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authorChristian Neukirchen <chneukirchen@gmail.com>2015-11-04 15:34:46 +0100
committerChristian Neukirchen <chneukirchen@gmail.com>2015-11-04 15:34:46 +0100
commit56480881978a4cb5813746232de9950d46cb3369 (patch)
tree66a2ab83d8ad600eaa9fd51058f4659a5f84bb53 /snooze.c
initial commit of snooze
Diffstat (limited to 'snooze.c')
-rw-r--r--snooze.c333
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;
+}