Cron format parser

Header file

#include "mln_cron.h"

Module

cron

Functions

mln_cron_parse

time_t mln_cron_parse(mln_string_t *exp, time_t base);

Description: Calculate the next available timestamp based on the given cron expression exp and the base timestamp base.

Supported cron syntax:

* wildcard, matches all values
N specific numeric value
N,N,N comma-separated value list
N-N range (supports wrap-around, e.g. 22-3 in the hour field means 22,23,0,1,2,3)
*/N step
N-N/N range combined with step
Month names: JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC (case-insensitive)
Weekday names: SUN, MON, TUE, WED, THU, FRI, SAT (case-insensitive)
Predefined macros: @yearly (or @annually), @monthly, @weekly, @daily (or @midnight), @hourly

Return value: timestamp of time_t type, or 0 if there is an error.

Example

#include "mln_cron.h"
#include <stdio.h>

int main(void)
{
    /* Basic wildcard */
    char p[] = "* * * * *";
    mln_string_t s;
    mln_string_nset(&s, p, sizeof(p)-1);
    time_t now = time(NULL);
    time_t next = mln_cron_parse(&s, now);
    printf("%lu %lu %s\n", (unsigned long)now, (unsigned long)next, ctime(&next));

    /* Using month and weekday names */
    char p2[] = "0 9 * JAN-JUN MON-FRI";
    mln_string_nset(&s, p2, sizeof(p2)-1);
    next = mln_cron_parse(&s, now);
    printf("next: %lu %s\n", (unsigned long)next, ctime(&next));

    /* Using predefined macros */
    char p3[] = "@daily";
    mln_string_nset(&s, p3, sizeof(p3)-1);
    next = mln_cron_parse(&s, now);
    printf("daily: %lu %s\n", (unsigned long)next, ctime(&next));

    return 0;
}

Cron Format Parser