X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=dss.c;h=3d00b0b38be37b50878375257d90f9871412c957;hp=1fa6d569895f36df3eaf7d8cde34b0bc5ef0e513;hb=27edbe5dcf615a3c445f719b5833af4d392c5874;hpb=985ee856a76b6cf415b2342dcfb44ac9192e5483

diff --git a/dss.c b/dss.c
index 1fa6d56..3d00b0b 100644
--- a/dss.c
+++ b/dss.c
@@ -9,6 +9,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <inttypes.h>
+#include <sys/time.h>
 #include <time.h>
 #include <sys/wait.h>
 #include <fnmatch.h>
@@ -25,12 +26,48 @@
 #include "daemon.h"
 #include "signal.h"
 #include "df.h"
+#include "time.h"
 
 
 struct gengetopt_args_info conf;
-char *dss_error_txt = NULL;
 static FILE *logfile;
-int signal_pipe;
+static int signal_pipe;
+
+/** Process id of current rsync process. */
+static pid_t rsync_pid;
+/** Whether the rsync process is currently stopped */
+static int rsync_stopped;
+/** Process id of current rm process. */
+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;
 
@@ -61,7 +98,9 @@ int call_command_handler(void)
  * incomplete, being deleted: 1204565370-incomplete.being_deleted
  */
 enum snapshot_status_flags {
+	/** The rsync process terminated successfully. */
 	SS_COMPLETE = 1,
+	/** The rm process is running to remove this snapshot. */
 	SS_BEING_DELETED = 2,
 };
 
@@ -107,6 +146,22 @@ __printf_1_2 void dss_msg(const char* fmt,...)
 	va_end(argp);
 }
 
+/**
+ * Return the desired number of snapshots of an interval.
+ */
+unsigned num_snapshots(int interval)
+{
+	unsigned n;
+
+	assert(interval >= 0);
+
+	if (interval >= conf.num_intervals_arg)
+		return 0;
+	n = conf.num_intervals_arg - interval - 1;
+	return 1 << n;
+}
+
+/* return: Whether dirname is a snapshot directory (0: no, 1: yes) */
 int is_snapshot(const char *dirname, int64_t now, struct snapshot *s)
 {
 	int i, ret;
@@ -124,10 +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;
@@ -156,15 +209,13 @@ 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;
 	s->flags = SS_COMPLETE;
-	if (strcmp(dot + 1, "being_deleted"))
+	if (!strcmp(dot + 1, "being_deleted"))
 		s->flags |= SS_BEING_DELETED;
 success:
 	s->name = dss_strdup(dirname);
@@ -201,22 +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;
@@ -239,7 +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)))
 
@@ -295,7 +346,26 @@ void free_snapshot_list(struct snapshot_list *sl)
 		free(s);
 	}
 	free(sl->interval_count);
+	sl->interval_count = NULL;
 	free(sl->snapshots);
+	sl->snapshots = NULL;
+	sl->num_snapshots = 0;
+}
+
+void stop_rsync_process(void)
+{
+	if (!rsync_pid || rsync_stopped)
+		return;
+	kill(SIGSTOP, rsync_pid);
+	rsync_stopped = 1;
+}
+
+void restart_rsync_process(void)
+{
+	if (!rsync_pid || !rsync_stopped)
+		return;
+	kill (SIGCONT, rsync_pid);
+	rsync_stopped = 0;
 }
 
 /**
@@ -319,33 +389,40 @@ 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();
-		if  (ret < 0)
+		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) {
 			ret = waitpid(pid, status, 0);
 			if (ret >= 0)
 				break;
-			if (errno != EINTR) /* error */
+			if (errno != EINTR) { /* error */
+				ret = -ERRNO_TO_DSS_ERROR(errno);
 				break;
+			}
 		}
+		/* SIGINT or SIGTERM */
 		DSS_WARNING_LOG("sending SIGTERM to pid %d\n", (int)pid);
 		kill(pid, SIGTERM);
 	}
-	if (ret < 0) {
-		ret = -ERRNO_TO_DSS_ERROR(errno);
-		make_err_msg("failed to wait for process %d", (int)pid);
-	} else
+	if (ret < 0)
+		DSS_ERROR_LOG("failed to wait for process %d\n", (int)pid);
+	else
 		log_termination_msg(pid, *status);
 	return ret;
 }
 
-int remove_snapshot(struct snapshot *s, pid_t *pid)
+int remove_snapshot(struct snapshot *s)
 {
 	int fds[3] = {0, 0, 0};
+	assert(!rm_pid);
 	char *new_name = being_deleted_name(s);
 	int ret = dss_rename(s->name, new_name);
 	char *argv[] = {"rm", "-rf", new_name, NULL};
@@ -353,13 +430,17 @@ int remove_snapshot(struct snapshot *s, pid_t *pid)
 	if (ret < 0)
 		goto out;
 	DSS_NOTICE_LOG("removing %s (interval = %i)\n", s->name, s->interval);
-	ret = dss_exec(pid, argv[0], argv, fds);
+	stop_rsync_process();
+	ret = dss_exec(&rm_pid, argv[0], argv, fds);
 out:
 	free(new_name);
 	return ret;
 }
 
-int remove_redundant_snapshot(struct snapshot_list *sl, pid_t *pid)
+/*
+ * return: 0: no redundant snapshots, 1: rm process started, negative: error
+ */
+int remove_redundant_snapshot(struct snapshot_list *sl)
 {
 	int ret, i, interval;
 	struct snapshot *s;
@@ -367,22 +448,22 @@ int remove_redundant_snapshot(struct snapshot_list *sl, pid_t *pid)
 
 	DSS_INFO_LOG("looking for intervals containing too many snapshots\n");
 	for (interval = conf.num_intervals_arg - 1; interval >= 0; interval--) {
-		unsigned keep = 1<<(conf.num_intervals_arg - interval - 1);
+		unsigned keep = num_snapshots(interval);
 		unsigned num = sl->interval_count[interval];
 		struct snapshot *victim = NULL, *prev = NULL;
 		int64_t score = LONG_MAX;
 
 		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 */
 		FOR_EACH_SNAPSHOT(s, i, sl) {
 			int64_t this_score;
 
-			DSS_DEBUG_LOG("checking %s\n", s->name);
+			//DSS_DEBUG_LOG("checking %s\n", s->name);
 			if (s->interval > interval) {
 				prev = s;
 				continue;
@@ -398,7 +479,7 @@ int remove_redundant_snapshot(struct snapshot_list *sl, pid_t *pid)
 			/* check if s is a better victim */
 			this_score = s->creation_time - prev->creation_time;
 			assert(this_score >= 0);
-			DSS_DEBUG_LOG("%s: score %lli\n", s->name, (long long)score);
+			//DSS_DEBUG_LOG("%s: score %lli\n", s->name, (long long)score);
 			if (this_score < score) {
 				score = this_score;
 				victim = s;
@@ -411,13 +492,13 @@ int remove_redundant_snapshot(struct snapshot_list *sl, pid_t *pid)
 				victim->name, victim->interval);
 			continue;
 		}
-		ret = remove_snapshot(victim, pid);
+		ret = remove_snapshot(victim);
 		return ret < 0? ret : 1;
 	}
 	return 0;
 }
 
-int remove_old_snapshot(struct snapshot_list *sl, pid_t *pid)
+int remove_outdated_snapshot(struct snapshot_list *sl)
 {
 	int i, ret;
 	struct snapshot *s;
@@ -432,7 +513,7 @@ int remove_old_snapshot(struct snapshot_list *sl, pid_t *pid)
 				s->name, s->interval);
 			continue;
 		}
-		ret = remove_snapshot(s, pid);
+		ret = remove_snapshot(s);
 		if (ret < 0)
 			return ret;
 		return 1;
@@ -440,116 +521,228 @@ int remove_old_snapshot(struct snapshot_list *sl, pid_t *pid)
 	return 0;
 }
 
-int wait_for_rm_process(pid_t pid)
+int handle_rm_exit(int status)
+{
+	rm_pid = 0;
+	if (!WIFEXITED(status))
+		return -E_INVOLUNTARY_EXIT;
+	if (WEXITSTATUS(status))
+		return -E_BAD_EXIT_CODE;
+	return 1;
+}
+
+int wait_for_rm_process(void)
 {
-	int status, es, ret = wait_for_process(pid, &status);
+	int status, ret = wait_for_process(rm_pid, &status);
+
 	if (ret < 0)
 		return ret;
-	if (!WIFEXITED(status)) {
-		ret = E_INVOLUNTARY_EXIT;
-		make_err_msg("rm process %d died involuntary", (int)pid);
-		return ret;
+	return handle_rm_exit(status);
+}
+
+void kill_process(pid_t pid)
+{
+	if (!pid)
+		return;
+	DSS_WARNING_LOG("sending SIGTERM to pid %d\n", (int)pid);
+	kill(pid, SIGTERM);
+}
+
+int check_config(void)
+{
+	if (conf.unit_interval_arg <= 0) {
+		DSS_ERROR_LOG("bad unit interval: %i\n", conf.unit_interval_arg);
+		return -E_INVALID_NUMBER;
 	}
-	es = WEXITSTATUS(status);
-	if (es) {
-		ret = -E_BAD_EXIT_CODE;
-		make_err_msg("rm process %d returned %d", (int)pid, es);
-		return ret;
+	DSS_DEBUG_LOG("unit interval: %i day(s)\n", conf.unit_interval_arg);
+	if (conf.num_intervals_arg <= 0) {
+		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);
 	return 1;
 }
 
-int com_run(void)
+/* exits on errors */
+void parse_config_file(int override)
 {
 	int ret;
+	char *config_file;
+	struct stat statbuf;
+	char *old_logfile_arg = NULL;
+	int old_daemon_given = 0;
 
-	if (conf.dry_run_given) {
-		make_err_msg("dry_run not supported by this command");
-		return -E_SYNTAX;
+	if (conf.config_file_given)
+		config_file = dss_strdup(conf.config_file_arg);
+	else {
+		char *home = get_homedir();
+		config_file = make_message("%s/.dssrc", home);
+		free(home);
 	}
-	ret = install_sighandler(SIGHUP);
+	if (override) { /* SIGHUP */
+		if (conf.logfile_given)
+			old_logfile_arg = dss_strdup(conf.logfile_arg);
+		old_daemon_given = conf.daemon_given;
+	}
+
+	ret = stat(config_file, &statbuf);
+	if (ret && conf.config_file_given) {
+		ret = -ERRNO_TO_DSS_ERROR(errno);
+		DSS_ERROR_LOG("failed to stat config file %s\n", config_file);
+		goto out;
+	}
+	if (!ret) {
+		struct cmdline_parser_params params = {
+			.override = override,
+			.initialize = 0,
+			.check_required = 1,
+			.check_ambiguity = 0
+		};
+		cmdline_parser_config_file(config_file, &conf, &params);
+	}
+	ret = check_config();
 	if (ret < 0)
-		return ret;
-	return 42;
+		goto out;
+	if (override) {
+		/* don't change daemon mode on SIGHUP */
+		conf.daemon_given = old_daemon_given;
+		close_log(logfile);
+		logfile = NULL;
+		if (conf.logfile_given)
+			free(old_logfile_arg);
+		else if (conf.daemon_given) { /* re-use old logfile */
+			conf.logfile_arg = old_logfile_arg;
+			conf.logfile_given = 1;
+		}
+	}
+	if (conf.logfile_given) {
+		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;
+	DSS_EMERG_LOG("%s\n", dss_strerror(-ret));
+	exit(EXIT_FAILURE);
 }
 
-void log_disk_space(struct disk_space *ds)
+void handle_sighup(void)
 {
-	DSS_INFO_LOG("free: %uM/%uM (%u%%), %u%% inodes unused\n",
-		ds->free_mb, ds->total_mb, ds->percent_free,
-		ds->percent_free_inodes);
+	DSS_NOTICE_LOG("SIGHUP\n");
+	parse_config_file(1);
 }
 
-int com_prune(void)
+int rename_incomplete_snapshot(int64_t start)
 {
+	char *old_name;
 	int ret;
-	struct snapshot_list sl;
-	pid_t pid;
-	struct disk_space ds;
 
-	ret = get_disk_space(".", &ds);
+	free(path_to_last_complete_snapshot);
+	ret = complete_name(start, get_current_time(),
+		&path_to_last_complete_snapshot);
 	if (ret < 0)
 		return ret;
-	log_disk_space(&ds);
-	for (;;) {
-		get_snapshot_list(&sl);
-		ret = remove_old_snapshot(&sl, &pid);
-		free_snapshot_list(&sl);
-		if (ret < 0)
-			return ret;
-		if (!ret)
-			break;
-		ret = wait_for_rm_process(pid);
-		if (ret < 0)
-			goto out;
-	}
-	for (;;) {
-		get_snapshot_list(&sl);
-		ret = remove_redundant_snapshot(&sl, &pid);
-		free_snapshot_list(&sl);
-		if (ret < 0)
-			return ret;
-		if (!ret)
-			break;
-		ret = wait_for_rm_process(pid);
-		if (ret < 0)
-			goto out;
-	}
-	return 1;
-out:
+	old_name = incomplete_name(start);
+	ret = dss_rename(old_name, path_to_last_complete_snapshot);
+	if (ret >= 0)
+		DSS_NOTICE_LOG("%s -> %s\n", old_name,
+			path_to_last_complete_snapshot);
+	free(old_name);
 	return ret;
 }
 
-struct newest_snapshot_data {
-	char * newest_name;
-	int64_t newest_creation_time;
-	int64_t now;
-};
+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;
 
-int get_newest_complete(const char *dirname, void *private)
+	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)
 {
-	struct newest_snapshot_data *nsd = private;
-	struct snapshot s;
-	int ret = is_snapshot(dirname, nsd->now, &s);
+	int es, ret;
 
-	if (ret <= 0)
-		return 1;
-	if (s.creation_time < nsd->newest_creation_time)
-		return 1;
-	nsd->newest_creation_time = s.creation_time;
-	free(nsd->newest_name);
-	nsd->newest_name = s.name;
-	return 1;
+	if (!WIFEXITED(status)) {
+		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) {
+		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;
+	rsync_stopped = 0;
+	return ret;
 }
 
 __malloc char *name_of_newest_complete_snapshot(void)
 {
-	struct newest_snapshot_data nsd = {
-		.now = get_current_time(),
-		.newest_creation_time = -1
-	};
-	for_each_subdir(get_newest_complete, &nsd);
-	return nsd.newest_name;
+	struct snapshot_list sl;
+	struct snapshot *s;
+	int i;
+	char *name = NULL;
+
+	get_snapshot_list(&sl);
+
+	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)
@@ -568,7 +761,7 @@ void create_rsync_argv(char ***argv, int64_t *num)
 		(*argv)[i++] = make_message("--link-dest=../%s", newest);
 		free(newest);
 	} else
-		DSS_INFO_LOG("no previous snapshot found");
+		DSS_INFO_LOG("no previous snapshot found\n");
 	if (conf.exclude_patterns_given) {
 		(*argv)[i++] = dss_strdup("--exclude-from");
 		(*argv)[i++] = dss_strdup(conf.exclude_patterns_arg);
@@ -597,70 +790,356 @@ void free_rsync_argv(char **argv)
 	free(argv);
 }
 
-int create_snapshot(char **argv, pid_t *pid)
+int pre_create_hook(void)
 {
-	int fds[3] = {0, 0, 0};
+	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;
+}
 
-	return dss_exec(pid, argv[0], argv, fds);
+int create_snapshot(char **argv)
+{
+	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);
+	ret = dss_exec(&rsync_pid, argv[0], argv, fds);
+	if (ret < 0)
+		return ret;
+	snapshot_creation_status = SCS_RSYNC_RUNNING;
+	return ret;
 }
 
-int rename_incomplete_snapshot(int64_t start)
+int handle_pre_create_hook_exit(int status)
+{
+	int es, ret;
+
+	if (!WIFEXITED(status)) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		ret = -E_INVOLUNTARY_EXIT;
+		goto out;
+	}
+	es = WEXITSTATUS(status);
+	if (es) {
+		snapshot_creation_status = SCS_READY;
+		compute_next_snapshot_time();
+		ret = -E_BAD_EXIT_CODE;
+		goto out;
+	}
+	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)
+{
+	int sig, ret = next_signal();
+
+	if (ret <= 0)
+		goto out;
+	sig = ret;
+	switch (sig) {
+	case SIGINT:
+	case SIGTERM:
+		restart_rsync_process();
+		kill_process(rsync_pid);
+		kill_process(rm_pid);
+		exit(EXIT_FAILURE);
+	case SIGHUP:
+		handle_sighup();
+		ret = 1;
+		break;
+	case SIGCHLD:
+		ret = handle_sigchld();
+		break;
+	}
+out:
+	if (ret < 0)
+		DSS_ERROR_LOG("%s\n", dss_strerror(-ret));
+}
+
+int remove_oldest_snapshot(struct snapshot_list *sl)
+{
+	struct snapshot *s = oldest_snapshot(sl);
+
+	if (!s) /* no snapshot found */
+		return 0;
+	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. */
+int disk_space_low(void)
+{
+	struct disk_space ds;
+	int ret = get_disk_space(".", &ds);
+
+	if (ret < 0)
+		return ret;
+	if (conf.min_free_mb_arg)
+		if (ds.free_mb < conf.min_free_mb_arg)
+			return 1;
+	if (conf.min_free_percent_arg)
+		if (ds.percent_free < conf.min_free_percent_arg)
+			return 1;
+	return 0;
+}
+
+int try_to_free_disk_space(int low_disk_space)
+{
+	int ret;
+	struct snapshot_list sl;
+
+	get_snapshot_list(&sl);
+	ret = remove_outdated_snapshot(&sl);
+	if (ret) /* error, or we are removing something */
+		goto out;
+	/* no outdated snapshot */
+	ret = remove_redundant_snapshot(&sl);
+	if (ret)
+		goto out;
+	ret = 0;
+	if (!low_disk_space)
+		goto out;
+	DSS_WARNING_LOG("disk space low and nothing obvious to remove\n");
+	ret = remove_oldest_snapshot(&sl);
+	if (ret)
+		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};
+
+	for (;;) {
+		fd_set rfds;
+		int low_disk_space;
+		char **rsync_argv;
+		struct timeval now, *tvp = &tv;
+
+		if (rsync_pid)
+			tv.tv_sec = 60; /* check every 60 seconds for free disk space */
+		else if (rm_pid)
+			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))
+			handle_signal();
+		if (rm_pid)
+			continue;
+		ret = disk_space_low();
+		if (ret < 0)
+			break;
+		low_disk_space = ret;
+		if (low_disk_space)
+			stop_rsync_process();
+		ret = try_to_free_disk_space(low_disk_space);
+		if (ret < 0)
+			break;
+		if (rm_pid)
+			continue;
+		restart_rsync_process();
+		gettimeofday(&now, NULL);
+		if (tv_diff(&next_snapshot_time, &now, &tv) > 0)
+			continue;
+		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;
+		}
+	}
+out:
+	return ret;
+}
+
+int com_run(void)
 {
-	char *old_name, *new_name;
 	int ret;
 
-	ret = complete_name(start, get_current_time(), &new_name);
+	if (conf.dry_run_given) {
+		DSS_ERROR_LOG("dry_run not supported by this command\n");
+		return -E_SYNTAX;
+	}
+	ret = install_sighandler(SIGHUP);
 	if (ret < 0)
 		return ret;
-	old_name = incomplete_name(start);
-	ret = dss_rename(old_name, new_name);
-	if (ret >= 0)
-		DSS_NOTICE_LOG("%s -> %s\n", old_name, new_name);
-	free(old_name);
-	free(new_name);
+	compute_next_snapshot_time();
+	return select_loop();
+}
+
+int com_prune(void)
+{
+	int ret;
+	struct snapshot_list sl;
+	struct disk_space ds;
+
+	ret = get_disk_space(".", &ds);
+	if (ret < 0)
+		return ret;
+	log_disk_space(&ds);
+	for (;;) {
+		get_snapshot_list(&sl);
+		ret = remove_outdated_snapshot(&sl);
+		free_snapshot_list(&sl);
+		if (ret < 0)
+			return ret;
+		if (!ret)
+			break;
+		ret = wait_for_rm_process();
+		if (ret < 0)
+			goto out;
+	}
+	for (;;) {
+		get_snapshot_list(&sl);
+		ret = remove_redundant_snapshot(&sl);
+		free_snapshot_list(&sl);
+		if (ret < 0)
+			return ret;
+		if (!ret)
+			break;
+		ret = wait_for_rm_process();
+		if (ret < 0)
+			goto out;
+	}
+	return 1;
+out:
 	return ret;
 }
 
 int com_create(void)
 {
-	int ret, status, es;
+	int ret, status;
 	char **rsync_argv;
-	int64_t snapshot_num;
-	pid_t pid;
 
-	create_rsync_argv(&rsync_argv, &snapshot_num);
 	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;
 	}
-	DSS_NOTICE_LOG("creating snapshot %lli\n", (long long)snapshot_num);
-	ret = create_snapshot(rsync_argv, &pid);
+	ret = pre_create_hook();
 	if (ret < 0)
-		goto out;
-	ret = wait_for_process(pid, &status);
+		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;
-	if (!WIFEXITED(status)) {
-		ret = E_INVOLUNTARY_EXIT;
-		make_err_msg("rsync process %d died involuntary", (int)pid);
+	ret = wait_for_process(rsync_pid, &status);
+	if (ret < 0)
 		goto out;
-	}
-	es = WEXITSTATUS(status);
-	if (es != 0 && es != 23 && es != 24) {
-		ret = -E_BAD_EXIT_CODE;
-		make_err_msg("rsync process %d returned %d", (int)pid, es);
+	ret = handle_rsync_exit(status);
+	if (ret < 0)
 		goto out;
-	}
-	ret = rename_incomplete_snapshot(snapshot_num);
+	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;
@@ -678,73 +1157,11 @@ int com_ls(void)
 	return 1;
 }
 
-/* TODO: Unlink pid file */
-__noreturn void clean_exit(int status)
-{
-	//kill(0, SIGTERM);
-	free(dss_error_txt);
-	exit(status);
-}
-
-int read_config_file(void)
-{
-	int ret;
-	char *config_file;
-	struct stat statbuf;
-
-	if (conf.config_file_given)
-		config_file = dss_strdup(conf.config_file_arg);
-	else {
-		char *home = get_homedir();
-		config_file = make_message("%s/.dssrc", home);
-		free(home);
-	}
-	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);
-		goto out;
-	}
-	if (!ret) {
-		struct cmdline_parser_params params = {
-			.override = 0,
-			.initialize = 0,
-			.check_required = 0,
-			.check_ambiguity = 0
-		};
-		cmdline_parser_config_file(config_file, &conf, &params);
-	}
-	if (!conf.source_dir_given || !conf.dest_dir_given) {
-		ret = -E_SYNTAX;
-		make_err_msg("you need to specify both source_dir and dest_dir");
-		goto out;
-	}
-	ret = 1;
-out:
-	free(config_file);
-	return ret;
-}
-
-int check_config(void)
-{
-	if (conf.unit_interval_arg <= 0) {
-		make_err_msg("bad unit interval: %i", 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);
-		return -E_INVALID_NUMBER;
-	}
-	DSS_DEBUG_LOG("number of intervals: %i\n", conf.num_intervals_arg);
-	return 1;
-}
-
 static void setup_signal_handling(void)
 {
 	int ret;
 
-	DSS_NOTICE_LOG("setting up signal handlers\n");
+	DSS_INFO_LOG("setting up signal handlers\n");
 	signal_pipe = signal_init(); /* always successful */
 	ret = install_sighandler(SIGINT);
 	if (ret < 0)
@@ -761,36 +1178,24 @@ err:
 	exit(EXIT_FAILURE);
 }
 
-
 int main(int argc, char **argv)
 {
 	int ret;
+	struct cmdline_parser_params params = {
+		.override = 0,
+		.initialize = 1,
+		.check_required = 0,
+		.check_ambiguity = 0
+	};
+
+	cmdline_parser_ext(argc, argv, &conf, &params); /* aborts on errors */
+	parse_config_file(0);
 
-	cmdline_parser(argc, argv, &conf); /* aborts on errors */
-	if (conf.inputs_num) {
-		ret = -E_SYNTAX;
-		make_err_msg("additional non-options given");
-		goto out;
-	}
-	ret = read_config_file();
-	if (ret < 0)
-		goto out;
-	ret = check_config();
-	if (ret < 0)
-		goto out;
-	if (conf.logfile_given) {
-		logfile = open_log(conf.logfile_arg);
-		log_welcome(conf.loglevel_arg);
-	}
-	ret = dss_chdir(conf.dest_dir_arg);
-	if (ret < 0)
-		goto out;
 	if (conf.daemon_given)
 		daemon_init();
 	setup_signal_handling();
 	ret = call_command_handler();
-out:
 	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);
 }