Developer CD Series 1994…tember: Reference Library/Dev.CD Sep 94.toast/Periodicals/develop/develop Issue 6/develop 6 code/TCP/NewsWatcher/NewsWatcher 2.0d15 source/source/datetime.c

C/C++ Source or Header | 1993-08-29 | 5.1 KB | 219 lines | [TEXT/KAHL]

/*----------------------------------------------------------------------------

    datetime.c

    This module converts RFC822 date/time lines into Mac-format date/time
    strings in local time.

    Portions copyright © 1990, Apple Computer.
    Portions copyright © 1993, Northwestern University.

----------------------------------------------------------------------------*/

#include <Script.h>
#include <Packages.h>

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>

#include "datetime.h"
#include "util.h"



/*----------------------------------------------------------------------------
    ParseNum

    Extract a long integer from a string.

    Entry:    *str = string.

    Exit:    function result = parsed number, or 0 if error.
            *str = pointer to first non-space character following parsed nubmer.

    A POINTER to a char* is passed in; it is adjusted to point to the
    next "word" after the number (skipping white space)

    Returns the number that was found, or 0.
----------------------------------------------------------------------------*/

static long ParseNum (char **str)
{
    long temp = 0;
    char *s = *str;

    while (*s && isdigit(*s))
        temp = temp * 10 + (*s++ - '0');
    while (*s && isspace(*s)) s++;
    *str = s;
    return temp;
}



/*----------------------------------------------------------------------------
    FindMonth

    Given a string that might be a month abbreviation, return the number
    of the month (starting with January = 1, ...).

    Entry:    str = month string.

    Exit:    function result = month ordinal, or 0 if can't parse.

    This isn't WorldScript-friendly, but it doesn't matter, since this
    function is only used for parsing RFC822 dates
----------------------------------------------------------------------------*/

static short FindMonth (const char *str)
{
    static const char *months[12] = {
        "JAN", "FEB", "MAR", "APR", "MAY", "JUN",
        "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"
    };
    short i;

    for (i = 0; i < 12; i++) {
        if (strcasecmp(str, months[i]) == 0) return i+1;
    }
    return 0;
}



/*----------------------------------------------------------------------------
    Parse822Date

    Parse a date/time that's in RFC822 header format:

    [Day, ] dd mmm [yy]yy hh:mm:ss [ GMT | (+|-) hhmm ]

    Entry:    date = RFC822 date/time string.

    Exit:    function result = number of seconds since January 1, 1904,
                the standard Mac date convention.
            function result = 0 if the date could not be parsed
----------------------------------------------------------------------------*/

unsigned long Parse822Date (char *date)
{
    DateTimeRec dt;
    unsigned long result;
    char chunk[20];
    char *s, *p;
    short sign;
    long tzDelta;

    memset(&dt, 0, sizeof(dt));

    s = date;
    if (p = strchr(date, ',')) s = p+1;        /* Skip day of week */

    while (*s && isspace(*s)) s++;            /* dd */
    dt.day = ParseNum(&s);

    p = chunk;                                /* mmm */
    while (*s && isalnum(*s) && p - chunk < sizeof(chunk)-1) *p++ = *s++;
    *p = 0;
    dt.month = FindMonth(chunk);

    while (*s && isspace(*s)) s++;            /* [yy]yy */
    dt.year = ParseNum(&s);
    if (dt.year < 21) {
        dt.year += 2000;
    } else if (dt.year < 100) {
        dt.year += 1900;
    }

    dt.hour = ParseNum(&s);                    /* hh */
    if (*s == ':') {
        s++;
        dt.minute = ParseNum(&s);            /* mm */
    }
    if (*s == ':') {
        s++;
        dt.second = ParseNum(&s);            /* ss */
    } else {
        return 0;
    }

    if (strcasecmp(s, "GMT") == 0) {        /* GMT */
        s += 3;
        while (*s && isspace(*s)) s++;
    }

    if ((*s == '-' || *s == '+') && isdigit(*(s+1)) ) {        /* (+|-) hhmm */
        if (*s == '-') {
            /* If the delta is negative, we have to ADD time to get GMT */
            sign = 1;
        } else {
            sign = -1;
        }
        s++;
        tzDelta = ParseNum(&s);
        dt.hour   += sign * (tzDelta / 100);        /* Hours */
        dt.minute += sign * (tzDelta % 100);        /* Minutes */
    }

    if (*s != 0) return 0;

    /* Convert to seconds since 1/1/1904 */

    Date2Secs(&dt, &result);
    return result;
}


/*----------------------------------------------------------------------------
    Cleanup822Date

    Converts an RFC822 date/time string into a Mac-style date/time string
    in local time.

    Entry:    date = RFC822 date/time string.

    Exit:    date = Mac-style date/time string.

    If the string cannot be parsed or converted, or if the Map control
    panel is not installed, the string is unchanged.
----------------------------------------------------------------------------*/

void Cleanup822Date (char *date)
{
    MachineLocation    loc;    /* Location info for this machine */
    long gmtOffset;            /* Offset from GMT, in seconds */
    unsigned long secs;
    char *s, *p;
    Str255 time;

    /* Get our location. Return if Map control panel not installed. */

    ReadLocation(&loc);
    if (loc.latitude == 0 && loc.longitude == 0 && loc.gmtFlags.gmtDelta == 0) return;

    /* Get our offset in seconds from GMT. */

    gmtOffset = loc.gmtFlags.gmtDelta & 0x00FFFFFF;
    if ((gmtOffset & 0x00800000) != 0) gmtOffset |= 0xFF000000;

    /* Try to parse the date we were passed. */

    secs = Parse822Date(date);
    if (secs == 0) return;

    /* Correct for our timezone. */

    secs += gmtOffset;

    /* Convert it back into a Mac-style date/time string. */

    IUDateString(secs, abbrevDate, (StringPtr)date);
    p2cstr((StringPtr)date);
    strcat(date, " ");
    IUTimeString(secs, true, time);
    strcat(date, p2cstr(time));
}