struct tm tm;  if (! localtime_r (&lt, &tm) || ((ltm.tm_sec ^ tm.tm_sec) | (ltm.tm_min ^ tm.tm_min) | (ltm.tm_hour ^ tm.tm_hour) | (ltm.tm_mday ^ tm.tm_mday) | (ltm.tm_mon ^ tm.tm_mon) | (ltm.tm_year ^ tm.tm_year)))
struct tm gtm; struct tm ltm; time_t lt;  ltm = *tp; lt = mktime (&ltm);  if (lt == (time_t) -1) {  struct tm tm;  if (! localtime_r (&lt, &tm) || ((ltm.tm_sec ^ tm.tm_sec) | (ltm.tm_min ^ tm.tm_min) | (ltm.tm_hour ^ tm.tm_hour) | (ltm.tm_mday ^ tm.tm_mday) | (ltm.tm_mon ^ tm.tm_mon) | (ltm.tm_year ^ tm.tm_year))) break; }  if (! gmtime_r (&lt, &gtm))
my_strftime (s, maxsize, format, tp)      char *s;      size_t maxsize;      const char *format;      const struct tm *tp;{  int hour12 = tp->tm_hour;#ifdef _NL_CURRENT  /* We cannot make the following values variables since we must delay     the evaluation of these values until really needed since some     expressions might not be valid in every situation.  The `struct tm'     might be generated by a strptime() call that initialized     only a few elements.  Dereference the pointers only if the format     requires this.  Then it is ok to fail if the pointers are invalid.  */# define a_wkday _NL_CURRENT (LC_TIME, ABDAY_1 + tp->tm_wday)# define f_wkday _NL_CURRENT (LC_TIME, DAY_1 + tp->tm_wday)# define a_month _NL_CURRENT (LC_TIME, ABMON_1 + tp->tm_mon)# define f_month _NL_CURRENT (LC_TIME, MON_1 + tp->tm_mon)# define ampm _NL_CURRENT (LC_TIME, tp->tm_hour > 11 ? PM_STR : AM_STR)# define aw_len strlen (a_wkday)# define am_len strlen (a_month)# define ap_len strlen (ampm)#else# if !HAVE_STRFTIME# define f_wkday (weekday_name[tp->tm_wday])# define f_month (month_name[tp->tm_mon])# define a_wkday f_wkday# define a_month f_month# define ampm ("AMPM" + 2 * (tp->tm_hour > 11))  size_t aw_len = 3;  size_t am_len = 3;  size_t ap_len = 2;# endif#endif  const char *zone;  size_t i = 0;  char *p = s;  const char *f;  zone = NULL;#if HAVE_TM_ZONE  /* The POSIX test suite assumes that setting     the environment variable TZ to a new value before calling strftime()     will influence the result (the %Z format) even if the information in     TP is computed with a totally different time zone.     This is bogus: though POSIX allows bad behavior like this,     POSIX does not require it.  Do the right thing instead.  */  zone = (const char *) tp->tm_zone;#endif#if HAVE_TZNAME && HAVE_TZSET  /* POSIX.1 8.1.1 requires that whenever strftime() 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  if (hour12 > 12)    hour12 -= 12;  else    if (hour12 == 0)      hour12 = 12;  for (f = format; *f != '\0'; ++f)    {      int pad = 0;		/* Padding for number ('-', '_', or 0).  */      int modifier;		/* Field modifier ('E', 'O', or 0).  */      int digits;		/* Max digits for numeric format.  */      int number_value; 	/* Numeric value to be printed.  */      int negative_number;	/* 1 if the number is negative.  */      const char *subfmt;      char *bufp;      char buf[1 + (sizeof (int) < sizeof (time_t)		    ? INT_STRLEN_BOUND (time_t)		    : INT_STRLEN_BOUND (int))];      int width = -1;      int to_lowcase = 0;      int to_uppcase = 0;      int change_case = 0;      int format_char;#if DO_MULTIBYTE       switch (*f)	{	case '%':	  break;	case '\a': case '\b': case '\t': case '\n':	case '\v': case '\f': case '\r':	case ' ': case '!': case '"': case '#': case '&': case'\'':	case '(': case ')': case '*': case '+': case ',': case '-':	case '.': case '/': case '0': case '1': case '2': case '3':	case '4': case '5': case '6': case '7': case '8': case '9':	case ':': case ';': case '<': case '=': case '>': case '?':	case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':	case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':	case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':	case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':	case 'Y': case 'Z': case '[': case'\\': case ']': case '^':	case '_': case 'a': case 'b': case 'c': case 'd': case 'e':	case 'f': case 'g': case 'h': case 'i': case 'j': case 'k':	case 'l': case 'm': case 'n': case 'o': case 'p': case 'q':	case 'r': case 's': case 't': case 'u': case 'v': case 'w':	case 'x': case 'y': case 'z': case '{': case '|': case '}':	case '~':	  /* The C Standard requires these 98 characters (plus '%') to	     be in the basic execution character set.  None of these	     characters can start a multibyte sequence, so they need	     not be analyzed further.  */	  add (1, *p = *f);	  continue;	default:	  /* Copy this multibyte sequence until we reach its end, find	     an error, or come back to the initial shift state.  */	  {	    mbstate_t mbstate = mbstate_zero;	    size_t len = 0;	    do	      {		size_t bytes = mbrlen (f + len, (size_t) -1, &mbstate);		if (bytes == 0)		  break;		if (bytes == (size_t) -2)		  {		    len += strlen (f + len);		    break;		  }		if (bytes == (size_t) -1)		  {		    len++;		    break;		  }		len += bytes;	      }	    while (! mbsinit (&mbstate));	    cpy (len, f);	    f += len - 1;	    continue;	  }	}#else /* ! DO_MULTIBYTE */      /* Either multibyte encodings are not supported, or they are	 safe for formats, so any non-'%' byte can be copied through.  */      if (*f != '%')	{	  add (1, *p = *f);	  continue;	}#endif /* ! DO_MULTIBYTE */      /* Check for flags that can modify a format.  */      while (1)	{	  switch (*++f)	    {	      /* This influences the number formats.  */	    case '_':	    case '-':	    case '0':	      pad = *f;	      continue;	      /* This changes textual output.  */	    case '^':	      to_uppcase = 1;	      continue;	    case '#':	      change_case = 1;	      continue;	    default:	      break;	    }	  break;	}      /* As a GNU extension we allow to specify the field width.  */      if (ISDIGIT (*f))	{	  width = 0;	  do	    {	      width *= 10;	      width += *f - '0';	      ++f;	    }	  while (ISDIGIT (*f));	}      /* Check for modifiers.  */      switch (*f)	{	case 'E':	case 'O':	  modifier = *f++;	  break;	default:	  modifier = 0;	  break;	}      /* Now do the specified format.  */      format_char = *f;      switch (format_char)	{#define DO_NUMBER(d, v) \	  digits = width == -1 ? d : width;				      \	  number_value = v; goto do_number#define DO_NUMBER_SPACEPAD(d, v) \	  digits = width == -1 ? d : width;				      \	  number_value = v; goto do_number_spacepad	case '%':	  if (modifier != 0)	    goto bad_format;	  add (1, *p = *f);	  break;	case 'a':	  if (modifier != 0)	    goto bad_format;	  if (change_case)	    {	      to_uppcase = 1;	      to_lowcase = 0;	    }#if defined _NL_CURRENT || !HAVE_STRFTIME	  cpy (aw_len, a_wkday);	  break;#else	  goto underlying_strftime;#endif	case 'A':	  if (modifier != 0)	    goto bad_format;	  if (change_case)	    {	      to_uppcase = 1;	      to_lowcase = 0;	    }#if defined _NL_CURRENT || !HAVE_STRFTIME	  cpy (strlen (f_wkday), f_wkday);	  break;#else	  goto underlying_strftime;#endif	case 'b':	case 'h':		/* POSIX.2 extension.  */	  if (modifier != 0)	    goto bad_format;#if defined _NL_CURRENT || !HAVE_STRFTIME	  cpy (am_len, a_month);	  break;#else	  goto underlying_strftime;#endif	case 'B':	  if (modifier != 0)	    goto bad_format;	  if (change_case)	    {	      to_uppcase = 1;	      to_lowcase = 0;	    }#if defined _NL_CURRENT || !HAVE_STRFTIME	  cpy (strlen (f_month), f_month);	  break;#else	  goto underlying_strftime;#endif	case 'c':	  if (modifier == 'O')	    goto bad_format;#ifdef _NL_CURRENT	  if (! (modifier == 'E'		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_D_T_FMT)) != '\0'))	    subfmt = _NL_CURRENT (LC_TIME, D_T_FMT);#else# if HAVE_STRFTIME	  goto underlying_strftime;# else	  subfmt = "%a %b %e %H:%M:%S %Y";# endif#endif	subformat:	  {	    char *old_start = p;	    size_t len = my_strftime (NULL, maxsize - i, subfmt, tp);	    if (len == 0 && *subfmt)	      return 0;	    add (len, my_strftime (p, maxsize - i, subfmt, tp));	    if (to_uppcase)	      while (old_start < p)		{		  *old_start = TOUPPER ((unsigned char) *old_start);		  ++old_start;		}	  }	  break;#if HAVE_STRFTIME && ! (defined _NL_CURRENT && HAVE_STRUCT_ERA_ENTRY)	underlying_strftime:	  {	    /* The relevant information is available only via the	       underlying strftime implementation, so use that.  */	    char ufmt[4];	    char *u = ufmt;	    char ubuf[1024]; /* enough for any single format in practice */	    size_t len;	    *u++ = '%';	    if (modifier != 0)	      *u++ = modifier;	    *u++ = format_char;	    *u = '\0';	    len = strftime (ubuf, sizeof ubuf, ufmt, tp);	    if (len == 0 && ubuf[0] != '\0')	      return 0;	    cpy (len, ubuf);	  }	  break;#endif	case 'C':		/* POSIX.2 extension.  */	  if (modifier == 'O')	    goto bad_format;	  if (modifier == 'E')	    {#if HAVE_STRUCT_ERA_ENTRY	      struct era_entry *era = _nl_get_era_entry (tp);	      if (era)		{		  size_t len = strlen (era->name_fmt);		  cpy (len, era->name_fmt);		  break;		}#else# if HAVE_STRFTIME	      goto underlying_strftime;# endif#endif	    }	  {	    int year = tp->tm_year + TM_YEAR_BASE;	    DO_NUMBER (1, year / 100 - (year % 100 < 0));	  }	case 'x':	  if (modifier == 'O')	    goto bad_format;#ifdef _NL_CURRENT	  if (! (modifier == 'E'		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_D_FMT)) != '\0'))	    subfmt = _NL_CURRENT (LC_TIME, D_FMT);	  goto subformat;#else# if HAVE_STRFTIME	  goto underlying_strftime;# else	  /* Fall through.  */# endif#endif	case 'D':		/* POSIX.2 extension.  */	  if (modifier != 0)	    goto bad_format;	  subfmt = "%m/%d/%y";	  goto subformat;	case 'd':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, tp->tm_mday);	case 'e':		/* POSIX.2 extension.  */	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER_SPACEPAD (2, tp->tm_mday);	  /* All numeric formats set DIGITS and NUMBER_VALUE and then	     jump to one of these two labels.  */	do_number_spacepad:	  /* Force `_' flag unless overwritten by `0' flag.  */	  if (pad != '0')	    pad = '_';	do_number:	  /* Format the number according to the MODIFIER flag.  */	  if (modifier == 'O' && 0 <= number_value)	    {#ifdef _NL_CURRENT	      /* Get the locale specific alternate representation of		 the number NUMBER_VALUE.  If none exist NULL is returned.  */	      const char *cp = _nl_get_alt_digit (number_value);	      if (cp != NULL)		{		  size_t digitlen = strlen (cp);		  if (digitlen != 0)		    {		      cpy (digitlen, cp);		      break;		    }		}#else# if HAVE_STRFTIME	      goto underlying_strftime;# endif#endif	    }	  {	    unsigned int u = number_value;	    bufp = buf + sizeof (buf);	    negative_number = number_value < 0;	    if (negative_number)	      u = -u;	    do	      *--bufp = u % 10 + '0';	    while ((u /= 10) != 0);  	  }	do_number_sign_and_padding:	  if (negative_number)	    *--bufp = '-';	  if (pad != '-')	    {	      int padding = digits - (buf + sizeof (buf) - bufp);	      if (pad == '_')		{		  while (0 < padding--)		    *--bufp = ' ';		}	      else		{		  bufp += negative_number;		  while (0 < padding--)		    *--bufp = '0';		  if (negative_number)		    *--bufp = '-';		}	    }	  cpy (buf + sizeof (buf) - bufp, bufp);	  break;	case 'F':	  if (modifier != 0)	    goto bad_format;	  subfmt = "%Y-%m-%d";	  goto subformat;	case 'H':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, tp->tm_hour);	case 'I':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, hour12);	case 'k':		/* GNU extension.  */	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER_SPACEPAD (2, tp->tm_hour);	case 'l':		/* GNU extension.  */	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER_SPACEPAD (2, hour12);	case 'j':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (3, 1 + tp->tm_yday);	case 'M':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, tp->tm_min);	case 'm':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, tp->tm_mon + 1);	case 'n':		/* POSIX.2 extension.  */	  add (1, *p = '\n');	  break;	case 'P':	  to_lowcase = 1;#if !defined _NL_CURRENT && HAVE_STRFTIME	  format_char = 'p';#endif	  /* FALLTHROUGH */	case 'p':	  if (change_case)	    {	      to_uppcase = 0;	      to_lowcase = 1;	    }#if defined _NL_CURRENT || !HAVE_STRFTIME	  cpy (ap_len, ampm);	  break;#else	  goto underlying_strftime;#endif	case 'R':		/* GNU extension.  */	  subfmt = "%H:%M";	  goto subformat;	case 'r':		/* POSIX.2 extension.  */#ifdef _NL_CURRENT	  if (*(subfmt = _NL_CURRENT (LC_TIME, T_FMT_AMPM)) == '\0')#endif	    subfmt = "%I:%M:%S %p";	  goto subformat;	case 'S':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, tp->tm_sec);	case 's':		/* GNU extension.  */  	  {	    struct tm ltm;	    time_t t;	    ltm = *tp;	    t = mktime (&ltm);	    /* Generate string value for T using time_t arithmetic;	       this works even if sizeof (long) < sizeof (time_t).  */	    bufp = buf + sizeof (buf);	    negative_number = t < 0;	    do	      {		int d = t % 10;		t /= 10;		if (negative_number)		  {		    d = -d;		    /* Adjust if division truncates to minus infinity.  */		    if (0 < -1 % 10 && d < 0)		      {			t++;			d += 10;		      }		  }		*--bufp = d + '0';	      }	    while (t != 0);	    digits = 1;	    goto do_number_sign_and_padding;	  }	case 'X':	  if (modifier == 'O')	    goto bad_format;#ifdef _NL_CURRENT	  if (! (modifier == 'E'		 && *(subfmt = _NL_CURRENT (LC_TIME, ERA_T_FMT)) != '\0'))	    subfmt = _NL_CURRENT (LC_TIME, T_FMT);	  goto subformat;#else# if HAVE_STRFTIME	  goto underlying_strftime;# else	  /* Fall through.  */# endif#endif	case 'T':		/* POSIX.2 extension.  */	  subfmt = "%H:%M:%S";	  goto subformat;	case 't':		/* POSIX.2 extension.  */	  add (1, *p = '\t');	  break;	case 'f':	case 'u':		/* POSIX.2 extension.  */	  DO_NUMBER (1, (tp->tm_wday - 1 + 7) % 7 + 1);	case 'U':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, (tp->tm_yday - tp->tm_wday + 7) / 7);	case 'V':	case 'g':		/* GNU extension.  */	case 'G':		/* GNU extension.  */	  if (modifier == 'E')	    goto bad_format;	  {	    int year = tp->tm_year + TM_YEAR_BASE;	    int days = iso_week_days (tp->tm_yday, tp->tm_wday);	    if (days < 0)	      {		/* This ISO week belongs to the previous year.  */		year--;		days = iso_week_days (tp->tm_yday + (365 + __isleap (year)),				      tp->tm_wday);	      }	    else	      {		int d = iso_week_days (tp->tm_yday - (365 + __isleap (year)),				       tp->tm_wday);		if (0 <= d)		  {		    /* This ISO week belongs to the next year.  */		    year++;		    days = d;		  }	      }	    switch (*f)	      {	      case 'g':		DO_NUMBER (2, (year % 100 + 100) % 100);	      case 'G':		DO_NUMBER (1, year);	      default:		DO_NUMBER (2, days / 7 + 1);	      }	  }	case 'W':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (2, (tp->tm_yday - (tp->tm_wday - 1 + 7) % 7 + 7) / 7);	case 'w':	  if (modifier == 'E')	    goto bad_format;	  DO_NUMBER (1, tp->tm_wday);	case 'Y':	  if (modifier == 'E')	    {#if HAVE_STRUCT_ERA_ENTRY	      struct era_entry *era = _nl_get_era_entry (tp);	      if (era)		{		  subfmt = strchr (era->name_fmt, '\0') + 1;		  goto subformat;		}#else# if HAVE_STRFTIME	      goto underlying_strftime;# endif#endif	    }	  if (modifier == 'O')	    goto bad_format;	  else	    DO_NUMBER (1, tp->tm_year + TM_YEAR_BASE);	case 'y':	  if (modifier == 'E')	    {#if HAVE_STRUCT_ERA_ENTRY	      struct era_entry *era = _nl_get_era_entry (tp);	      if (era)		{		  int delta = tp->tm_year - era->start_date[0];		  DO_NUMBER (1, (era->offset				 + (era->direction == '-' ? -delta : delta)));		}#else# if HAVE_STRFTIME	      goto underlying_strftime;# endif#endif	    }	  DO_NUMBER (2, (tp->tm_year % 100 + 100) % 100);	case 'Z':	  if (change_case)	    {	      to_uppcase = 0;	      to_lowcase = 1;	    }#if HAVE_TZNAME	  /* The tzset() call might have changed the value.  */	  if (!(zone && *zone) && tp->tm_isdst >= 0)	    zone = tzname[tp->tm_isdst];#endif	  if (! zone)	    zone = "";		/* POSIX.2 requires the empty string here.  */	  cpy (strlen (zone), zone);	  break;	case 'z':		/* GNU extension.  */	  if (tp->tm_isdst < 0)	    break;	  {	    int diff;#if HAVE_TM_GMTOFF	    diff = tp->tm_gmtoff;#else	    struct tm gtm;	    struct tm ltm;	    time_t lt;	    ltm = *tp;	    lt = mktime (&ltm);	    if (lt == (time_t) -1)	      {		/* mktime returns -1 for errors, but -1 is also a		   valid time_t value.  Check whether an error really		   occurred.  */		struct tm tm;		if (! localtime_r (&lt, &tm)		    || ((ltm.tm_sec ^ tm.tm_sec)			| (ltm.tm_min ^ tm.tm_min)			| (ltm.tm_hour ^ tm.tm_hour)			| (ltm.tm_mday ^ tm.tm_mday)			| (ltm.tm_mon ^ tm.tm_mon)			| (ltm.tm_year ^ tm.tm_year)))		  break;	      }	    if (! gmtime_r (&lt, &gtm))	      break;	    diff = tm_diff (&ltm, &gtm);#endif	    if (diff < 0)	      {		add (1, *p = '-');		diff = -diff;	      }	    else	      add (1, *p = '+');	    diff /= 60;	    DO_NUMBER (4, (diff / 60) * 100 + diff % 60);	  }	case '\0':		/* GNU extension: % at end of format.  */	    --f;	    /* Fall through.  */	default:	  /* Unknown format; output the format, including the '%',	     since this is most likely the right thing to do if a	     multibyte string has been misparsed.  */	bad_format:	  {	    int flen;	    for (flen = 1; f[1 - flen] != '%'; flen++)	      continue;	    cpy (flen, &f[1 - flen]);	  }	  break;	}    }  if (p && i < maxsize)    *p = '\0';  return i;}