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strftime.c

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)strftime.c    5.11 (Berkeley) 2/24/91";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/time.h>
#include <tzfile.h>
#include <string.h>

static char *afmt[] = {
      "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
};
static char *Afmt[] = {
      "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
      "Saturday",
};
static char *bfmt[] = {
      "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
      "Oct", "Nov", "Dec",
};
static char *Bfmt[] = {
      "January", "February", "March", "April", "May", "June", "July",
      "August", "September", "October", "November", "December",
};

static size_t gsize;
static char *pt;
static int _add(), _conv(), _secs();

size_t
strftime(s, maxsize, format, t)
      char *s;
      size_t maxsize;
      const char *format;
      const struct tm *t;
{
      static size_t _fmt();

      pt = s;
      if ((gsize = maxsize) < 1)
            return(0);
      if (_fmt(format, t)) {
            *pt = '\0';
            return(maxsize - gsize);
      }
      return(0);
}

static size_t
_fmt(format, t)
      register char *format;
      struct tm *t;
{
      for (; *format; ++format) {
            if (*format == '%')
                  switch(*++format) {
                  case '\0':
                        --format;
                        break;
                  case 'A':
                        if (t->tm_wday < 0 || t->tm_wday > 6)
                              return(0);
                        if (!_add(Afmt[t->tm_wday]))
                              return(0);
                        continue;
                  case 'a':
                        if (t->tm_wday < 0 || t->tm_wday > 6)
                              return(0);
                        if (!_add(afmt[t->tm_wday]))
                              return(0);
                        continue;
                  case 'B':
                        if (t->tm_mon < 0 || t->tm_mon > 11)
                              return(0);
                        if (!_add(Bfmt[t->tm_mon]))
                              return(0);
                        continue;
                  case 'b':
                  case 'h':
                        if (t->tm_mon < 0 || t->tm_mon > 11)
                              return(0);
                        if (!_add(bfmt[t->tm_mon]))
                              return(0);
                        continue;
                  case 'C':
                        if (!_fmt("%a %b %e %H:%M:%S %Y", t))
                              return(0);
                        continue;
                  case 'c':
                        if (!_fmt("%m/%d/%y %H:%M:%S", t))
                              return(0);
                        continue;
                  case 'D':
                        if (!_fmt("%m/%d/%y", t))
                              return(0);
                        continue;
                  case 'd':
                        if (!_conv(t->tm_mday, 2, '0'))
                              return(0);
                        continue;
                  case 'e':
                        if (!_conv(t->tm_mday, 2, ' '))
                              return(0);
                        continue;
                  case 'H':
                        if (!_conv(t->tm_hour, 2, '0'))
                              return(0);
                        continue;
                  case 'I':
                        if (!_conv(t->tm_hour % 12 ?
                            t->tm_hour % 12 : 12, 2, '0'))
                              return(0);
                        continue;
                  case 'j':
                        if (!_conv(t->tm_yday + 1, 3, '0'))
                              return(0);
                        continue;
                  case 'k':
                        if (!_conv(t->tm_hour, 2, ' '))
                              return(0);
                        continue;
                  case 'l':
                        if (!_conv(t->tm_hour % 12 ?
                            t->tm_hour % 12 : 12, 2, ' '))
                              return(0);
                        continue;
                  case 'M':
                        if (!_conv(t->tm_min, 2, '0'))
                              return(0);
                        continue;
                  case 'm':
                        if (!_conv(t->tm_mon + 1, 2, '0'))
                              return(0);
                        continue;
                  case 'n':
                        if (!_add("\n"))
                              return(0);
                        continue;
                  case 'p':
                        if (!_add(t->tm_hour >= 12 ? "PM" : "AM"))
                              return(0);
                        continue;
                  case 'R':
                        if (!_fmt("%H:%M", t))
                              return(0);
                        continue;
                  case 'r':
                        if (!_fmt("%I:%M:%S %p", t))
                              return(0);
                        continue;
                  case 'S':
                        if (!_conv(t->tm_sec, 2, '0'))
                              return(0);
                        continue;
                  case 's':
                        if (!_secs(t))
                              return(0);
                        continue;
                  case 'T':
                  case 'X':
                        if (!_fmt("%H:%M:%S", t))
                              return(0);
                        continue;
                  case 't':
                        if (!_add("\t"))
                              return(0);
                        continue;
                  case 'U':
                        if (!_conv((t->tm_yday + 7 - t->tm_wday) / 7,
                            2, '0'))
                              return(0);
                        continue;
                  case 'W':
                        if (!_conv((t->tm_yday + 7 -
                            (t->tm_wday ? (t->tm_wday - 1) : 6))
                            / 7, 2, '0'))
                              return(0);
                        continue;
                  case 'w':
                        if (!_conv(t->tm_wday, 1, '0'))
                              return(0);
                        continue;
                  case 'x':
                        if (!_fmt("%m/%d/%y", t))
                              return(0);
                        continue;
                  case 'y':
                        if (!_conv((t->tm_year + TM_YEAR_BASE)
                            % 100, 2, '0'))
                              return(0);
                        continue;
                  case 'Y':
                        if (!_conv(t->tm_year + TM_YEAR_BASE, 4, '0'))
                              return(0);
                        continue;
                  case 'Z':
                        if (!t->tm_zone || !_add(t->tm_zone))
                              return(0);
                        continue;
                  case '%':
                  /*
                   * X311J/88-090 (4.12.3.5): if conversion char is
                   * undefined, behavior is undefined.  Print out the
                   * character itself as printf(3) does.
                   */
                  default:
                        break;
            }
            if (!gsize--)
                  return(0);
            *pt++ = *format;
      }
      return(gsize);
}

static
_secs(t)
      struct tm *t;
{
      static char buf[15];
      register time_t s;
      register char *p;
      struct tm tmp;

      /* Make a copy, mktime(3) modifies the tm struct. */
      tmp = *t;
      s = mktime(&tmp);
      for (p = buf + sizeof(buf) - 2; s > 0 && p > buf; s /= 10)
            *p-- = s % 10 + '0';
      return(_add(++p));
}

static
_conv(n, digits, pad)
      int n, digits;
      char pad;
{
      static char buf[10];
      register char *p;

      for (p = buf + sizeof(buf) - 2; n > 0 && p > buf; n /= 10, --digits)
            *p-- = n % 10 + '0';
      while (p > buf && digits-- > 0)
            *p-- = pad;
      return(_add(++p));
}

static
_add(str)
      register char *str;
{
      for (;; ++pt, --gsize) {
            if (!gsize)
                  return(0);
            if (!(*pt = *str++))
                  return(1);
      }
}

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