path: root/camel/broken-date-parser.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 *  Authors: Jeffrey Stedfast <fejj@ximian.com>
 *
 *  Copyright 2000 Ximian, Inc. (www.ximian.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <glib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/time.h>
#include <time.h>

#include "broken-date-parser.h"

#define d(x) x

#define NUMERIC_CHARS          "1234567890"
#define WEEKDAY_CHARS          "SundayMondayTuesdayWednesdayThursdayFridaySaturday"
#define MONTH_CHARS            "JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember"
#define TIMEZONE_ALPHA_CHARS   "UTCGMTESTEDTCSTCDTMSTPSTPDTZAMNY()"
#define TIMEZONE_NUMERIC_CHARS "-+1234567890"
#define TIME_CHARS             "1234567890:"

#define DATE_TOKEN_NON_NUMERIC          (1 << 0)
#define DATE_TOKEN_NON_WEEKDAY          (1 << 1)
#define DATE_TOKEN_NON_MONTH            (1 << 2)
#define DATE_TOKEN_NON_TIME             (1 << 3)
#define DATE_TOKEN_HAS_COLON            (1 << 4)
#define DATE_TOKEN_NON_TIMEZONE_ALPHA   (1 << 5)
#define DATE_TOKEN_NON_TIMEZONE_NUMERIC (1 << 6)
#define DATE_TOKEN_HAS_SIGN             (1 << 7)

static unsigned char datetok_table[256] = {
        128,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111, 79, 79,111,175,111,175,111,111,
         38, 38, 38, 38, 38, 38, 38, 38, 38, 38,119,111,111,111,111,111,
        111, 75,111, 79, 75, 79,105, 79,111,111,107,111,111, 73, 75,107,
         79,111,111, 73, 77, 79,111,109,111, 79, 79,111,111,111,111,111,
        111,105,107,107,109,105,111,107,105,105,111,111,107,107,105,105,
        107,111,105,105,105,105,107,111,111,105,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
        111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,
};

/* hrm, is there a library for this shit? */
static struct {
    char *name;
    int offset;
} tz_offsets [] = {
    { "UT", 0 },
    { "GMT", 0 },
    { "EST", -500 },    /* these are all US timezones.  bloody yanks */
    { "EDT", -400 },
    { "CST", -600 },
    { "CDT", -500 },
    { "MST", -700 },
    { "MDT", -600 },
    { "PST", -800 },
    { "PDT", -700 },
    { "Z", 0 },
    { "A", -100 },
    { "M", -1200 },
    { "N", 100 },
    { "Y", 1200 },
};

static char *tm_months[] = {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

static char *tm_days[] = {
    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};


struct _date_token {
    struct _date_token *next;
    const unsigned char *start;
    unsigned int len;
    unsigned int mask;
};

/* This is where it gets ugly... */
static struct _date_token *
datetok (const char *date)
{
    struct _date_token *tokens = NULL, *token, *tail = (struct _date_token *) &tokens;
    const unsigned char *start, *end;
    unsigned int mask;
    
    start = date;
    while (*start) {
        /* kill leading whitespace */
        for ( ; *start && isspace ((int) *start); start++);
        
        mask = 0;
        
        /* find the end of this token */
        for (end = start; *end && !strchr ("-/,\t\r\n ", *end); end++) {
            mask |= datetok_table[*end];
        }
        
        if (end != start) {
            token = g_malloc (sizeof (struct _date_token));
            token->next = NULL;
            token->start = start;
            token->len = end - start;
            token->mask = mask;
            
            tail->next = token;
            tail = token;
        }
        
        if (*end)
            start = end + 1;
        else
            break;
    }
    
    return tokens;
}

static int
decode_int (const unsigned char *in, unsigned int inlen)
{
    register const unsigned char *inptr;
    const unsigned char *inend;
    int sign = 1, val = 0;
    
    inptr = in;
    inend = in + inlen;
    
    if (*inptr == '-') {
        sign = -1;
        inptr++;
    } else if (*inptr == '+')
        inptr++;
    
    for ( ; inptr < inend; inptr++) {
        if (!isdigit ((int) *inptr))
            return  -1;
        else
            val = (val * 10) + (*inptr - '0');
    }
    
    val *= sign;
    
    return val;
}

static int
get_wday (const unsigned char *in, unsigned int inlen)
{
    int wday;
    
    if (inlen < 3)
        return -1;
    
    for (wday = 0; wday < 7; wday++)
        if (!strncasecmp (in, tm_days[wday], 3))
            return wday;
    
    return -1;  /* unknown week day */
}

static int
get_mday (const unsigned char *in, unsigned int inlen)
{
    int mday;
    
    mday = decode_int (in, inlen);
    
    if (mday < 0 || mday > 31)
        mday = -1;
    
    return mday;
}

static int
get_month (const unsigned char *in, unsigned int inlen)
{
    int i;
    
    if (inlen < 3)
        return -1;
    
    for (i = 0; i < 12; i++)
        if (!strncasecmp (in, tm_months[i], 3))
            return i;
    
    return -1;  /* unknown month */
}

static int
get_year (const unsigned char *in, unsigned int inlen)
{
    int year;
    
    year = decode_int (in, inlen);
    if (year == -1)
        return -1;
    
    if (year < 100)
        year += (year < 70) ? 2000 : 1900;
    
    if (year < 1969)
        return -1;
    
    return year;
}

static gboolean
get_time (const unsigned char *in, unsigned int inlen, int *hour, int *min, int *sec)
{
    register const unsigned char *inptr;
    const unsigned char *inend;
    int *val, colons = 0;
    
    *hour = *min = *sec = 0;
    
    inend = in + inlen;
    val = hour;
    for (inptr = in; inptr < inend; inptr++) {
        if (*inptr == ':') {
            colons++;
            switch (colons) {
            case 1:
                val = min;
                break;
            case 2:
                val = sec;
                break;
            default:
                return FALSE;
            }
        } else if (!isdigit ((int) *inptr))
            return FALSE;
        else
            *val = (*val * 10) + (*inptr - '0');
    }
    
    return TRUE;
}

static int
get_tzone (struct _date_token **token)
{
    int i;
    
    for (i = 0; *token && i < 2; *token = (*token)->next, i++) {
        const unsigned char *inptr = (*token)->start;
        unsigned int inlen = (*token)->len;
        
        if (*inptr == '+' || *inptr == '-') {
            return decode_int (inptr, inlen);
        } else {
            int t;
            
            if (*inptr == '(')
                inptr++;
            
            for (t = 0; t < 15; t++) {
                unsigned int len = MIN (strlen (tz_offsets[t].name), inlen - 1);
                
                if (!strncmp (inptr, tz_offsets[t].name, len))
                    return tz_offsets[t].offset;
            }
        }
    }
    
    return -1;
}

/* This is where things get interesting... ;-) */

#define date_token_mask(t)  (((struct _date_token *) t)->mask)
#define is_numeric(t)       ((date_token_mask (t) & DATE_TOKEN_NON_NUMERIC) == 0)
#define is_weekday(t)       ((date_token_mask (t) & DATE_TOKEN_NON_WEEKDAY) == 0)
#define is_month(t)         ((date_token_mask (t) & DATE_TOKEN_NON_MONTH) == 0)
#define is_time(t)          (((date_token_mask (t) & DATE_TOKEN_NON_TIME) == 0) && (date_token_mask (t) & DATE_TOKEN_HAS_COLON))
#define is_tzone_alpha(t)   ((date_token_mask (t) & DATE_TOKEN_NON_TIMEZONE_ALPHA) == 0)
#define is_tzone_numeric(t) (((date_token_mask (t) & DATE_TOKEN_NON_TIMEZONE_NUMERIC) == 0) && (date_token_mask (t) & DATE_TOKEN_HAS_SIGN))
#define is_tzone(t)         (is_tzone_alpha (t) || is_tzone_numeric (t))

static time_t
decode_broken_date (struct _date_token *tokens, int *tzone)
{
    gboolean got_wday, got_month, got_tzone;
    int hour, min, sec, offset, n;
    struct _date_token *token;
    struct tm tm;
    time_t time;
    
    memset ((void *) &tm, 0, sizeof (struct tm));
    got_wday = got_month = got_tzone = FALSE;
    offset = 0;
    
    token = tokens;
    while (token) {
        if (is_weekday (token) && !got_wday) {
            if ((n = get_wday (token->start, token->len)) != -1) {
                d(printf ("weekday; "));
                got_wday = TRUE;
                tm.tm_wday = n;
                goto next_token;
            }
        }
        
        if (is_month (token) && !got_month) {
            if ((n = get_month (token->start, token->len)) != -1) {
                d(printf ("month; "));
                got_month = TRUE;
                tm.tm_mon = n;
                goto next_token;
            }
        }
        
        if (is_time (token) && !tm.tm_hour && !tm.tm_min && !tm.tm_sec) {
            if (get_time (token->start, token->len, &hour, &min, &sec)) {
                d(printf ("time; "));
                tm.tm_hour = hour;
                tm.tm_min = min;
                tm.tm_sec = sec;
                goto next_token;
            }
        }
        
        if (is_tzone (token) && !got_tzone) {
            struct _date_token *t = token;
            
            if ((n = get_tzone (&t)) != -1) {
                d(printf ("tzone; "));
                got_tzone = TRUE;
                offset = n;
                goto next_token;
            }
        }
        
        if (is_numeric (token)) {
            if (token->len == 4 && !tm.tm_year) {
                if ((n = get_year (token->start, token->len)) != -1) {
                    d(printf ("year; "));
                    tm.tm_year = n - 1900;
                    goto next_token;
                }
            } else {
                if (!got_month && !got_wday && token->next && is_numeric (token->next)) {
                    d(printf ("mon; "));
                    n = decode_int (token->start, token->len);
                    got_month = TRUE;
                    tm.tm_mon = n - 1;
                    goto next_token;
                } else if (!tm.tm_mday && (n = get_mday (token->start, token->len)) != -1) {
                    d(printf ("mday; "));
                    tm.tm_mday = n;
                    goto next_token;
                } else if (!tm.tm_year) {
                    d(printf ("2-digit year; "));
                    n = get_year (token->start, token->len);
                    tm.tm_year = n - 1900;
                    goto next_token;
                }
            }
        }
        
        d(printf ("???; "));
        
    next_token:
        
        token = token->next;
    }
    
    d(printf ("\n"));
    
    time = mktime (&tm);
#if defined (HAVE_TIMEZONE)
    time -= timezone;
#elif defined (HAVE_TM_GMTOFF)
    time += tm.tm_gmtoff;
#else
#error Neither HAVE_TIMEZONE nor HAVE_TM_GMTOFF defined. Rerun autoheader, autoconf, etc.
#endif
    
    /* t is now GMT of the time we want, but not offset by the timezone ... */
    
    /* this should convert the time to the GMT equiv time */
    time -= ((offset / 100) * 60 * 60) + (offset % 100) * 60;
    
    if (tzone)
        *tzone = offset;
    
    return time;
}


/**
 * parse_broken_date:
 * @datestr: input date string
 * @saveoffset:
 *
 * Decodes the rfc822/broken date string and saves the GMT offset into
 * @saveoffset if non-NULL.
 *
 * Returns the time_t representation of the date string specified by
 * @in. If 'saveoffset' is non-NULL, the value of the timezone offset
 * will be stored.
 **/
time_t
parse_broken_date (const char *datestr, int *saveoffset)
{
    struct _date_token *token, *tokens;
    time_t date;
    
    tokens = datetok (datestr);
    
    date = decode_broken_date (tokens, saveoffset);
    
    /* cleanup */
    while (tokens) {
        token = tokens;
        tokens = tokens->next;
        g_free (token);
    }
    
    return date;
}





#ifdef DATETOK_STANDALONE

static void
table_init ()
{
    int i;
    
    memset (datetok_table, 0, sizeof (datetok_table));
    
    for (i = 0; i < 256; i++) {
        if (!strchr (NUMERIC_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_NUMERIC;
        
        if (!strchr (WEEKDAY_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_WEEKDAY;
        
        if (!strchr (MONTH_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_MONTH;
        
        if (!strchr (TIME_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_TIME;
        
        if (!strchr (TIMEZONE_ALPHA_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_TIMEZONE_ALPHA;
        
        if (!strchr (TIMEZONE_NUMERIC_CHARS, i))
            datetok_table[i] |= DATE_TOKEN_NON_TIMEZONE_NUMERIC;
        
        if (((char) i) == ':')
            datetok_table[i] |= DATE_TOKEN_HAS_COLON;
        
        if (strchr ("+-", i))
            datetok_table[i] |= DATE_TOKEN_HAS_SIGN;
    }
    
    printf ("static unsigned int datetok_table[256] = {");
    for (i = 0; i < 256; i++) {
        if (i % 16 == 0)
            printf ("\n\t");
        printf ("%3d,", datetok_table[i]);
    }
    printf ("\n};\n");
}


int main (int argc, char **argv)
{
    time_t date;
    int offset;
    
    /*table_init ();*/
    
    date = parse_broken_date (argv[1], &offset);
    printf ("%d; %d\n", date, offset);
    
    return 0;
}

#endif /* DATETOK_STANDALONE */