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| -rw-r--r-- | snooze.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/snooze.c b/snooze.c new file mode 100644 index 0000000..ce6d93d --- /dev/null +++ b/snooze.c @@ -0,0 +1,333 @@ +/* + * snooze - run a command at a particular time + * + * To the extent possible under law, + * Christian Neukirchen <chneukirchen@gmail.com> + * has waived all copyright and related or neighboring rights to this work. + * http://creativecommons.org/publicdomain/zero/1.0/ + */ + +/* +##% gcc -Os -Wall -g -o $STEM $FILE -Wextra -Wwrite-strings +*/ + +#include <sys/stat.h> +#include <sys/types.h> + +#include <ctype.h> +#include <errno.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include <unistd.h> + +#ifdef __linux__ +#include <sys/auxv.h> +#endif + +static long slack = 60; +#define SLEEP_PHASE 300 +static int nflag, vflag; + +static int timewait = 1; +static int randdelay = 0; +static char *timefile; + +static sig_atomic_t alarm_rang = 0; + +static void +wakeup(int sig) +{ + (void)sig; + alarm_rang = 1; +} + +static long +parse_int(char **s, size_t minn, size_t maxn) +{ + long n; + char *end; + + errno = 0; + n = strtol(*s, &end, 10); + if (errno) { + perror("strtol"); + exit(1); + } + if (n < (long)minn || n >= (long)maxn) { + fprintf(stderr, "number outside %zd <= n < %zd\n", minn, maxn); + exit(1); + } + *s = end; + return n; +} + +static int +parse(char *expr, char *buf, long bufsiz, int offset) +{ + char *s; + long i, n = 0, n0 = 0; + + memset(buf, ' ', bufsiz); + + s = expr; + while (*s) { + switch (*s) { + case '0': case '1': case '2': case '3': case '4': + case '5': case '6': case '7': case '8': case '9': + n = parse_int(&s, -offset, bufsiz); + buf[n+offset] = '*'; + break; + case '-': + n0 = n; + s++; + n = parse_int(&s, -offset, bufsiz); + for (i = n0; i <= n; i++) + buf[i+offset] = '*'; + break; + case '/': + s++; + n0 = n; + n = parse_int(&s, -offset, bufsiz); + if (n == 0) // / = * + n = 1; + for (i = n0; i < bufsiz; i += n) + buf[i+offset] = '*'; + break; + case ',': + s++; + n = 0; + break; + case '*': + s++; + n = 0; + for (i = 0; i < bufsiz; i++) + buf[i+offset] = '*'; + break; + default: + fprintf(stderr, "can't parse: %s %s\n", expr, s); + exit(1); + } + } + + return 0; +} + +char weekday[8] = {0}; +char dayofmonth[31] = {0}; +char month[12] = {0}; +char dayofyear[366] = {0}; +char weekofyear[53] = {0}; +char hour[24] = {0}; +char minute[60] = {0}; +char second[61] = {0}; + +int +isoweek(struct tm *tm) +{ + /* ugh, but easier than the correct formula... */ + char weekstr[3]; + char *w = weekstr; + strftime(weekstr, sizeof weekstr, "%V", tm); + return parse_int(&w, 1, 54); +} + +time_t +find_next(time_t from) +{ + time_t t; + struct tm *tm; + + t = from; + tm = localtime(&t); + +next_day: + while (!(weekday[tm->tm_wday] == '*' + && dayofmonth[tm->tm_mday-1] == '*' + && month[tm->tm_mon] == '*' + && weekofyear[isoweek(tm)] == '*' + && dayofyear[tm->tm_yday] == '*')) { + if (month[tm->tm_mon] != '*') { + // if month is not good, step month + tm->tm_mon++; + tm->tm_mday = 1; + } else { + tm->tm_mday++; + } + + tm->tm_sec = 0; + tm->tm_min = 0; + tm->tm_hour = 0; + + t = mktime(tm); + if (t > from+(365*24*60*60)) // no result within a year + return -1; + } + + int y = tm->tm_yday; // save yday + + while (!(hour[tm->tm_hour] == '*' + && minute[tm->tm_min] == '*' + && second[tm->tm_sec] == '*')) { + if (hour[tm->tm_hour] != '*') { + tm->tm_hour++; + tm->tm_min = 0; + tm->tm_sec = 0; + } else if (minute[tm->tm_min] != '*') { + tm->tm_min++; + tm->tm_sec = 0; + } else { + tm->tm_sec++; + } + t = mktime(tm); + if (tm->tm_yday != y) // hit a different day, retry... + goto next_day; + } + + return t; +} + +static char isobuf[25]; +char * +isotime(const struct tm *tm) +{ + strftime(isobuf, sizeof isobuf, "%FT%T%z", tm); + return isobuf; +} + +int main(int argc, char *argv[]) +{ + int c; + time_t now = time(0); + + /* default: every day at 00:00:00 */ + memset(weekday, '*', sizeof weekday); + memset(dayofmonth, '*', sizeof dayofmonth); + memset(month, '*', sizeof month); + memset(dayofyear, '*', sizeof dayofyear); + memset(weekofyear, '*', sizeof weekofyear); + hour[0] = '*'; + minute[0] = '*'; + second[0] = '*'; + + while ((c = getopt(argc, argv, "D:W:H:M:S:T:R:d:m:ns:t:vw:")) != -1) + switch(c) { + case 'D': parse(optarg, dayofyear, sizeof dayofyear, -1); break; + case 'W': parse(optarg, weekofyear, sizeof weekofyear, -1); break; + case 'H': parse(optarg, hour, sizeof hour, 0); break; + case 'M': parse(optarg, minute, sizeof minute, 0); break; + case 'S': parse(optarg, second, sizeof second, 0); break; + case 'd': parse(optarg, dayofmonth, sizeof dayofmonth, -1); break; + case 'm': parse(optarg, month, sizeof month, -1); break; + case 'w': parse(optarg, weekday, sizeof weekday, 0); + // special case: sunday is both 0 and 7. + if (weekday[7] == '*') + weekday[0] = '*'; + break; + case 'n': nflag++; break; + case 'v': vflag++; break; + case 's': slack = atoi(optarg); break; + case 'T': timewait = atoi(optarg); break; + case 't': timefile = optarg; break; + case 'R': randdelay = atoi(optarg); break; + default: + fprintf(stderr, "Usage: %s [-nv] [-t timefile] [-T timewait] [-R randdelay] [-s slack]\n" + " [-d mday] [-m mon] [-w wday] [-D yday] [-W yweek] [-H hour] [-M min] [-S sec] COMMAND...\n" + "Timespec: exact: 1,3,5\n" + " range: 1-7\n" + " every n-th: /10\n", argv[0]); + exit(2); + } + + time_t start = now + 1; + + if (timefile) { + struct stat st; + if (stat(timefile, &st) < 0) { + if (errno != ENOENT) + perror("stat"); + } else { + if (st.st_mtime + timewait > start) + start = st.st_mtime + timewait; + } + } + + if (randdelay) { + long delay; +#ifdef __linux__ + long rnd = getauxval(AT_RANDOM); + if (rnd > 0) + delay = rnd % randdelay; + else +#endif + { + srand48(getpid() ^ start); + delay = lrand48() % randdelay; + } + if (vflag) + printf("randomly delaying by %lds.\n", delay); + start += delay; + } + + time_t t = find_next(start); + if (t < 0) { + fprintf(stderr, "no satisfying date found within a year.\n"); + exit(2); + } + + if (nflag) { + /* dry-run, just output the next 5 dates. */ + int i; + for (i = 0; i < 5; i++) { + if (t > 0) + printf("%s\n", isotime(localtime(&t))); + t = find_next(t + 1); + } + exit(0); + } + + struct tm *tm = localtime(&t); + if (vflag) + printf("Snoozing until %s\n", isotime(tm)); + + // setup SIGALRM handler to force early execution + struct sigaction sa; + sa.sa_handler = &wakeup; + sa.sa_flags = SA_RESTART; + sigfillset(&sa.sa_mask); + sigaction(SIGALRM, &sa, NULL); // XXX error handling + + while (!alarm_rang) { + now = time(0); + t = mktime(tm); + if (t <= now) { + if (now - t <= slack) // still about time + break; + else { // reschedule to next event + if (vflag) + printf("Missed execution at %s\n", isobuf); + t = find_next(now + 1); + tm = localtime(&t); + if (vflag) + printf("Snoozing until %s\n", isotime(tm)); + } + } else { + // do some sleeping, but not more than SLEEP_PHASE + struct timespec ts; + ts.tv_nsec = 0; + ts.tv_sec = t - now > SLEEP_PHASE ? SLEEP_PHASE : t - now; + nanosleep(&ts, 0); + // we just iterate again when this exits early + } + } + + // no command to run, the outside script can go on + if (argc == optind) + return 0; + + execvp(argv[optind], argv+optind); + perror("execvp"); + return 255; +} |