Add wireless status detection and monitoring functions

spa/plugins/alsa/alsa-udev.c

@@ -276,6 +276,168 @@ static void unescape(const char *src, char *dst)
 	*d = 0;
 }
 
+static enum wireless_status read_wireless_status(const char *sysfs_path)
+{
+	char buf[16];
+	ssize_t sz;
+	int fd;
+
+	fd = open(sysfs_path, O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		return WIRELESS_STATUS_UNKNOWN;
+
+	sz = read(fd, buf, sizeof(buf) - 1);
+	close(fd);
+
+	if (sz <= 0)
+		return WIRELESS_STATUS_UNKNOWN;
+
+	buf[sz] = '\0';
+	if (buf[sz - 1] == '\n')
+		buf[sz - 1] = '\0';
+
+	if (spa_streq(buf, "connected"))
+		return WIRELESS_STATUS_CONNECTED;
+	if (spa_streq(buf, "disconnected"))
+		return WIRELESS_STATUS_DISCONNECTED;
+
+	return WIRELESS_STATUS_UNKNOWN;
+}
+
+static bool is_usb_interface_dir(const char *name)
+{
+	const char *colon = strchr(name, ':');
+	if (!colon || !strchr(name, '-'))
+		return false;
+
+	for (const char *p = colon + 1; *p; p++)
+		if (*p != '.' && !(*p >= '0' && *p <= '9'))
+			return false;
+
+	return true;
+}
+
+static char *check_wireless_status_at_path(struct impl *this, const char *path)
+{
+	char wireless_path[PATH_MAX];
+	char *result;
+	int res;
+
+	res = spa_scnprintf(wireless_path, sizeof(wireless_path),
+			    "%s/wireless_status", path);
+	if (res < 0 || (size_t)res >= sizeof(wireless_path))
+		return NULL;
+
+	if (access(wireless_path, R_OK) < 0)
+		return NULL;
+
+	result = strdup(wireless_path);
+	if (!result)
+		spa_log_error(this->log, "failed to allocate wireless_status path");
+	return result;
+}
+
+static char *search_siblings_for_wireless_status(struct impl *this, const char *parent_path)
+{
+	struct dirent *entry;
+	char *result = NULL;
+	int count = 0;
+
+	spa_autoptr(DIR) parent_dir = opendir(parent_path);
+	if (!parent_dir)
+		return NULL;
+
+	while ((entry = readdir(parent_dir)) != NULL) {
+		char sibling_path[PATH_MAX];
+		char *path;
+		int res;
+
+		if (entry->d_name[0] == '.')
+			continue;
+
+		if (!is_usb_interface_dir(entry->d_name))
+			continue;
+
+		if (entry->d_type != DT_UNKNOWN && entry->d_type != DT_DIR)
+			continue;
+
+		res = spa_scnprintf(sibling_path, sizeof(sibling_path),
+				    "%s/%s", parent_path, entry->d_name);
+		if (res < 0 || (size_t)res >= sizeof(sibling_path))
+			continue;
+
+		path = check_wireless_status_at_path(this, sibling_path);
+		if (path) {
+			count++;
+			if (!result)
+				result = path;
+			else
+				free(path);
+		}
+	}
+
+	if (count > 1)
+		spa_log_info(this->log, "found %d wireless_status files, using first one", count);
+
+	return result;
+}
+
+static char *find_wireless_status_path(struct impl *this, const char *card_syspath)
+{
+	char usb_device_path[PATH_MAX];
+	char *last_slash, *result;
+	int i, res;
+
+	res = spa_scnprintf(usb_device_path, sizeof(usb_device_path), "%s", card_syspath);
+	if (res < 0 || (size_t)res >= sizeof(usb_device_path))
+		return NULL;
+
+	result = check_wireless_status_at_path(this, usb_device_path);
+	if (result)
+		return result;
+
+	for (i = 0; i < MAX_PARENT_TRAVERSAL_DEPTH; i++) {
+		last_slash = strrchr(usb_device_path, '/');
+		if (!last_slash || last_slash == usb_device_path)
+			break;
+
+		*last_slash = '\0';
+
+		result = search_siblings_for_wireless_status(this, usb_device_path);
+		if (result)
+			return result;
+	}
+
+	return NULL;
+}
+
+static void update_wireless_status(struct impl *this, struct card *card)
+{
+	enum wireless_status status;
+	bool disconnected;
+
+	if (!card->wireless_status_path)
+		return;
+
+	status = read_wireless_status(card->wireless_status_path);
+
+	if (status == WIRELESS_STATUS_UNKNOWN) {
+		spa_log_info(this->log, "card %u wireless_status unreadable, removing monitor",
+			     card->card_nr);
+		free(card->wireless_status_path);
+		card->wireless_status_path = NULL;
+		card->wireless_disconnected = false;
+		return;
+	}
+
+	disconnected = (status == WIRELESS_STATUS_DISCONNECTED);
+	if (disconnected != card->wireless_disconnected) {
+		spa_log_info(this->log, "card %u wireless device %s",
+			     card->card_nr, disconnected ? "disconnected" : "connected");
+		card->wireless_disconnected = disconnected;
+	}
+}
+
 static int check_device_pcm_class(const char *devname)
 {
 	char path[PATH_MAX];
@@ -906,6 +1068,23 @@ static int start_inotify(struct impl *this)
 	return 0;
 }
 
+static struct card *find_card_by_wireless_status_path(struct impl *this, const char *syspath)
+{
+	char wireless_path[PATH_MAX];
+	int res;
+
+	res = spa_scnprintf(wireless_path, sizeof(wireless_path), "%s/wireless_status", syspath);
+	if (res < 0 || (size_t)res >= sizeof(wireless_path))
+		return NULL;
+
+	for (unsigned int i = 0; i < this->n_cards; i++) {
+		if (this->cards[i].wireless_status_path &&
+		    spa_streq(this->cards[i].wireless_status_path, wireless_path))
+			return &this->cards[i];
+	}
+	return NULL;
+}
+
 static void impl_on_fd_events(struct spa_source *source)
 {
 	struct impl *this = source->data;