source: MondoRescue/branches/stable/mindi-busybox/coreutils/cal.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Calendar implementation for busybox
 *
 * See original copyright at the end of this file
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* BB_AUDIT SUSv3 compliant with -j and -y extensions (from util-linux). */
/* BB_AUDIT BUG: The output of 'cal -j 1752' is incorrect.  The upstream
 * BB_AUDIT BUG: version in util-linux seems to be broken as well. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/cal.html */

/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
 *
 * Major size reduction... over 50% (>1.5k) on i386.
 */

#include "libbb.h"

/* We often use "unsigned" intead of "int", it's easier to div on most CPUs */

#define THURSDAY        4       /* for reformation */
#define SATURDAY        6       /* 1 Jan 1 was a Saturday */

#define FIRST_MISSING_DAY   639787      /* 3 Sep 1752 */
#define NUMBER_MISSING_DAYS 11      /* 11 day correction */

#define MAXDAYS         42      /* max slots in a month array */
#define SPACE           -1      /* used in day array */

static const unsigned char days_in_month[] ALIGN1 = {
    0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

static const unsigned char sep1752[] ALIGN1 = {
         1, 2,  14, 15, 16,
    17, 18, 19, 20, 21, 22, 23,
    24, 25, 26, 27, 28, 29, 30
};

static unsigned julian;

/* leap year -- account for Gregorian reformation in 1752 */
static int leap_year(unsigned yr)
{
    if (yr <= 1752)
        return !(yr % 4);
    return (!(yr % 4) && (yr % 100)) || !(yr % 400);
}

/* number of centuries since 1700, not inclusive */
#define centuries_since_1700(yr) \
    ((yr) > 1700 ? (yr) / 100 - 17 : 0)

/* number of centuries since 1700 whose modulo of 400 is 0 */
#define quad_centuries_since_1700(yr) \
    ((yr) > 1600 ? ((yr) - 1600) / 400 : 0)

/* number of leap years between year 1 and this year, not inclusive */
#define leap_years_since_year_1(yr) \
    ((yr) / 4 - centuries_since_1700(yr) + quad_centuries_since_1700(yr))

static void center(char *, unsigned, unsigned);
static void day_array(unsigned, unsigned, unsigned *);
static void trim_trailing_spaces_and_print(char *);

static void blank_string(char *buf, size_t buflen);
static char *build_row(char *p, unsigned *dp);

#define DAY_LEN     3       /* 3 spaces per day */
#define J_DAY_LEN   (DAY_LEN + 1)
#define WEEK_LEN    20      /* 7 * 3 - one space at the end */
#define J_WEEK_LEN  (WEEK_LEN + 7)
#define HEAD_SEP    2       /* spaces between day headings */

int cal_main(int argc, char **argv);
int cal_main(int argc, char **argv)
{
    struct tm *local_time;
    struct tm zero_tm;
    time_t now;
    unsigned month, year, flags, i;
    char *month_names[12];
    char day_headings[28];  /* 28 for julian, 21 for nonjulian */
    char buf[40];

    flags = getopt32(argv, "jy");
    julian = flags & 1;
    month = 0;
    argv += optind;
    argc -= optind;

    if (argc > 2) {
        bb_show_usage();
    }

    if (!argc) {
        time(&now);
        local_time = localtime(&now);
        year = local_time->tm_year + 1900;
        if (!(flags & 2)) {
            month = local_time->tm_mon + 1;
        }
    } else {
        if (argc == 2) {
            month = xatou_range(*argv++, 1, 12);
        }
        year = xatou_range(*argv, 1, 9999);
    }

    blank_string(day_headings, sizeof(day_headings) - 7 + 7*julian);

    i = 0;
    do {
        zero_tm.tm_mon = i;
        strftime(buf, sizeof(buf), "%B", &zero_tm);
        month_names[i] = xstrdup(buf);

        if (i < 7) {
            zero_tm.tm_wday = i;
            strftime(buf, sizeof(buf), "%a", &zero_tm);
            strncpy(day_headings + i * (3+julian) + julian, buf, 2);
        }
    } while (++i < 12);

    if (month) {
        unsigned row, len, days[MAXDAYS];
        unsigned *dp = days;
        char lineout[30];

        day_array(month, year, dp);
        len = sprintf(lineout, "%s %d", month_names[month - 1], year);
        printf("%*s%s\n%s\n",
               ((7*julian + WEEK_LEN) - len) / 2, "",
               lineout, day_headings);
        for (row = 0; row < 6; row++) {
            build_row(lineout, dp)[0] = '\0';
            dp += 7;
            trim_trailing_spaces_and_print(lineout);
        }
    } else {
        unsigned row, which_cal, week_len, days[12][MAXDAYS];
        unsigned *dp;
        char lineout[80];

        sprintf(lineout, "%d", year);
        center(lineout,
               (WEEK_LEN * 3 + HEAD_SEP * 2)
               + julian * (J_WEEK_LEN * 2 + HEAD_SEP
                           - (WEEK_LEN * 3 + HEAD_SEP * 2)),
               0);
        puts("\n");     /* two \n's */
        for (i = 0; i < 12; i++) {
            day_array(i + 1, year, days[i]);
        }
        blank_string(lineout, sizeof(lineout));
        week_len = WEEK_LEN + julian * (J_WEEK_LEN - WEEK_LEN);
        for (month = 0; month < 12; month += 3-julian) {
            center(month_names[month], week_len, HEAD_SEP);
            if (!julian) {
                center(month_names[month + 1], week_len, HEAD_SEP);
            }
            center(month_names[month + 2 - julian], week_len, 0);
            printf("\n%s%*s%s", day_headings, HEAD_SEP, "", day_headings);
            if (!julian) {
                printf("%*s%s", HEAD_SEP, "", day_headings);
            }
            putchar('\n');
            for (row = 0; row < (6*7); row += 7) {
                for (which_cal = 0; which_cal < 3-julian; which_cal++) {
                    dp = days[month + which_cal] + row;
                    build_row(lineout + which_cal * (week_len + 2), dp);
                }
                /* blank_string took care of nul termination. */
                trim_trailing_spaces_and_print(lineout);
            }
        }
    }

    fflush_stdout_and_exit(0);
}

/*
 * day_array --
 *  Fill in an array of 42 integers with a calendar.  Assume for a moment
 *  that you took the (maximum) 6 rows in a calendar and stretched them
 *  out end to end.  You would have 42 numbers or spaces.  This routine
 *  builds that array for any month from Jan. 1 through Dec. 9999.
 */
static void day_array(unsigned month, unsigned year, unsigned *days)
{
    unsigned long temp;
    unsigned i;
    unsigned day, dw, dm;

    memset(days, SPACE, MAXDAYS * sizeof(int));

    if ((month == 9) && (year == 1752)) {
        /* Assumes the Gregorian reformation eliminates
         * 3 Sep. 1752 through 13 Sep. 1752.
         */
        unsigned j_offset = julian * 244;
        size_t oday = 0;

        do {
            days[oday+2] = sep1752[oday] + j_offset;
        } while (++oday < sizeof(sep1752));

        return;
    }

    /* day_in_year
     * return the 1 based day number within the year
     */
    day = 1;
    if ((month > 2) && leap_year(year)) {
        ++day;
    }

    i = month;
    while (i) {
        day += days_in_month[--i];
    }

    /* day_in_week
     * return the 0 based day number for any date from 1 Jan. 1 to
     * 31 Dec. 9999.  Assumes the Gregorian reformation eliminates
     * 3 Sep. 1752 through 13 Sep. 1752.  Returns Thursday for all
     * missing days.
     */
    temp = (long)(year - 1) * 365 + leap_years_since_year_1(year - 1) + day;
    if (temp < FIRST_MISSING_DAY) {
        dw = ((temp - 1 + SATURDAY) % 7);
    } else {
        dw = (((temp - 1 + SATURDAY) - NUMBER_MISSING_DAYS) % 7);
    }

    if (!julian) {
        day = 1;
    }

    dm = days_in_month[month];
    if ((month == 2) && leap_year(year)) {
        ++dm;
    }

    do {
        days[dw++] = day++;
    } while (--dm);
}

static void trim_trailing_spaces_and_print(char *s)
{
    char *p = s;

    while (*p) {
        ++p;
    }
    while (p != s) {
        --p;
        if (!(isspace)(*p)) {   /* We want the function... not the inline. */
            p[1] = '\0';
            break;
        }
    }

    puts(s);
}

static void center(char *str, unsigned len, unsigned separate)
{
    unsigned n = strlen(str);
    len -= n;
    printf("%*s%*s", (len/2) + n, str, (len/2) + (len % 2) + separate, "");
}

static void blank_string(char *buf, size_t buflen)
{
    memset(buf, ' ', buflen);
    buf[buflen-1] = '\0';
}

static char *build_row(char *p, unsigned *dp)
{
    unsigned col, val, day;

    memset(p, ' ', (julian + DAY_LEN) * 7);

    col = 0;
    do {
        day = *dp++;
        if (day != SPACE) {
            if (julian) {
                ++p;
                if (day >= 100) {
                    *p = '0';
                    p[-1] = (day / 100) + '0';
                    day %= 100;
                }
            }
            val = day / 10;
            if (val > 0) {
                *p = val + '0';
            }
            *++p = day % 10 + '0';
            p += 2;
        } else {
            p += DAY_LEN + julian;
        }
    } while (++col < 7);

    return p;
}

/*
 * Copyright (c) 1989, 1993, 1994
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kim Letkeman.
 *
 * 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. 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.
 */