From 12e3795a830bfce28a59678ab343a93f634de1d8 Mon Sep 17 00:00:00 2001
From: Nathaniel Wesley Filardo <nwfilardo@gmail.com>
Date: Sat, 13 Jun 2020 04:00:15 +0100
Subject: [PATCH] cron: permit entry.schedule() to reuse existing

---
 app/modules/cron.c   | 11 +++++++----
 docs/modules/cron.md |  4 ++--
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/app/modules/cron.c b/app/modules/cron.c
index 2b528ebf7f..4688b70f85 100644
--- a/app/modules/cron.c
+++ b/app/modules/cron.c
@@ -136,10 +136,13 @@ static size_t lcron_findindex(lua_State *L, cronent_ud_t *ud) {
 
 static int lcron_schedule(lua_State *L) {
   cronent_ud_t *ud = luaL_checkudata(L, 1, "cron.entry");
-  char *strdesc = (char*)luaL_checkstring(L, 2);
-  struct cronent_desc desc;
-  lcron_parsedesc(L, strdesc, &desc);
-  ud->desc = desc;
+  char *strdesc = (char*)luaL_optstring(L, 2, NULL);
+
+  if (strdesc != NULL) {
+    struct cronent_desc desc;
+    lcron_parsedesc(L, strdesc, &desc);
+    ud->desc = desc;
+  }
 
   size_t i = lcron_findindex(L, ud);
 
diff --git a/docs/modules/cron.md b/docs/modules/cron.md
index 09c2fe91e8..9568cdee04 100644
--- a/docs/modules/cron.md
+++ b/docs/modules/cron.md
@@ -83,10 +83,10 @@ end)
 
 ## cron.entry:schedule()
 
-Sets a new schedule mask.
+Sets a new schedule mask and/or restores an unscheduled entry.
 
 #### Syntax
-`schedule(mask)`
+`schedule([mask])`
 
 #### Parameters
 - `mask` - [crontab](https://en.wikipedia.org/wiki/Cron#Overview)-like string mask for schedule