From c802de2cf99a3a0aced705b544a8f3038e69f657 Mon Sep 17 00:00:00 2001
From: Johannes Schlatow <johannes.schlatow@genode-labs.com>
Date: Thu, 8 Apr 2021 16:37:32 +0200
Subject: [PATCH] event_filter: add <ignore-key> node

Fixes genodelabs#4069
---
 repos/os/src/server/event_filter/README       |  4 +++
 .../os/src/server/event_filter/remap_source.h | 26 ++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/repos/os/src/server/event_filter/README b/repos/os/src/server/event_filter/README
index 87aa2992bc..0add22e18e 100644
--- a/repos/os/src/server/event_filter/README
+++ b/repos/os/src/server/event_filter/README
@@ -27,6 +27,10 @@ one of the following filters:
   the key name as 'name' attribute, may feature an optional 'to' attribute
   with the name of the key that should be reported instead of 'name'.
 
+  It may also contain any number of '<ignore-key>' nodes to completely mute
+  certain keys. Each of those nodes has the key name as 'name' attribute.
+  This rule is applied before remapping.
+
   A '<remap>' node may contain '<include>' nodes, which include further
   content into the '<remap>' node. The included ROM must have a '<remap>'
   top-level node.
diff --git a/repos/os/src/server/event_filter/remap_source.h b/repos/os/src/server/event_filter/remap_source.h
index 890b5e93cb..3e79ca6e27 100644
--- a/repos/os/src/server/event_filter/remap_source.h
+++ b/repos/os/src/server/event_filter/remap_source.h
@@ -37,6 +37,7 @@ class Event_filter::Remap_source : public Source, Source::Filter
 		};
 
 		Key _keys[Input::KEY_MAX];
+		bool _ignore_keys[Input::KEY_MAX] { };
 
 		Owner _owner;
 
@@ -61,13 +62,16 @@ class Event_filter::Remap_source : public Source, Source::Filter
 			 * The range of the 'key' is checked by the 'Event' handle methods,
 			 * so it is safe to use as array index.
 			 */
-			auto remap = [&] (Input::Keycode key) { return _keys[key].code; };
+			auto remap  = [&] (Input::Keycode key) { return _keys[key].code; };
+			auto ignore = [&] (Input::Keycode key) { return _ignore_keys[key]; };
 
 			event.handle_press([&] (Input::Keycode key, Codepoint codepoint) {
-				destination.submit(Input::Press_char{remap(key), codepoint}); });
+				if (!ignore(key))
+					destination.submit(Input::Press_char{remap(key), codepoint}); });
 
 			event.handle_release([&] (Input::Keycode key) {
-				destination.submit(Input::Release{remap(key)}); });
+				if (!ignore(key))
+					destination.submit(Input::Release{remap(key)}); });
 		}
 
 		void _apply_config(Xml_node const config, unsigned const max_recursion = 4)
@@ -118,6 +122,22 @@ class Event_filter::Remap_source : public Source, Source::Filter
 					warning("invalid key name ", key_name); }
 				return;
 			}
+
+			/*
+			 * Handle ignore-key nodes
+			 */
+			if (node.type() == "ignore-key") {
+				Key_name const key_name = node.attribute_value("name", Key_name());
+
+				try {
+					for_each_key_with_name(key_name, [&] (Input::Keycode code) {
+						_ignore_keys[code] = true;
+					});
+				}
+				catch (Unknown_key) {
+					warning("invalid key name ", key_name); }
+				return;
+			}
 		}
 
 	public: