From 028011a8169b7b447c6a91b4a32c302ac4199db4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Tue, 4 Oct 2022 21:09:43 +0200
Subject: [PATCH] =?UTF-8?q?module/sway-xkb:=20don=E2=80=99t=20add=20the=20?=
 =?UTF-8?q?=E2=80=9Csame=E2=80=9D=20device=20multiple=20times?=
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Not sure if Sway bug or not, but we’ve seen Sway presenting multiple
input devices with the exact same ID (and nothing else differentiating
them).

This caused a crash in the sway-xkb module, since we didn’t check if
we were already tracking the device, and thus bumped the
“num_existing_inputs” variable multiple times for the same input
object.

This lead to a content() returning an array with uninitialized
elements, and thus a crash.

Closes #229
---
 CHANGELOG.md       |  3 +++
 modules/sway-xkb.c | 10 +++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 532530a..ade384d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -115,6 +115,8 @@
 * network: missing SSID (recent kernels, or possibly wireless drivers,
   no longer provide the SSID in the `NL80211_CMD_NEW_STATION`
   response) ([#226][226]).
+* sway-xkb: crash when compositor presents multiple inputs with
+  identical IDs ([#229][229]).
 
 [169]: https://codeberg.org/dnkl/yambar/issues/169
 [172]: https://codeberg.org/dnkl/yambar/issues/172
@@ -123,6 +125,7 @@
 [198]: https://codeberg.org/dnkl/yambar/issues/198
 [221]: https://codeberg.org/dnkl/yambar/issues/221
 [226]: https://codeberg.org/dnkl/yambar/issues/226
+[229]: https://codeberg.org/dnkl/yambar/issues/229
 
 
 ### Security
diff --git a/modules/sway-xkb.c b/modules/sway-xkb.c
index 6ee3e3a..3f2e965 100644
--- a/modules/sway-xkb.c
+++ b/modules/sway-xkb.c
@@ -67,6 +67,7 @@ content(struct module *mod)
 
     mtx_lock(&mod->lock);
 
+    assert(m->num_existing_inputs <= m->num_inputs);
     struct exposable *particles[max(m->num_existing_inputs, 1)];
 
     for (size_t i = 0, j = 0; i < m->num_inputs; i++) {
@@ -120,9 +121,12 @@ handle_input_reply(int type, const struct json_object *json, void *_mod)
         struct input *input = NULL;
         for (size_t i = 0; i < m->num_inputs; i++) {
             struct input *maybe_input = &m->inputs[i];
-            if (strcmp(maybe_input->identifier, id) == 0) {
+            if (strcmp(maybe_input->identifier, id) == 0 && !maybe_input->exists)
+            {
                 input = maybe_input;
 
+                LOG_DBG("adding: %s", id);
+
                 mtx_lock(&mod->lock);
                 input->exists = true;
                 m->num_existing_inputs++;
@@ -209,6 +213,8 @@ handle_input_event(int type, const struct json_object *json, void *_mod)
 
     if (is_removed) {
         if (input->exists) {
+            LOG_DBG("removing: %s", id);
+
             mtx_lock(&mod->lock);
             input->exists = false;
             m->num_existing_inputs--;
@@ -220,6 +226,8 @@ handle_input_event(int type, const struct json_object *json, void *_mod)
 
     if (is_added) {
         if (!input->exists) {
+            LOG_DBG("adding: %s", id);
+
             mtx_lock(&mod->lock);
             input->exists = true;
             m->num_existing_inputs++;