genstamp.c

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// This program is open source software.  Use, duplication, or disclosure
// is subject to the terms of the GNU General Public License, version 3.
 
 
// Function to generate RFC822-compliant textual time/date stamp
 
#include "sysdep.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include "genstamp.h"
 
static char *months[] = {
    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
 
static char *weekdays[] = {
    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
 
// Supplied with a unix timestamp, generate an RFC822-compliant textual
// time and date stamp.
long datestring(char *buf, size_t n, time_t xtime, int which_format) {
    struct tm t;
 
    long offset;
    char offsign;
 
    localtime_r(&xtime, &t);
 
    // Convert "seconds west of GMT" to "hours/minutes offset"
#ifdef HAVE_STRUCT_TM_TM_GMTOFF
    offset = t.tm_gmtoff;
#else
    offset = timezone;
#endif
    if (offset > 0) {
        offsign = '+';
    }
    else {
        offset = 0L - offset;
        offsign = '-';
    }
    offset = ( (offset / 3600) * 100 ) + ( offset % 60 );
 
    switch(which_format) {
 
        case DATESTRING_RFC822:
            return snprintf(
                buf, n,
                "%s, %02d %s %04d %02d:%02d:%02d %c%04ld",
                weekdays[t.tm_wday],
                t.tm_mday,
                months[t.tm_mon],
                t.tm_year + 1900,
                t.tm_hour,
                t.tm_min,
                t.tm_sec,
                offsign, offset
                );
        break;
 
        case DATESTRING_IMAP:
            return snprintf(
                buf, n,
                "%02d-%s-%04d %02d:%02d:%02d %c%04ld",
                t.tm_mday,
                months[t.tm_mon],
                t.tm_year + 1900,
                t.tm_hour,
                t.tm_min,
                t.tm_sec,
                offsign, offset
                );
        break;
 
    }
    return 0;
}