From db47ced634bec2c2322e318340b0781fcabd05d7 Mon Sep 17 00:00:00 2001
From: Guillaume Melquiond <guillaume.melquiond@gmail.com>
Date: Tue, 10 Aug 2010 17:16:22 +0000
Subject: [PATCH] Allowed [message] in start events for single player mode.

To avoid replay issues, it forcefully quits the game in multiplayer
instead of displaying a WML error and continuing.
---
 src/game_events.cpp |  2 +-
 src/replay.cpp      | 17 +++++++++++++++--
 src/replay.hpp      | 33 +++++++++++++++++++++------------
 3 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/src/game_events.cpp b/src/game_events.cpp
index bff17d6e24e..60c0d585cb4 100644
--- a/src/game_events.cpp
+++ b/src/game_events.cpp
@@ -2763,7 +2763,7 @@ WML_HANDLER_FUNCTION(message, event_info, cfg)
 	}
 	else
 	{
-		config choice = mp_sync::get_user_choice("input", msg);
+		config choice = mp_sync::get_user_choice("input", msg, 0, true);
 		option_chosen = choice["value"];
 		text_input_result = choice["text"].str();
 	}
diff --git a/src/replay.cpp b/src/replay.cpp
index 5e991215113..3e629d930d3 100644
--- a/src/replay.cpp
+++ b/src/replay.cpp
@@ -1201,9 +1201,22 @@ void replay_network_sender::commit_and_sync()
 	}
 }
 
-config mp_sync::get_user_choice(const std::string &name, const user_choice &uch, int side)
+config mp_sync::get_user_choice(const std::string &name, const user_choice &uch,
+	int side, bool force_sp)
 {
-	if (resources::state_of_game->phase() == game_state::PLAY)
+	if (force_sp && network::nconnections() != 0 &&
+	    resources::state_of_game->phase() != game_state::PLAY)
+	{
+		/* We are in a multiplayer game, during an early event which
+		   prevents synchronization, and the WML is not interested
+		   in a random result. We cannot silently ignore the issue,
+		   since it would lead to a broken replay. To be sure that
+		   the WML does not catch the error and keep the game going,
+		   we use a sticky exception to forcefully quit. */
+		ERR_REPLAY << "MP synchronization does not work during prestart and start events.";
+		throw end_level_exception(QUIT);
+	}
+	if (resources::state_of_game->phase() == game_state::PLAY || force_sp)
 	{
 		/* We have to communicate with the player and store the
 		   choices in the replay. So a decision will be made on
diff --git a/src/replay.hpp b/src/replay.hpp
index 94165e33326..fc17b6ac4e7 100644
--- a/src/replay.hpp
+++ b/src/replay.hpp
@@ -213,23 +213,32 @@ struct user_choice
 
 /**
  * Performs a choice for WML events.
+ *
  * The choice is synchronized across all the multiplayer clients and
  * stored into the replay. The function object is called if the local
  * client is responsible for making the choice.
- * @param name tag used for storing the choice into the replay.
- * @param side the number of the side responsible for making the choice. 
- *		- defaults to currently active side.
+ * @param name Tag used for storing the choice into the replay.
+ * @param side The number of the side responsible for making the choice.
+ *             If zero, it defaults to the currently active side.
+ * @param force_sp If true, user choice will happen in prestart and start
+ *                 events too. But if used for these events in multiplayer,
+ *                 an exception will be thrown instead.
  *
- * @note In order to prevent issues with sync, crash, or infinite loop, a number of precautions 
- *		must be taken when getting a choice from a specific side.
- *		- The calling function must enter a loop to wait for network sync if the side is non-local.
- *			- This loop must end when a response is received in the replay.
- *		- The server must recognize @name replay commands as legal from non-active players.
- *			- Preferably the server should be notified about which player the data is expected from, 
- *			and discard data from unexpected players.
- *		- do_replay_handle must ignore the @name replay command when the originating player's turn is reached.
+ * @note In order to prevent issues with sync, crash, or infinite loop, a
+ *       number of precautions must be taken when getting a choice from a
+ *       specific side.
+ *       - The calling function must enter a loop to wait for network sync
+ *         if the side is non-local. This loop must end when a response is
+ *         received in the replay.
+ *       - The server must recognize @name replay commands as legal from
+ *         non-active players. Preferably the server should be notified
+ *         about which player the data is expected from, and discard data
+ *         from unexpected players.
+ *       - do_replay_handle must ignore the @name replay command when the
+ *         originating player's turn is reached.
  */
-config get_user_choice(const std::string &name, const user_choice &uch, int side = 0);
+config get_user_choice(const std::string &name, const user_choice &uch,
+	int side = 0, bool force_sp = false);
 
 }