use a real UUID for the stage ID

stepmania/src/CryptManager.cpp

@@ -396,6 +396,24 @@ RString CryptManager::GetPublicKeyFileName()
 	return PUBLIC_KEY_PATH;
 }
 
+/* Generate a version 4 random UUID. */
+RString CryptManager::GenerateRandomUUID()
+{
+	uint32_t buf[4];
+	CryptManager::GetRandomBytes( buf, sizeof(buf) );
+
+	buf[1] &= 0xFFFF0FFF;
+	buf[1] |= 0x00004000;
+	buf[2] &= 0x0FFFFFFF;
+	buf[2] |= 0xA0000000;
+
+	return ssprintf("%08x-%04x-%04x-%04x-%04x%08x\n",
+			buf[0],
+			buf[1] >> 16, buf[1] & 0xFFFF,
+			buf[2] >> 16, buf[2] & 0xFFFF,
+			buf[3]);
+}
+
 /*
  * (c) 2004-2007 Chris Danford, Glenn Maynard
  * All rights reserved.

stepmania/src/CryptManager.h

@@ -21,6 +21,7 @@ public:
 	static bool Verify( RageFileBasic &file, RString sSignature, RString sPublicKey );
 
 	static void GetRandomBytes( void *pData, int iBytes );
+	static RString GenerateRandomUUID();
 
 	static RString GetMD5ForFile( RString fn );		// in binary
 	static RString GetMD5ForString( RString sData );	// in binary

stepmania/src/GameState.cpp

@@ -8,6 +8,7 @@
 #include "CharacterManager.h"
 #include "CommonMetrics.h"
 #include "Course.h"
+#include "CryptManager.h"
 #include "Foreach.h"
 #include "Game.h"
 #include "GameCommand.h"
@@ -692,6 +693,7 @@ void GameState::BeginStage()
 		if( CurrentOptionsDisqualifyPlayer(pn) )
 			STATSMAN->m_CurStageStats.m_player[pn].m_bDisqualified = true;
 	m_bEarnedExtraStage = false;
+	m_sStageGUID = CryptManager::GenerateRandomUUID();
 }
 
 void GameState::CancelStage()

stepmania/src/GameState.h

@@ -86,6 +86,7 @@ public:
 
 	/* This is set to a random number per-game/round; it can be used for a random seed. */
 	int				m_iGameSeed, m_iStageSeed;
+	RString				m_sStageGUID;
 
 	bool		PlayersCanJoin() const;	// true if it's not too late for a player to join
 	int 		GetCoinsNeededToJoin() const;

stepmania/src/StatsManager.cpp

@@ -192,8 +192,7 @@ XNode* MakeRecentScoreNode( const StageStats &ss, Trail *pTrail, const PlayerSta
 
 	XNode* pHighScore = pss.m_HighScore.CreateNode();
 	pHighScore->AppendChild("Pad", mp);
-	RString sStageGuid = ssprintf("%08x-0000-1000-0000-53FA337761C6", GAMESTATE->m_iStageSeed);
-	pHighScore->AppendChild("StageGuid", sStageGuid);
+	pHighScore->AppendChild("StageGuid", GAMESTATE->m_sStageGUID);
 
 	pNode->AppendChild( pHighScore );