/*
 *	amicron.c
 *
 *	Public Domain (p) No Rights Reserved
 *
 *	This program operates as a daemon, waking up every minute
 *	to execute the CRONTAB table.  Logging errors to CRONERR.
 *
 *	Put in startup-sequence as:
 *		run newcli con:0/140/160/50/CronTask s:startcron
 *  The startcron file contains one line:
 *		amicron
 *
 *	Some notes are included below concerning the cron table
 *	file format.  In this version the cron table file is left
 *	on disk and not moved to core, and  the command character
 *	to signify a newline '%' is not used.
 *
 *	Some cron table entry examples:
 *
 *	Print the date in the crontask window every minute:
 *		* * * * * date
 *
 *	Print the date in the crontask window on the hour, every hour:
 *		0 * * * * date
 *
 *	Run uupc at 4:30 am every day except Sat and Sun:
 *		30 4 * * 1-5 uupc -siscuva
 *
 *	Backup the files every other day at 7:30 pm:
 *		30 19 * * 1,3,5 sdbackup -s LAST dh0: incbkup_1:
 *
 */

/* 
 * Public Domain (p) by S. R. Sampson
 * Version 2.3, October 1987
 * Amiga port by Rick Schaeffer October 1987
 *
 * Rick Schaeffer          UUCP:  seismo!uunet!iscuva!ricks!ricks
 * E. 13611 26th Ave.      Phone: (509)928-3533
 * Spokane, WA  99216
 */
 
#include <stdio.h>
#include <time.h>
#include <errno.h>

#define TRUE 1
#define FALSE 0

#define CRONTAB "Sys:usr/spool/cron/crontab"
#define CRONERR "Sys:usr/spool/cron/cronerr"
 
#define MAXLINE	132
#define SIZE	64
 
extern	int	errno;
 
int	eof;
char	min[SIZE], hour[SIZE], day[SIZE],
	month[SIZE], wday[SIZE], command[SIZE];
char	*tokv[] = { min, hour, day, month, wday };
FILE	*fd, *err;
 
 
/*
 *	This is the basics, ready for bells and whistles
 *
 */
 
void main()
{
	void wakeup();
 
	/*
	 *	fopen() will create the file if it does not exist.
	 *	Any other errors will be output to stderr at startup.
	 */
        
	if ((err = fopen(CRONERR, "a")) == (FILE *)NULL)  {
		perror("cron");
		exit(1);
		}
 
	for (;;)  {
		wakeup();
		Delay(50*59);	/* sleep for one minute */
		}
}
 
void wakeup()
{
	register struct tm *tm;
	struct tm *localtime();
	char *ctime();
	long cur_time;
 
	time(&cur_time);		/* get the current time */
	tm = localtime(&cur_time);	/* break it down */
 
	fd = fopen(CRONTAB, "r");
 
	eof = FALSE;
 
	while (!eof)  {
		if (getline() && match(min,tm->tm_min) &&
		   match(hour,tm->tm_hour) && match(day,tm->tm_mday) &&
		   match(month,tm->tm_mon) && match(wday,tm->tm_wday))  {
 
			fexecl("Run","Run",command,NULL);
			}
		}
	fclose(fd);
}
 
 
/*
 *	A line consists of six fields.  The first five are:
 *
 *		minute:         0-59
 *		hour:           0-23
 *		day:            1-31
 *		month:          1-12
 *		weekday:        0-6 (Sunday = 0)
 *
 *	The fields are seperated by spaces or tabs, with the
 *	first field left justified (no leading spaces or tabs).
 *	See below for optional field syntax.
 *
 *	The last field is the command field.  This command will
 *	be executed by the CLI just as if typed from a console.
 */
 
int getline()
{
	register char *p;
	register int   i;
	char    buffer[MAXLINE], *scanner(), *fgets();
 
	if (fgets(buffer, sizeof buffer, fd) == NULL)  {
		eof = TRUE;
		return(FALSE);
		}
 
	for (p = buffer, i = 0; i < 5; i++)  {
		if ((p = scanner(tokv[i], p)) == (char *)NULL)
			return(FALSE);
		}
 
	strcpy(command, p);     /* scoop the command */
	return(TRUE);
}
 
 
char *scanner(token, offset)
register char   *token;		/* target buffer to receive scanned token */
register char   *offset;	/* place holder into source buffer */
{
	while ((*offset != ' ') && (*offset != '\t') && *offset)
		*token++ = *offset++;
 
	/*
	 *      Check for possible error condition
	 */
         
	if (!*offset)
		return ((char *)NULL);
 
	*token = '\0';
        
	while ((*offset == ' ') || (*offset == '\t'))
		offset++;
 
	return (offset);
}
 
 
/*
 *	This routine will match the left string with the right number.
 *
 *	The string can contain the following syntax:
 *
 *	*		This will return TRUE for any number
 *	x,y [,z, ...]	This will return TRUE for any number given.
 *	x-y		This will return TRUE for any number within
 *			the range of x thru y.
 */
 
int match(left, right)
register char   *left;
register int    right;
{
	register int	n;
	register char	c;
 
	n = 0;
	if (!strcmp(left, "*"))
		return(TRUE);
 
	while ((c = *left++) && (c >= '0') && (c <= '9'))
		n  =  (n * 10) + c - '0';
 
	switch (c)  {
		case '\0':
			return (right == n);
 
		case ',':
			if (right == n)
				return(TRUE);
			do {
				n = 0;
				while ((c = *left++) && (c >= '0') && (c <= '9'))
					n = (n * 10) + c - '0';
 				if (right == n)
					return(TRUE);
				} while (c == ',');
			return(FALSE);
 
		case '-':
			if (right < n)
				return(FALSE);
 
			n = 0;
			while ((c = *left++) && (c >= '0') && (c <= '9'))
				n = (n * 10) + c - '0';
 
			return(right <= n);
		}
}