[thirdparty/glibc.git] / time / strptime_l.c

/* Copyright (C) 2002-2024 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <ctype.h>
#include <langinfo.h>
#include <limits.h>
#include <string.h>
#include <time.h>
#include <stdbool.h>

#ifdef _LIBC
# define HAVE_LOCALTIME_R 0
# include "../locale/localeinfo.h"

# define time_t __time64_t
# define __localtime_r(t, tp) __localtime64_r (t, tp)
#endif

#if ! HAVE_LOCALTIME_R && ! defined localtime_r
# ifdef _LIBC
#  define localtime_r __localtime_r
# else
/* Approximate localtime_r as best we can in its absence.  */
#  define localtime_r my_localtime_r
static struct tm *localtime_r (const time_t *, struct tm *);
static struct tm *
localtime_r (const time_t *t, struct tm *tp)
{
  struct tm *l = localtime (t);
  if (! l)
    return 0;
  *tp = *l;
  return tp;
}
# endif /* ! _LIBC */
#endif /* ! HAVE_LOCALTIME_R && ! defined (localtime_r) */


#define match_char(ch1, ch2) if (ch1 != ch2) return NULL
#if defined __GNUC__ && __GNUC__ >= 2
# define match_string(cs1, s2) \
  ({ size_t len = strlen (cs1);						      \
     int result = __strncasecmp_l ((cs1), (s2), len, locale) == 0;	      \
     if (result) (s2) += len;						      \
     result; })
#else
/* Oh come on.  Get a reasonable compiler.  */
# define match_string(cs1, s2) \
  (strncasecmp ((cs1), (s2), strlen (cs1)) ? 0 : ((s2) += strlen (cs1), 1))
#endif
/* We intentionally do not use isdigit() for testing because this will
   lead to problems with the wide character version.  */
#define get_number(from, to, n) \
  do {									      \
    int __n = n;							      \
    val = 0;								      \
    while (ISSPACE (*rp))						      \
      ++rp;								      \
    if (*rp < '0' || *rp > '9')						      \
      return NULL;							      \
    do {								      \
      val *= 10;							      \
      val += *rp++ - '0';						      \
    } while (--__n > 0 && val * 10 <= to && *rp >= '0' && *rp <= '9');	      \
    if (val < from || val > to)						      \
      return NULL;							      \
  } while (0)
#ifdef _NL_CURRENT
# define get_alt_number(from, to, n) \
  ({									      \
     __label__ do_normal;						      \
									      \
     if (s.decided != raw)						      \
       {								      \
	 val = _nl_parse_alt_digit (&rp HELPER_LOCALE_ARG);		      \
	 if (val == -1 && s.decided != loc)				      \
	   {								      \
	     s.decided = loc;						      \
	     goto do_normal;						      \
	   }								      \
	if (val < from || val > to)					      \
	  return NULL;							      \
       }								      \
     else								      \
       {								      \
       do_normal:							      \
	 get_number (from, to, n);					      \
       }								      \
    0;									      \
  })
#else
# define get_alt_number(from, to, n) \
  /* We don't have the alternate representation.  */			      \
  get_number(from, to, n)
#endif
#define recursive(new_fmt) \
  (*(new_fmt) != '\0'							      \
   && (rp = __strptime_internal (rp, (new_fmt), tm, &s LOCALE_ARG)) != NULL)


#ifdef _LIBC
/* This is defined in locale/C-time.c in the GNU libc.  */
extern const struct __locale_data _nl_C_LC_TIME attribute_hidden;

# define weekday_name (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (DAY_1)].string)
# define ab_weekday_name \
  (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABDAY_1)].string)
# define month_name (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (MON_1)].string)
# define ab_month_name (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ABMON_1)].string)
# define alt_month_name \
  (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (ALTMON_1)].string)
# define ab_alt_month_name \
  (&_nl_C_LC_TIME.values[_NL_ITEM_INDEX (_NL_ABALTMON_1)].string)
# define HERE_D_T_FMT (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (D_T_FMT)].string)
# define HERE_D_FMT (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (D_FMT)].string)
# define HERE_AM_STR (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (AM_STR)].string)
# define HERE_PM_STR (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (PM_STR)].string)
# define HERE_T_FMT_AMPM \
  (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (T_FMT_AMPM)].string)
# define HERE_T_FMT (_nl_C_LC_TIME.values[_NL_ITEM_INDEX (T_FMT)].string)

# define strncasecmp(s1, s2, n) __strncasecmp (s1, s2, n)
#else
static char const weekday_name[][10] =
  {
    "Sunday", "Monday", "Tuesday", "Wednesday",
    "Thursday", "Friday", "Saturday"
  };
static char const ab_weekday_name[][4] =
  {
    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
  };
static char const month_name[][10] =
  {
    "January", "February", "March", "April", "May", "June",
    "July", "August", "September", "October", "November", "December"
  };
static char const ab_month_name[][4] =
  {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
  };
# define HERE_D_T_FMT "%a %b %e %H:%M:%S %Y"
# define HERE_D_FMT "%m/%d/%y"
# define HERE_AM_STR "AM"
# define HERE_PM_STR "PM"
# define HERE_T_FMT_AMPM "%I:%M:%S %p"
# define HERE_T_FMT "%H:%M:%S"

static const unsigned short int __mon_yday[2][13] =
  {
    /* Normal years.  */
    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
    /* Leap years.  */
    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
  };
#endif

#if defined _LIBC
/* We use this code also for the extended locale handling where the
   function gets as an additional argument the locale which has to be
   used.  To access the values we have to redefine the _NL_CURRENT
   macro.  */
# define strptime		__strptime_l
# undef _NL_CURRENT
# define _NL_CURRENT(category, item) \
  (current->values[_NL_ITEM_INDEX (item)].string)
# undef _NL_CURRENT_WORD
# define _NL_CURRENT_WORD(category, item) \
  (current->values[_NL_ITEM_INDEX (item)].word)
# define LOCALE_PARAM , locale_t locale
# define LOCALE_ARG , locale
# define HELPER_LOCALE_ARG , current
# define ISSPACE(Ch) __isspace_l (Ch, locale)
#else
# define LOCALE_PARAM
# define LOCALE_ARG
# define HELPER_LOCALE_ARG
# define ISSPACE(Ch) isspace (Ch)
#endif


#ifndef __isleap
/* Nonzero if YEAR is a leap year (every 4 years,
   except every 100th isn't, and every 400th is).  */
# define __isleap(year)	\
  ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
#endif

/* Compute the day of the week.  */
static void
day_of_the_week (struct tm *tm)
{
  /* We know that January 1st 1970 was a Thursday (= 4).  Compute the
     difference between this data in the one on TM and so determine
     the weekday.  */
  int corr_year = 1900 + tm->tm_year - (tm->tm_mon < 2);
  int wday = (-473
	      + (365 * (tm->tm_year - 70))
	      + (corr_year / 4)
	      - ((corr_year / 4) / 25) + ((corr_year / 4) % 25 < 0)
	      + (((corr_year / 4) / 25) / 4)
	      + __mon_yday[0][tm->tm_mon]
	      + tm->tm_mday - 1);
  tm->tm_wday = ((wday % 7) + 7) % 7;
}

/* Compute the day of the year.  */
static void
day_of_the_year (struct tm *tm)
{
  tm->tm_yday = (__mon_yday[__isleap (1900 + tm->tm_year)][tm->tm_mon]
		 + (tm->tm_mday - 1));
}


#ifdef _LIBC
char *
#else
static char *
#endif
__strptime_internal (const char *rp, const char *fmt, struct tm *tmp,
		     void *statep LOCALE_PARAM)
{
#ifdef _LIBC
  struct __locale_data *const current = locale->__locales[LC_TIME];
#endif

  const char *rp_backup;
  const char *rp_longest;
  int cnt;
  int cnt_longest;
  size_t val;
  size_t num_eras;
  struct era_entry *era = NULL;
  enum ptime_locale_status { not, loc, raw } decided_longest;
  struct __strptime_state
  {
    unsigned int have_I : 1;
    unsigned int have_wday : 1;
    unsigned int have_yday : 1;
    unsigned int have_mon : 1;
    unsigned int have_mday : 1;
    unsigned int have_uweek : 1;
    unsigned int have_wweek : 1;
    unsigned int is_pm : 1;
    unsigned int want_century : 1;
    unsigned int want_era : 1;
    unsigned int want_xday : 1;
    enum ptime_locale_status decided : 2;
    signed char week_no;
    signed char century;
    int era_cnt;
  } s;
  struct tm tmb;
  struct tm *tm;

  if (statep == NULL)
    {
      memset (&s, 0, sizeof (s));
      s.century = -1;
      s.era_cnt = -1;
#ifdef _NL_CURRENT
      s.decided = not;
#else
      s.decided = raw;
#endif
      tm = tmp;
    }
  else
    {
      s = *(struct __strptime_state *) statep;
      tmb = *tmp;
      tm = &tmb;
    }

  while (*fmt != '\0')
    {
      /* A white space in the format string matches 0 more or white
	 space in the input string.  */
      if (ISSPACE (*fmt))
	{
	  while (ISSPACE (*rp))
	    ++rp;
	  ++fmt;
	  continue;
	}

      /* Any character but `%' must be matched by the same character
	 in the input string.  */
      if (*fmt != '%')
	{
	  match_char (*fmt++, *rp++);
	  continue;
	}

      ++fmt;
      /* We discard strftime modifiers.  */
      while (*fmt == '-' || *fmt == '_' || *fmt == '0'
	     || *fmt == '^' || *fmt == '#')
	++fmt;

      /* And field width.  */
      while (*fmt >= '0' && *fmt <= '9')
	++fmt;

      /* In some cases, modifiers are handled by adjusting state and
         then restarting the switch statement below.  */
    start_over:

      /* Make back up of current processing pointer.  */
      rp_backup = rp;

      switch (*fmt++)
	{
	case '%':
	  /* Match the `%' character itself.  */
	  match_char ('%', *rp++);
	  break;
	case 'a':
	case 'A':
	  /* Match day of week.  */
	  rp_longest = NULL;
	  decided_longest = s.decided;
	  cnt_longest = -1;
	  for (cnt = 0; cnt < 7; ++cnt)
	    {
	      const char *trp;
#ifdef _NL_CURRENT
	      if (s.decided !=raw)
		{
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, DAY_1 + cnt), trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, DAY_1 + cnt),
				     weekday_name[cnt]))
			decided_longest = loc;
		    }
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, ABDAY_1 + cnt), trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, ABDAY_1 + cnt),
				     ab_weekday_name[cnt]))
			decided_longest = loc;
		    }
		}
#endif
	      if (s.decided != loc
		  && (((trp = rp, match_string (weekday_name[cnt], trp))
		       && trp > rp_longest)
		      || ((trp = rp, match_string (ab_weekday_name[cnt], rp))
			  && trp > rp_longest)))
		{
		  rp_longest = trp;
		  cnt_longest = cnt;
		  decided_longest = raw;
		}
	    }
	  if (rp_longest == NULL)
	    /* Does not match a weekday name.  */
	    return NULL;
	  rp = rp_longest;
	  s.decided = decided_longest;
	  tm->tm_wday = cnt_longest;
	  s.have_wday = 1;
	  break;
	case 'b':
	case 'B':
	case 'h':
	  /* Match month name.  */
	  rp_longest = NULL;
	  decided_longest = s.decided;
	  cnt_longest = -1;
	  for (cnt = 0; cnt < 12; ++cnt)
	    {
	      const char *trp;
#ifdef _NL_CURRENT
	      if (s.decided !=raw)
		{
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, MON_1 + cnt), trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, MON_1 + cnt),
				     month_name[cnt]))
			decided_longest = loc;
		    }
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, ABMON_1 + cnt), trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, ABMON_1 + cnt),
				     ab_month_name[cnt]))
			decided_longest = loc;
		    }
#ifdef _LIBC
		  /* Now check the alt month.  */
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt), trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, ALTMON_1 + cnt),
				     alt_month_name[cnt]))
			decided_longest = loc;
		    }
		  trp = rp;
		  if (match_string (_NL_CURRENT (LC_TIME, _NL_ABALTMON_1 + cnt),
				    trp)
		      && trp > rp_longest)
		    {
		      rp_longest = trp;
		      cnt_longest = cnt;
		      if (s.decided == not
			  && strcmp (_NL_CURRENT (LC_TIME, _NL_ABALTMON_1 + cnt),
				     alt_month_name[cnt]))
			decided_longest = loc;
		    }
#endif
		}
#endif
	      if (s.decided != loc
		  && (((trp = rp, match_string (month_name[cnt], trp))
		       && trp > rp_longest)
		      || ((trp = rp, match_string (ab_month_name[cnt], trp))
			  && trp > rp_longest)
#ifdef _LIBC
		      || ((trp = rp, match_string (alt_month_name[cnt], trp))
			  && trp > rp_longest)
		      || ((trp = rp, match_string (ab_alt_month_name[cnt], trp))
			  && trp > rp_longest)
#endif
	      ))
		{
		  rp_longest = trp;
		  cnt_longest = cnt;
		  decided_longest = raw;
		}
	    }
	  if (rp_longest == NULL)
	    /* Does not match a month name.  */
	    return NULL;
	  rp = rp_longest;
	  s.decided = decided_longest;
	  tm->tm_mon = cnt_longest;
	  s.have_mon = 1;
	  s.want_xday = 1;
	  break;
	case 'c':
	  /* Match locale's date and time format.  */
#ifdef _NL_CURRENT
	  if (s.decided != raw)
	    {
	      if (!recursive (_NL_CURRENT (LC_TIME, D_T_FMT)))
		{
		  if (s.decided == loc)
		    return NULL;
		  else
		    rp = rp_backup;
		}
	      else
		{
		  if (s.decided == not
		      && strcmp (_NL_CURRENT (LC_TIME, D_T_FMT), HERE_D_T_FMT))
		    s.decided = loc;
		  s.want_xday = 1;
		  break;
		}
	      s.decided = raw;
	    }
#endif
	  if (!recursive (HERE_D_T_FMT))
	    return NULL;
	  s.want_xday = 1;
	  break;
	case 'C':
	  /* Match century number.  */
	match_century:
	  get_number (0, 99, 2);
	  s.century = val;
	  s.want_xday = 1;
	  break;
	case 'd':
	case 'e':
	  /* Match day of month.  */
	  get_number (1, 31, 2);
	  tm->tm_mday = val;
	  s.have_mday = 1;
	  s.want_xday = 1;
	  break;
	case 'F':
	  if (!recursive ("%Y-%m-%d"))
	    return NULL;
	  s.want_xday = 1;
	  break;
	case 'x':
#ifdef _NL_CURRENT
	  if (s.decided != raw)
	    {
	      if (!recursive (_NL_CURRENT (LC_TIME, D_FMT)))
		{
		  if (s.decided == loc)
		    return NULL;
		  else
		    rp = rp_backup;
		}
	      else
		{
		  if (s.decided == not
		      && strcmp (_NL_CURRENT (LC_TIME, D_FMT), HERE_D_FMT))
		    s.decided = loc;
		  s.want_xday = 1;
		  break;
		}
	      s.decided = raw;
	    }
#endif
	  /* Fall through.  */
	case 'D':
	  /* Match standard day format.  */
	  if (!recursive (HERE_D_FMT))
	    return NULL;
	  s.want_xday = 1;
	  break;
	case 'k':
	case 'H':
	  /* Match hour in 24-hour clock.  */
	  get_number (0, 23, 2);
	  tm->tm_hour = val;
	  s.have_I = 0;
	  break;
	case 'l':
	  /* Match hour in 12-hour clock.  GNU extension.  */
	case 'I':
	  /* Match hour in 12-hour clock.  */
	  get_number (1, 12, 2);
	  tm->tm_hour = val % 12;
	  s.have_I = 1;
	  break;
	case 'j':
	  /* Match day number of year.  */
	  get_number (1, 366, 3);
	  tm->tm_yday = val - 1;
	  s.have_yday = 1;
	  break;
	case 'm':
	  /* Match number of month.  */
	  get_number (1, 12, 2);
	  tm->tm_mon = val - 1;
	  s.have_mon = 1;
	  s.want_xday = 1;
	  break;
	case 'M':
	  /* Match minute.  */
	  get_number (0, 59, 2);
	  tm->tm_min = val;
	  break;
	case 'n':
	case 't':
	  /* Match any white space.  */
	  while (ISSPACE (*rp))
	    ++rp;
	  break;
	case 'p':
	  /* Match locale's equivalent of AM/PM.  */
#ifdef _NL_CURRENT
	  if (s.decided != raw)
	    {
	      if (match_string (_NL_CURRENT (LC_TIME, AM_STR), rp))
		{
		  if (strcmp (_NL_CURRENT (LC_TIME, AM_STR), HERE_AM_STR))
		    s.decided = loc;
		  s.is_pm = 0;
		  break;
		}
	      if (match_string (_NL_CURRENT (LC_TIME, PM_STR), rp))
		{
		  if (strcmp (_NL_CURRENT (LC_TIME, PM_STR), HERE_PM_STR))
		    s.decided = loc;
		  s.is_pm = 1;
		  break;
		}
	      s.decided = raw;
	    }
#endif
	  if (!match_string (HERE_AM_STR, rp))
	    {
	      if (match_string (HERE_PM_STR, rp))
		s.is_pm = 1;
	      else
		return NULL;
	    }
	  else
	    s.is_pm = 0;
	  break;
	case 'r':
#ifdef _NL_CURRENT
	  if (s.decided != raw)
	    {
	      if (!recursive (_NL_CURRENT (LC_TIME, T_FMT_AMPM)))
		{
		  if (s.decided == loc)
		    return NULL;
		  else
		    rp = rp_backup;
		}
	      else
		{
		  if (s.decided == not
		      && strcmp (_NL_CURRENT (LC_TIME, T_FMT_AMPM),
				 HERE_T_FMT_AMPM))
		    s.decided = loc;
		  break;
		}
	      s.decided = raw;
	    }
#endif
	  if (!recursive (HERE_T_FMT_AMPM))
	    return NULL;
	  break;
	case 'R':
	  if (!recursive ("%H:%M"))
	    return NULL;
	  break;
	case 's':
	  {
	    /* The number of seconds may be very high so we cannot use
	       the `get_number' macro.  Instead read the number
	       character for character and construct the result while
	       doing this.  */
	    time_t secs = 0;
	    if (*rp < '0' || *rp > '9')
	      /* We need at least one digit.  */
	      return NULL;

	    do
	      {
		secs *= 10;
		secs += *rp++ - '0';
	      }
	    while (*rp >= '0' && *rp <= '9');

	    if (localtime_r (&secs, tm) == NULL)
	      /* Error in function.  */
	      return NULL;
	  }
	  break;
	case 'S':
	  get_number (0, 61, 2);
	  tm->tm_sec = val;
	  break;
	case 'X':
#ifdef _NL_CURRENT
	  if (s.decided != raw)
	    {
	      if (!recursive (_NL_CURRENT (LC_TIME, T_FMT)))
		{
		  if (s.decided == loc)
		    return NULL;
		  else
		    rp = rp_backup;
		}
	      else
		{
		  if (strcmp (_NL_CURRENT (LC_TIME, T_FMT), HERE_T_FMT))
		    s.decided = loc;
		  break;
		}
	      s.decided = raw;
	    }
#endif
	  /* Fall through.  */
	case 'T':
	  if (!recursive (HERE_T_FMT))
	    return NULL;
	  break;
	case 'u':
	  get_number (1, 7, 1);
	  tm->tm_wday = val % 7;
	  s.have_wday = 1;
	  break;
	case 'g':
	  get_number (0, 99, 2);
	  /* XXX This cannot determine any field in TM.  */
	  break;
	case 'G':
	  if (*rp < '0' || *rp > '9')
	    return NULL;
	  /* XXX Ignore the number since we would need some more
	     information to compute a real date.  */
	  do
	    ++rp;
	  while (*rp >= '0' && *rp <= '9');
	  break;
	case 'U':
	  get_number (0, 53, 2);
	  s.week_no = val;
	  s.have_uweek = 1;
	  break;
	case 'W':
	  get_number (0, 53, 2);
	  s.week_no = val;
	  s.have_wweek = 1;
	  break;
	case 'V':
	  get_number (0, 53, 2);
	  /* XXX This cannot determine any field in TM without some
	     information.  */
	  break;
	case 'w':
	  /* Match number of weekday.  */
	  get_number (0, 6, 1);
	  tm->tm_wday = val;
	  s.have_wday = 1;
	  break;
	case 'y':
	match_year_in_century:
	  /* Match year within century.  */
	  get_number (0, 99, 2);
	  /* The "Year 2000: The Millennium Rollover" paper suggests that
	     values in the range 69-99 refer to the twentieth century.  */
	  tm->tm_year = val >= 69 ? val : val + 100;
	  /* Indicate that we want to use the century, if specified.  */
	  s.want_century = 1;
	  s.want_xday = 1;
	  break;
	case 'Y':
	  /* Match year including century number.  */
	  get_number (0, 9999, 4);
	  tm->tm_year = val - 1900;
	  s.want_century = 0;
	  s.want_xday = 1;
	  break;
	case 'Z':
	  /* Read timezone but perform no conversion.  */
	  while (ISSPACE (*rp))
	    rp++;
	  while (!ISSPACE (*rp) && *rp != '\0')
	    rp++;
	  break;
	case 'z':
	  /* We recognize four formats:
	     1. Two digits specify hours.
	     2. Four digits specify hours and minutes.
	     3. Two digits, ':', and two digits specify hours and minutes.
	     4. 'Z' is equivalent to +0000.  */
	  {
	    val = 0;
	    while (ISSPACE (*rp))
	      ++rp;
	    if (*rp == 'Z')
	      {
		++rp;
		tm->tm_gmtoff = 0;
		break;
	      }
	    if (*rp != '+' && *rp != '-')
	      return NULL;
	    bool neg = *rp++ == '-';
	    int n = 0;
	    while (n < 4 && *rp >= '0' && *rp <= '9')
	      {
		val = val * 10 + *rp++ - '0';
		++n;
		if (*rp == ':' && n == 2 && isdigit (*(rp + 1)))
		  ++rp;
	      }
	    if (n == 2)
	      val *= 100;
	    else if (n != 4)
	      /* Only two or four digits recognized.  */
	      return NULL;
	    else if (val % 100 >= 60)
	      /* Minutes valid range is 0 through 59.  */
	      return NULL;
	    tm->tm_gmtoff = (val / 100) * 3600 + (val % 100) * 60;
	    if (neg)
	      tm->tm_gmtoff = -tm->tm_gmtoff;
	  }
	  break;
	case 'E':
#ifdef _NL_CURRENT
	  switch (*fmt++)
	    {
	    case 'c':
	      /* Match locale's alternate date and time format.  */
	      if (s.decided != raw)
		{
		  const char *fmt = _NL_CURRENT (LC_TIME, ERA_D_T_FMT);

		  if (*fmt == '\0')
		    fmt = _NL_CURRENT (LC_TIME, D_T_FMT);

		  if (!recursive (fmt))
		    {
		      if (s.decided == loc)
			return NULL;
		      else
			rp = rp_backup;
		    }
		  else
		    {
		      if (strcmp (fmt, HERE_D_T_FMT))
			s.decided = loc;
		      s.want_xday = 1;
		      break;
		    }
		  s.decided = raw;
		}
	      /* The C locale has no era information, so use the
		 normal representation.  */
	      if (!recursive (HERE_D_T_FMT))
		return NULL;
	      s.want_xday = 1;
	      break;
	    case 'C':
	      if (s.decided != raw)
		{
		  if (s.era_cnt >= 0)
		    {
		      era = _nl_select_era_entry (s.era_cnt HELPER_LOCALE_ARG);
		      if (era != NULL && match_string (era->era_name, rp))
			{
			  s.decided = loc;
			  break;
			}
		      else
			return NULL;
		    }

		  num_eras = _NL_CURRENT_WORD (LC_TIME,
					       _NL_TIME_ERA_NUM_ENTRIES);
		  for (s.era_cnt = 0; s.era_cnt < (int) num_eras;
		       ++s.era_cnt, rp = rp_backup)
		    {
		      era = _nl_select_era_entry (s.era_cnt
						  HELPER_LOCALE_ARG);
		      if (era != NULL && match_string (era->era_name, rp))
			{
			  s.decided = loc;
			  break;
			}
		    }
		  if (s.era_cnt != (int) num_eras)
		    break;

		  s.era_cnt = -1;
		  if (s.decided == loc)
		    return NULL;

		  s.decided = raw;
		}
	      /* The C locale has no era information, so use the
		 normal representation.  */
	      goto match_century;
 	    case 'y':
	      if (s.decided != raw)
		{
		  get_number(0, 9999, 4);
		  tm->tm_year = val;
		  s.want_era = 1;
		  s.want_xday = 1;
		  s.want_century = 1;

		  if (s.era_cnt >= 0)
		    {
		      assert (s.decided == loc);

		      era = _nl_select_era_entry (s.era_cnt HELPER_LOCALE_ARG);
		      bool match = false;
		      if (era != NULL)
			{
			  int delta = ((tm->tm_year - era->offset)
				       * era->absolute_direction);
			  /* The difference between two sets of years
			     does not include the final year itself,
			     therefore add 1 to the difference to
			     account for that final year.  */
			  match = (delta >= 0
				   && delta < (((int64_t) era->stop_date[0]
						- (int64_t) era->start_date[0])
					       * era->absolute_direction
					       + 1));
			}
		      if (! match)
			return NULL;

		      break;
		    }

		  num_eras = _NL_CURRENT_WORD (LC_TIME,
					       _NL_TIME_ERA_NUM_ENTRIES);
		  for (s.era_cnt = 0; s.era_cnt < (int) num_eras; ++s.era_cnt)
		    {
		      era = _nl_select_era_entry (s.era_cnt
						  HELPER_LOCALE_ARG);
		      if (era != NULL)
			{
			  int delta = ((tm->tm_year - era->offset)
				       * era->absolute_direction);
			  /* See comment above about year difference + 1.  */
			  if (delta >= 0
			      && delta < (((int64_t) era->stop_date[0]
					   - (int64_t) era->start_date[0])
					  * era->absolute_direction
					  + 1))
			    {
			      s.decided = loc;
			      break;
			    }
			}
		    }
		  if (s.era_cnt != (int) num_eras)
		    break;

		  s.era_cnt = -1;
		  if (s.decided == loc)
		    return NULL;

		  s.decided = raw;
		}

	      goto match_year_in_century;
	    case 'Y':
	      if (s.decided != raw)
		{
		  num_eras = _NL_CURRENT_WORD (LC_TIME,
					       _NL_TIME_ERA_NUM_ENTRIES);
		  for (s.era_cnt = 0; s.era_cnt < (int) num_eras;
		       ++s.era_cnt, rp = rp_backup)
		    {
		      era = _nl_select_era_entry (s.era_cnt HELPER_LOCALE_ARG);
		      if (era != NULL && recursive (era->era_format))
			break;
		    }
		  if (s.era_cnt == (int) num_eras)
		    {
		      s.era_cnt = -1;
		      if (s.decided == loc)
			return NULL;
		      else
			rp = rp_backup;
		    }
		  else
		    {
		      s.decided = loc;
		      break;
		    }

		  s.decided = raw;
		}
	      get_number (0, 9999, 4);
	      tm->tm_year = val - 1900;
	      s.want_century = 0;
	      s.want_xday = 1;
	      break;
	    case 'x':
	      if (s.decided != raw)
		{
		  const char *fmt = _NL_CURRENT (LC_TIME, ERA_D_FMT);

		  if (*fmt == '\0')
		    fmt = _NL_CURRENT (LC_TIME, D_FMT);

		  if (!recursive (fmt))
		    {
		      if (s.decided == loc)
			return NULL;
		      else
			rp = rp_backup;
		    }
		  else
		    {
		      if (strcmp (fmt, HERE_D_FMT))
			s.decided = loc;
		      break;
		    }
		  s.decided = raw;
		}
	      if (!recursive (HERE_D_FMT))
		return NULL;
	      break;
	    case 'X':
	      if (s.decided != raw)
		{
		  const char *fmt = _NL_CURRENT (LC_TIME, ERA_T_FMT);

		  if (*fmt == '\0')
		    fmt = _NL_CURRENT (LC_TIME, T_FMT);

		  if (!recursive (fmt))
		    {
		      if (s.decided == loc)
			return NULL;
		      else
			rp = rp_backup;
		    }
		  else
		    {
		      if (strcmp (fmt, HERE_T_FMT))
			s.decided = loc;
		      break;
		    }
		  s.decided = raw;
		}
	      if (!recursive (HERE_T_FMT))
		return NULL;
	      break;
	    default:
	      return NULL;
	    }
	  break;
#else
	  /* We have no information about the era format.  Just use
	     the normal format.  */
	  if (*fmt != 'c' && *fmt != 'C' && *fmt != 'y' && *fmt != 'Y'
	      && *fmt != 'x' && *fmt != 'X')
	    /* This is an illegal format.  */
	    return NULL;

	  goto start_over;
#endif
	case 'O':
	  switch (*fmt++)
	    {
	    case 'b':
	    case 'B':
	    case 'h':
	      /* Match month name.  Reprocess as plain 'B'.  */
	      fmt--;
	      goto start_over;
	    case 'd':
	    case 'e':
	      /* Match day of month using alternate numeric symbols.  */
	      get_alt_number (1, 31, 2);
	      tm->tm_mday = val;
	      s.have_mday = 1;
	      s.want_xday = 1;
	      break;
	    case 'H':
	      /* Match hour in 24-hour clock using alternate numeric
		 symbols.  */
	      get_alt_number (0, 23, 2);
	      tm->tm_hour = val;
	      s.have_I = 0;
	      break;
	    case 'I':
	      /* Match hour in 12-hour clock using alternate numeric
		 symbols.  */
	      get_alt_number (1, 12, 2);
	      tm->tm_hour = val % 12;
	      s.have_I = 1;
	      break;
	    case 'm':
	      /* Match month using alternate numeric symbols.  */
	      get_alt_number (1, 12, 2);
	      tm->tm_mon = val - 1;
	      s.have_mon = 1;
	      s.want_xday = 1;
	      break;
	    case 'M':
	      /* Match minutes using alternate numeric symbols.  */
	      get_alt_number (0, 59, 2);
	      tm->tm_min = val;
	      break;
	    case 'S':
	      /* Match seconds using alternate numeric symbols.  */
	      get_alt_number (0, 61, 2);
	      tm->tm_sec = val;
	      break;
	    case 'U':
	      get_alt_number (0, 53, 2);
	      s.week_no = val;
	      s.have_uweek = 1;
	      break;
	    case 'W':
	      get_alt_number (0, 53, 2);
	      s.week_no = val;
	      s.have_wweek = 1;
	      break;
	    case 'V':
	      get_alt_number (0, 53, 2);
	      /* XXX This cannot determine any field in TM without
		 further information.  */
	      break;
	    case 'w':
	      /* Match number of weekday using alternate numeric symbols.  */
	      get_alt_number (0, 6, 1);
	      tm->tm_wday = val;
	      s.have_wday = 1;
	      break;
	    case 'y':
	      /* Match year within century using alternate numeric symbols.  */
	      get_alt_number (0, 99, 2);
	      tm->tm_year = val >= 69 ? val : val + 100;
	      s.want_xday = 1;
	      break;
	    default:
	      return NULL;
	    }
	  break;
	default:
	  return NULL;
	}
    }

  if (statep != NULL)
    {
      /* Recursive invocation, returning success, so
	 update parent's struct tm and state.  */
      *(struct __strptime_state *) statep = s;
      *tmp = tmb;
      return (char *) rp;
    }

  if (s.have_I && s.is_pm)
    tm->tm_hour += 12;

  if (s.century != -1)
    {
      if (s.want_century)
	tm->tm_year = tm->tm_year % 100 + (s.century - 19) * 100;
      else
	/* Only the century, but not the year.  Strange, but so be it.  */
	tm->tm_year = (s.century - 19) * 100;
    }

  if (s.era_cnt != -1)
    {
      era = _nl_select_era_entry (s.era_cnt HELPER_LOCALE_ARG);
      if (era == NULL)
	return NULL;
      if (s.want_era)
	tm->tm_year = (era->start_date[0]
		       + ((tm->tm_year - era->offset)
			  * era->absolute_direction));
      else
	/* Era start year assumed.  */
	tm->tm_year = era->start_date[0];
    }
  else
    if (s.want_era)
      {
	/* No era found but we have seen an E modifier.  Rectify some
	   values.  */
	if (s.want_century && s.century == -1 && tm->tm_year < 69)
	  tm->tm_year += 100;
      }

  if (s.want_xday && !s.have_wday)
    {
      if ( !(s.have_mon && s.have_mday) && s.have_yday)
	{
	  /* We don't have tm_mon and/or tm_mday, compute them.  */
	  int t_mon = 0;
	  while (__mon_yday[__isleap(1900 + tm->tm_year)][t_mon] <= tm->tm_yday)
	      t_mon++;
	  if (!s.have_mon)
	      tm->tm_mon = t_mon - 1;
	  if (!s.have_mday)
	      tm->tm_mday =
		(tm->tm_yday
		 - __mon_yday[__isleap(1900 + tm->tm_year)][t_mon - 1] + 1);
	  s.have_mon = 1;
	  s.have_mday = 1;
	}
      /* Don't crash in day_of_the_week if tm_mon is uninitialized.  */
      if (s.have_mon || (unsigned) tm->tm_mon <= 11)
	day_of_the_week (tm);
    }

  if (s.want_xday && !s.have_yday && (s.have_mon || (unsigned) tm->tm_mon <= 11))
    day_of_the_year (tm);

  if ((s.have_uweek || s.have_wweek) && s.have_wday)
    {
      int save_wday = tm->tm_wday;
      int save_mday = tm->tm_mday;
      int save_mon = tm->tm_mon;
      int w_offset = s.have_uweek ? 0 : 1;

      tm->tm_mday = 1;
      tm->tm_mon = 0;
      day_of_the_week (tm);
      if (s.have_mday)
	tm->tm_mday = save_mday;
      if (s.have_mon)
	tm->tm_mon = save_mon;

      if (!s.have_yday)
	tm->tm_yday = ((7 - (tm->tm_wday - w_offset)) % 7
		       + (s.week_no - 1) * 7
		       + (save_wday - w_offset + 7) % 7);

      if (!s.have_mday || !s.have_mon)
	{
	  int t_mon = 0;
	  while (__mon_yday[__isleap(1900 + tm->tm_year)][t_mon]
		 <= tm->tm_yday)
	    t_mon++;
	  if (!s.have_mon)
	    tm->tm_mon = t_mon - 1;
	  if (!s.have_mday)
	      tm->tm_mday =
		(tm->tm_yday
		 - __mon_yday[__isleap(1900 + tm->tm_year)][t_mon - 1] + 1);
	}

      tm->tm_wday = save_wday;
    }

  return (char *) rp;
}


char *
strptime (const char *buf, const char *format, struct tm *tm LOCALE_PARAM)
{
  return __strptime_internal (buf, format, tm, NULL LOCALE_ARG);
}

#ifdef _LIBC
weak_alias (__strptime_l, strptime_l)
#endif