Bluetooth: TBS: Fix return value of handle_string_long_read

The function may return a BT_GATT_ERR which is a negative
value that cannot be returned as uint8_t. Change the function
to use int instead and document the return values.

Signed-off-by: Emil Gydesen <[email protected]>

Author: Thalley

subsys/bluetooth/audio/tbs_client.c

@@ -855,9 +855,13 @@ static bool can_add_string_to_net_buf(const struct net_buf_simple *buf, size_t l
 	return buf->len + len + sizeof('\0') <= buf->size;
 }
 
-/* Common function to read tbs_client strings which may require long reads */
-static uint8_t handle_string_long_read(struct bt_tbs_instance *inst, uint8_t err, const void *data,
-				       uint16_t offset, uint16_t length, bool truncatable)
+/**
+ * Common function to read tbs_client strings which may require long reads
+ *
+ * @return BT_GATT_ITER_CONTINUE, BT_GATT_ITER_STOP or a negative value if there's an error
+ */
+static int handle_string_long_read(struct bt_tbs_instance *inst, uint8_t err, const void *data,
+				   uint16_t offset, uint16_t length, bool truncatable)
 {
 	if (err != 0) {
 		LOG_DBG("err: %u", err);
@@ -889,7 +893,9 @@ static uint8_t handle_string_long_read(struct bt_tbs_instance *inst, uint8_t err
 
 			return BT_GATT_ITER_CONTINUE;
 		}
-	}
+	} /* else we are done reading and since the buffer is always 0-initialized, it will have the
+	   *  NULL terminator automatically
+	   */
 
 	return BT_GATT_ITER_STOP;
 }