From 47b70b6ca81b9addb97f42a614022a0a18efb3aa Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Mon, 18 Nov 2019 13:22:44 +0900
Subject: [PATCH] ctl: card: add an API to lock element from writing

---
 src/ctl/alsactl.map |  1 +
 src/ctl/card.c      | 26 ++++++++++++++++++++++++++
 src/ctl/card.h      |  3 +++
 tests/alsactl-card  |  1 +
 4 files changed, 31 insertions(+)

diff --git a/src/ctl/alsactl.map b/src/ctl/alsactl.map
index cb1ed2b..9d3f50a 100644
--- a/src/ctl/alsactl.map
+++ b/src/ctl/alsactl.map
@@ -16,6 +16,7 @@ ALSA_GOBJECT_0_0_0 {
     "alsactl_card_open";
     "alsactl_card_get_info";
     "alsactl_card_get_elem_id_list";
+    "alsactl_card_lock_elem";
 
     "alsactl_card_info_get_type";
 
diff --git a/src/ctl/card.c b/src/ctl/card.c
index 065d6e1..4d9e08b 100644
--- a/src/ctl/card.c
+++ b/src/ctl/card.c
@@ -225,3 +225,29 @@ void alsactl_card_get_elem_id_list(ALSACtlCard *self, GList **entries,
 
     deallocate_elem_ids(&list);
 }
+
+/**
+ * alsactl_card_lock_elem:
+ * @self: A #ALSACtlCard.
+ * @elem_id: A #ALSACtlElemId.
+ * @lock: whether to lock or unlock the element.
+ * @error: A #GError.
+ *
+ * Lock/Unlock indicated element not to be written by the other processes.
+ */
+void alsactl_card_lock_elem(ALSACtlCard *self, const ALSACtlElemId *elem_id,
+                            gboolean lock, GError **error)
+{
+    ALSACtlCardPrivate *priv;
+    int ret;
+
+    g_return_if_fail(ALSACTL_IS_CARD(self));
+    priv = alsactl_card_get_instance_private(self);
+
+    if (lock)
+        ret = ioctl(priv->fd, SNDRV_CTL_IOCTL_ELEM_LOCK, elem_id);
+    else
+        ret = ioctl(priv->fd, SNDRV_CTL_IOCTL_ELEM_UNLOCK, elem_id);
+    if (ret < 0)
+        generate_error(error, errno);
+}
diff --git a/src/ctl/card.h b/src/ctl/card.h
index cd1397e..526c917 100644
--- a/src/ctl/card.h
+++ b/src/ctl/card.h
@@ -58,6 +58,9 @@ void alsactl_card_get_info(ALSACtlCard *self, ALSACtlCardInfo **card_info,
 void alsactl_card_get_elem_id_list(ALSACtlCard *self, GList **entries,
                                    GError **error);
 
+void alsactl_card_lock_elem(ALSACtlCard *self, const ALSACtlElemId *elem_id,
+                            gboolean lock, GError **error);
+
 G_END_DECLS
 
 #endif
diff --git a/tests/alsactl-card b/tests/alsactl-card
index 12f51de..2b550e7 100644
--- a/tests/alsactl-card
+++ b/tests/alsactl-card
@@ -18,6 +18,7 @@ methods = (
     'open',
     'get_info',
     'get_elem_id_list',
+    'lock_elem',
 )
 signals = ()
 
-- 
2.47.3