port/locale/strftime.c

/*
 * Copyright 2013 Garrett D'Amore <garrett@damore.org>
 * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley. The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "lint.h"
#include "tzfile.h"
#include <fcntl.h>
#include <sys/stat.h>
#include <string.h>
#include <stdio.h>
#include <locale.h>
#include "timelocal.h"
#include "localeimpl.h"

static char *_add(const char *, char *, const char *);
static char *_conv(int, const char *, char *, const char *);
static char *_fmt(locale_t, const char *, const struct tm *, char *,
    const char * const);
static char *_yconv(int, int, int, int, char *, const char *);

extern char *tzname[];

#define IN_NONE 0
#define IN_SOME 1
#define IN_THIS 2
#define IN_ALL  3

#define PAD_DEFAULT 0
#define PAD_LESS    1
#define PAD_SPACE   2
#define PAD_ZERO    3

static const char *fmt_padding[][4] = {
    /* DEFAULT, LESS,   SPACE,  ZERO */
#define PAD_FMT_MONTHDAY    0
#define PAD_FMT_HMS     0
#define PAD_FMT_CENTURY     0
#define PAD_FMT_SHORTYEAR   0
#define PAD_FMT_MONTH       0
#define PAD_FMT_WEEKOFYEAR  0
#define PAD_FMT_DAYOFMONTH  0
    { "%02d",   "%d",   "%2d",  "%02d" },
#define PAD_FMT_SDAYOFMONTH 1
#define PAD_FMT_SHMS        1
    { "%2d",    "%d",   "%2d",  "%02d" },
#define PAD_FMT_DAYOFYEAR   2
    { "%03d",   "%d",   "%3d",  "%03d" },
#define PAD_FMT_YEAR        3
    { "%04d",   "%d",   "%4d",  "%04d" }
};


size_t
strftime_l(char *_RESTRICT_KYWD s, size_t maxsize,
    const char *_RESTRICT_KYWD format, const struct tm *_RESTRICT_KYWD t,
    locale_t loc)
{
    char *p;

    tzset();
    p = _fmt(loc, ((format == NULL) ? "%c" : format), t, s, s + maxsize);
    if (p == s + maxsize)
        return (0);
    *p = '\0';
    return (p - s);
}

size_t
strftime(char *_RESTRICT_KYWD s, size_t maxsize,
    const char *_RESTRICT_KYWD format, const struct tm *_RESTRICT_KYWD t)
{
    return (strftime_l(s, maxsize, format, t, uselocale(NULL)));
}

static char *
_fmt(locale_t loc, const char *format, const struct tm *t, char *pt,
    const char * const ptlim)
{
    int Ealternative, Oalternative, PadIndex;
    const struct lc_time *tptr = loc->time;

#define PADDING(x)  fmt_padding[x][PadIndex]

    for (; *format; ++format) {
        if (*format == '%') {
            Ealternative = 0;
            Oalternative = 0;
            PadIndex     = PAD_DEFAULT;
label:
            switch (*++format) {
            case '\0':
                --format;
                break;
            case 'A':
                pt = _add((t->tm_wday < 0 ||
                    t->tm_wday >= DAYSPERWEEK) ?
                    "?" : tptr->weekday[t->tm_wday],
                    pt, ptlim);
                continue;
            case 'a':
                pt = _add((t->tm_wday < 0 ||
                    t->tm_wday >= DAYSPERWEEK) ?
                    "?" : tptr->wday[t->tm_wday],
                    pt, ptlim);
                continue;
            case 'B':
                pt = _add((t->tm_mon < 0 ||
                    t->tm_mon >= MONSPERYEAR) ?
                    "?" : (tptr->month)[t->tm_mon],
                    pt, ptlim);
                continue;
            case 'b':
            case 'h':
                pt = _add((t->tm_mon < 0 ||
                    t->tm_mon >= MONSPERYEAR) ?
                    "?" : tptr->mon[t->tm_mon],
                    pt, ptlim);
                continue;
            case 'C':
                /*
                 * %C used to do a...
                 *  _fmt("%a %b %e %X %Y", t);
                 * ...whereas now POSIX 1003.2 calls for
                 * something completely different.
                 * (ado, 1993-05-24)
                 */
                pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
                    pt, ptlim);
                continue;
            case 'c':
                pt = _fmt(loc, tptr->c_fmt, t, pt, ptlim);
                continue;
            case 'D':
                pt = _fmt(loc, "%m/%d/%y", t, pt, ptlim);
                continue;
            case 'd':
                pt = _conv(t->tm_mday,
                    PADDING(PAD_FMT_DAYOFMONTH), pt, ptlim);
                continue;
            case 'E':
                if (Ealternative || Oalternative)
                    break;
                Ealternative++;
                goto label;
            case 'O':
                /*
                 * C99 locale modifiers.
                 * The sequences
                 *  %Ec %EC %Ex %EX %Ey %EY
                 *  %Od %oe %OH %OI %Om %OM
                 *  %OS %Ou %OU %OV %Ow %OW %Oy
                 * are supposed to provide alternate
                 * representations.
                 */
                if (Ealternative || Oalternative)
                    break;
                Oalternative++;
                goto label;
            case 'e':
                pt = _conv(t->tm_mday,
                    PADDING(PAD_FMT_SDAYOFMONTH), pt, ptlim);
                continue;
            case 'F':
                pt = _fmt(loc, "%Y-%m-%d", t, pt, ptlim);
                continue;
            case 'H':
                pt = _conv(t->tm_hour, PADDING(PAD_FMT_HMS),
                    pt, ptlim);
                continue;
            case 'I':
                pt = _conv((t->tm_hour % 12) ?
                    (t->tm_hour % 12) : 12,
                    PADDING(PAD_FMT_HMS), pt, ptlim);
                continue;
            case 'j':
                pt = _conv(t->tm_yday + 1,
                    PADDING(PAD_FMT_DAYOFYEAR), pt, ptlim);
                continue;
            case 'k':
                /*
                 * This used to be...
                 *  _conv(t->tm_hour % 12 ?
                 *      t->tm_hour % 12 : 12, 2, ' ');
                 * ...and has been changed to the below to
                 * match SunOS 4.1.1 and Arnold Robbins'
                 * strftime version 3.0. That is, "%k" and
                 * "%l" have been swapped.
                 * (ado, 1993-05-24)
                 */
                pt = _conv(t->tm_hour,
                    PADDING(PAD_FMT_SHMS), pt, ptlim);
                continue;
            case 'l':
                /*
                 * This used to be...
                 *  _conv(t->tm_hour, 2, ' ');
                 * ...and has been changed to the below to
                 * match SunOS 4.1.1 and Arnold Robbin's
                 * strftime version 3.0. That is, "%k" and
                 * "%l" have been swapped.
                 * (ado, 1993-05-24)
                 */
                pt = _conv((t->tm_hour % 12) ?
                    (t->tm_hour % 12) : 12,
                    PADDING(PAD_FMT_SHMS), pt, ptlim);
                continue;
            case 'M':
                pt = _conv(t->tm_min, PADDING(PAD_FMT_HMS),
                    pt, ptlim);
                continue;
            case 'm':
                pt = _conv(t->tm_mon + 1,
                    PADDING(PAD_FMT_MONTH),
                    pt, ptlim);
                continue;
            case 'n':
                pt = _add("\n", pt, ptlim);
                continue;
            case 'p':
                pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
                    tptr->pm : tptr->am, pt, ptlim);
                continue;
            case 'R':
                pt = _fmt(loc, "%H:%M", t, pt, ptlim);
                continue;
            case 'r':
                pt = _fmt(loc, tptr->ampm_fmt, t, pt, ptlim);
                continue;
            case 'S':
                pt = _conv(t->tm_sec, PADDING(PAD_FMT_HMS),
                    pt, ptlim);
                continue;

            case 's':
            {
                struct tm tm;
                char *buf;

                tm = *t;
                (void) asprintf(&buf, "%ld", mktime(&tm));
                pt = _add(buf, pt, ptlim);
                continue;
            }

            case 'T':
                pt = _fmt(loc, "%H:%M:%S", t, pt, ptlim);
                continue;
            case 't':
                pt = _add("\t", pt, ptlim);
                continue;
            case 'U':
                pt = _conv((t->tm_yday + DAYSPERWEEK -
                    t->tm_wday) / DAYSPERWEEK,
                    PADDING(PAD_FMT_WEEKOFYEAR),
                    pt, ptlim);
                continue;
            case 'u':
                /*
                 * From Arnold Robbins' strftime version 3.0:
                 * "ISO 8601: Weekday as a decimal number
                 * [1 (Monday) - 7]"
                 * (ado, 1993-05-24)
                 */
                pt = _conv((t->tm_wday == 0) ?
                    DAYSPERWEEK : t->tm_wday,
                    "%d", pt, ptlim);
                continue;
            case 'V':   /* ISO 8601 week number */
            case 'G':   /* ISO 8601 year (four digits) */
            case 'g':   /* ISO 8601 year (two digits) */
/*
 * From Arnold Robbins' strftime version 3.0: "the week number of the
 * year (the first Monday as the first day of week 1) as a decimal number
 * (01-53)."
 * (ado, 1993-05-24)
 *
 * From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
 * "Week 01 of a year is per definition the first week which has the
 * Thursday in this year, which is equivalent to the week which contains
 * the fourth day of January. In other words, the first week of a new year
 * is the week which has the majority of its days in the new year. Week 01
 * might also contain days from the previous year and the week before week
 * 01 of a year is the last week (52 or 53) of the previous year even if
 * it contains days from the new year. A week starts with Monday (day 1)
 * and ends with Sunday (day 7). For example, the first week of the year
 * 1997 lasts from 1996-12-30 to 1997-01-05..."
 * (ado, 1996-01-02)
 */
            {
                int year;
                int base;
                int yday;
                int wday;
                int w;

                year = t->tm_year;
                base = TM_YEAR_BASE;
                yday = t->tm_yday;
                wday = t->tm_wday;
                for (;;) {
                    int len;
                    int bot;
                    int top;

                    len = isleap_sum(year, base) ?
                        DAYSPERLYEAR : DAYSPERNYEAR;
                    /*
                     * What yday (-3 ... 3) does
                     * the ISO year begin on?
                     */
                    bot = ((yday + 11 - wday) %
                        DAYSPERWEEK) - 3;
                    /*
                     * What yday does the NEXT
                     * ISO year begin on?
                     */
                    top = bot - (len % DAYSPERWEEK);
                    if (top < -3)
                        top += DAYSPERWEEK;
                    top += len;
                    if (yday >= top) {
                        ++base;
                        w = 1;
                        break;
                    }
                    if (yday >= bot) {
                        w = 1 + ((yday - bot) /
                            DAYSPERWEEK);
                        break;
                    }
                    --base;
                    yday += isleap_sum(year, base) ?
                        DAYSPERLYEAR : DAYSPERNYEAR;
                }
#ifdef XPG4_1994_04_09
                if ((w == 52 && t->tm_mon == TM_JANUARY) ||
                    (w == 1 && t->tm_mon == TM_DECEMBER))
                    w = 53;
#endif /* defined XPG4_1994_04_09 */
                if (*format == 'V')
                    pt = _conv(w,
                        PADDING(PAD_FMT_WEEKOFYEAR),
                        pt, ptlim);
                else if (*format == 'g') {
                    pt = _yconv(year, base, 0, 1,
                        pt, ptlim);
                } else
                    pt = _yconv(year, base, 1, 1,
                        pt, ptlim);
            }
                continue;
            case 'v':
                /*
                 * From Arnold Robbins' strftime version 3.0:
                 * "date as dd-bbb-YYYY"
                 * (ado, 1993-05-24)
                 */
                pt = _fmt(loc, "%e-%b-%Y", t, pt, ptlim);
                continue;
            case 'W':
                pt = _conv((t->tm_yday + DAYSPERWEEK -
                    (t->tm_wday ?
                    (t->tm_wday - 1) :
                    (DAYSPERWEEK - 1))) / DAYSPERWEEK,
                    PADDING(PAD_FMT_WEEKOFYEAR),
                    pt, ptlim);
                continue;
            case 'w':
                pt = _conv(t->tm_wday, "%d", pt, ptlim);
                continue;
            case 'X':
                pt = _fmt(loc, tptr->X_fmt, t, pt, ptlim);
                continue;
            case 'x':
                pt = _fmt(loc, tptr->x_fmt, t, pt, ptlim);
                continue;
            case 'y':
                pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
                    pt, ptlim);
                continue;
            case 'Y':
                pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
                    pt, ptlim);
                continue;
            case 'Z':
                if (t->tm_isdst >= 0)
                    pt = _add(tzname[t->tm_isdst != 0],
                        pt, ptlim);
                /*
                 * C99 says that %Z must be replaced by the
                 * empty string if the time zone is not
                 * determinable.
                 */
                continue;
            case 'z':
                {
                int     diff;
                char const *    sign;

                if (t->tm_isdst < 0)
                    continue;
                /*
                 * C99 says that the UTC offset must
                 * be computed by looking only at
                 * tm_isdst. This requirement is
                 * incorrect, since it means the code
                 * must rely on magic (in this case
                 * altzone and timezone), and the
                 * magic might not have the correct
                 * offset. Doing things correctly is
                 * tricky and requires disobeying C99;
                 * see GNU C strftime for details.
                 * For now, punt and conform to the
                 * standard, even though it's incorrect.
                 *
                 * C99 says that %z must be replaced by the
                 * empty string if the time zone is not
                 * determinable, so output nothing if the
                 * appropriate variables are not available.
                 */
                if (t->tm_isdst == 0)
                    diff = -timezone;
                else
                    diff = -altzone;
                if (diff < 0) {
                    sign = "-";
                    diff = -diff;
                } else
                    sign = "+";
                pt = _add(sign, pt, ptlim);
                diff /= SECSPERMIN;
                diff = (diff / MINSPERHOUR) * 100 +
                    (diff % MINSPERHOUR);
                pt = _conv(diff, PADDING(PAD_FMT_YEAR),
                    pt, ptlim);
                }
                continue;
            case '+':
                pt = _fmt(loc, tptr->date_fmt, t, pt, ptlim);
                continue;
            case '-':
                if (PadIndex != PAD_DEFAULT)
                    break;
                PadIndex = PAD_LESS;
                goto label;
            case '_':
                if (PadIndex != PAD_DEFAULT)
                    break;
                PadIndex = PAD_SPACE;
                goto label;
            case '0':
                if (PadIndex != PAD_DEFAULT)
                    break;
                PadIndex = PAD_ZERO;
                goto label;
            case '%':
            /*
             * X311J/88-090 (4.12.3.5): if conversion char is
             * undefined, behavior is undefined. Print out the
             * character itself as printf(3) also does.
             */
            default:
                break;
            }
        }
        if (pt == ptlim)
            break;
        *pt++ = *format;
    }
    return (pt);
}

static char *
_conv(const int n, const char *format, char *const pt,
    const char *const ptlim)
{
    char    buf[12];

    (void) sprintf(buf, format, n);
    return (_add(buf, pt, ptlim));
}

static char *
_add(const char *str, char *pt, const char *const ptlim)
{
    while (pt < ptlim && (*pt = *str++) != '\0')
        ++pt;
    return (pt);
}

/*
 * POSIX and the C Standard are unclear or inconsistent about
 * what %C and %y do if the year is negative or exceeds 9999.
 * Use the convention that %C concatenated with %y yields the
 * same output as %Y, and that %Y contains at least 4 bytes,
 * with more only if necessary.
 */

static char *
_yconv(const int a, const int b, const int convert_top, const int convert_yy,
    char *pt, const char * const ptlim)
{
    register int    lead;
    register int    trail;

#define DIVISOR 100
    trail = a % DIVISOR + b % DIVISOR;
    lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
    trail %= DIVISOR;
    if (trail < 0 && lead > 0) {
        trail += DIVISOR;
        --lead;
    } else if (lead < 0 && trail > 0) {
        trail -= DIVISOR;
        ++lead;
    }
    if (convert_top) {
        if (lead == 0 && trail < 0)
            pt = _add("-0", pt, ptlim);
        else    pt = _conv(lead, "%02d", pt, ptlim);
    }
    if (convert_yy)
        pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
    return (pt);
}