[PATCH BlueZ 7/9] AVRCP: Don't respond with errors when no player is registered

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Some devices w.g. Sony MW600 will stop using certain commands if an
error happen, so the code now just fake a player and once a real
player is registered it takes place of the fake one.
---
 audio/avrcp.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 63 insertions(+), 14 deletions(-)

diff --git a/audio/avrcp.c b/audio/avrcp.c
index 295a1e1..1ed6a24 100644
--- a/audio/avrcp.c
+++ b/audio/avrcp.c
@@ -477,6 +477,17 @@ void avrcp_player_event(struct avrcp_player *player, uint8_t id, void *data)
 	return;
 }
 
+static void *player_get_metadata(struct avrcp_player *player, uint32_t attr)
+{
+	if (player != NULL)
+		return player->cb->get_metadata(attr, player->user_data);
+
+	if (attr == AVRCP_MEDIA_ATTRIBUTE_TITLE)
+		return "";
+
+	return NULL;
+}
+
 static uint16_t player_write_media_attribute(struct avrcp_player *player,
 						uint32_t id, uint8_t *buf,
 						uint16_t *pos,
@@ -489,7 +500,7 @@ static uint16_t player_write_media_attribute(struct avrcp_player *player,
 
 	DBG("%u", id);
 
-	value = player->cb->get_metadata(id, player->user_data);
+	value = player_get_metadata(player, id);
 	if (value == NULL) {
 		*offset = 0;
 		return 0;
@@ -588,6 +599,9 @@ static int player_set_attribute(struct avrcp_player *player,
 {
 	DBG("Change attribute: %u %u", attr, val);
 
+	if (player == NULL)
+		return -ENOENT;
+
 	return player->cb->set_setting(attr, val, player->user_data);
 }
 
@@ -597,6 +611,9 @@ static int player_get_attribute(struct avrcp_player *player, uint8_t attr)
 
 	DBG("attr %u", attr);
 
+	if (player == NULL)
+		return -ENOENT;
+
 	value = player->cb->get_setting(attr, player->user_data);
 	if (value < 0)
 		DBG("attr %u not supported by player", attr);
@@ -653,7 +670,7 @@ static uint8_t avrcp_handle_list_player_attributes(struct avrcp *session,
 	uint16_t len = ntohs(pdu->params_len);
 	unsigned int i;
 
-	if (len != 0 || player == NULL) {
+	if (len != 0) {
 		pdu->params_len = htons(1);
 		pdu->params[0] = AVRCP_STATUS_INVALID_PARAM;
 		return AVC_CTYPE_REJECTED;
@@ -685,7 +702,7 @@ static uint8_t avrcp_handle_list_player_values(struct avrcp *session,
 	uint16_t len = ntohs(pdu->params_len);
 	unsigned int i;
 
-	if (len != 1 || player == NULL)
+	if (len != 1)
 		goto err;
 
 	if (player_get_attribute(player, pdu->params[0]) < 0)
@@ -707,6 +724,15 @@ err:
 	return AVC_CTYPE_REJECTED;
 }
 
+static GList *player_list_metadata(struct avrcp_player *player)
+{
+	if (player != NULL)
+		return player->cb->list_metadata(player->user_data);
+
+	return g_list_prepend(NULL,
+				GUINT_TO_POINTER(AVRCP_MEDIA_ATTRIBUTE_TITLE));
+}
+
 static uint8_t avrcp_handle_get_element_attributes(struct avrcp *session,
 						struct avrcp_header *pdu,
 						uint8_t transaction)
@@ -719,7 +745,7 @@ static uint8_t avrcp_handle_get_element_attributes(struct avrcp *session,
 	GList *attr_ids;
 	uint16_t offset;
 
-	if (len < 9 || identifier != 0 || player == NULL)
+	if (len < 9 || identifier != 0)
 		goto err;
 
 	nattr = pdu->params[8];
@@ -732,7 +758,7 @@ static uint8_t avrcp_handle_get_element_attributes(struct avrcp *session,
 		 * Return all available information, at least
 		 * title must be returned if there's a track selected.
 		 */
-		attr_ids = player->cb->list_metadata(player->user_data);
+		attr_ids = player_list_metadata(player);
 		len = g_list_length(attr_ids);
 	} else {
 		unsigned int i;
@@ -788,8 +814,7 @@ static uint8_t avrcp_handle_get_current_player_value(struct avrcp *session,
 	uint8_t *settings;
 	unsigned int i;
 
-	if (player == NULL || len <= 1 || pdu->params[0] != len - 1 ||
-							player == NULL)
+	if (len <= 1 || pdu->params[0] != len - 1)
 		goto err;
 
 	/*
@@ -922,6 +947,14 @@ err:
 	return AVC_CTYPE_REJECTED;
 }
 
+static uint32_t player_get_position(struct avrcp_player *player)
+{
+	if (player == NULL)
+		return 0;
+
+	return player->cb->get_position(player->user_data);
+}
+
 static uint8_t avrcp_handle_get_play_status(struct avrcp *session,
 						struct avrcp_header *pdu,
 						uint8_t transaction)
@@ -932,15 +965,15 @@ static uint8_t avrcp_handle_get_play_status(struct avrcp *session,
 	uint32_t duration;
 	void *pduration;
 
-	if (len != 0 || player == NULL) {
+	if (len != 0) {
 		pdu->params_len = htons(1);
 		pdu->params[0] = AVRCP_STATUS_INVALID_PARAM;
 		return AVC_CTYPE_REJECTED;
 	}
 
-	position = player->cb->get_position(player->user_data);
-	pduration = player->cb->get_metadata(AVRCP_MEDIA_ATTRIBUTE_DURATION,
-							player->user_data);
+	position = player_get_position(player);
+	pduration = player_get_metadata(player,
+					AVRCP_MEDIA_ATTRIBUTE_DURATION);
 	if (pduration != NULL)
 		duration = htonl(GPOINTER_TO_UINT(pduration));
 	else
@@ -957,6 +990,22 @@ static uint8_t avrcp_handle_get_play_status(struct avrcp *session,
 	return AVC_CTYPE_STABLE;
 }
 
+static uint64_t player_get_uid(struct avrcp_player *player)
+{
+	if (player == NULL)
+		return UINT64_MAX;
+
+	return player->cb->get_status(player->user_data);
+}
+
+static uint8_t player_get_status(struct avrcp_player *player)
+{
+	if (player == NULL)
+		return AVRCP_PLAY_STATUS_STOPPED;
+
+	return player->cb->get_status(player->user_data);
+}
+
 static uint8_t avrcp_handle_register_notification(struct avrcp *session,
 						struct avrcp_header *pdu,
 						uint8_t transaction)
@@ -970,18 +1019,18 @@ static uint8_t avrcp_handle_register_notification(struct avrcp *session,
 	 * one is applicable only for EVENT_PLAYBACK_POS_CHANGED. See AVRCP
 	 * 1.3 spec, section 5.4.2.
 	 */
-	if (len != 5 || player == NULL)
+	if (len != 5)
 		goto err;
 
 	switch (pdu->params[0]) {
 	case AVRCP_EVENT_STATUS_CHANGED:
 		len = 2;
-		pdu->params[1] = player->cb->get_status(player->user_data);
+		pdu->params[1] = player_get_status(player);
 
 		break;
 	case AVRCP_EVENT_TRACK_CHANGED:
 		len = 9;
-		uid = player->cb->get_uid(player->user_data);
+		uid = player_get_uid(player);
 		memcpy(&pdu->params[1], &uid, sizeof(uint64_t));
 
 		break;
-- 
1.7.11.4