From d299420fbe9737a91176296c81abd0753e1f9061 Mon Sep 17 00:00:00 2001
From: darosior <darosior@protonmail.com>
Date: Sat, 29 Jun 2019 13:44:20 +0200
Subject: [PATCH] lightningd/plugin_hook: make it possible to unregister a hook

This adds 'plugin_unregister_hook' and 'plugin_unregister_hook_all'
functions to unregister a given hook a plugin registered, or all hooks a
plugin registered for. Since hooks can only be registered once, it's
useful in the case a new plugin is added which would be prefered for
hook registration over an already loaded plugin.
---
 lightningd/plugin_hook.c | 26 ++++++++++++++++++++++++++
 lightningd/plugin_hook.h |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/lightningd/plugin_hook.c b/lightningd/plugin_hook.c
index 54e7098ee..bd620db70 100644
--- a/lightningd/plugin_hook.c
+++ b/lightningd/plugin_hook.c
@@ -39,6 +39,32 @@ bool plugin_hook_register(struct plugin *plugin, const char *method)
 	return true;
 }
 
+bool plugin_hook_unregister(struct plugin *plugin, const char *method)
+{
+	struct plugin_hook *hook = plugin_hook_by_name(method);
+	if (!hook) {
+		/* No such hook name registered */
+		return false;
+	} else if (hook->plugin == NULL) {
+		/* This name is not registered */
+		return false;
+	}
+	hook->plugin = NULL;
+	return true;
+}
+
+void plugin_hook_unregister_all(struct plugin *plugin)
+{
+	static struct plugin_hook **hooks = NULL;
+	static size_t num_hooks;
+	if (!hooks)
+		hooks = autodata_get(hooks, &num_hooks);
+
+	for (size_t i = 0; i < num_hooks; i++)
+		if (hooks[i]->plugin == plugin)
+			hooks[i]->plugin = NULL;
+}
+
 /**
  * Callback to be passed to the jsonrpc_request.
  *
diff --git a/lightningd/plugin_hook.h b/lightningd/plugin_hook.h
index 76d9b6fea..4869d69e9 100644
--- a/lightningd/plugin_hook.h
+++ b/lightningd/plugin_hook.h
@@ -102,6 +102,12 @@ void plugin_hook_call_(struct lightningd *ld, const struct plugin_hook *hook,
 
 bool plugin_hook_register(struct plugin *plugin, const char *method);
 
+/* Unregister a hook a plugin has registered for */
+bool plugin_hook_unregister(struct plugin *plugin, const char *method);
+
+/* Unregister all hooks a plugin has registered for */
+void plugin_hook_unregister_all(struct plugin *plugin);
+
 /* Special sync plugin hook for db: changes[] are SQL statements, with optional
  * final command appended. */
 void plugin_hook_db_sync(struct db *db, const char **changes, const char *final);