root/strftime.c

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DEFINITIONS

This source file includes following definitions.
  1. adddecl
  2. max
  3. rb_strftime
  4. isleap
  5. iso8601wknum
  6. weeknumber
  7. strftime
  8. main

/* -*- c-file-style: "linux" -*- */

/*
 * strftime.c
 *
 * Public-domain implementation of ANSI C library routine.
 *
 * It's written in old-style C for maximal portability.
 * However, since I'm used to prototypes, I've included them too.
 *
 * If you want stuff in the System V ascftime routine, add the SYSV_EXT define.
 * For extensions from SunOS, add SUNOS_EXT.
 * For stuff needed to implement the P1003.2 date command, add POSIX2_DATE.
 * For VMS dates, add VMS_EXT.
 * For a an RFC822 time format, add MAILHEADER_EXT.
 * For ISO week years, add ISO_DATE_EXT.
 * For complete POSIX semantics, add POSIX_SEMANTICS.
 *
 * The code for %c, %x, and %X now follows the 1003.2 specification for
 * the POSIX locale.
 * This version ignores LOCALE information.
 * It also doesn't worry about multi-byte characters.
 * So there.
 *
 * This file is also shipped with GAWK (GNU Awk), gawk specific bits of
 * code are included if GAWK is defined.
 *
 * Arnold Robbins
 * January, February, March, 1991
 * Updated March, April 1992
 * Updated April, 1993
 * Updated February, 1994
 * Updated May, 1994
 * Updated January, 1995
 * Updated September, 1995
 * Updated January, 1996
 *
 * Fixes from ado@elsie.nci.nih.gov
 * February 1991, May 1992
 * Fixes from Tor Lillqvist tml@tik.vtt.fi
 * May, 1993
 * Further fixes from ado@elsie.nci.nih.gov
 * February 1994
 * %z code from chip@chinacat.unicom.com
 * Applied September 1995
 * %V code fixed (again) and %G, %g added,
 * January 1996
 */

#include "ruby/ruby.h"

#ifndef GAWK
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <errno.h>
#endif
#if defined(TM_IN_SYS_TIME) || !defined(GAWK)
#include <sys/types.h>
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#endif
#include <math.h>

/* defaults: season to taste */
#define SYSV_EXT        1       /* stuff in System V ascftime routine */
#define SUNOS_EXT       1       /* stuff in SunOS strftime routine */
#define POSIX2_DATE     1       /* stuff in Posix 1003.2 date command */
#define VMS_EXT         1       /* include %v for VMS date format */
#define MAILHEADER_EXT  1       /* add %z for HHMM format */
#define ISO_DATE_EXT    1       /* %G and %g for year of ISO week */
#ifndef GAWK
#define POSIX_SEMANTICS 1       /* call tzset() if TZ changes */
#endif

#if defined(ISO_DATE_EXT)
#if ! defined(POSIX2_DATE)
#define POSIX2_DATE     1
#endif
#endif

#if defined(POSIX2_DATE)
#if ! defined(SYSV_EXT)
#define SYSV_EXT        1
#endif
#if ! defined(SUNOS_EXT)
#define SUNOS_EXT       1
#endif
#endif

#if defined(POSIX2_DATE)
#define adddecl(stuff)  stuff
#else
#define adddecl(stuff)
#endif

#undef strchr   /* avoid AIX weirdness */

#if !defined __STDC__ && !defined _WIN32
#define const   /**/
static int weeknumber();
adddecl(static int iso8601wknum();)
#else
static int weeknumber(const struct tm *timeptr, int firstweekday);
adddecl(static int iso8601wknum(const struct tm *timeptr);)
#endif

#ifdef STDC_HEADERS
#include <stdlib.h>
#include <string.h>
#else
extern void *malloc();
extern void *realloc();
extern char *getenv();
extern char *strchr();
#endif

#define range(low, item, hi)    max(low, min(item, hi))

#if defined __WIN32__ || defined _WIN32
#define DLL_IMPORT __declspec(dllimport)
#endif
#ifndef DLL_IMPORT
#define DLL_IMPORT
#endif
#if !defined(OS2) && defined(HAVE_TZNAME)
extern DLL_IMPORT char *tzname[2];
#ifdef HAVE_DAYLIGHT
extern DLL_IMPORT int daylight;
#endif
#ifdef HAVE_VAR_TIMEZONE
extern DLL_IMPORT TYPEOF_VAR_TIMEZONE timezone;
#endif
#ifdef HAVE_VAR_ALTZONE
extern DLL_IMPORT TYPEOF_VAR_ALTZONE altzone;
#endif
#endif

#undef min      /* just in case */

/* min --- return minimum of two numbers */

#ifndef __STDC__
static inline int
min(a, b)
int a, b;
#else
static inline int
min(int a, int b)
#endif
{
        return (a < b ? a : b);
}

#undef max      /* also, just in case */

/* max --- return maximum of two numbers */

#ifndef __STDC__
static inline int
max(a, b)
int a, b;
#else
static inline int
max(int a, int b)
#endif
{
        return (a > b ? a : b);
}

#ifdef NO_STRING_LITERAL_CONCATENATION
#error No string literal concatenation
#endif

/* strftime --- produce formatted time */

size_t
rb_strftime(char *s, size_t maxsize, const char *format, const struct tm *timeptr, const struct timespec *ts, int gmt)
{
        char *endp = s + maxsize;
        char *start = s;
        const char *sp, *tp;
        auto char tbuf[100];
        long off;
        int i, w;
        long y;
        static short first = 1;
#ifdef POSIX_SEMANTICS
        static char *savetz = NULL;
        static int savetzlen = 0;
        char *tz;
#endif /* POSIX_SEMANTICS */
#ifndef HAVE_TM_ZONE
#ifndef HAVE_TM_NAME
#if ((defined(MAILHEADER_EXT) && !HAVE_VAR_TIMEZONE && HAVE_GETTIMEOFDAY) || \
     (!HAVE_TZNAME && HAVE_TIMEZONE))
        struct timeval tv;
        struct timezone zone;
#endif
#endif /* HAVE_TM_NAME */
#endif /* HAVE_TM_ZONE */
        int precision, flags;
        char padding;
        enum {LEFT, CHCASE, LOWER, UPPER, LOCALE_O, LOCALE_E};
#define BIT_OF(n) (1U<<(n))

        /* various tables, useful in North America */
        static const char days_l[][10] = {
                "Sunday", "Monday", "Tuesday", "Wednesday",
                "Thursday", "Friday", "Saturday",
        };
        static const char months_l[][10] = {
                "January", "February", "March", "April",
                "May", "June", "July", "August", "September",
                "October", "November", "December",
        };
        static const char ampm[][3] = { "AM", "PM", };

        if (s == NULL || format == NULL || timeptr == NULL || maxsize == 0)
                return 0;

        /* quick check if we even need to bother */
        if (strchr(format, '%') == NULL && strlen(format) + 1 >= maxsize) {
        err:
                errno = ERANGE;
                return 0;
        }

#ifndef POSIX_SEMANTICS
        if (first) {
                tzset();
                first = 0;
        }
#else   /* POSIX_SEMANTICS */
        tz = getenv("TZ");
        if (first) {
                if (tz != NULL) {
                        int tzlen = strlen(tz);

                        savetz = (char *) malloc(tzlen + 1);
                        if (savetz != NULL) {
                                savetzlen = tzlen + 1;
                                strcpy(savetz, tz);
                        }
                }
                tzset();
                first = 0;
        }
        /* if we have a saved TZ, and it is different, recapture and reset */
        if (tz && savetz && (tz[0] != savetz[0] || strcmp(tz, savetz) != 0)) {
                i = strlen(tz) + 1;
                if (i > savetzlen) {
                        savetz = (char *) realloc(savetz, i);
                        if (savetz) {
                                savetzlen = i;
                                strcpy(savetz, tz);
                        }
                } else
                        strcpy(savetz, tz);
                tzset();
        }
#endif  /* POSIX_SEMANTICS */

        for (; *format && s < endp - 1; format++) {
#define FLAG_FOUND() do { \
                        if (precision > 0 || flags & (BIT_OF(LOCALE_E)|BIT_OF(LOCALE_O))) \
                                goto unknown; \
                } while (0)
#define NEEDS(n) do if (s + (n) >= endp - 1) goto err; while (0)
#define FILL_PADDING(i) do { \
        if (!(flags & BIT_OF(LEFT)) && precision > i) { \
                NEEDS(precision); \
                memset(s, padding ? padding : ' ', precision - i); \
                s += precision - i; \
        } \
        else { \
                NEEDS(i); \
        } \
} while (0);
#define FMT(def_pad, def_prec, fmt, val) \
                do { \
                        int l; \
                        if (precision <= 0) precision = (def_prec); \
                        if (flags & BIT_OF(LEFT)) precision = 1; \
                        l = snprintf(s, endp - s, \
                                     ((padding == '0' || (!padding && def_pad == '0')) ? "%0*"fmt : "%*"fmt), \
                                     precision, val); \
                        if (l < 0) goto err; \
                        s += l; \
                } while (0)
#define STRFTIME(fmt) \
                do { \
                        i = rb_strftime(s, endp - s, fmt, timeptr, ts, gmt); \
                        if (!i) return 0; \
                        if (precision > i) {\
                                memmove(s + precision - i, s, i);\
                                memset(s, padding ? padding : ' ', precision - i); \
                                s += precision; \
                        }\
                        else s += i; \
                } while (0)

                if (*format != '%') {
                        *s++ = *format;
                        continue;
                }
                tp = tbuf;
                sp = format;
                precision = -1;
                flags = 0;
                padding = 0;
        again:
                switch (*++format) {
                case '\0':
                        format--;
                        goto unknown;

                case '%':
                        FILL_PADDING(1);
                        *s++ = '%';
                        continue;

                case 'a':       /* abbreviated weekday name */
                        if (flags & BIT_OF(CHCASE)) {
                                flags &= ~(BIT_OF(LOWER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(UPPER);
                        }
                        if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6)
                                i = 1, tp = "?";
                        else
                                i = 3, tp = days_l[timeptr->tm_wday];
                        break;

                case 'A':       /* full weekday name */
                        if (flags & BIT_OF(CHCASE)) {
                                flags &= ~(BIT_OF(LOWER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(UPPER);
                        }
                        if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6)
                                i = 1, tp = "?";
                        else
                                i = strlen(tp = days_l[timeptr->tm_wday]);
                        break;

#ifdef SYSV_EXT
                case 'h':       /* abbreviated month name */
#endif
                case 'b':       /* abbreviated month name */
                        if (flags & BIT_OF(CHCASE)) {
                                flags &= ~(BIT_OF(LOWER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(UPPER);
                        }
                        if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11)
                                i = 1, tp = "?";
                        else
                                i = 3, tp = months_l[timeptr->tm_mon];
                        break;

                case 'B':       /* full month name */
                        if (flags & BIT_OF(CHCASE)) {
                                flags &= ~(BIT_OF(LOWER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(UPPER);
                        }
                        if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11)
                                i = 1, tp = "?";
                        else
                                i = strlen(tp = months_l[timeptr->tm_mon]);
                        break;

                case 'c':       /* appropriate date and time representation */
                        STRFTIME("%a %b %e %H:%M:%S %Y");
                        continue;

                case 'd':       /* day of the month, 01 - 31 */
                        i = range(1, timeptr->tm_mday, 31);
                        FMT('0', 2, "d", i);
                        continue;

                case 'H':       /* hour, 24-hour clock, 00 - 23 */
                        i = range(0, timeptr->tm_hour, 23);
                        FMT('0', 2, "d", i);
                        continue;

                case 'I':       /* hour, 12-hour clock, 01 - 12 */
                        i = range(0, timeptr->tm_hour, 23);
                        if (i == 0)
                                i = 12;
                        else if (i > 12)
                                i -= 12;
                        FMT('0', 2, "d", i);
                        continue;

                case 'j':       /* day of the year, 001 - 366 */
                        FMT('0', 3, "d", timeptr->tm_yday + 1);
                        continue;

                case 'm':       /* month, 01 - 12 */
                        i = range(0, timeptr->tm_mon, 11);
                        FMT('0', 2, "d", i + 1);
                        continue;

                case 'M':       /* minute, 00 - 59 */
                        i = range(0, timeptr->tm_min, 59);
                        FMT('0', 2, "d", i);
                        continue;

                case 'p':       /* AM or PM based on 12-hour clock */
                case 'P':       /* am or pm based on 12-hour clock */
                        if ((*format == 'p' && (flags & BIT_OF(CHCASE))) ||
                            (*format == 'P' && !(flags & (BIT_OF(CHCASE)|BIT_OF(UPPER))))) {
                                flags &= ~(BIT_OF(UPPER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(LOWER);
                        }
                        i = range(0, timeptr->tm_hour, 23);
                        if (i < 12)
                                tp = ampm[0];
                        else
                                tp = ampm[1];
                        i = 2;
                        break;

                case 's':
                        FMT('0', 1, "d", (int) ts->tv_sec);
                        continue;

                case 'S':       /* second, 00 - 60 */
                        i = range(0, timeptr->tm_sec, 60);
                        FMT('0', 2, "d", i);
                        continue;

                case 'U':       /* week of year, Sunday is first day of week */
                        FMT('0', 2, "d", weeknumber(timeptr, 0));
                        continue;

                case 'w':       /* weekday, Sunday == 0, 0 - 6 */
                        i = range(0, timeptr->tm_wday, 6);
                        FMT('0', 1, "d", i);
                        continue;

                case 'W':       /* week of year, Monday is first day of week */
                        FMT('0', 2, "d", weeknumber(timeptr, 1));
                        continue;

                case 'x':       /* appropriate date representation */
                        STRFTIME("%m/%d/%y");
                        continue;

                case 'X':       /* appropriate time representation */
                        STRFTIME("%H:%M:%S");
                        continue;

                case 'y':       /* year without a century, 00 - 99 */
                        i = timeptr->tm_year % 100;
                        FMT('0', 2, "d", i);
                        continue;

                case 'Y':       /* year with century */
                        FMT('0', 1, "ld", 1900L + timeptr->tm_year);
                        continue;

#ifdef MAILHEADER_EXT
                /*
                 * From: Chip Rosenthal <chip@chinacat.unicom.com>
                 * Date: Sun, 19 Mar 1995 00:33:29 -0600 (CST)
                 * 
                 * Warning: the %z [code] is implemented by inspecting the
                 * timezone name conditional compile settings, and
                 * inferring a method to get timezone offsets. I've tried
                 * this code on a couple of machines, but I don't doubt
                 * there is some system out there that won't like it.
                 * Maybe the easiest thing to do would be to bracket this
                 * with an #ifdef that can turn it off. The %z feature
                 * would be an admittedly obscure one that most folks can
                 * live without, but it would be a great help to those of
                 * us that muck around with various message processors.
                 */
                case 'z':       /* time zone offset east of GMT e.g. -0600 */
                        if (precision < 4) precision = 4;
                        NEEDS(precision + 1);
                        if (gmt) {
                                off = 0;
                        }
                        else {
#ifdef HAVE_TM_NAME
                                /*
                                 * Systems with tm_name probably have tm_tzadj as
                                 * secs west of GMT.  Convert to mins east of GMT.
                                 */
                                off = -timeptr->tm_tzadj / 60;
#else /* !HAVE_TM_NAME */
#ifdef HAVE_TM_ZONE
                                /*
                                 * Systems with tm_zone probably have tm_gmtoff as
                                 * secs east of GMT.  Convert to mins east of GMT.
                                 */
                                off = timeptr->tm_gmtoff / 60;
#else /* !HAVE_TM_ZONE */
#if HAVE_VAR_TIMEZONE
#if HAVE_VAR_ALTZONE
                                off = -(daylight ? timezone : altzone) / 60;
#else
                                off = -timezone / 60;
#endif
#else /* !HAVE_VAR_TIMEZONE */
#ifdef HAVE_GETTIMEOFDAY
                                gettimeofday(&tv, &zone);
                                off = -zone.tz_minuteswest;
#else
                                /* no timezone info, then calc by myself */
                                {
                                        struct tm utc;
                                        time_t now;
                                        time(&now);
                                        utc = *gmtime(&now);
                                        off = (now - mktime(&utc)) / 60;
                                }
#endif
#endif /* !HAVE_VAR_TIMEZONE */
#endif /* !HAVE_TM_ZONE */
#endif /* !HAVE_TM_NAME */
                        }
                        if (off < 0) {
                                off = -off;
                                *s++ = '-';
                        } else {
                                *s++ = '+';
                        }
                        off = off/60*100 + off%60;
                        i = snprintf(s, endp - s, (padding == ' ' ? "%*ld" : "%.*ld"),
                                     precision - (precision > 4), off);
                        if (i < 0) goto err;
                        s += i;
                        continue;
#endif /* MAILHEADER_EXT */

                case 'Z':       /* time zone name or abbrevation */
                        if (flags & BIT_OF(CHCASE)) {
                                flags &= ~(BIT_OF(UPPER)|BIT_OF(CHCASE));
                                flags |= BIT_OF(LOWER);
                        }
                        if (gmt) {
                                i = 3;
                                tp = "UTC";
                                break;
                        }
#ifdef HAVE_TZNAME
                        i = (daylight && timeptr->tm_isdst > 0); /* 0 or 1 */
                        tp = tzname[i];
#else
#ifdef HAVE_TM_ZONE
                        tp = timeptr->tm_zone;
#else
#ifdef HAVE_TM_NAME
                        tp = timeptr->tm_name;
#else
#ifdef HAVE_TIMEZONE
                        gettimeofday(& tv, & zone);
#ifdef TIMEZONE_VOID
                        tp = timezone();
#else
                        tp = timezone(zone.tz_minuteswest, timeptr->tm_isdst > 0);
#endif /* TIMEZONE_VOID */
#endif /* HAVE_TIMEZONE */
#endif /* HAVE_TM_NAME */
#endif /* HAVE_TM_ZONE */
#endif /* HAVE_TZNAME */
                        i = strlen(tp);
                        break;

#ifdef SYSV_EXT
                case 'n':       /* same as \n */
                        FILL_PADDING(1);
                        *s++ = '\n';
                        continue;

                case 't':       /* same as \t */
                        FILL_PADDING(1);
                        *s++ = '\t';
                        continue;

                case 'D':       /* date as %m/%d/%y */
                        STRFTIME("%m/%d/%y");
                        continue;

                case 'e':       /* day of month, blank padded */
                        FMT(' ', 2, "d", range(1, timeptr->tm_mday, 31));
                        continue;

                case 'r':       /* time as %I:%M:%S %p */
                        STRFTIME("%I:%M:%S %p");
                        continue;

                case 'R':       /* time as %H:%M */
                        STRFTIME("%H:%M");
                        continue;

                case 'T':       /* time as %H:%M:%S */
                        STRFTIME("%H:%M:%S");
                        continue;
#endif

#ifdef SUNOS_EXT
                case 'k':       /* hour, 24-hour clock, blank pad */
                        i = range(0, timeptr->tm_hour, 23);
                        FMT(' ', 2, "d", i);
                        continue;

                case 'l':       /* hour, 12-hour clock, 1 - 12, blank pad */
                        i = range(0, timeptr->tm_hour, 23);
                        if (i == 0)
                                i = 12;
                        else if (i > 12)
                                i -= 12;
                        FMT(' ', 2, "d", i);
                        continue;
#endif


#ifdef VMS_EXT
                case 'v':       /* date as dd-bbb-YYYY */
                        w = snprintf(s, endp - s, "%2d-%3.3s-%4ld",
                                     range(1, timeptr->tm_mday, 31),
                                     months_l[range(0, timeptr->tm_mon, 11)],
                                     timeptr->tm_year + 1900L);
                        if (w < 0) goto err;
                        for (i = 3; i < 6; i++)
                                if (ISLOWER(s[i]))
                                        s[i] = TOUPPER(s[i]);
                        s += w;
                        continue;
#endif


#ifdef POSIX2_DATE
                case 'C':
                        FMT('0', 2, "ld", (timeptr->tm_year + 1900L) / 100);
                        continue;


                case 'E':
                        /* POSIX locale extensions, ignored for now */
                        flags |= BIT_OF(LOCALE_E);
                        goto again;
                case 'O':
                        /* POSIX locale extensions, ignored for now */
                        flags |= BIT_OF(LOCALE_O);
                        goto again;

                case 'V':       /* week of year according ISO 8601 */
                        FMT('0', 2, "d", iso8601wknum(timeptr));
                        continue;

                case 'u':
                /* ISO 8601: Weekday as a decimal number [1 (Monday) - 7] */
                        FMT('0', 1, "d", timeptr->tm_wday == 0 ? 7 : timeptr->tm_wday);
                        continue;
#endif  /* POSIX2_DATE */

#ifdef ISO_DATE_EXT
                case 'G':
                case 'g':
                        /*
                         * Year of ISO week.
                         *
                         * If it's December but the ISO week number is one,
                         * that week is in next year.
                         * If it's January but the ISO week number is 52 or
                         * 53, that week is in last year.
                         * Otherwise, it's this year.
                         */
                        w = iso8601wknum(timeptr);
                        if (timeptr->tm_mon == 11 && w == 1)
                                y = 1900L + timeptr->tm_year + 1;
                        else if (timeptr->tm_mon == 0 && w >= 52)
                                y = 1900L + timeptr->tm_year - 1;
                        else
                                y = 1900L + timeptr->tm_year;

                        if (*format == 'G')
                                FMT('0', 1, "ld", y);
                        else
                                FMT('0', 2, "ld", y % 100);
                        continue;
#endif /* ISO_DATE_EXT */


                case 'L':
                        w = 3;
                        goto subsec;

                case 'N':
                        /*
                         * fractional second digits. default is 9 digits
                         * (nanosecond).
                         *
                         * %3N  millisecond (3 digits)
                         * %6N  microsecond (6 digits)
                         * %9N  nanosecond (9 digits)
                         */
                        w = 9;
                subsec:
                        {
                                long n = ts->tv_nsec;

                                if (precision <= 0) {
                                    precision = w;
                                }
                                NEEDS(precision);
                                if (precision < w) {
                                        snprintf(tbuf, w + 1, "%.*ld", w, n);
                                        memcpy(s, tbuf, precision);
                                }
                                else {
                                        snprintf(s, endp - s, "%.*ld", w, n);
                                        memset(s + w, '0', precision - w);
                                }
                                s += precision;
                        }
                        continue;

                case 'F':       /*  Equivalent to %Y-%m-%d */
                        {
                                int mon, mday;
                                mon = range(0, timeptr->tm_mon, 11) + 1;
                                mday = range(1, timeptr->tm_mday, 31);
                                i = snprintf(s, endp - s, "%ld-%02d-%02d",
                                             1900L + timeptr->tm_year, mon, mday);
                                if (i < 0)
                                        goto err;
                                s += i;
                        }
                        continue;

                case '-':
                        FLAG_FOUND();
                        flags |= BIT_OF(LEFT);
                        padding = precision = 0;
                        goto again;

                case '^':
                        FLAG_FOUND();
                        flags |= BIT_OF(UPPER);
                        goto again;

                case '#':
                        FLAG_FOUND();
                        flags |= BIT_OF(CHCASE);
                        goto again;

                case '_':
                        FLAG_FOUND();
                        padding = ' ';
                        goto again;

                case '0':
                        padding = '0';
                case '1':  case '2': case '3': case '4':
                case '5': case '6':  case '7': case '8': case '9':
                        {
                                char *e;
                                precision = (int)strtoul(format, &e, 10);
                                format = e - 1;
                                goto again;
                        }

                default:
                unknown:
                        i = format - sp + 1;
                        tp = sp;
                        precision = -1;
                        flags = 0;
                        padding = 0;
                        break;
                }
                if (i) {
                        FILL_PADDING(i);
                        memcpy(s, tp, i);
                        switch (flags & (BIT_OF(UPPER)|BIT_OF(LOWER))) {
                        case BIT_OF(UPPER):
                                do {
                                        if (ISLOWER(*s)) *s = TOUPPER(*s);
                                } while (s++, --i);
                                break;
                        case BIT_OF(LOWER):
                                do {
                                        if (ISUPPER(*s)) *s = TOLOWER(*s);
                                } while (s++, --i);
                                break;
                        default:
                                s += i;
                                break;
                        }
                }
        }
        if (s >= endp) {
                goto err;
        }
        if (*format == '\0') {
                *s = '\0';
                return (s - start);
        } else
                return 0;
}

/* isleap --- is a year a leap year? */

#ifndef __STDC__
static int
isleap(year)
long year;
#else
static int
isleap(long year)
#endif
{
        return ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
}


#ifdef POSIX2_DATE
/* iso8601wknum --- compute week number according to ISO 8601 */

#ifndef __STDC__
static int
iso8601wknum(timeptr)
const struct tm *timeptr;
#else
static int
iso8601wknum(const struct tm *timeptr)
#endif
{
        /*
         * From 1003.2:
         *      If the week (Monday to Sunday) containing January 1
         *      has four or more days in the new year, then it is week 1;
         *      otherwise it is the highest numbered week of the previous
         *      year (52 or 53), and the next week is week 1.
         *
         * ADR: This means if Jan 1 was Monday through Thursday,
         *      it was week 1, otherwise week 52 or 53.
         *
         * XPG4 erroneously included POSIX.2 rationale text in the
         * main body of the standard. Thus it requires week 53.
         */

        int weeknum, jan1day;

        /* get week number, Monday as first day of the week */
        weeknum = weeknumber(timeptr, 1);

        /*
         * With thanks and tip of the hatlo to tml@tik.vtt.fi
         *
         * What day of the week does January 1 fall on?
         * We know that
         *      (timeptr->tm_yday - jan1.tm_yday) MOD 7 ==
         *              (timeptr->tm_wday - jan1.tm_wday) MOD 7
         * and that
         *      jan1.tm_yday == 0
         * and that
         *      timeptr->tm_wday MOD 7 == timeptr->tm_wday
         * from which it follows that. . .
         */
        jan1day = timeptr->tm_wday - (timeptr->tm_yday % 7);
        if (jan1day < 0)
                jan1day += 7;

        /*
         * If Jan 1 was a Monday through Thursday, it was in
         * week 1.  Otherwise it was last year's highest week, which is
         * this year's week 0.
         *
         * What does that mean?
         * If Jan 1 was Monday, the week number is exactly right, it can
         *      never be 0.
         * If it was Tuesday through Thursday, the weeknumber is one
         *      less than it should be, so we add one.
         * Otherwise, Friday, Saturday or Sunday, the week number is
         * OK, but if it is 0, it needs to be 52 or 53.
         */
        switch (jan1day) {
        case 1:         /* Monday */
                break;
        case 2:         /* Tuesday */
        case 3:         /* Wednesday */
        case 4:         /* Thursday */
                weeknum++;
                break;
        case 5:         /* Friday */
        case 6:         /* Saturday */
        case 0:         /* Sunday */
                if (weeknum == 0) {
#ifdef USE_BROKEN_XPG4
                        /* XPG4 (as of March 1994) says 53 unconditionally */
                        weeknum = 53;
#else
                        /* get week number of last week of last year */
                        struct tm dec31ly;      /* 12/31 last year */
                        dec31ly = *timeptr;
                        dec31ly.tm_year--;
                        dec31ly.tm_mon = 11;
                        dec31ly.tm_mday = 31;
                        dec31ly.tm_wday = (jan1day == 0) ? 6 : jan1day - 1;
                        dec31ly.tm_yday = 364 + isleap(dec31ly.tm_year + 1900L);
                        weeknum = iso8601wknum(& dec31ly);
#endif
                }
                break;
        }

        if (timeptr->tm_mon == 11) {
                /*
                 * The last week of the year
                 * can be in week 1 of next year.
                 * Sigh.
                 *
                 * This can only happen if
                 *      M   T  W
                 *      29  30 31
                 *      30  31
                 *      31
                 */
                int wday, mday;

                wday = timeptr->tm_wday;
                mday = timeptr->tm_mday;
                if (   (wday == 1 && (mday >= 29 && mday <= 31))
                    || (wday == 2 && (mday == 30 || mday == 31))
                    || (wday == 3 &&  mday == 31))
                        weeknum = 1;
        }

        return weeknum;
}
#endif

/* weeknumber --- figure how many weeks into the year */

/* With thanks and tip of the hatlo to ado@elsie.nci.nih.gov */

#ifndef __STDC__
static int
weeknumber(timeptr, firstweekday)
const struct tm *timeptr;
int firstweekday;
#else
static int
weeknumber(const struct tm *timeptr, int firstweekday)
#endif
{
        int wday = timeptr->tm_wday;
        int ret;

        if (firstweekday == 1) {
                if (wday == 0)  /* sunday */
                        wday = 6;
                else
                        wday--;
        }
        ret = ((timeptr->tm_yday + 7 - wday) / 7);
        if (ret < 0)
                ret = 0;
        return ret;
}

#if 0
/* ADR --- I'm loathe to mess with ado's code ... */

Date:         Wed, 24 Apr 91 20:54:08 MDT
From: Michal Jaegermann <audfax!emory!vm.ucs.UAlberta.CA!NTOMCZAK>
To: arnold@audiofax.com

Hi Arnold,
in a process of fixing of strftime() in libraries on Atari ST I grabbed
some pieces of code from your own strftime.  When doing that it came
to mind that your weeknumber() function compiles a little bit nicer
in the following form:
/*
 * firstweekday is 0 if starting in Sunday, non-zero if in Monday
 */
{
    return (timeptr->tm_yday - timeptr->tm_wday +
            (firstweekday ? (timeptr->tm_wday ? 8 : 1) : 7)) / 7;
}
How nicer it depends on a compiler, of course, but always a tiny bit.

   Cheers,
   Michal
   ntomczak@vm.ucs.ualberta.ca
#endif

#ifdef  TEST_STRFTIME

/*
 * NAME:
 *      tst
 *
 * SYNOPSIS:
 *      tst
 *
 * DESCRIPTION:
 *      "tst" is a test driver for the function "strftime".
 *
 * OPTIONS:
 *      None.
 *
 * AUTHOR:
 *      Karl Vogel
 *      Control Data Systems, Inc.
 *      vogelke@c-17igp.wpafb.af.mil
 *
 * BUGS:
 *      None noticed yet.
 *
 * COMPILE:
 *      cc -o tst -DTEST_STRFTIME strftime.c
 */

/* ADR: I reformatted this to my liking, and deleted some unneeded code. */

#ifndef NULL
#include        <stdio.h>
#endif
#include        <sys/time.h>
#include        <string.h>

#define         MAXTIME         132

/*
 * Array of time formats.
 */

static char *array[] =
{
        "(%%A)      full weekday name, var length (Sunday..Saturday)  %A",
        "(%%B)       full month name, var length (January..December)  %B",
        "(%%C)                                               Century  %C",
        "(%%D)                                       date (%%m/%%d/%%y)  %D",
        "(%%E)                           Locale extensions (ignored)  %E",
        "(%%H)                          hour (24-hour clock, 00..23)  %H",
        "(%%I)                          hour (12-hour clock, 01..12)  %I",
        "(%%M)                                       minute (00..59)  %M",
        "(%%O)                           Locale extensions (ignored)  %O",
        "(%%R)                                 time, 24-hour (%%H:%%M)  %R",
        "(%%S)                                       second (00..60)  %S",
        "(%%T)                              time, 24-hour (%%H:%%M:%%S)  %T",
        "(%%U)    week of year, Sunday as first day of week (00..53)  %U",
        "(%%V)                    week of year according to ISO 8601  %V",
        "(%%W)    week of year, Monday as first day of week (00..53)  %W",
        "(%%X)     appropriate locale time representation (%H:%M:%S)  %X",
        "(%%Y)                           year with century (1970...)  %Y",
        "(%%Z) timezone (EDT), or blank if timezone not determinable  %Z",
        "(%%a)          locale's abbreviated weekday name (Sun..Sat)  %a",
        "(%%b)            locale's abbreviated month name (Jan..Dec)  %b",
        "(%%c)           full date (Sat Nov  4 12:02:33 1989)%n%t%t%t  %c",
        "(%%d)                             day of the month (01..31)  %d",
        "(%%e)               day of the month, blank-padded ( 1..31)  %e",
        "(%%h)                                should be same as (%%b)  %h",
        "(%%j)                            day of the year (001..366)  %j",
        "(%%k)               hour, 24-hour clock, blank pad ( 0..23)  %k",
        "(%%l)               hour, 12-hour clock, blank pad ( 0..12)  %l",
        "(%%m)                                        month (01..12)  %m",
        "(%%p)              locale's AM or PM based on 12-hour clock  %p",
        "(%%r)                   time, 12-hour (same as %%I:%%M:%%S %%p)  %r",
        "(%%u) ISO 8601: Weekday as decimal number [1 (Monday) - 7]   %u",
        "(%%v)                                VMS date (dd-bbb-YYYY)  %v",
        "(%%w)                       day of week (0..6, Sunday == 0)  %w",
        "(%%x)                appropriate locale date representation  %x",
        "(%%y)                      last two digits of year (00..99)  %y",
        "(%%z)      timezone offset east of GMT as HHMM (e.g. -0500)  %z",
        (char *) NULL
};

/* main routine. */

int
main(argc, argv)
int argc;
char **argv;
{
        long time();

        char *next;
        char string[MAXTIME];

        int k;
        int length;

        struct tm *tm;

        long clock;

        /* Call the function. */

        clock = time((long *) 0);
        tm = localtime(&clock);

        for (k = 0; next = array[k]; k++) {
                length = strftime(string, MAXTIME, next, tm);
                printf("%s\n", string);
        }

        exit(0);
}
#endif  /* TEST_STRFTIME */

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