minix3/commands/at/at.c

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2020-02-21 00:59:27 +05:30
/* 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>
#include <limits.h>
#include <signal.h>
#include <errno.h>
#define STARTDAY 0 /* see ctime(3) */
#define LEAPDAY (STARTDAY+59)
#define MAXDAYNR (STARTDAY+365)
#define NODAY (-2)
char CRONPID[] = "/usr/run/cron.pid";
int main(int argc, char **argv, char **envp);
int getltim(char *t);
int getlday(char *m, char *d);
int digitstring(char *s);
int main(int argc, char **argv, char **envp)
{
int i, c, mask, ltim, year, lday = NODAY;
char buf[64], job[30], pastjob[35], *dp, *sp;
struct tm *p;
long clk;
FILE *fp;
char pwd[PATH_MAX+1];
/*-------------------------------------------------------------------------*
* 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 (getcwd(pwd, sizeof(pwd)) == NULL) {
fprintf(stderr, "%s: cannot determine current directory: %s\n",
argv[0], strerror(errno));
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);
sprintf(pastjob, "/usr/spool/at/past/%02d.%03d.%04d.%02d",
year % 100, lday, ltim, getpid() % 100);
mask= umask(0077);
if ((fp = fopen(pastjob, "w")) == NULL) {
fprintf(stderr, "%s: cannot create %s: %s\n",
argv[0], pastjob, strerror(errno));
exit(1);
}
/*-------------------------------------------------------------------------*
* write environment and command(s) to 'at'job file *
*-------------------------------------------------------------------------*/
i = 0;
while ((sp= envp[i++]) != NULL) {
dp = buf;
while ((c= *sp++) != '\0' && c != '=' && dp < buf+sizeof(buf)-1)
*dp++ = c;
if (c != '=') continue;
*dp = '\0';
fprintf(fp, "%s='", buf);
while (*sp != 0) {
if (*sp == '\'')
fprintf(fp, "'\\''");
else
fputc(*sp, fp);
sp++;
}
fprintf(fp, "'; export %s\n", buf);
}
fprintf(fp, "cd '%s'\n", pwd);
fprintf(fp, "umask %o\n", mask);
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(pastjob, getuid(), getgid()) == -1) {
fprintf(stderr, "%s: cannot set ownership of %s: %s\n",
argv[0], pastjob, strerror(errno));
unlink(pastjob);
exit(1);
}
/* "Arm" the job. */
if (rename(pastjob, job) == -1) {
fprintf(stderr, "%s: cannot move %s to %s: %s\n",
argv[0], pastjob, job, strerror(errno));
unlink(pastjob);
exit(1);
}
printf("%s: %s created\n", argv[0], job);
/* Alert cron to the new situation. */
if ((fp= fopen(CRONPID, "r")) != NULL) {
unsigned long pid;
pid= 0;
while ((c= fgetc(fp)) != EOF && c != '\n') {
if ((unsigned) (c - '0') >= 10) { pid= 0; break; }
pid= 10*pid + (c - '0');
if (pid >= 30000) { pid= 0; break; }
}
if (pid > 1) kill((pid_t) pid, SIGHUP);
}
return(0);
}
/*-------------------------------------------------------------------------*
* getltim() return((time OK) ? daytime : -1) *
*-------------------------------------------------------------------------*/
int getltim(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(char *m, char *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(char *s)
{
while (*s >= '0' && *s <= '9') s++;
return((*s == '\0') ? 1 : 0);
}