From e4a83b946107d7724b7e7b73d45a885d8918ced0 Mon Sep 17 00:00:00 2001
From: Thomas Schoebel-Theuer <mars@box>
Date: Sun, 1 Mar 2020 14:55:44 +0100
Subject: [PATCH] infra: introduce ordered_readlink()

---
 kernel/sy_old/mars_main.c  | 16 ++++++++--------
 kernel/sy_old/strategy.h   |  4 ++++
 kernel/sy_old/sy_generic.c | 11 +++++++++++
 kernel/sy_old/sy_net.c     |  2 +-
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/kernel/sy_old/mars_main.c b/kernel/sy_old/mars_main.c
index bcd9e4af..c968b414 100644
--- a/kernel/sy_old/mars_main.c
+++ b/kernel/sy_old/mars_main.c
@@ -1129,12 +1129,12 @@ int compare_replaylinks(struct mars_rotate *rot, const char *hosta, const char *
 		goto done;
 	}
 
-	a = mars_readlink(linka);
+	a = ordered_readlink(linka);
 	if (unlikely(!a || !a[0])) {
 		MARS_ERR_TO(rot->log_say, "cannot read replaylink '%s'\n", linka);
 		goto done;
 	}
-	b = mars_readlink(linkb);
+	b = ordered_readlink(linkb);
 	if (unlikely(!b || !b[0])) {
 		MARS_ERR_TO(rot->log_say, "cannot read replaylink '%s'\n", linkb);
 		goto done;
@@ -1208,7 +1208,7 @@ int _update_link_when_necessary(struct mars_rotate *rot, const char *type, const
 	/* Check whether something really has changed (avoid
 	 * useless/disturbing timestamp updates)
 	 */
-	check = mars_readlink(new);
+	check = ordered_readlink(new);
 	if (check && !strcmp(check, old)) {
 		MARS_DBG("%s symlink '%s' -> '%s' has not changed\n", type, old, new);
 		res = 0;
@@ -1278,7 +1278,7 @@ int _update_version_link(struct mars_rotate *rot, struct trans_logger_info *inf)
 			      inf->inf_sequence > rot->inf_prev_sequence + 1) &&
 			     rot->inf_prev_sequence != 0)) {
 			char *skip_path = path_make("%s/skip-check-%s", rot->parent_path, my_id());
-			char *skip_link = mars_readlink(skip_path);
+			char *skip_link = ordered_readlink(skip_path);
 			char *msg = "";
 			int skip_nr = -1;
 			int nr_char = 0;
@@ -1303,7 +1303,7 @@ int _update_version_link(struct mars_rotate *rot, struct trans_logger_info *inf)
 			MARS_ERR("no MEM\n");
 			goto out;
 		}
-		prev_link = mars_readlink(prev);
+		prev_link = ordered_readlink(prev);
 		rot->inf_prev_sequence = inf->inf_sequence;
 	}
 
@@ -2482,7 +2482,7 @@ int peer_thread(void *data)
 					peer->peer);
 				goto free_and_restart;
 			}
-			my_uuid = mars_readlink("/mars/uuid");
+			my_uuid = ordered_readlink("/mars/uuid");
 			if (unlikely(!my_uuid)) {
 				MARS_ERR("cannot determine my own uuid for peer %s\n", peer->peer);
 				make_msg(peer_pairs, "cannot determine my own uuid");
@@ -2925,7 +2925,7 @@ void _create_new_logfile(const char *path)
 static
 const char *__get_link_path(const char *_linkpath, const char **linkpath)
 {
-	const char *res = mars_readlink(_linkpath);
+	const char *res = ordered_readlink(_linkpath);
 
 	if (linkpath)
 		*linkpath = _linkpath;
@@ -4912,7 +4912,7 @@ int _update_syncstatus(struct mars_rotate *rot, struct copy_brick *copy, char *p
 		 */
 		syncpos_path = path_make("%s/syncpos-%s", rot->parent_path, my_id());
 		peer_replay_path = path_make("%s/replay-%s", rot->parent_path, peer);
-		peer_replay_link = mars_readlink(peer_replay_path);
+		peer_replay_link = ordered_readlink(peer_replay_path);
 		if (unlikely(!peer_replay_link || !peer_replay_link[0])) {
 			MARS_ERR("cannot read peer replay link '%s'\n", peer_replay_path);
 			goto done;
diff --git a/kernel/sy_old/strategy.h b/kernel/sy_old/strategy.h
index bc1ae732..bfda4a98 100644
--- a/kernel/sy_old/strategy.h
+++ b/kernel/sy_old/strategy.h
@@ -209,6 +209,10 @@ extern void mars_remaining_space(const char *fspath, loff_t *total, loff_t *rema
 
 /* Timestamp Ordering */
 
+#define MARS_DELETED_STR ".deleted"
+
+extern char *ordered_readlink(const char *path);
+
 extern int ordered_unlink(const char *path,
 			  const struct lamport_time *stamp,
 			  int serial,
diff --git a/kernel/sy_old/sy_generic.c b/kernel/sy_old/sy_generic.c
index 8fee430e..e1a189dc 100644
--- a/kernel/sy_old/sy_generic.c
+++ b/kernel/sy_old/sy_generic.c
@@ -977,6 +977,17 @@ int ordered_symlink(const char *oldpath, const char *newpath, const struct lampo
 	return status;
 }
 
+
+char *ordered_readlink(const char *path)
+{
+	char *res = mars_readlink(path);
+
+	if (!strcmp(res, MARS_DELETED_STR)) {
+		*res = '\0';
+	}
+	return res;
+}
+
 //////////////////////////////////////////////////////////////
 
 // thread binding
diff --git a/kernel/sy_old/sy_net.c b/kernel/sy_old/sy_net.c
index 488d2845..f6b65127 100644
--- a/kernel/sy_old/sy_net.c
+++ b/kernel/sy_old/sy_net.c
@@ -52,7 +52,7 @@ char *_mars_translate_hostname(const char *name)
 		goto done;
 	}
 
-	trans = mars_readlink(tmp);
+	trans = ordered_readlink(tmp);
 	if (trans && trans[0]) {
 		MARS_DBG("'%s' => '%s'\n", tmp, trans);
 		brick_string_free(res);