Cleanup for guild position change (#7405)

Fixes #7387
This not really fully fixes it, but it makes it more clear.
Additionally changed to structs.

Thanks to @MrAntares

src/map/clif.cpp

@@ -14175,38 +14175,35 @@ void clif_parse_GuildChangePositionInfo(int fd, struct map_session_data *sd)
 
 /// Request to update the position of guild members (CZ_REQ_CHANGE_MEMBERPOS).
 /// 0155 <packet len>.W { <account id>.L <char id>.L <position id>.L }*
-void clif_parse_GuildChangeMemberPosition(int fd, struct map_session_data *sd)
-{
-	int i;
-	struct s_packet_db* info = &packet_db[RFIFOW(fd,0)];
-	int len = RFIFOW(fd,info->pos[0]);
-	int idxgpos = info->pos[1];
-
+void clif_parse_GuildChangeMemberPosition( int fd, struct map_session_data *sd ){
 	if(!sd->state.gmaster_flag)
 		return;
 
+	struct PACKET_CZ_REQ_CHANGE_MEMBERPOS* p = (struct PACKET_CZ_REQ_CHANGE_MEMBERPOS*)RFIFOP( fd, 0 );
 
-	// Guild leadership change
-	if( len == 16 && RFIFOL(fd,12) == 0 ){
-		if( !battle_config.guild_leaderchange_woe && is_agit_start() ){
-			clif_msg(sd, GUILD_MASTER_WOE);
-			return;
-		}
+	int16 entries = ( p->packetLength - sizeof( *p ) ) / sizeof( p->list[0] );
 
-		if( battle_config.guild_leaderchange_delay && DIFF_TICK(time(NULL),sd->guild->last_leader_change) < battle_config.guild_leaderchange_delay ){
-			clif_msg(sd, GUILD_MASTER_DELAY);
-			return;
-		}
+	for( int16 i = 0; i < entries; i++ ){
+		struct PACKET_CZ_REQ_CHANGE_MEMBERPOS_sub& entry = p->list[i];
 
-		guild_gm_change(sd->status.guild_id, RFIFOL(fd, 8));
-		return;
-	}
+		// Guild leadership change
+		if( entry.position == 0 ){
+			if( !battle_config.guild_leaderchange_woe && is_agit_start() ){
+				clif_msg( sd, GUILD_MASTER_WOE );
+				return;
+			}
 
-	for(i=idxgpos;i<len;i+=12){
-		int position = RFIFOL(fd,i+8);
+			if( battle_config.guild_leaderchange_delay && DIFF_TICK( time( nullptr ),sd->guild->last_leader_change ) < battle_config.guild_leaderchange_delay ){
+				clif_msg( sd, GUILD_MASTER_DELAY );
+				return;
+			}
 
-		if( position > 0 ){
-			guild_change_memberposition(sd->status.guild_id,RFIFOL(fd,i),RFIFOL(fd,i+4),position);
+			guild_gm_change( sd->status.guild_id, entry.CID );
+
+			// No further entries will be processed - the requesting player lost his guild master status
+			return;
+		}else if( entry.position > 0 ){
+			guild_change_memberposition( sd->status.guild_id, entry.AID, entry.CID, entry.position );
 		}
 	}
 }

src/map/clif_packetdb.hpp

@@ -236,7 +236,7 @@
 	packet(0x0152,-1);
 	parseable_packet(0x0153,-1,clif_parse_GuildChangeEmblem,2,4);
 	packet(0x0154,-1);
-	parseable_packet(0x0155,-1,clif_parse_GuildChangeMemberPosition,2,4);
+	parseable_packet( HEADER_CZ_REQ_CHANGE_MEMBERPOS, -1, clif_parse_GuildChangeMemberPosition, 0 );
 	packet(0x0156,-1);
 	packet(0x0157,6);
 	packet(0x0158,-1);

src/map/packets.hpp

@@ -355,6 +355,18 @@ struct PACKET_CZ_PC_SELL_ITEMLIST {
 	PACKET_CZ_PC_SELL_ITEMLIST_sub sellList[];
 } __attribute__((packed));
 
+struct PACKET_CZ_REQ_CHANGE_MEMBERPOS_sub{
+	uint32 AID;
+	uint32 CID;
+	int32 position;
+} __attribute__((packed));
+
+struct PACKET_CZ_REQ_CHANGE_MEMBERPOS{
+	int16 packetType;
+	int16 packetLength;
+	struct PACKET_CZ_REQ_CHANGE_MEMBERPOS_sub list[];
+} __attribute__((packed));
+
 // NetBSD 5 and Solaris don't like pragma pack but accept the packed attribute
 #if !defined( sun ) && ( !defined( __NETBSD__ ) || __NetBSD_Version__ >= 600000000 )
 	#pragma pack( pop )
@@ -365,6 +377,7 @@ DEFINE_PACKET_HEADER(ZC_BROADCAST, 0x9a)
 DEFINE_PACKET_HEADER(ZC_ITEM_ENTRY, 0x9d)
 DEFINE_PACKET_HEADER(ZC_PC_PURCHASE_RESULT, 0xca)
 DEFINE_PACKET_HEADER(ZC_MVP_GETTING_ITEM, 0x10a)
+DEFINE_PACKET_HEADER(CZ_REQ_CHANGE_MEMBERPOS, 0x155)
 DEFINE_PACKET_HEADER(CZ_REQMAKINGITEM, 0x18e)
 DEFINE_PACKET_HEADER(ZC_ACK_REQMAKINGITEM, 0x18f)
 DEFINE_PACKET_HEADER(CZ_REQ_MAKINGARROW, 0x1ae)