From 4b740d5c8cff9591c666476cc0d3aef0cb637e62 Mon Sep 17 00:00:00 2001
From: papush!
Date: Fri, 4 Jul 2025 23:58:36 +0200
Subject: support hotplugging when udev rules are used to change device perms

---
 src/main.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 52 insertions(+), 3 deletions(-)

diff --git a/src/main.c b/src/main.c
index 00c6eb2..63b6c3d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,13 +20,39 @@
 
 
 struct pollfd pfds[NPFDS] = {0};
+int open_devices[NPFDS] = {0};
 int test_mode = 0;
 uint64_t keys[KEYS_SIZE] = {0};
 
 
-void add_device(const char name[static 1])
+int parse_device_name(const char name[static 1], unsigned long *device_id)
 {
 	if (strncmp(name, "event", strlen("event")) != 0)
+	{
+		return -1;
+	}
+	char *endptr;
+	*device_id = strtoul(name + strlen("event"), &endptr, 10);
+	if (*endptr != '\0')
+	{
+		return -1;
+	}
+	return 0;
+}
+
+void add_device(const char name[static 1])
+{
+	unsigned long device_id;
+	if (parse_device_name(name, &device_id) == -1)
+	{
+		return;
+	}
+	if (device_id >= NPFDS)
+	{
+		fprintf(stderr, "exceeded device limit\n");
+		return;
+	}
+	if (open_devices[device_id])
 	{
 		return;
 	}
@@ -38,6 +64,7 @@ void add_device(const char name[static 1])
 		fprintf(stderr, "failed to open device: %s: %s\n", path, strerror(errno));
 		return;
 	}
+	open_devices[device_id] = 1;
 	for (size_t i = 1; i < NPFDS; i++)
 	{
 		if (pfds[i].fd < 0)
@@ -48,6 +75,20 @@ void add_device(const char name[static 1])
 	}
 }
 
+void del_device(const char name[static 1])
+{
+	unsigned long device_id;
+	if (parse_device_name(name, &device_id) == -1)
+	{
+		return;
+	}
+	if (device_id >= NPFDS)
+	{
+		return;
+	}
+	open_devices[device_id] = 0;
+}
+
 void process_inotify_watch(int inotify_fd)
 {
 	char buf[sizeof (struct inotify_event) + NAME_MAX + 1] = {0};
@@ -67,7 +108,14 @@ void process_inotify_watch(int inotify_fd)
 			fputs("inotify error (filesystem unmounted?)", stderr);
 			exit(EXIT_FAILURE);
 		}
-		add_device(event->name);
+		else if (event->mask & IN_DELETE)
+		{
+			del_device(event->name);
+		}
+		else
+		{
+			add_device(event->name);
+		}
 	}
 }
 
@@ -165,7 +213,8 @@ int run(const char *bindings_file_path)
 		fprintf(stderr, "inotify_init1 failed: %s\n", strerror(errno));
 		return EXIT_FAILURE;
 	}
-	int watch_fd = inotify_add_watch(inotify_fd, "/dev/input/", IN_CREATE);
+	int watch_fd = inotify_add_watch(inotify_fd, "/dev/input/",
+	                                 IN_CREATE | IN_ATTRIB | IN_DELETE);
 	if (watch_fd < 0)
 	{
 		fprintf(stderr, "inotify_add_watch failed: %s\n", strerror(errno));
-- 
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