Allow changing color of unused player slots

doc/lua/functions.md

@@ -230,7 +230,10 @@ Change the players team.
 
 **SetColor(color or colorIdx)**  
 Sets the players color by index or directly if its alpha value is not zero.
-Duplicate color values are possible, so you have to ensure unique colors if you want them!
+When the color is currently used by an active player/AI, a new one will be chosen out of the standard player colors.  
+You can change the colors freely for slots not yet taken, so if the final distribution of colors is unique,
+they will be kept after using e.g. `SetAI`.  
+In any case, using `SetAI` will ensure a unique color.
 
 **Close()**  
 Closes a spot kicking any player or AI there.

libs/s25main/SavedFile.cpp

@@ -1,11 +1,13 @@
-// Copyright (C) 2005 - 2024 Settlers Freaks (sf-team at siedler25.org)
+// Copyright (C) 2005 - 2026 Settlers Freaks (sf-team at siedler25.org)
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "SavedFile.h"
 #include "BasePlayerInfo.h"
 #include "RTTR_Version.h"
 #include "enum_cast.hpp"
+#include "helpers/format.hpp"
+#include "gameData/MaxPlayers.h"
 #include "libendian/ConvertEndianess.h"
 #include "s25util/BinaryFile.h"
 #include "s25util/Serializer.h"
@@ -145,6 +147,11 @@ void SavedFile::ReadPlayerData(BinaryFile& file)
     Serializer ser;
     ser.ReadFromFile(file);
     const unsigned playerCt = ser.PopUnsignedChar();
+    if(playerCt > MAX_PLAYERS)
+    {
+        throw std::length_error(
+          helpers::format(_("Number of players (%1%) exceeds maximum allowed of %2%!"), playerCt, MAX_PLAYERS));
+    }
     players.reserve(playerCt);
     for(unsigned i = 0; i < playerCt; i++)
     {

libs/s25main/network/GameServer.cpp

@@ -1,4 +1,4 @@
-// Copyright (C) 2005 - 2024 Settlers Freaks (sf-team at siedler25.org)
+// Copyright (C) 2005 - 2026 Settlers Freaks (sf-team at siedler25.org)
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -177,7 +177,11 @@ bool GameServer::Start(const CreateServerInfo& csi, const MapDescription& map, c
         LOG.write("Map %1% has no players!\n") % mapinfo.filepath;
         return false;
     }
-
+    if(playerInfos.size() > MAX_PLAYERS)
+    {
+        LOG.write("Map %1% has too many players! (%1% > %2%)\n") % mapinfo.filepath % playerInfos.size() % MAX_PLAYERS;
+        return false;
+    }
     if(!mapinfo.mapData.CompressFromFile(mapinfo.filepath, &mapinfo.mapChecksum))
         return false;
 
@@ -1587,10 +1591,9 @@ void GameServer::SendAsyncLog(const bfs::path& asyncLogFilePath)
 void GameServer::CheckAndSetColor(unsigned playerIdx, unsigned newColor)
 {
     RTTR_Assert(playerIdx < playerInfos.size());
-    RTTR_Assert(playerInfos.size() <= PLAYER_COLORS.size()); // Else we may not find a valid color!
-
-    JoinPlayerInfo& player = playerInfos[playerIdx];
-    RTTR_Assert(player.isUsed()); // Should only set colors for taken spots
+    // If either of those fails we may not find a valid color!
+    static_assert(PLAYER_COLORS.size() >= MAX_PLAYERS, "Not enough player colors defined!");
+    RTTR_Assert(playerInfos.size() <= PLAYER_COLORS.size());
 
     // Get colors used by other players
     std::set<unsigned> takenColors;
@@ -1610,9 +1613,9 @@ void GameServer::CheckAndSetColor(unsigned playerIdx, unsigned newColor)
     while(helpers::contains(takenColors, newColor))
         newColor = PLAYER_COLORS[(++newColorIdx) % PLAYER_COLORS.size()];
 
+    JoinPlayerInfo& player = playerInfos[playerIdx];
     if(player.color == newColor)
         return;
-
     player.color = newColor;
 
     SendToAll(GameMessage_Player_Color(playerIdx, player.color));