218 lines
6 KiB
C
218 lines
6 KiB
C
/* at - run a command at a specified time Author: Jan Looyen */
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#include <sys/types.h>
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#include <time.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <limits.h>
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#include <signal.h>
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#include <errno.h>
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#define STARTDAY 0 /* see ctime(3) */
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#define LEAPDAY (STARTDAY+59)
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#define MAXDAYNR (STARTDAY+365)
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#define NODAY (-2)
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char CRONPID[] = "/usr/run/cron.pid";
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int main(int argc, char **argv, char **envp);
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int getltim(char *t);
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int getlday(char *m, char *d);
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int digitstring(char *s);
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int main(int argc, char **argv, char **envp)
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{
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int i, c, mask, ltim, year, lday = NODAY;
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char buf[64], job[30], pastjob[35], *dp, *sp;
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struct tm *p;
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long clk;
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FILE *fp;
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char pwd[PATH_MAX+1];
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/*-------------------------------------------------------------------------*
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* check arguments & pipe to "pwd" *
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*-------------------------------------------------------------------------*/
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if (argc < 2 || argc > 5) {
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fprintf(stderr, "Usage: %s time [month day] [file]\n", argv[0]);
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exit(1);
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}
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if ((ltim = getltim(argv[1])) == -1) {
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fprintf(stderr, "%s: wrong time specification\n", argv[0]);
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exit(1);
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}
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if ((argc == 4 || argc == 5) && (lday = getlday(argv[2], argv[3])) == -1) {
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fprintf(stderr, "%s: wrong date specification\n", argv[0]);
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exit(1);
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}
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if ((argc == 3 || argc == 5) && open(argv[argc - 1], O_RDONLY) == -1) {
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fprintf(stderr, "%s: cannot find: %s\n", argv[0], argv[argc - 1]);
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exit(1);
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}
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if (getcwd(pwd, sizeof(pwd)) == NULL) {
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fprintf(stderr, "%s: cannot determine current directory: %s\n",
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argv[0], strerror(errno));
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exit(1);
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}
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/*-------------------------------------------------------------------------*
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* determine execution time and create 'at' job file *
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*-------------------------------------------------------------------------*/
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time(&clk);
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p = localtime(&clk);
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year = p->tm_year;
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if (lday == NODAY) { /* no [month day] given */
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lday = p->tm_yday;
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if (ltim <= (p->tm_hour * 100 + p->tm_min)) {
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lday++;
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if ((lday == MAXDAYNR && (year % 4)) || lday == MAXDAYNR + 1) {
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lday = STARTDAY;
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year++;
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}
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}
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} else
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switch (year % 4) {
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case 0:
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if (lday < p->tm_yday ||
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(lday == p->tm_yday &&
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ltim <= (p->tm_hour * 100 + p->tm_min))) {
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year++;
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if (lday > LEAPDAY) lday--;
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}
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break;
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case 1:
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case 2:
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if (lday > LEAPDAY) lday--;
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if (lday < p->tm_yday ||
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(lday == p->tm_yday &&
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ltim <= (p->tm_hour * 100 + p->tm_min)))
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year++;
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break;
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case 3:
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if (lday < ((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) ||
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(lday ==((lday > LEAPDAY) ? p->tm_yday + 1 : p->tm_yday) &&
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ltim <= (p->tm_hour * 100 + p->tm_min)))
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year++;
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else if (lday > LEAPDAY)
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lday--;
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break;
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}
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sprintf(job, "/usr/spool/at/%02d.%03d.%04d.%02d",
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year % 100, lday, ltim, getpid() % 100);
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sprintf(pastjob, "/usr/spool/at/past/%02d.%03d.%04d.%02d",
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year % 100, lday, ltim, getpid() % 100);
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mask= umask(0077);
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if ((fp = fopen(pastjob, "w")) == NULL) {
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fprintf(stderr, "%s: cannot create %s: %s\n",
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argv[0], pastjob, strerror(errno));
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exit(1);
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}
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/*-------------------------------------------------------------------------*
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* write environment and command(s) to 'at'job file *
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*-------------------------------------------------------------------------*/
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i = 0;
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while ((sp= envp[i++]) != NULL) {
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dp = buf;
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while ((c= *sp++) != '\0' && c != '=' && dp < buf+sizeof(buf)-1)
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*dp++ = c;
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if (c != '=') continue;
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*dp = '\0';
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fprintf(fp, "%s='", buf);
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while (*sp != 0) {
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if (*sp == '\'')
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fprintf(fp, "'\\''");
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else
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fputc(*sp, fp);
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sp++;
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}
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fprintf(fp, "'; export %s\n", buf);
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}
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fprintf(fp, "cd '%s'\n", pwd);
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fprintf(fp, "umask %o\n", mask);
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if (argc == 3 || argc == 5)
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fprintf(fp, "%s\n", argv[argc - 1]);
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else /* read from stdinput */
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while ((c = getchar()) != EOF) putc(c, fp);
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fclose(fp);
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if (chown(pastjob, getuid(), getgid()) == -1) {
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fprintf(stderr, "%s: cannot set ownership of %s: %s\n",
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argv[0], pastjob, strerror(errno));
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unlink(pastjob);
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exit(1);
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}
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/* "Arm" the job. */
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if (rename(pastjob, job) == -1) {
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fprintf(stderr, "%s: cannot move %s to %s: %s\n",
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argv[0], pastjob, job, strerror(errno));
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unlink(pastjob);
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exit(1);
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}
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printf("%s: %s created\n", argv[0], job);
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/* Alert cron to the new situation. */
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if ((fp= fopen(CRONPID, "r")) != NULL) {
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unsigned long pid;
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pid= 0;
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while ((c= fgetc(fp)) != EOF && c != '\n') {
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if ((unsigned) (c - '0') >= 10) { pid= 0; break; }
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pid= 10*pid + (c - '0');
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if (pid >= 30000) { pid= 0; break; }
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}
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if (pid > 1) kill((pid_t) pid, SIGHUP);
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}
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return(0);
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}
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/*-------------------------------------------------------------------------*
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* getltim() return((time OK) ? daytime : -1) *
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*-------------------------------------------------------------------------*/
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int getltim(char *t)
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{
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if (t[4] == '\0' && t[3] >= '0' && t[3] <= '9' &&
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t[2] >= '0' && t[2] <= '5' && t[1] >= '0' && t[1] <= '9' &&
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(t[0] == '0' || t[0] == '1' || (t[1] <= '3' && t[0] == '2')))
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return(atoi(t));
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else
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return(-1);
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}
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/*-------------------------------------------------------------------------*
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* getlday() return ((date OK) ? yearday : -1) *
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*-------------------------------------------------------------------------*/
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int getlday(char *m, char *d)
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{
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int i, day, im;
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static int cumday[] = {0, 0, 31, 60, 91, 121, 152,
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182, 213, 244, 274, 305, 335};
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static struct date {
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char *mon;
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int dcnt;
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} *pc, kal[] = {
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{ "Jan", 31 }, { "Feb", 29 }, { "Mar", 31 }, { "Apr", 30 },
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{ "May", 31 }, { "Jun", 30 }, { "Jul", 31 }, { "Aug", 31 },
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{ "Sep", 30 }, { "Oct", 31 }, { "Nov", 30 }, { "Dec", 31 },
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};
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pc = kal;
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im = (digitstring(m)) ? atoi(m) : 0;
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m[0] &= 0337;
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for (i = 1; i < 13 && strcmp(m, pc->mon) && im != i; i++, pc++);
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if (i < 13 && (day = (digitstring(d)) ? atoi(d) : 0) && day <= pc->dcnt) {
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if (!STARTDAY) day--;
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return(day + cumday[i]);
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} else
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return(-1);
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}
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int digitstring(char *s)
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{
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while (*s >= '0' && *s <= '9') s++;
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return((*s == '\0') ? 1 : 0);
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}
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