/* at - run a command at a specified time	Author: Jan Looyen */#include <sys/types.h>#include <time.h>#include <fcntl.h>#include <unistd.h>#include <stdlib.h>#include <string.h>#include <sys/stat.h>#include <stdio.h>#define	STARTDAY	0	/* see ctime(3)	 */#define	LEAPDAY		STARTDAY+59#define	MAXDAYNR	STARTDAY+365#define	NODAY		-2_PROTOTYPE(int main, (int argc, char **argv, char **envp));_PROTOTYPE(int getltim, (char *t));_PROTOTYPE(int getlday, (char *m, char *d));_PROTOTYPE(int digitstring, (char *s));int main(argc, argv, envp)int argc;char **argv, **envp;{  int i, c, count, ltim, year, lday = NODAY;  char buf[10], job[30], *dp, *sp;  struct tm *p;  long clk;  FILE *fp, *pin;/*-------------------------------------------------------------------------* *	check arguments	& pipe to "pwd"				           * *-------------------------------------------------------------------------*/  if (argc < 2 || argc > 5) {	fprintf(stderr, "Usage: %s time [month day] [file]\n", argv[0]);	exit(1);  }  if ((ltim = getltim(argv[1])) == -1) {	fprintf(stderr, "%s: wrong time specification\n", argv[0]);	exit(1);  }  if ((argc == 4 || argc == 5) && (lday = getlday(argv[2], argv[3])) == -1) {	fprintf(stderr, "%s: wrong date specification\n", argv[0]);	exit(1);  }  if ((argc == 3 || argc == 5) && open(argv[argc - 1], O_RDONLY) == -1) {	fprintf(stderr, "%s: cannot find: %s\n", argv[0], argv[argc - 1]);	exit(1);  }  if ((pin = popen("pwd", "r")) == NULL) {	fprintf(stderr, "%s: cannot open pipe to cmd 'pwd'\n", argv[0]);	exit(1);  }/*-------------------------------------------------------------------------* *	determine execution time and create 'at' job file		   * *-------------------------------------------------------------------------*/  time(&clk);  p = localtime(&clk);  year = p->tm_year;  if (lday == NODAY) {		/* no [month day] given */	lday = p->tm_yday;	if (ltim <= (p->tm_hour * 100 + p->tm_min)) {		lday++;		if ((lday == MAXDAYNR && (year % 4)) || lday == MAXDAYNR + 1) {			lday = STARTDAY;			year++;		}	}  } else	switch (year % 4) {	    case 0:		if (lday < p->tm_yday ||		    (lday == p->tm_yday &&		    ltim <= (p->tm_hour * 100 + p->tm_min))) {			year++;			if (lday > LEAPDAY) lday--;		}		break;	    case 1:	    case 2:		if (lday > LEAPDAY) lday--;		if (lday < p->tm_yday ||		    (lday == p->tm_yday &&		     ltim <= (p->tm_hour * 100 + p->tm_min)))			year++;		break;	    case 3:		if (lday < ((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) ||		    (lday ==((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) &&		     ltim <= (p->tm_hour * 100 + p->tm_min)))			year++;		else if (lday > LEAPDAY)			lday--;		break;	}  sprintf(job, "/usr/spool/at/%02d.%03d.%04d.%02d",	year % 100, lday, ltim, getpid() % 100);  if ((fp = fopen(job, "w")) == NULL) {	fprintf(stderr, "%s: cannot create %s\n", argv[0], job);	exit(1);  }/*-------------------------------------------------------------------------* *	write environment and command(s) to 'at'job file		   * *-------------------------------------------------------------------------*/  i = 0;  while (envp[i] != NULL) {	count = 1;	dp = buf;	sp = envp[i];	while ((*dp++ = *sp++) != '=') count++;	*--dp = '\0';	fprintf(fp, "%s='%s'; export %s\n", buf, &envp[i++][count], buf);  }  fprintf(fp, "cd ");  while ((c = getc(pin)) != EOF) putc(c, fp);  fprintf(fp, "umask %o\n", umask(0));  if (argc == 3 || argc == 5)	fprintf(fp, "%s\n", argv[argc - 1]);  else				/* read from stdinput */	while ((c = getchar()) != EOF) putc(c, fp);  fclose(fp);  if (chown(job, getuid(), getgid()) == -1)	unlink(job);		 /* else there could be a security hole */  printf("%s: %s created\n", argv[0], job);  return(0);}/*-------------------------------------------------------------------------* *	getltim()		return((time OK) ? daytime : -1)	   * *-------------------------------------------------------------------------*/int getltim(t)char *t;{  if (t[4] == '\0' && t[3] >= '0' && t[3] <= '9' &&      t[2] >= '0' && t[2] <= '5' && t[1] >= '0' && t[1] <= '9' &&      (t[0] == '0' || t[0] == '1' || (t[1] <= '3' && t[0] == '2')))	return(atoi(t));  else	return(-1);}/*-------------------------------------------------------------------------* *	getlday()		return ((date OK) ? yearday : -1)	   * *-------------------------------------------------------------------------*/int getlday(m, d)char *m, *d;{  int i, day, im;  static int cumday[] = {0, 0, 31, 60, 91, 121, 152,		       182, 213, 244, 274, 305, 335};  static struct date {	char *mon;	int dcnt;  } *pc,   kal[] = {	"Jan", 31, "Feb", 29, "Mar", 31, "Apr", 30,	"May", 31, "Jun", 30, "Jul", 31, "Aug", 31,	"Sep", 30, "Oct", 31, "Nov", 30, "Dec", 31  };  pc = kal;  im = (digitstring(m)) ? atoi(m) : 0;  m[0] &= 0337;  for (i = 1; i < 13 && strcmp(m, pc->mon) && im != i; i++, pc++);  if (i < 13 && (day = (digitstring(d)) ? atoi(d) : 0) && day <= pc->dcnt) {	if (!STARTDAY) day--;	return(day + cumday[i]);  } else	return(-1);}int digitstring(s)char *s;{  while (*s >= '0' && *s <= '9') s++;  return((*s == '\0') ? 1 : 0);}