From a1673203a15d1398fd5d273d0a0388f61cac8c18 Mon Sep 17 00:00:00 2001
From: Claudio Takahasi <claudio.takahasi@openbossa.org>
Date: Fri, 21 Mar 2014 16:16:34 -0300
Subject: [PATCH] gatt: Assign read callback for external services

This patch adds the callback for reading the external characteristic
Value. Internally, GDBusProxy implementation tracks all properties Value
changes consequently Value can be ready directly from the proxy without
additional method calls.
---
 src/gatt-dbus.c | 42 +++++++++++++++++++++++++++++++++++++++++-
 src/gatt.h      |  2 +-
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/gatt-dbus.c b/src/gatt-dbus.c
index 6c4cdf7c4..a5a862bf0 100644
--- a/src/gatt-dbus.c
+++ b/src/gatt-dbus.c
@@ -139,6 +139,46 @@ static void proxy_removed(GDBusProxy *proxy, void *user_data)
 	eapp->proxies = g_slist_remove(eapp->proxies, proxy);
 }
 
+static void proxy_read_cb(struct btd_attribute *attr,
+				btd_attr_read_result_t result, void *user_data)
+{
+	DBusMessageIter iter, array;
+	GDBusProxy *proxy;
+	uint8_t *value;
+	int len;
+
+	/*
+	 * Remote device is trying to read the informed attribute,
+	 * "Value" should be read from the proxy. GDBusProxy tracks
+	 * properties changes automatically, it is not necessary to
+	 * get the value directly from the GATT server.
+	 */
+	proxy = g_hash_table_lookup(proxy_hash, attr);
+	if (!proxy) {
+		result(-ENOENT, NULL, 0, user_data);
+		return;
+	}
+
+	if (!g_dbus_proxy_get_property(proxy, "Value", &iter)) {
+		/* Unusual situation, read property will checked earlier */
+		result(-EPERM, NULL, 0, user_data);
+		return;
+	}
+
+	if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_ARRAY) {
+		DBG("External service inconsistent!");
+		result(-EPERM, NULL, 0, user_data);
+		return;
+	}
+
+	dbus_message_iter_recurse(&iter, &array);
+	dbus_message_iter_get_fixed_array(&array, &value, &len);
+
+	DBG("attribute: %p read %d bytes", attr, len);
+
+	result(0, value, len, user_data);
+}
+
 static int register_external_service(const struct external_app *eapp,
 							GDBusProxy *proxy)
 {
@@ -198,7 +238,7 @@ static int register_external_characteristics(GSList *proxies)
 		 * Reference table 3.5: Characteristic Properties bit field.
 		 */
 
-		attr = btd_gatt_add_char(&uuid, 0x00, NULL);
+		attr = btd_gatt_add_char(&uuid, 0x00, proxy_read_cb);
 		if (attr == NULL)
 			return -EINVAL;
 
diff --git a/src/gatt.h b/src/gatt.h
index e446fa070..daa8d54b9 100644
--- a/src/gatt.h
+++ b/src/gatt.h
@@ -32,7 +32,7 @@ void gatt_cleanup(void);
  * ready to be read from the service implementation. Result callback is
  * the asynchronous function that should be used to inform the caller
  * the read value.
- * @err:	error in errno format.
+ * @err:	error in -errno format.
  * @value:	pointer to value
  * @len:	length of value
  * @user_data:	user_data passed in btd_attr_read_t callback
-- 
2.47.3