minix/commands/at/at.c

   1 /* at - run a command at a specified time       Author: Jan Looyen */
   2
   3 #include <sys/types.h>
   4 #include <time.h>
   5 #include <fcntl.h>
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <sys/stat.h>
  10 #include <stdio.h>
  11 #include <limits.h>
  12 #include <signal.h>
  13 #include <errno.h>
  14
  15 #define STARTDAY        0       /* see ctime(3)  */
  16 #define LEAPDAY         (STARTDAY+59)
  17 #define MAXDAYNR        (STARTDAY+365)
  18 #define NODAY           (-2)
  19 char CRONPID[]  =       "/usr/run/cron.pid";
  20
  21 int main(int argc, char **argv, char **envp);
  22 int getltim(char *t);
  23 int getlday(char *m, char *d);
  24 int digitstring(char *s);
  25
  26 int main(int argc, char **argv, char **envp)
  27 {
  28   int i, c, mask, ltim, year, lday = NODAY;
  29   char buf[64], job[30], pastjob[35], *dp, *sp;
  30   struct tm *p;
  31   time_t clk;
  32   FILE *fp;
  33   char pwd[PATH_MAX+1];
  34
  35 /*-------------------------------------------------------------------------*
  36  *      check arguments & pipe to "pwd"                                    *
  37  *-------------------------------------------------------------------------*/
  38   if (argc < 2 || argc > 5) {
  39         fprintf(stderr, "Usage: %s time [month day] [file]\n", argv[0]);
  40         exit(1);
  41   }
  42   if ((ltim = getltim(argv[1])) == -1) {
  43         fprintf(stderr, "%s: wrong time specification\n", argv[0]);
  44         exit(1);
  45   }
  46   if ((argc == 4 || argc == 5) && (lday = getlday(argv[2], argv[3])) == -1) {
  47         fprintf(stderr, "%s: wrong date specification\n", argv[0]);
  48         exit(1);
  49   }
  50   if ((argc == 3 || argc == 5) && open(argv[argc - 1], O_RDONLY) == -1) {
  51         fprintf(stderr, "%s: cannot find: %s\n", argv[0], argv[argc - 1]);
  52         exit(1);
  53   }
  54   if (getcwd(pwd, sizeof(pwd)) == NULL) {
  55         fprintf(stderr, "%s: cannot determine current directory: %s\n",
  56                 argv[0], strerror(errno));
  57         exit(1);
  58   }
  59
  60 /*-------------------------------------------------------------------------*
  61  *      determine execution time and create 'at' job file                  *
  62  *-------------------------------------------------------------------------*/
  63   time(&clk);
  64   p = localtime(&clk);
  65   year = p->tm_year;
  66   if (lday == NODAY) {          /* no [month day] given */
  67         lday = p->tm_yday;
  68         if (ltim <= (p->tm_hour * 100 + p->tm_min)) {
  69                 lday++;
  70                 if ((lday == MAXDAYNR && (year % 4)) || lday == MAXDAYNR + 1) {
  71                         lday = STARTDAY;
  72                         year++;
  73                 }
  74         }
  75   } else
  76         switch (year % 4) {
  77             case 0:
  78                 if (lday < p->tm_yday ||
  79                     (lday == p->tm_yday &&
  80                     ltim <= (p->tm_hour * 100 + p->tm_min))) {
  81                         year++;
  82                         if (lday > LEAPDAY) lday--;
  83                 }
  84                 break;
  85             case 1:
  86             case 2:
  87                 if (lday > LEAPDAY) lday--;
  88                 if (lday < p->tm_yday ||
  89                     (lday == p->tm_yday &&
  90                      ltim <= (p->tm_hour * 100 + p->tm_min)))
  91                         year++;
  92                 break;
  93             case 3:
  94                 if (lday < ((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) ||
  95                     (lday ==((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) &&
  96                      ltim <= (p->tm_hour * 100 + p->tm_min)))
  97                         year++;
  98                 else if (lday > LEAPDAY)
  99                         lday--;
 100                 break;
 101         }
 102   sprintf(job, "/usr/spool/at/%02d.%03d.%04d.%02d",
 103         year % 100, lday, ltim, getpid() % 100);
 104   sprintf(pastjob, "/usr/spool/at/past/%02d.%03d.%04d.%02d",
 105         year % 100, lday, ltim, getpid() % 100);
 106   mask= umask(0077);
 107   if ((fp = fopen(pastjob, "w")) == NULL) {
 108         fprintf(stderr, "%s: cannot create %s: %s\n",
 109                 argv[0], pastjob, strerror(errno));
 110         exit(1);
 111   }
 112
 113 /*-------------------------------------------------------------------------*
 114  *      write environment and command(s) to 'at'job file                   *
 115  *-------------------------------------------------------------------------*/
 116   i = 0;
 117   while ((sp= envp[i++]) != NULL) {
 118         dp = buf;
 119         while ((c= *sp++) != '\0' && c != '=' && dp < buf+sizeof(buf)-1)
 120                 *dp++ = c;
 121         if (c != '=') continue;
 122         *dp = '\0';
 123         fprintf(fp, "%s='", buf);
 124         while (*sp != 0) {
 125                 if (*sp == '\'')
 126                         fprintf(fp, "'\\''");
 127                 else
 128                         fputc(*sp, fp);
 129                 sp++;
 130         }
 131         fprintf(fp, "'; export %s\n", buf);
 132   }
 133   fprintf(fp, "cd '%s'\n", pwd);
 134   fprintf(fp, "umask %o\n", mask);
 135   if (argc == 3 || argc == 5)
 136         fprintf(fp, "%s\n", argv[argc - 1]);
 137   else                          /* read from stdinput */
 138         while ((c = getchar()) != EOF) putc(c, fp);
 139   fclose(fp);
 140
 141   if (chown(pastjob, getuid(), getgid()) == -1) {
 142         fprintf(stderr, "%s: cannot set ownership of %s: %s\n",
 143                 argv[0], pastjob, strerror(errno));
 144         unlink(pastjob);
 145         exit(1);
 146   }
 147   /* "Arm" the job. */
 148   if (rename(pastjob, job) == -1) {
 149         fprintf(stderr, "%s: cannot move %s to %s: %s\n",
 150                 argv[0], pastjob, job, strerror(errno));
 151         unlink(pastjob);
 152         exit(1);
 153   }
 154   printf("%s: %s created\n", argv[0], job);
 155
 156   /* Alert cron to the new situation. */
 157   if ((fp= fopen(CRONPID, "r")) != NULL) {
 158         unsigned long pid;
 159
 160         pid= 0;
 161         while ((c= fgetc(fp)) != EOF && c != '\n') {
 162                 if ((unsigned) (c - '0') >= 10) { pid= 0; break; }
 163                 pid= 10*pid + (c - '0');
 164                 if (pid >= 30000) { pid= 0; break; }
 165         }
 166         if (pid > 1) kill((pid_t) pid, SIGHUP);
 167   }
 168   return(0);
 169 }
 170
 171 /*-------------------------------------------------------------------------*
 172  *      getltim()               return((time OK) ? daytime : -1)           *
 173  *-------------------------------------------------------------------------*/
 174 int getltim(char *t)
 175 {
 176   if (t[4] == '\0' && t[3] >= '0' && t[3] <= '9' &&
 177       t[2] >= '0' && t[2] <= '5' && t[1] >= '0' && t[1] <= '9' &&
 178       (t[0] == '0' || t[0] == '1' || (t[1] <= '3' && t[0] == '2')))
 179         return(atoi(t));
 180   else
 181         return(-1);
 182 }
 183
 184 /*-------------------------------------------------------------------------*
 185  *      getlday()               return ((date OK) ? yearday : -1)          *
 186  *-------------------------------------------------------------------------*/
 187 int getlday(char *m, char *d)
 188 {
 189   int i, day, im;
 190   static int cumday[] = {0, 0, 31, 60, 91, 121, 152,
 191                        182, 213, 244, 274, 305, 335};
 192   static struct date {
 193         char *mon;
 194         int dcnt;
 195   } *pc, kal[] = {
 196         { "Jan", 31 }, { "Feb", 29 }, { "Mar", 31 }, { "Apr", 30 },
 197         { "May", 31 }, { "Jun", 30 }, { "Jul", 31 }, { "Aug", 31 },
 198         { "Sep", 30 }, { "Oct", 31 }, { "Nov", 30 }, { "Dec", 31 },
 199   };
 200
 201   pc = kal;
 202   im = (digitstring(m)) ? atoi(m) : 0;
 203   m[0] &= 0337;
 204   for (i = 1; i < 13 && strcmp(m, pc->mon) && im != i; i++, pc++);
 205   if (i < 13 && (day = (digitstring(d)) ? atoi(d) : 0) && day <= pc->dcnt) {
 206         if (!STARTDAY) day--;
 207         return(day + cumday[i]);
 208   } else
 209         return(-1);
 210 }
 211
 212
 213
 214 int digitstring(char *s)
 215 {
 216   while (*s >= '0' && *s <= '9') s++;
 217   return((*s == '\0') ? 1 : 0);
 218 }