Support inotify to watch crontab directories

.gitignore

@@ -1,2 +1,6 @@
 *.swp
 protos.h
+*.o
+crond
+crontab
+config

database.c

@@ -18,6 +18,7 @@
 #define ALL_DOW    (FIRST_DOW|SECOND_DOW|THIRD_DOW|FOURTH_DOW|FIFTH_DOW|LAST_DOW)
 
 Prototype void CheckUpdates(const char *dpath, const char *user_override, time_t t1, time_t t2);
+Prototype void CheckFile(const char *dpath, const char *fileName, const char *user_override);
 Prototype void SynchronizeDir(const char *dpath, const char *user_override, int initial_scan);
 Prototype void ReadTimestamps(const char *user);
 Prototype int TestJobs(time_t t1, time_t t2);
@@ -216,18 +217,7 @@ SynchronizeDir(const char *dpath, const char *user_override, int initial_scan)
 	 */
 	if ((dir = opendir(dpath)) != NULL) {
 		while ((den = readdir(dir)) != NULL) {
-			if (strchr(den->d_name, '.') != NULL)
-				continue;
-			if (strcmp(den->d_name, CRONUPDATE) == 0)
-				continue;
-			if (user_override) {
-				SynchronizeFile(dpath, den->d_name, user_override);
-			} else if (getpwnam(den->d_name)) {
-				SynchronizeFile(dpath, den->d_name, den->d_name);
-			} else {
-				printlogf(LOG_WARNING, "ignoring %s/%s (non-existent user)\n",
-						dpath, den->d_name);
-			}
+			CheckFile(dpath, den->d_name, user_override);
 		}
 		closedir(dir);
 	} else {
@@ -237,6 +227,22 @@ SynchronizeDir(const char *dpath, const char *user_override, int initial_scan)
 	}
 }
 
+void
+CheckFile(const char *dpath, const char *fileName, const char *user_override)
+{
+	if (strchr(fileName, '.') != NULL)
+		return;
+	if (strcmp(fileName, CRONUPDATE) == 0)
+		return;
+	if (user_override) {
+		SynchronizeFile(dpath, fileName, user_override);
+	} else if (getpwnam(fileName)) {
+		SynchronizeFile(dpath, fileName, fileName);
+	} else {
+		printlogf(LOG_WARNING, "ignoring %s/%s (non-existent user)\n",
+				dpath, fileName);
+	}
+}
 
 void
 ReadTimestamps(const char *user)

defs.h

@@ -45,6 +45,11 @@
 #include <string.h>
 #include <stdio.h>
 
+#ifdef USE_INOTIFY
+#include <poll.h>
+#include <sys/inotify.h>
+#endif
+
 #define Prototype extern
 #define arysize(ary)	(sizeof(ary)/sizeof((ary)[0]))
 

main.c

@@ -301,9 +301,67 @@ main(int ac, char **av)
 		long dt;
 		short rescan = 60;
 		short stime = 60;
+#ifdef USE_INOTIFY
+		int notify;
+		int wd[2];
+		const char *watchDirs[2] = { CDir, SCDir };
+		struct pollfd fds[1];
+		int poll_num;
+		notify = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
+		if (notify == -1) {
+			printlogf(LOG_ERR, "Failed to initialize inotify: %m\n");
+			exit(EXIT_FAILURE);
+		}
+		for (i = 0; i < 2; ++i) {
+			wd[i] = inotify_add_watch(notify, watchDirs[i], IN_CLOSE_WRITE | IN_DELETE);
+			if (wd[i] == -1) {
+				printlogf(LOG_ERR, "Cannot watch '%s': %m\n", watchDirs[i]);
+				exit(EXIT_FAILURE);
+			}
+		}
+		fds[0].fd = notify;
+		fds[0].events = POLLIN;
+#endif
 
 		for (;;) {
-			sleep((stime + 1) - (short)(time(NULL) % stime));
+			int seconds_to_wait = (stime + 1) - (short)(time(NULL) % stime);
+#ifdef USE_INOTIFY
+			/* Follows example from Linux inotify man page */
+			poll_num = poll(fds, 1, seconds_to_wait * 1000);
+			if (poll_num == -1) {
+				if (errno == EINTR)
+					continue;
+				printlogf(LOG_ERR, "Poll failed: %m\n");
+				exit(EXIT_FAILURE);
+			}
+			if (poll_num > 0) {
+				char buf[4096] __attribute__ ((aligned(__alignof__(struct inotify_event))));
+				const struct inotify_event *event;
+				ssize_t len;
+				char *ptr;
+				for (;;) {
+					len = read(notify, buf, sizeof buf);
+					if (len == -1 && errno != EAGAIN) {
+						printlogf(LOG_ERR, "Read from inotify failed: %m\n");
+						exit(EXIT_FAILURE);
+					}
+					if (len <= 0)
+						break;
+					for (ptr = buf; ptr < buf + len; ptr += sizeof(struct inotify_event) + event->len) {
+						event = (const struct inotify_event *) ptr;
+						if (event->mask & (IN_CLOSE_WRITE | IN_DELETE)) {
+							if (event->wd == wd[0])
+								CheckFile(CDir, event->name, NULL);
+							else
+								CheckFile(SCDir, event->name, "root");
+						}
+					}
+				}
+				continue; /* sleep again */
+			}
+#else
+			sleep(seconds_to_wait);
+#endif
 
 			t2 = time(NULL);
 			dt = t2 - t1;