X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=dss.c;h=3d00b0b38be37b50878375257d90f9871412c957;hp=d77fef2f8cb31704c619d6cda61fd68570bbbe35;hb=27edbe5dcf615a3c445f719b5833af4d392c5874;hpb=9c4bc98761828cbe3997e071ad5b4d24eb52e599

diff --git a/dss.c b/dss.c
index d77fef2..3d00b0b 100644
--- a/dss.c
+++ b/dss.c
@@ -30,7 +30,6 @@
 
 
 struct gengetopt_args_info conf;
-char *dss_error_txt = NULL;
 static FILE *logfile;
 static int signal_pipe;
 
@@ -42,9 +41,33 @@ static int rsync_stopped;
 static pid_t rm_pid;
 /** When the next snapshot is due. */
 struct timeval next_snapshot_time;
+/** The pid of the pre-create hook. */
+pid_t pre_create_hook_pid;
+/** The pid of the post-create hook. */
+pid_t post_create_hook_pid;
+
 /* Creation time of the snapshot currently being created. */
 int64_t current_snapshot_creation_time;
 
+static char *path_to_last_complete_snapshot;
+
+enum {
+	/** We are ready to take the next snapshot. */
+	SCS_READY,
+	/** The pre-creation hook has been started. */
+	SCS_PRE_HOOK_RUNNING,
+	/** The pre-creation hook exited successfully. */
+	SCS_PRE_HOOK_SUCCESS,
+	/** The rsync process is running. */
+	SCS_RSYNC_RUNNING,
+	/** The rsync process exited successfully. */
+	SCS_RSYNC_SUCCESS,
+	/** The post-create hook has been started- */
+	SCS_POST_HOOK_RUNNING,
+};
+
+static unsigned snapshot_creation_status;
+
 
 DEFINE_DSS_ERRLIST;
 
@@ -89,19 +112,6 @@ struct snapshot {
 	unsigned interval;
 };
 
-/*
- * An edge snapshot is either the oldest one or the newest one.
- *
- * We need to find either of them occasionally: The create code
- * needs to know the newest snapshot because that is the one
- * used as the link destination dir. The pruning code needs to
- * find the oldest one in case disk space becomes low.
- */
-struct edge_snapshot_data {
-	int64_t now;
-	struct snapshot snap;
-};
-
 __printf_2_3 void dss_log(int ll, const char* fmt,...)
 {
 	va_list argp;
@@ -169,10 +179,8 @@ int is_snapshot(const char *dirname, int64_t now, struct snapshot *s)
 	tmp[i] = '\0';
 	ret = dss_atoi64(tmp, &num);
 	free(tmp);
-	if (ret < 0) {
-		free(dss_error_txt);
+	if (ret < 0)
 		return 0;
-	}
 	assert(num >= 0);
 	if (num > now)
 		return 0;
@@ -201,10 +209,8 @@ int is_snapshot(const char *dirname, int64_t now, struct snapshot *s)
 	tmp[i] = '\0';
 	ret = dss_atoi64(tmp, &num);
 	free(tmp);
-	if (ret < 0) {
-		free(dss_error_txt);
+	if (ret < 0)
 		return 0;
-	}
 	if (num > now)
 		return 0;
 	s->completion_time = num;
@@ -246,22 +252,14 @@ int complete_name(int64_t start, int64_t end, char **result)
 	time_t *end_seconds = (time_t *) (uint64_t *)&end; /* STFU, gcc */
 	char start_str[200], end_str[200];
 
-	if (!localtime_r(start_seconds, &start_tm)) {
-		make_err_msg("%lli", (long long)start);
+	if (!localtime_r(start_seconds, &start_tm))
 		return -E_LOCALTIME;
-	}
-	if (!localtime_r(end_seconds, &end_tm)) {
-		make_err_msg("%lli", (long long)end);
+	if (!localtime_r(end_seconds, &end_tm))
 		return -E_LOCALTIME;
-	}
-	if (!strftime(start_str, sizeof(start_str), "%a_%b_%d_%Y_%H_%M_%S", &start_tm)) {
-		make_err_msg("%lli", (long long)start);
+	if (!strftime(start_str, sizeof(start_str), "%a_%b_%d_%Y_%H_%M_%S", &start_tm))
 		return -E_STRFTIME;
-	}
-	if (!strftime(end_str, sizeof(end_str), "%a_%b_%d_%Y_%H_%M_%S", &end_tm)) {
-		make_err_msg("%lli", (long long)end);
+	if (!strftime(end_str, sizeof(end_str), "%a_%b_%d_%Y_%H_%M_%S", &end_tm))
 		return -E_STRFTIME;
-	}
 	*result = make_message("%lli-%lli.%s-%s", (long long) start, (long long) end,
 		start_str, end_str);
 	return 1;
@@ -284,7 +282,15 @@ struct snapshot_list {
 #define FOR_EACH_SNAPSHOT(s, i, sl) \
 	for ((i) = 0; (i) < (sl)->num_snapshots && ((s) = (sl)->snapshots[(i)]); (i)++)
 
+#define FOR_EACH_SNAPSHOT_REVERSE(s, i, sl) \
+	for ((i) = (sl)->num_snapshots; (i) > 0 && ((s) = (sl)->snapshots[(i - 1)]); (i)--)
 
+static inline struct snapshot *oldest_snapshot(struct snapshot_list *sl)
+{
+	if (!sl->num_snapshots)
+		return NULL;
+	return sl->snapshots[0];
+}
 
 #define NUM_COMPARE(x, y) ((int)((x) < (y)) - (int)((x) > (y)))
 
@@ -383,10 +389,14 @@ int wait_for_process(pid_t pid, int *status)
 
 	DSS_DEBUG_LOG("Waiting for process %d to terminate\n", (int)pid);
 	for (;;) {
-		pause();
-		ret = next_signal();
+		fd_set rfds;
+
+		FD_ZERO(&rfds);
+		FD_SET(signal_pipe, &rfds);
+		ret = dss_select(signal_pipe + 1, &rfds, NULL, NULL);
 		if (ret < 0)
 			break;
+		ret = next_signal();
 		if (!ret)
 			continue;
 		if (ret == SIGCHLD) {
@@ -403,7 +413,7 @@ int wait_for_process(pid_t pid, int *status)
 		kill(pid, SIGTERM);
 	}
 	if (ret < 0)
-		make_err_msg("failed to wait for process %d", (int)pid);
+		DSS_ERROR_LOG("failed to wait for process %d\n", (int)pid);
 	else
 		log_termination_msg(pid, *status);
 	return ret;
@@ -445,8 +455,8 @@ int remove_redundant_snapshot(struct snapshot_list *sl)
 
 		if (keep >= num)
 			missing += keep - num;
-		DSS_DEBUG_LOG("interval %i: keep: %u, have: %u, missing: %u\n",
-			interval, keep, num, missing);
+//		DSS_DEBUG_LOG("interval %i: keep: %u, have: %u, missing: %u\n",
+//			interval, keep, num, missing);
 		if (keep + missing >= num)
 			continue;
 		/* redundant snapshot in this interval, pick snapshot with lowest score */
@@ -513,23 +523,12 @@ int remove_outdated_snapshot(struct snapshot_list *sl)
 
 int handle_rm_exit(int status)
 {
-	int es, ret;
-
-	if (!WIFEXITED(status)) {
-		make_err_msg("rm process %d died involuntary", (int)rm_pid);
-		ret = -E_INVOLUNTARY_EXIT;
-		goto out;
-	}
-	es = WEXITSTATUS(status);
-	if (es) {
-		make_err_msg("rm process %d returned %d", (int)rm_pid, es);
-		ret = -E_BAD_EXIT_CODE;
-		goto out;
-	}
-	ret = 1;
 	rm_pid = 0;
-out:
-	return ret;
+	if (!WIFEXITED(status))
+		return -E_INVOLUNTARY_EXIT;
+	if (WEXITSTATUS(status))
+		return -E_BAD_EXIT_CODE;
+	return 1;
 }
 
 int wait_for_rm_process(void)
@@ -552,12 +551,12 @@ void kill_process(pid_t pid)
 int check_config(void)
 {
 	if (conf.unit_interval_arg <= 0) {
-		make_err_msg("bad unit interval: %i", conf.unit_interval_arg);
+		DSS_ERROR_LOG("bad unit interval: %i\n", conf.unit_interval_arg);
 		return -E_INVALID_NUMBER;
 	}
 	DSS_DEBUG_LOG("unit interval: %i day(s)\n", conf.unit_interval_arg);
 	if (conf.num_intervals_arg <= 0) {
-		make_err_msg("bad number of intervals  %i", conf.num_intervals_arg);
+		DSS_ERROR_LOG("bad number of intervals  %i\n", conf.num_intervals_arg);
 		return -E_INVALID_NUMBER;
 	}
 	DSS_DEBUG_LOG("number of intervals: %i\n", conf.num_intervals_arg);
@@ -589,7 +588,7 @@ void parse_config_file(int override)
 	ret = stat(config_file, &statbuf);
 	if (ret && conf.config_file_given) {
 		ret = -ERRNO_TO_DSS_ERROR(errno);
-		make_err_msg("failed to stat config file %s", config_file);
+		DSS_ERROR_LOG("failed to stat config file %s\n", config_file);
 		goto out;
 	}
 	if (!ret) {
@@ -620,12 +619,14 @@ void parse_config_file(int override)
 		logfile = open_log(conf.logfile_arg);
 		log_welcome(conf.loglevel_arg);
 	}
+	DSS_EMERG_LOG("loglevel: %d\n", conf.loglevel_arg);
+//	cmdline_parser_dump(logfile? logfile : stdout, &conf);
 	ret = dss_chdir(conf.dest_dir_arg);
 out:
 	free(config_file);
 	if (ret >= 0)
 		return;
-	log_err_msg(EMERG, -ret);
+	DSS_EMERG_LOG("%s\n", dss_strerror(-ret));
 	exit(EXIT_FAILURE);
 }
 
@@ -637,69 +638,111 @@ void handle_sighup(void)
 
 int rename_incomplete_snapshot(int64_t start)
 {
-	char *old_name, *new_name;
+	char *old_name;
 	int ret;
 
-	ret = complete_name(start, get_current_time(), &new_name);
+	free(path_to_last_complete_snapshot);
+	ret = complete_name(start, get_current_time(),
+		&path_to_last_complete_snapshot);
 	if (ret < 0)
 		return ret;
 	old_name = incomplete_name(start);
-	ret = dss_rename(old_name, new_name);
+	ret = dss_rename(old_name, path_to_last_complete_snapshot);
 	if (ret >= 0)
-		DSS_NOTICE_LOG("%s -> %s\n", old_name, new_name);
+		DSS_NOTICE_LOG("%s -> %s\n", old_name,
+			path_to_last_complete_snapshot);
 	free(old_name);
-	free(new_name);
 	return ret;
 }
 
+void compute_next_snapshot_time(void)
+{
+	struct timeval now, unit_interval = {.tv_sec = 24 * 3600 * conf.unit_interval_arg},
+		tmp, diff;
+	int64_t x = 0;
+	unsigned wanted = num_snapshots(0), num_complete_snapshots = 0;
+	int i, ret;
+	struct snapshot *s = NULL;
+	struct snapshot_list sl;
+
+	assert(snapshot_creation_status == SCS_READY);
+	current_snapshot_creation_time = 0;
+	get_snapshot_list(&sl);
+	FOR_EACH_SNAPSHOT(s, i, &sl) {
+		if (!(s->flags & SS_COMPLETE))
+			continue;
+		num_complete_snapshots++;
+		x += s->completion_time - s->creation_time;
+	}
+	assert(x >= 0);
+	if (num_complete_snapshots)
+		x /= num_complete_snapshots; /* avg time to create one snapshot */
+	x *= wanted; /* time to create all snapshots in interval 0 */
+	tmp.tv_sec = x;
+	tmp.tv_usec = 0;
+	ret = tv_diff(&unit_interval, &tmp, &diff); /* total sleep time per unit interval */
+	gettimeofday(&now, NULL);
+	if (ret < 0 || !s)
+		goto min_sleep;
+	tv_divide(wanted, &diff, &tmp); /* sleep time betweeen two snapshots */
+	diff.tv_sec = s->completion_time;
+	diff.tv_usec = 0;
+	tv_add(&diff, &tmp, &next_snapshot_time);
+	if (tv_diff(&now, &next_snapshot_time, NULL) < 0)
+		goto out;
+min_sleep:
+	next_snapshot_time = now;
+	next_snapshot_time.tv_sec += 60;
+out:
+	free_snapshot_list(&sl);
+}
+
 int handle_rsync_exit(int status)
 {
 	int es, ret;
 
 	if (!WIFEXITED(status)) {
-		make_err_msg("rsync process %d died involuntary", (int)rsync_pid);
+		DSS_ERROR_LOG("rsync process %d died involuntary\n", (int)rsync_pid);
 		ret = -E_INVOLUNTARY_EXIT;
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
 		goto out;
 	}
 	es = WEXITSTATUS(status);
 	if (es != 0 && es != 23 && es != 24) {
-		make_err_msg("rsync process %d returned %d", (int)rsync_pid, es);
+		DSS_ERROR_LOG("rsync process %d returned %d\n", (int)rsync_pid, es);
 		ret = -E_BAD_EXIT_CODE;
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
 		goto out;
 	}
 	ret = rename_incomplete_snapshot(current_snapshot_creation_time);
+	if (ret < 0)
+		goto out;
+	snapshot_creation_status = SCS_RSYNC_SUCCESS;
 out:
 	rsync_pid = 0;
-	current_snapshot_creation_time = 0;
 	rsync_stopped = 0;
 	return ret;
 }
 
-int get_newest_complete(const char *dirname, void *private)
+__malloc char *name_of_newest_complete_snapshot(void)
 {
-	struct edge_snapshot_data *esd = private;
-	struct snapshot s;
-	int ret = is_snapshot(dirname, esd->now, &s);
+	struct snapshot_list sl;
+	struct snapshot *s;
+	int i;
+	char *name = NULL;
 
-	if (ret <= 0)
-		return 1;
-	if (s.flags != SS_COMPLETE) /* incomplete or being deleted */
-		return 1;
-	if (s.creation_time < esd->snap.creation_time)
-		return 1;
-	free(esd->snap.name);
-	esd->snap = s;
-	return 1;
-}
+	get_snapshot_list(&sl);
 
-__malloc char *name_of_newest_complete_snapshot(void)
-{
-	struct edge_snapshot_data esd = {
-		.now = get_current_time(),
-		.snap = {.creation_time = -1}
-	};
-	for_each_subdir(get_newest_complete, &esd);
-	return esd.snap.name;
+	FOR_EACH_SNAPSHOT_REVERSE(s, i, &sl) {
+		if (s->flags != SS_COMPLETE) /* incomplete or being deleted */
+			continue;
+		name = dss_strdup(s->name);
+		break;
+	}
+	free_snapshot_list(&sl);
+	return name;
 }
 
 void create_rsync_argv(char ***argv, int64_t *num)
@@ -747,45 +790,103 @@ void free_rsync_argv(char **argv)
 	free(argv);
 }
 
+int pre_create_hook(void)
+{
+	int ret, fds[3] = {0, 0, 0};
+
+	if (!conf.pre_create_hook_given) {
+		snapshot_creation_status = SCS_PRE_HOOK_SUCCESS;
+		return 0;
+	}
+	DSS_NOTICE_LOG("executing %s\n", conf.pre_create_hook_arg);
+	ret = dss_exec_cmdline_pid(&pre_create_hook_pid,
+		conf.pre_create_hook_arg, fds);
+	if (ret < 0)
+		return ret;
+	snapshot_creation_status = SCS_PRE_HOOK_RUNNING;
+	return ret;
+}
+
+int post_create_hook(void)
+{
+	int ret, fds[3] = {0, 0, 0};
+	char *cmd;
+
+	if (!conf.post_create_hook_given) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		return 0;
+	}
+	cmd = make_message("%s %s", conf.post_create_hook_arg,
+		path_to_last_complete_snapshot);
+	DSS_NOTICE_LOG("executing %s\n", cmd);
+	ret = dss_exec_cmdline_pid(&post_create_hook_pid, cmd, fds);
+	free(cmd);
+	if (ret < 0)
+		return ret;
+	snapshot_creation_status = SCS_POST_HOOK_RUNNING;
+	return ret;
+}
+
 int create_snapshot(char **argv)
 {
-	int fds[3] = {0, 0, 0};
-	char *name = incomplete_name(current_snapshot_creation_time);
+	int ret, fds[3] = {0, 0, 0};
+	char *name;
 
+	name = incomplete_name(current_snapshot_creation_time);
 	DSS_NOTICE_LOG("creating new snapshot %s\n", name);
 	free(name);
-	return dss_exec(&rsync_pid, argv[0], argv, fds);
+	ret = dss_exec(&rsync_pid, argv[0], argv, fds);
+	if (ret < 0)
+		return ret;
+	snapshot_creation_status = SCS_RSYNC_RUNNING;
+	return ret;
 }
 
-void compute_next_snapshot_time(struct snapshot_list *sl)
+int handle_pre_create_hook_exit(int status)
 {
-	struct timeval now, unit_interval = {.tv_sec = 24 * 3600 * conf.unit_interval_arg},
-		tmp, diff;
-	int64_t x = 0;
-	unsigned wanted = num_snapshots(0), num_complete_snapshots = 0;
-	int i, ret;
-	struct snapshot *s;
+	int es, ret;
 
-	gettimeofday(&now, NULL);
-	FOR_EACH_SNAPSHOT(s, i, sl) {
-		if (!(s->flags & SS_COMPLETE))
-			continue;
-		num_complete_snapshots++;
-		x += s->completion_time - s->creation_time;
+	if (!WIFEXITED(status)) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		ret = -E_INVOLUNTARY_EXIT;
+		goto out;
 	}
-	assert(x >= 0);
-	if (num_complete_snapshots)
-		x /= num_complete_snapshots; /* avg time to create one snapshot */
-	x *= wanted; /* time to create all snapshots in interval 0 */
-	tmp.tv_sec = x;
-	tmp.tv_usec = 0;
-	ret = tv_diff(&unit_interval, &tmp, &diff); /* time between creation */
-	if (ret < 0) {
-		next_snapshot_time = now;
-		return;
+	es = WEXITSTATUS(status);
+	if (es) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		ret = -E_BAD_EXIT_CODE;
+		goto out;
 	}
-	tv_divide(wanted, &diff, &tmp);
-	tv_add(&now, &tmp, &next_snapshot_time);
+	snapshot_creation_status = SCS_PRE_HOOK_SUCCESS;
+	ret = 1;
+out:
+	pre_create_hook_pid = 0;
+	return ret;
+}
+
+int handle_sigchld()
+{
+	pid_t pid;
+	int status, ret = reap_child(&pid, &status);
+
+	if (ret <= 0)
+		return ret;
+	if (pid == rsync_pid)
+		return handle_rsync_exit(status);
+	if (pid == rm_pid)
+		return handle_rm_exit(status);
+	if (pid == pre_create_hook_pid)
+		return handle_pre_create_hook_exit(status);
+	if (pid == post_create_hook_pid) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		return 1;
+	}
+	DSS_EMERG_LOG("BUG: unknown process %d died\n", (int)pid);
+	exit(EXIT_FAILURE);
 }
 
 void handle_signal(void)
@@ -796,8 +897,6 @@ void handle_signal(void)
 		goto out;
 	sig = ret;
 	switch (sig) {
-		int status;
-		pid_t pid;
 	case SIGINT:
 	case SIGTERM:
 		restart_rsync_process();
@@ -809,53 +908,24 @@ void handle_signal(void)
 		ret = 1;
 		break;
 	case SIGCHLD:
-		ret = reap_child(&pid, &status);
-		if (ret <= 0)
-			break;
-		assert(pid == rsync_pid || pid == rm_pid);
-		if (pid == rsync_pid)
-			ret = handle_rsync_exit(status);
-		else
-			ret = handle_rm_exit(status);
+		ret = handle_sigchld();
+		break;
 	}
 out:
 	if (ret < 0)
-		log_err_msg(ERROR, -ret);
+		DSS_ERROR_LOG("%s\n", dss_strerror(-ret));
 }
 
-int get_oldest(const char *dirname, void *private)
+int remove_oldest_snapshot(struct snapshot_list *sl)
 {
-	struct edge_snapshot_data *esd = private;
-	struct snapshot s;
-	int ret = is_snapshot(dirname, esd->now, &s);
-
-	if (ret <= 0)
-		return 1;
-	if (s.creation_time > esd->snap.creation_time)
-		return 1;
-	free(esd->snap.name);
-	esd->snap = s;
-	return 1;
-}
+	struct snapshot *s = oldest_snapshot(sl);
 
-int remove_oldest_snapshot()
-{
-	int ret;
-	struct edge_snapshot_data esd = {
-		.now = get_current_time(),
-		.snap = {.creation_time = LLONG_MAX}
-	};
-	for_each_subdir(get_oldest, &esd);
-	if (!esd.snap.name) /* no snapshot found */
+	if (!s) /* no snapshot found */
 		return 0;
-	DSS_INFO_LOG("oldest snapshot: %s\n", esd.snap.name);
-	ret = 0;
-	if (esd.snap.creation_time == current_snapshot_creation_time)
-		goto out; /* do not remove the snapshot currently being created */
-	ret = remove_snapshot(&esd.snap);
-out:
-	free(esd.snap.name);
-	return ret;
+	DSS_INFO_LOG("oldest snapshot: %s\n", s->name);
+	if (s->creation_time == current_snapshot_creation_time)
+		return 0; /* do not remove the snapshot currently being created */
+	return remove_snapshot(s);
 }
 
 /* TODO: Also consider number of inodes. */
@@ -875,55 +945,56 @@ int disk_space_low(void)
 	return 0;
 }
 
-int try_to_free_disk_space(int low_disk_space, struct snapshot_list *sl)
+int try_to_free_disk_space(int low_disk_space)
 {
 	int ret;
+	struct snapshot_list sl;
 
-	ret = remove_outdated_snapshot(sl);
+	get_snapshot_list(&sl);
+	ret = remove_outdated_snapshot(&sl);
 	if (ret) /* error, or we are removing something */
-		return ret;
+		goto out;
 	/* no outdated snapshot */
-	ret = remove_redundant_snapshot(sl);
+	ret = remove_redundant_snapshot(&sl);
 	if (ret)
-		return ret;
+		goto out;
+	ret = 0;
 	if (!low_disk_space)
-		return 0;
+		goto out;
 	DSS_WARNING_LOG("disk space low and nothing obvious to remove\n");
-	ret = remove_oldest_snapshot();
+	ret = remove_oldest_snapshot(&sl);
 	if (ret)
-		return ret;
-	make_err_msg("uhuhu: not enough disk space for a single snapshot");
-	return  -ENOSPC;
+		goto out;
+	DSS_CRIT_LOG("uhuhu: not enough disk space for a single snapshot\n");
+	ret= -ENOSPC;
+out:
+	free_snapshot_list(&sl);
+	return ret;
 }
 
 int select_loop(void)
 {
 	int ret;
 	struct timeval tv = {.tv_sec = 0, .tv_usec = 0};
-	struct snapshot_list sl = {.num_snapshots = 0};
 
 	for (;;) {
-		struct timeval now, *tvp = &tv;
 		fd_set rfds;
 		int low_disk_space;
 		char **rsync_argv;
+		struct timeval now, *tvp = &tv;
 
-		free_snapshot_list(&sl);
-		get_snapshot_list(&sl);
-		compute_next_snapshot_time(&sl);
-		FD_ZERO(&rfds);
-		FD_SET(signal_pipe, &rfds);
 		if (rsync_pid)
-			tv.tv_sec = 60;
+			tv.tv_sec = 60; /* check every 60 seconds for free disk space */
 		else if (rm_pid)
-			tvp = NULL;
+			tvp = NULL; /* sleep until rm process dies */
+		FD_ZERO(&rfds);
+		FD_SET(signal_pipe, &rfds);
+		DSS_DEBUG_LOG("tvp: %p, tv_sec: %lu\n", tvp, (long unsigned) tv.tv_sec);
 		ret = dss_select(signal_pipe + 1, &rfds, NULL, tvp);
 		if (ret < 0)
 			return ret;
-		if (FD_ISSET(signal_pipe, &rfds)) {
+		if (FD_ISSET(signal_pipe, &rfds))
 			handle_signal();
-			continue;
-		}
 		if (rm_pid)
 			continue;
 		ret = disk_space_low();
@@ -932,26 +1003,42 @@ int select_loop(void)
 		low_disk_space = ret;
 		if (low_disk_space)
 			stop_rsync_process();
-		ret = try_to_free_disk_space(low_disk_space, &sl);
+		ret = try_to_free_disk_space(low_disk_space);
 		if (ret < 0)
 			break;
 		if (rm_pid)
 			continue;
-		if (rsync_pid) {
-			restart_rsync_process();
-			continue;
-		}
-		/* neither rsync nor rm are running. Start rsync? */
+		restart_rsync_process();
 		gettimeofday(&now, NULL);
 		if (tv_diff(&next_snapshot_time, &now, &tv) > 0)
 			continue;
-		create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
-		ret = create_snapshot(rsync_argv);
-		free_rsync_argv(rsync_argv);
-		if (ret < 0)
-			break;
+		switch (snapshot_creation_status) {
+		case SCS_READY:
+			ret = pre_create_hook();
+			if (ret < 0)
+				goto out;
+			continue;
+		case SCS_PRE_HOOK_RUNNING:
+			continue;
+		case SCS_PRE_HOOK_SUCCESS:
+			create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
+			ret = create_snapshot(rsync_argv);
+			free_rsync_argv(rsync_argv);
+			if (ret < 0)
+				goto out;
+			continue;
+		case SCS_RSYNC_RUNNING:
+			continue;
+		case SCS_RSYNC_SUCCESS:
+			ret = post_create_hook();
+			if (ret < 0)
+				goto out;
+			continue;
+		case SCS_POST_HOOK_RUNNING:
+			continue;
+		}
 	}
-	free_snapshot_list(&sl);
+out:
 	return ret;
 }
 
@@ -960,22 +1047,16 @@ int com_run(void)
 	int ret;
 
 	if (conf.dry_run_given) {
-		make_err_msg("dry_run not supported by this command");
+		DSS_ERROR_LOG("dry_run not supported by this command\n");
 		return -E_SYNTAX;
 	}
 	ret = install_sighandler(SIGHUP);
 	if (ret < 0)
 		return ret;
+	compute_next_snapshot_time();
 	return select_loop();
 }
 
-void log_disk_space(struct disk_space *ds)
-{
-	DSS_INFO_LOG("free: %uM/%uM (%u%%), %u%% inodes unused\n",
-		ds->free_mb, ds->total_mb, ds->percent_free,
-		ds->percent_free_inodes);
-}
-
 int com_prune(void)
 {
 	int ret;
@@ -1020,20 +1101,33 @@ int com_create(void)
 	int ret, status;
 	char **rsync_argv;
 
-	create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 	if (conf.dry_run_given) {
 		int i;
 		char *msg = NULL;
+		create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 		for (i = 0; rsync_argv[i]; i++) {
 			char *tmp = msg;
 			msg = make_message("%s%s%s", tmp? tmp : "",
 				tmp? " " : "", rsync_argv[i]);
 			free(tmp);
 		}
+		free_rsync_argv(rsync_argv);
 		dss_msg("%s\n", msg);
 		free(msg);
 		return 1;
 	}
+	ret = pre_create_hook();
+	if (ret < 0)
+		return ret;
+	if (pre_create_hook_pid) {
+		ret = wait_for_process(pre_create_hook_pid, &status);
+		if (ret < 0)
+			return ret;
+		ret = handle_pre_create_hook_exit(status);
+		if (ret < 0)
+			return ret;
+	}
+	create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 	ret = create_snapshot(rsync_argv);
 	if (ret < 0)
 		goto out;
@@ -1041,6 +1135,11 @@ int com_create(void)
 	if (ret < 0)
 		goto out;
 	ret = handle_rsync_exit(status);
+	if (ret < 0)
+		goto out;
+	post_create_hook();
+	if (post_create_hook_pid)
+		ret = wait_for_process(post_create_hook_pid, &status);
 out:
 	free_rsync_argv(rsync_argv);
 	return ret;
@@ -1058,11 +1157,6 @@ int com_ls(void)
 	return 1;
 }
 
-__noreturn void clean_exit(int status)
-{
-	free(dss_error_txt);
-	exit(status);
-}
 static void setup_signal_handling(void)
 {
 	int ret;
@@ -1096,11 +1190,12 @@ int main(int argc, char **argv)
 
 	cmdline_parser_ext(argc, argv, &conf, &params); /* aborts on errors */
 	parse_config_file(0);
+
 	if (conf.daemon_given)
 		daemon_init();
 	setup_signal_handling();
 	ret = call_command_handler();
 	if (ret < 0)
-		log_err_msg(EMERG, -ret);
-	clean_exit(ret >= 0? EXIT_SUCCESS : EXIT_FAILURE);
+		DSS_EMERG_LOG("%s\n", dss_strerror(-ret));
+	exit(ret >= 0? EXIT_SUCCESS : EXIT_FAILURE);
 }