSun) { /* Ending Sunday */
     /* 01:59:59 PDT -> 01:00:00 PST */
     if (st.tm_hour < 1) {
       retVal.tp_dst_offset = 3600L;
     } else {
       retVal.tp_dst_offset = 0L;
     }
   } else { /* After ending Sunday */
     retVal.tp_dst_offset = 0L;
   }
 } else {
   retVal.tp_dst_offset = 0L;
 }
 return retVal;
}

/*
*------------------------------------------------------------------------
*
* PR_GMTParameters --
*
*     Returns the PRTimeParameters for Greenwich Mean Time.
*     Trivially, both the tp_gmt_offset and tp_dst_offset fields are 0.
*
*------------------------------------------------------------------------
*/

PR_IMPLEMENT(PRTimeParameters)
PR_GMTParameters(const PRExplodedTime* gmt) {
 PRTimeParameters retVal = {0, 0};
 return retVal;
}

/*
* The following code implements PR_ParseTimeString().  It is based on
* ns/lib/xp/xp_time.c, revision 1.25, by Jamie Zawinski <jwz@netscape.com>.
*/

/*
* We only recognize the abbreviations of a small subset of time zones
* in North America, Europe, and Japan.
*
* PST/PDT: Pacific Standard/Daylight Time
* MST/MDT: Mountain Standard/Daylight Time
* CST/CDT: Central Standard/Daylight Time
* EST/EDT: Eastern Standard/Daylight Time
* AST: Atlantic Standard Time
* NST: Newfoundland Standard Time
* GMT: Greenwich Mean Time
* BST: British Summer Time
* MET: Middle Europe Time
* EET: Eastern Europe Time
* JST: Japan Standard Time
*/

typedef enum {
 TT_UNKNOWN,

 TT_SUN,
 TT_MON,
 TT_TUE,
 TT_WED,
 TT_THU,
 TT_FRI,
 TT_SAT,

 TT_JAN,
 TT_FEB,
 TT_MAR,
 TT_APR,
 TT_MAY,
 TT_JUN,
 TT_JUL,
 TT_AUG,
 TT_SEP,
 TT_OCT,
 TT_NOV,
 TT_DEC,

 TT_PST,
 TT_PDT,
 TT_MST,
 TT_MDT,
 TT_CST,
 TT_CDT,
 TT_EST,
 TT_EDT,
 TT_AST,
 TT_NST,
 TT_GMT,
 TT_BST,
 TT_MET,
 TT_EET,
 TT_JST
} TIME_TOKEN;

/*
* This parses a time/date string into a PRTime
* (microseconds after "1-Jan-1970 00:00:00 GMT").
* It returns PR_SUCCESS on success, and PR_FAILURE
* if the time/date string can't be parsed.
*
* Many formats are handled, including:
*
*   14 Apr 89 03:20:12
*   14 Apr 89 03:20 GMT
*   Fri, 17 Mar 89 4:01:33
*   Fri, 17 Mar 89 4:01 GMT
*   Mon Jan 16 16:12 PDT 1989
*   Mon Jan 16 16:12 +0130 1989
*   6 May 1992 16:41-JST (Wednesday)
*   22-AUG-1993 10:59:12.82
*   22-AUG-1993 10:59pm
*   22-AUG-1993 12:59am
*   22-AUG-1993 12:59 PM
*   Friday, August 04, 1995 3:54 PM
*   06/21/95 04:24:34 PM
*   20/06/95 21:07
*   95-06-08 19:32:48 EDT
*
* If the input string doesn't contain a description of the timezone,
* we consult the `default_to_gmt' to decide whether the string should
* be interpreted relative to the local time zone (PR_FALSE) or GMT (PR_TRUE).
* The correct value for this argument depends on what standard specified
* the time string which you are parsing.
*/

PR_IMPLEMENT(PRStatus)
PR_ParseTimeStringToExplodedTime(const char* string, PRBool default_to_gmt,
                                PRExplodedTime* result) {
 TIME_TOKEN dotw = TT_UNKNOWN;
 TIME_TOKEN month = TT_UNKNOWN;
 TIME_TOKEN zone = TT_UNKNOWN;
 int zone_offset = -1;
 int dst_offset = 0;
 int date = -1;
 PRInt32 year = -1;
 int hour = -1;
 int min = -1;
 int sec = -1;
 struct tm* localTimeResult;

 const char* rest = string;

 int iterations = 0;

 PR_ASSERT(string && result);
 if (!string || !result) {
   return PR_FAILURE;
 }

 while (*rest) {
   if (iterations++ > 1000) {
     return PR_FAILURE;
   }

   switch (*rest) {
     case 'a':
     case 'A':
       if (month == TT_UNKNOWN && (rest[1] == 'p' || rest[1] == 'P') &&
           (rest[2] == 'r' || rest[2] == 'R')) {
         month = TT_APR;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_AST;
       } else if (month == TT_UNKNOWN && (rest[1] == 'u' || rest[1] == 'U') &&
                  (rest[2] == 'g' || rest[2] == 'G')) {
         month = TT_AUG;
       }
       break;
     case 'b':
     case 'B':
       if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_BST;
       }
       break;
     case 'c':
     case 'C':
       if (zone == TT_UNKNOWN && (rest[1] == 'd' || rest[1] == 'D') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_CDT;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_CST;
       }
       break;
     case 'd':
     case 'D':
       if (month == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
           (rest[2] == 'c' || rest[2] == 'C')) {
         month = TT_DEC;
       }
       break;
     case 'e':
     case 'E':
       if (zone == TT_UNKNOWN && (rest[1] == 'd' || rest[1] == 'D') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_EDT;
       } else if (zone == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_EET;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_EST;
       }
       break;
     case 'f':
     case 'F':
       if (month == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
           (rest[2] == 'b' || rest[2] == 'B')) {
         month = TT_FEB;
       } else if (dotw == TT_UNKNOWN && (rest[1] == 'r' || rest[1] == 'R') &&
                  (rest[2] == 'i' || rest[2] == 'I')) {
         dotw = TT_FRI;
       }
       break;
     case 'g':
     case 'G':
       if (zone == TT_UNKNOWN && (rest[1] == 'm' || rest[1] == 'M') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_GMT;
       }
       break;
     case 'j':
     case 'J':
       if (month == TT_UNKNOWN && (rest[1] == 'a' || rest[1] == 'A') &&
           (rest[2] == 'n' || rest[2] == 'N')) {
         month = TT_JAN;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_JST;
       } else if (month == TT_UNKNOWN && (rest[1] == 'u' || rest[1] == 'U') &&
                  (rest[2] == 'l' || rest[2] == 'L')) {
         month = TT_JUL;
       } else if (month == TT_UNKNOWN && (rest[1] == 'u' || rest[1] == 'U') &&
                  (rest[2] == 'n' || rest[2] == 'N')) {
         month = TT_JUN;
       }
       break;
     case 'm':
     case 'M':
       if (month == TT_UNKNOWN && (rest[1] == 'a' || rest[1] == 'A') &&
           (rest[2] == 'r' || rest[2] == 'R')) {
         month = TT_MAR;
       } else if (month == TT_UNKNOWN && (rest[1] == 'a' || rest[1] == 'A') &&
                  (rest[2] == 'y' || rest[2] == 'Y')) {
         month = TT_MAY;
       } else if (zone == TT_UNKNOWN && (rest[1] == 'd' || rest[1] == 'D') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_MDT;
       } else if (zone == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_MET;
       } else if (dotw == TT_UNKNOWN && (rest[1] == 'o' || rest[1] == 'O') &&
                  (rest[2] == 'n' || rest[2] == 'N')) {
         dotw = TT_MON;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_MST;
       }
       break;
     case 'n':
     case 'N':
       if (month == TT_UNKNOWN && (rest[1] == 'o' || rest[1] == 'O') &&
           (rest[2] == 'v' || rest[2] == 'V')) {
         month = TT_NOV;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_NST;
       }
       break;
     case 'o':
     case 'O':
       if (month == TT_UNKNOWN && (rest[1] == 'c' || rest[1] == 'C') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         month = TT_OCT;
       }
       break;
     case 'p':
     case 'P':
       if (zone == TT_UNKNOWN && (rest[1] == 'd' || rest[1] == 'D') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_PDT;
       } else if (zone == TT_UNKNOWN && (rest[1] == 's' || rest[1] == 'S') &&
                  (rest[2] == 't' || rest[2] == 'T')) {
         zone = TT_PST;
       }
       break;
     case 's':
     case 'S':
       if (dotw == TT_UNKNOWN && (rest[1] == 'a' || rest[1] == 'A') &&
           (rest[2] == 't' || rest[2] == 'T')) {
         dotw = TT_SAT;
       } else if (month == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
                  (rest[2] == 'p' || rest[2] == 'P')) {
         month = TT_SEP;
       } else if (dotw == TT_UNKNOWN && (rest[1] == 'u' || rest[1] == 'U') &&
                  (rest[2] == 'n' || rest[2] == 'N')) {
         dotw = TT_SUN;
       }
       break;
     case 't':
     case 'T':
       if (dotw == TT_UNKNOWN && (rest[1] == 'h' || rest[1] == 'H') &&
           (rest[2] == 'u' || rest[2] == 'U')) {
         dotw = TT_THU;
       } else if (dotw == TT_UNKNOWN && (rest[1] == 'u' || rest[1] == 'U') &&
                  (rest[2] == 'e' || rest[2] == 'E')) {
         dotw = TT_TUE;
       }
       break;
     case 'u':
     case 'U':
       if (zone == TT_UNKNOWN && (rest[1] == 't' || rest[1] == 'T') &&
           !(rest[2] >= 'A' && rest[2] <= 'Z') &&
           !(rest[2] >= 'a' && rest[2] <= 'z'))
       /* UT is the same as GMT but UTx is not. */
       {
         zone = TT_GMT;
       }
       break;
     case 'w':
     case 'W':
       if (dotw == TT_UNKNOWN && (rest[1] == 'e' || rest[1] == 'E') &&
           (rest[2] == 'd' || rest[2] == 'D')) {
         dotw = TT_WED;
       }
       break;

     case '+':
     case '-': {
       const char* end;
       int sign;
       if (zone_offset != -1) {
         /* already got one... */
         rest++;
         break;
       }
       if (zone != TT_UNKNOWN && zone != TT_GMT) {
         /* GMT+0300 is legal, but PST+0300 is not. */
         rest++;
         break;
       }

       sign = ((*rest == '+') ? 1 : -1);
       rest++; /* move over sign */
       end = rest;
       while (*end >= '0' && *end <= '9') {
         end++;
       }
       if (rest == end) { /* no digits here */
         break;
       }

       if ((end - rest) == 4) /* offset in HHMM */
         zone_offset = (((((rest[0] - '0') * 10) + (rest[1] - '0')) * 60) +
                        (((rest[2] - '0') * 10) + (rest[3] - '0')));
       else if ((end - rest) == 2)
       /* offset in hours */
       {
         zone_offset = (((rest[0] - '0') * 10) + (rest[1] - '0')) * 60;
       } else if ((end - rest) == 1)
       /* offset in hours */
       {
         zone_offset = (rest[0] - '0') * 60;
       } else
       /* 3 or >4 */
       {
         break;
       }

       zone_offset *= sign;
       zone = TT_GMT;
       break;
     }

     case '0':
     case '1':
     case '2':
     case '3':
     case '4':
     case '5':
     case '6':
     case '7':
     case '8':
     case '9': {
       int tmp_hour = -1;
       int tmp_min = -1;
       int tmp_sec = -1;
       const char* end = rest + 1;
       while (*end >= '0' && *end <= '9') {
         end++;
       }

       /* end is now the first character after a range of digits. */

       if (*end == ':') {
         if (hour >= 0 && min >= 0) { /* already got it */
           break;
         }

         /* We have seen "[0-9]+:", so this is probably HH:MM[:SS] */
         if ((end - rest) > 2)
         /* it is [0-9][0-9][0-9]+: */
         {
           break;
         }
         if ((end - rest) == 2)
           tmp_hour = ((rest[0] - '0') * 10 + (rest[1] - '0'));
         else {
           tmp_hour = (rest[0] - '0');
         }

         /* move over the colon, and parse minutes */

         rest = ++end;
         while (*end >= '0' && *end <= '9') {
           end++;
         }

         if (end == rest)
         /* no digits after first colon? */
         {
           break;
         }
         if ((end - rest) > 2)
         /* it is [0-9][0-9][0-9]+: */
         {
           break;
         }
         if ((end - rest) == 2)
           tmp_min = ((rest[0] - '0') * 10 + (rest[1] - '0'));
         else {
           tmp_min = (rest[0] - '0');
         }

         /* now go for seconds */
         rest = end;
         if (*rest == ':') {
           rest++;
         }
         end = rest;
         while (*end >= '0' && *end <= '9') {
           end++;
         }

         if (end == rest) /* no digits after second colon - that's ok. */
           ;
         else if ((end - rest) > 2)
         /* it is [0-9][0-9][0-9]+: */
         {
           break;
         }
         else if ((end - rest) == 2)
           tmp_sec = ((rest[0] - '0') * 10 + (rest[1] - '0'));
         else {
           tmp_sec = (rest[0] - '0');
         }

         /* If we made it here, we've parsed hour and min,
            and possibly sec, so it worked as a unit. */

         /* skip over whitespace and see if there's an AM or PM
            directly following the time.
          */
         if (tmp_hour <= 12) {
           const char* s = end;
           while (*s && (*s == ' ' || *s == '\t')) {
             s++;
           }
           if ((s[0] == 'p' || s[0] == 'P') && (s[1] == 'm' || s[1] == 'M'))
           /* 10:05pm == 22:05, and 12:05pm == 12:05 */
           {
             tmp_hour = (tmp_hour == 12 ? 12 : tmp_hour + 12);
           } else if (tmp_hour == 12 && (s[0] == 'a' || s[0] == 'A') &&
                      (s[1] == 'm' || s[1] == 'M'))
           /* 12:05am == 00:05 */
           {
             tmp_hour = 0;
           }
         }

         hour = tmp_hour;
         min = tmp_min;
         sec = tmp_sec;
         rest = end;
         break;
       }
       if ((*end == '/' || *end == '-') && end[1] >= '0' && end[1] <= '9') {
         /* Perhaps this is 6/16/95, 16/6/95, 6-16-95, or 16-6-95
            or even 95-06-05...
            #### But it doesn't handle 1995-06-22.
          */
         int n1, n2, n3;
         const char* s;

         if (month != TT_UNKNOWN)
         /* if we saw a month name, this can't be. */
         {
           break;
         }

         s = rest;

         n1 = (*s++ - '0'); /* first 1 or 2 digits */
         if (*s >= '0' && *s <= '9') {
           n1 = n1 * 10 + (*s++ - '0');
         }

         if (*s != '/' && *s != '-') { /* slash */
           break;
         }
         s++;

         if (*s < '0' || *s > '9') { /* second 1 or 2 digits */
           break;
         }
         n2 = (*s++ - '0');
         if (*s >= '0' && *s <= '9') {
           n2 = n2 * 10 + (*s++ - '0');
         }

         if (*s != '/' && *s != '-') { /* slash */
           break;
         }
         s++;

         if (*s < '0' || *s > '9') { /* third 1, 2, 4, or 5 digits */
           break;
         }
         n3 = (*s++ - '0');
         if (*s >= '0' && *s <= '9') {
           n3 = n3 * 10 + (*s++ - '0');
         }

         if (*s >= '0' && *s <= '9') /* optional digits 3, 4, and 5 */
         {
           n3 = n3 * 10 + (*s++ - '0');
           if (*s < '0' || *s > '9') {
             break;
           }
           n3 = n3 * 10 + (*s++ - '0');
           if (*s >= '0' && *s <= '9') {
             n3 = n3 * 10 + (*s++ - '0');
           }
         }

         if ((*s >= '0' && *s <= '9') || /* followed by non-alphanum */
             (*s >= 'A' && *s <= 'Z') || (*s >= 'a' && *s <= 'z')) {
           break;
         }

         /* Ok, we parsed three 1-2 digit numbers, with / or -
            between them.  Now decide what the hell they are
            (DD/MM/YY or MM/DD/YY or YY/MM/DD.)
          */

         if (n1 > 31 || n1 == 0) /* must be YY/MM/DD */
         {
           if (n2 > 12) {
             break;
           }
           if (n3 > 31) {
             break;
           }
           year = n1;
           if (year < 70) {
             year += 2000;
           } else if (year < 100) {
             year += 1900;
           }
           month = (TIME_TOKEN)(n2 + ((int)TT_JAN) - 1);
           date = n3;
           rest = s;
           break;
         }

         if (n1 > 12 && n2 > 12) /* illegal */
         {
           rest = s;
           break;
         }

         if (n3 < 70) {
           n3 += 2000;
         } else if (n3 < 100) {
           n3 += 1900;
         }

         if (n1 > 12) /* must be DD/MM/YY */
         {
           date = n1;
           month = (TIME_TOKEN)(n2 + ((int)TT_JAN) - 1);
           year = n3;
         } else /* assume MM/DD/YY */
         {
           /* #### In the ambiguous case, should we consult the
              locale to find out the local default? */
           month = (TIME_TOKEN)(n1 + ((int)TT_JAN) - 1);
           date = n2;
           year = n3;
         }
         rest = s;
       } else if ((*end >= 'A' && *end <= 'Z') || (*end >= 'a' && *end <= 'z'))
         /* Digits followed by non-punctuation - what's that? */
         ;
       else if ((end - rest) == 5) /* five digits is a year */
         year = (year < 0 ? ((rest[0] - '0') * 10000L +
                             (rest[1] - '0') * 1000L + (rest[2] - '0') * 100L +
                             (rest[3] - '0') * 10L + (rest[4] - '0'))
                          : year);
       else if ((end - rest) == 4) /* four digits is a year */
         year = (year < 0 ? ((rest[0] - '0') * 1000L + (rest[1] - '0') * 100L +
                             (rest[2] - '0') * 10L + (rest[3] - '0'))
                          : year);
       else if ((end - rest) == 2) /* two digits - date or year */
       {
         int n = ((rest[0] - '0') * 10 + (rest[1] - '0'));
         /* If we don't have a date (day of the month) and we see a number
              less than 32, then assume that is the date.

                  Otherwise, if we have a date and not a year, assume this is
            the year.  If it is less than 70, then assume it refers to the 21st
                  century.  If it is two digits (>= 70), assume it refers to
            this century.  Otherwise, assume it refers to an unambiguous year.

                  The world will surely end soon.
            */
         if (date < 0 && n < 32) {
           date = n;
         } else if (year < 0) {
           if (n < 70) {
             year = 2000 + n;
           } else if (n < 100) {
             year = 1900 + n;
           } else {
             year = n;
           }
         }
         /* else what the hell is this. */
       } else if ((end - rest) == 1) { /* one digit - date */
         date = (date < 0 ? (rest[0] - '0') : date);
       }
       /* else, three or more than five digits - what's that? */

       break;
     }
   }

   /* Skip to the end of this token, whether we parsed it or not.
          Tokens are delimited by whitespace, or ,;-/
          But explicitly not :+-.
    */
   while (*rest && *rest != ' ' && *rest != '\t' && *rest != ',' &&
          *rest != ';' && *rest != '-' && *rest != '+' && *rest != '/' &&
          *rest != '(' && *rest != ')' && *rest != '[' && *rest != ']') {
     rest++;
   }
   /* skip over uninteresting chars. */
 SKIP_MORE:
   while (*rest && (*rest == ' ' || *rest == '\t' || *rest == ',' ||
                    *rest == ';' || *rest == '/' || *rest == '(' ||
                    *rest == ')' || *rest == '[' || *rest == ']')) {
     rest++;
   }

   /* "-" is ignored at the beginning of a token if we have not yet
          parsed a year (e.g., the second "-" in "30-AUG-1966"), or if
          the character after the dash is not a digit. */
   if (*rest == '-' &&
       ((rest > string && isalpha((unsigned char)rest[-1]) && year < 0) ||
        rest[1] < '0' || rest[1] > '9')) {
     rest++;
     goto SKIP_MORE;
   }
 }

 if (zone != TT_UNKNOWN && zone_offset == -1) {
   switch (zone) {
     case TT_PST:
       zone_offset = -8 * 60;
       break;
     case TT_PDT:
       zone_offset = -8 * 60;
       dst_offset = 1 * 60;
       break;
     case TT_MST:
       zone_offset = -7 * 60;
       break;
     case TT_MDT:
       zone_offset = -7 * 60;
       dst_offset = 1 * 60;
       break;
     case TT_CST:
       zone_offset = -6 * 60;
       break;
     case TT_CDT:
       zone_offset = -6 * 60;
       dst_offset = 1 * 60;
       break;
     case TT_EST:
       zone_offset = -5 * 60;
       break;
     case TT_EDT:
       zone_offset = -5 * 60;
       dst_offset = 1 * 60;
       break;
     case TT_AST:
       zone_offset = -4 * 60;
       break;
     case TT_NST:
       zone_offset = -3 * 60 - 30;
       break;
     case TT_GMT:
       zone_offset = 0 * 60;
       break;
     case TT_BST:
       zone_offset = 0 * 60;
       dst_offset = 1 * 60;
       break;
     case TT_MET:
       zone_offset = 1 * 60;
       break;
     case TT_EET:
       zone_offset = 2 * 60;
       break;
     case TT_JST:
       zone_offset = 9 * 60;
       break;
     default:
       PR_ASSERT(0);
       break;
   }
 }

 /* If we didn't find a year, month, or day-of-the-month, we can't
        possibly parse this, and in fact, mktime() will do something random
        (I'm seeing it return "Tue Feb  5 06:28:16 2036", which is no doubt
        a numerologically significant date... */
 if (month == TT_UNKNOWN || date == -1 || year == -1 || year > PR_INT16_MAX) {
   return PR_FAILURE;
 }

 memset(result, 0, sizeof(*result));
 if (sec != -1) {
   result->tm_sec = sec;
 }
 if (min != -1) {
   result->tm_min = min;
 }
 if (hour != -1) {
   result->tm_hour = hour;
 }
 if (date != -1) {
   result->tm_mday = date;
 }
 if (month != TT_UNKNOWN) {
   result->tm_month = (((int)month) - ((int)TT_JAN));
 }
 if (year != -1) {
   result->tm_year = year;
 }
 if (dotw != TT_UNKNOWN) {
   result->tm_wday = (((int)dotw) - ((int)TT_SUN));
 }
 /*
  * Mainly to compute wday and yday, but normalized time is also required
  * by the check below that works around a Visual C++ 2005 mktime problem.
  */
 PR_NormalizeTime(result, PR_GMTParameters);
 /* The remaining work is to set the gmt and dst offsets in tm_params. */

 if (zone == TT_UNKNOWN && default_to_gmt) {
   /* No zone was specified, so pretend the zone was GMT. */
   zone = TT_GMT;
   zone_offset = 0;
 }

 if (zone_offset == -1) {
   /* no zone was specified, and we're to assume that everything
     is local. */
   struct tm localTime;
   time_t secs;

   PR_ASSERT(result->tm_month > -1 && result->tm_mday > 0 &&
             result->tm_hour > -1 && result->tm_min > -1 &&
             result->tm_sec > -1);

   /*
    * To obtain time_t from a tm structure representing the local
    * time, we call mktime().  However, we need to see if we are
    * on 1-Jan-1970 or before.  If we are, we can't call mktime()
    * because mktime() will crash on win16. In that case, we
    * calculate zone_offset based on the zone offset at
    * 00:00:00, 2 Jan 1970 GMT, and subtract zone_offset from the
    * date we are parsing to transform the date to GMT.  We also
    * do so if mktime() returns (time_t) -1 (time out of range).
    */

   /* month, day, hours, mins and secs are always non-negative
      so we dont need to worry about them. */
   if (result->tm_year >= 1970) {
     PRInt64 usec_per_sec;

     localTime.tm_sec = result->tm_sec;
     localTime.tm_min = result->tm_min;
     localTime.tm_hour = result->tm_hour;
     localTime.tm_mday = result->tm_mday;
     localTime.tm_mon = result->tm_month;
     localTime.tm_year = result->tm_year - 1900;
     /* Set this to -1 to tell mktime "I don't care".  If you set
        it to 0 or 1, you are making assertions about whether the
        date you are handing it is in daylight savings mode or not;
        and if you're wrong, it will "fix" it for you. */
     localTime.tm_isdst = -1;

#if _MSC_VER == 1400 /* 1400 = Visual C++ 2005 (8.0) */
     /*
      * mktime will return (time_t) -1 if the input is a date
      * after 23:59:59, December 31, 3000, US Pacific Time (not
      * UTC as documented):
      * http://msdn.microsoft.com/en-us/library/d1y53h2a(VS.80).aspx
      * But if the year is 3001, mktime also invokes the invalid
      * parameter handler, causing the application to crash.  This
      * problem has been reported in
      * http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=266036.
      * We avoid this crash by not calling mktime if the date is
      * out of range.  To use a simple test that works in any time
      * zone, we consider year 3000 out of range as well.  (See
      * bug 480740.)
      */
     if (result->tm_year >= 3000) {
       /* Emulate what mktime would have done. */
       errno = EINVAL;
       secs = (time_t)-1;
     } else {
       secs = mktime(&localTime);
     }
#else
     secs = mktime(&localTime);
#endif
     if (secs != (time_t)-1) {
       PRTime usecs64;
       LL_I2L(usecs64, secs);
       LL_I2L(usec_per_sec, PR_USEC_PER_SEC);
       LL_MUL(usecs64, usecs64, usec_per_sec);
       PR_ExplodeTime(usecs64, PR_LocalTimeParameters, result);
       return PR_SUCCESS;
     }
   }

   /* So mktime() can't handle this case.  We assume the
      zone_offset for the date we are parsing is the same as
      the zone offset on 00:00:00 2 Jan 1970 GMT. */
   secs = 86400;
   localTimeResult = MT_safe_localtime(&secs, &localTime);
   PR_ASSERT(localTimeResult != NULL);
   if (localTimeResult == NULL) {
     return PR_FAILURE;
   }
   zone_offset = localTime.tm_min + 60 * localTime.tm_hour +
                 1440 * (localTime.tm_mday - 2);
 }

 result->tm_params.tp_gmt_offset = zone_offset * 60;
 result->tm_params.tp_dst_offset = dst_offset * 60;

 return PR_SUCCESS;
}

PR_IMPLEMENT(PRStatus)
PR_ParseTimeString(const char* string, PRBool default_to_gmt, PRTime* result) {
 PRExplodedTime tm;
 PRStatus rv;

 rv = PR_ParseTimeStringToExplodedTime(string, default_to_gmt, &tm);
 if (rv != PR_SUCCESS) {
   return rv;
 }

 *result = PR_ImplodeTime(&tm);

 return PR_SUCCESS;
}

/*
*******************************************************************
*******************************************************************
**
**    OLD COMPATIBILITY FUNCTIONS
**
*******************************************************************
*******************************************************************
*/

/*
*-----------------------------------------------------------------------
*
* PR_FormatTime --
*
*     Format a time value into a buffer. Same semantics as strftime().
*
*-----------------------------------------------------------------------
*/

PR_IMPLEMENT(PRUint32)
PR_FormatTime(char* buf, int buflen, const char* fmt,
             const PRExplodedTime* time) {
 size_t rv;
 struct tm a;
 struct tm* ap;

 if (time) {
   ap = &a;
   a.tm_sec = time->tm_sec;
   a.tm_min = time->tm_min;
   a.tm_hour = time->tm_hour;
   a.tm_mday = time->tm_mday;
   a.tm_mon = time->tm_month;
   a.tm_wday = time->tm_wday;
   a.tm_year = time->tm_year - 1900;
   a.tm_yday = time->tm_yday;
   a.tm_isdst = time->tm_params.tp_dst_offset ? 1 : 0;

   /*
    * On some platforms, for example SunOS 4, struct tm has two
    * additional fields: tm_zone and tm_gmtoff.
    */

#if (__GLIBC__ >= 2) || defined(NETBSD) || defined(OPENBSD) || \
   defined(FREEBSD) || defined(DARWIN) || defined(ANDROID)
   a.tm_zone = NULL;
   a.tm_gmtoff = time->tm_params.tp_gmt_offset + time->tm_params.tp_dst_offset;
#endif
 } else {
   ap = NULL;
 }

 rv = strftime(buf, buflen, fmt, ap);
 if (!rv && buf && buflen > 0) {
   /*
    * When strftime fails, the contents of buf are indeterminate.
    * Some callers don't check the return value from this function,
    * so store an empty string in buf in case they try to print it.
    */
   buf[0] = '\0';
 }
 return rv;
}

/*
* The following string arrays and macros are used by PR_FormatTimeUSEnglish().
*/

static const char* abbrevDays[] = {"Sun", "Mon", "Tue", "Wed",
                                  "Thu", "Fri", "Sat"};

static const char* days[] = {"Sunday",   "Monday", "Tuesday", "Wednesday",
                            "Thursday", "Friday", "Saturday"};

static const char* abbrevMonths[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

static const char* months[] = {"January",   "February", "March",    "April",
                              "May",       "June",     "July",     "August",
                              "September", "October",  "November", "December"};

/*
* Add a single character to the given buffer, incrementing the buffer pointer
* and decrementing the buffer size. Return 0 on error.
*/
#define ADDCHAR(buf, bufSize, ch) \
 do {                            \
   if (bufSize < 1) {            \
     *(--buf) = '\0';            \
     return 0;                   \
   }                             \
   *buf++ = ch;                  \
   bufSize--;                    \
 } while (0)

/*
* Add a string to the given buffer, incrementing the buffer pointer
* and decrementing the buffer size appropriately.  Return 0 on error.
*/
#define ADDSTR(buf, bufSize, str)   \
 do {                              \
   PRUint32 strSize = strlen(str); \
   if (strSize > bufSize) {        \
     if (bufSize == 0)             \
       *(--buf) = '\0';            \
     else                          \
       *buf = '\0';                \
     return 0;                     \
   }                               \
   memcpy(buf, str, strSize);      \
   buf += strSize;                 \
   bufSize -= strSize;             \
 } while (0)

/* Needed by PR_FormatTimeUSEnglish() */
static unsigned int pr_WeekOfYear(const PRExplodedTime* time,
                                 unsigned int firstDayOfWeek);

/***********************************************************************************
*
* Description:
*  This is a dumbed down version of strftime that will format the date in US
*  English regardless of the setting of the global locale.  This functionality
*is needed to write things like MIME headers which must always be in US
*English.
*
**********************************************************************************/

PR_IMPLEMENT(PRUint32)
PR_FormatTimeUSEnglish(char* buf, PRUint32 bufSize, const char* format,
                      const PRExplodedTime* time) {
 char* bufPtr = buf;
 const char* fmtPtr;
 char tmpBuf[40];
 const int tmpBufSize = sizeof(tmpBuf);

 for (fmtPtr = format; *fmtPtr != '\0'; fmtPtr++) {
   if (*fmtPtr != '%') {
     ADDCHAR(bufPtr, bufSize, *fmtPtr);
   } else {
     switch (*(++fmtPtr)) {
       case '%':
         /* escaped '%' character */
         ADDCHAR(bufPtr, bufSize, '%');
         break;

       case 'a':
         /* abbreviated weekday name */
         ADDSTR(bufPtr, bufSize, abbrevDays[time->tm_wday]);
         break;

       case 'A':
         /* full weekday name */
         ADDSTR(bufPtr, bufSize, days[time->tm_wday]);
         break;

       case 'b':
         /* abbreviated month name */
         ADDSTR(bufPtr, bufSize, abbrevMonths[time->tm_month]);
         break;

       case 'B':
         /* full month name */
         ADDSTR(bufPtr, bufSize, months[time->tm_month]);
         break;

       case 'c':
         /* Date and time. */
         PR_FormatTimeUSEnglish(tmpBuf, tmpBufSize, "%a %b %d %H:%M:%S %Y",
                                time);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'd':
         /* day of month ( 01 - 31 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld", time->tm_mday);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'e':
         /* day of month with space prefix for single digits ( 1 - 31 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%2ld", time->tm_mday);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'H':
         /* hour ( 00 - 23 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld", time->tm_hour);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'I':
         /* hour ( 01 - 12 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld",
                     (time->tm_hour % 12) ? time->tm_hour % 12 : (PRInt32)12);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'j':
         /* day number of year ( 001 - 366 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.3d", time->tm_yday + 1);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'm':
         /* month number ( 01 - 12 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld", time->tm_month + 1);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'M':
         /* minute ( 00 - 59 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld", time->tm_min);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'p':
         /* locale's equivalent of either AM or PM */
         ADDSTR(bufPtr, bufSize, (time->tm_hour < 12) ? "AM" : "PM");
         break;

       case 'S':
         /* seconds ( 00 - 61 ), allows for leap seconds */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2ld", time->tm_sec);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'U':
         /* week number of year ( 00 - 53  ),  Sunday  is  the first day of
          * week 1 */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2d", pr_WeekOfYear(time, 0));
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'w':
         /* weekday number ( 0 - 6 ), Sunday = 0 */
         PR_snprintf(tmpBuf, tmpBufSize, "%d", time->tm_wday);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'W':
         /* Week number of year ( 00 - 53  ),  Monday  is  the first day of
          * week 1 */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2d", pr_WeekOfYear(time, 1));
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'x':
         /* Date representation */
         PR_FormatTimeUSEnglish(tmpBuf, tmpBufSize, "%m/%d/%y", time);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'X':
         /* Time representation. */
         PR_FormatTimeUSEnglish(tmpBuf, tmpBufSize, "%H:%M:%S", time);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'y':
         /* year within century ( 00 - 99 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.2d", time->tm_year % 100);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'Y':
         /* year as ccyy ( for example 1986 ) */
         PR_snprintf(tmpBuf, tmpBufSize, "%.4d", time->tm_year);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       case 'Z':
         /* Time zone name or no characters if  no  time  zone exists.
          * Since time zone name is supposed to be independant of locale, we
          * defer to PR_FormatTime() for this option.
          */
         PR_FormatTime(tmpBuf, tmpBufSize, "%Z", time);
         ADDSTR(bufPtr, bufSize, tmpBuf);
         break;

       default:
         /* Unknown format.  Simply copy format into output buffer. */
         ADDCHAR(bufPtr, bufSize, '%');
         ADDCHAR(bufPtr, bufSize, *fmtPtr);
         break;
     }
   }
 }

 ADDCHAR(bufPtr, bufSize, '\0');
 return (PRUint32)(bufPtr - buf - 1);
}

/***********************************************************************************
*
* Description:
*  Returns the week number of the year (0-53) for the given time.
*firstDayOfWeek is the day on which the week is considered to start (0=Sun,
*1=Mon, ...). Week 1 starts the first time firstDayOfWeek occurs in the year.
*In other words, a partial week at the start of the year is considered week 0.
*
**********************************************************************************/

static unsigned int pr_WeekOfYear(const PRExplodedTime* time,
                                 unsigned int firstDayOfWeek) {
 int dayOfWeek;
 int dayOfYear;

 /* Get the day of the year for the given time then adjust it to represent the
  * first day of the week containing the given time.
  */
 dayOfWeek = time->tm_wday - firstDayOfWeek;
 if (dayOfWeek < 0) {
   dayOfWeek += 7;
 }

 dayOfYear = time->tm_yday - dayOfWeek;

 if (dayOfYear <= 0) {
   /* If dayOfYear is <= 0, it is in the first partial week of the year. */
   return 0;
 }

 /* Count the number of full weeks ( dayOfYear / 7 ) then add a week if there
  * are any days left over ( dayOfYear % 7 ).  Because we are only counting to
  * the first day of the week containing the given time, rather than to the
  * actual day representing the given time, any days in week 0 will be
  * "absorbed" as extra days in the given week.
  */
 return (dayOfYear / 7) + ((dayOfYear % 7) == 0 ? 0 : 1);
}