From 51526948c014bbf40b595f0a5413c0ff934cfc59 Mon Sep 17 00:00:00 2001
From: Alibek Omarov <a1ba.omarov@gmail.com>
Date: Fri, 20 May 2022 18:09:52 +0300
Subject: [PATCH] engine: server: make PEntityOfEntIndex bug-compatible with
 GoldSrc

Add new undocumented GoldSrc eiface function, PEntityOfEntIndexAllEntities,
a bug-free version of PEntityOfEntIndex

Ref: https://github.com/ValveSoftware/halflife/issues/2272
---
 engine/common/common.h  |  1 -
 engine/eiface.h         |  3 +++
 engine/server/server.h  |  1 -
 engine/server/sv_game.c | 49 ++++++++++++++++++++++++++---------------
 4 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/engine/common/common.h b/engine/common/common.h
index 3b6d3277..f96eda0d 100644
--- a/engine/common/common.h
+++ b/engine/common/common.h
@@ -756,7 +756,6 @@ void pfnDrawSetTextColor( float r, float g, float b );
 void pfnDrawConsoleStringLen( const char *pText, int *length, int *height );
 void *Cache_Check( poolhandle_t mempool, struct cache_user_s *c );
 void COM_TrimSpace( const char *source, char *dest );
-edict_t* pfnPEntityOfEntIndex( int iEntIndex );
 void pfnGetModelBounds( model_t *mod, float *mins, float *maxs );
 void pfnCVarDirectSet( cvar_t *var, const char *szValue );
 int COM_CheckParm( char *parm, char **ppnext );
diff --git a/engine/eiface.h b/engine/eiface.h
index 87b21130..e18cdedb 100644
--- a/engine/eiface.h
+++ b/engine/eiface.h
@@ -278,6 +278,9 @@ typedef struct enginefuncs_s
 	void	(*pfnQueryClientCvarValue)( const edict_t *player, const char *cvarName );
 	void	(*pfnQueryClientCvarValue2)( const edict_t *player, const char *cvarName, int requestID );
 	int	(*pfnCheckParm)( char *parm, char **ppnext );
+
+	// added in 8279
+	edict_t* (*pfnPEntityOfEntIndexAllEntities)( int iEntIndex );
 } enginefuncs_t;
 // ONLY ADD NEW FUNCTIONS TO THE END OF THIS STRUCT.  INTERFACE VERSION IS FROZEN AT 138
 
diff --git a/engine/server/server.h b/engine/server/server.h
index 2bfd8b18..4775397f 100644
--- a/engine/server/server.h
+++ b/engine/server/server.h
@@ -628,7 +628,6 @@ void SV_StartSound( edict_t *ent, int chan, const char *sample, float vol, float
 edict_t *SV_FindGlobalEntity( string_t classname, string_t globalname );
 qboolean SV_CreateStaticEntity( struct sizebuf_s *msg, int index );
 void SV_SendUserReg( sizebuf_t *msg, sv_user_message_t *user );
-edict_t* pfnPEntityOfEntIndex( int iEntIndex );
 int pfnIndexOfEdict( const edict_t *pEdict );
 void pfnWriteBytes( const byte *bytes, int count );
 void SV_UpdateBaseVelocity( edict_t *ent );
diff --git a/engine/server/sv_game.c b/engine/server/sv_game.c
index c3f25eb0..35626d83 100644
--- a/engine/server/sv_game.c
+++ b/engine/server/sv_game.c
@@ -60,6 +60,21 @@ qboolean SV_CheckEdict( const edict_t *e, const char *file, const int line )
 }
 #endif
 
+static edict_t *SV_PEntityOfEntIndex( const int iEntIndex, const qboolean allentities )
+{
+	edict_t *pEdict = EDICT_NUM( iEntIndex );
+	qboolean player = allentities ? iEntIndex <= svs.maxclients : iEntIndex < svs.maxclients;
+
+	if( !SV_IsValidEdict( pEdict ))
+		return NULL;
+
+	if( !player && !pEdict->pvPrivateData )
+		return NULL;
+
+	return pEdict;
+}
+
+
 /*
 =============
 EntvarsDescription
@@ -586,7 +601,7 @@ void SV_RestartAmbientSounds( void )
 			continue;
 
 		S_StopSound( si->entnum, si->channel, si->name );
-		SV_StartSound( pfnPEntityOfEntIndex( si->entnum ), CHAN_STATIC, si->name, si->volume, si->attenuation, 0, si->pitch );
+		SV_StartSound( SV_PEntityOfEntIndex( si->entnum, true ), CHAN_STATIC, si->name, si->volume, si->attenuation, 0, si->pitch );
 	}
 
 #if !XASH_DEDICATED // TODO: ???
@@ -640,10 +655,10 @@ void SV_RestartDecals( void )
 	for( i = 0; i < host.numdecals; i++ )
 	{
 		entry = &host.decalList[i];
-		modelIndex = pfnPEntityOfEntIndex( entry->entityIndex )->v.modelindex;
+		modelIndex = SV_PEntityOfEntIndex( entry->entityIndex, true )->v.modelindex;
 
 		// game override
-		if( SV_RestoreCustomDecal( entry, pfnPEntityOfEntIndex( entry->entityIndex ), false ))
+		if( SV_RestoreCustomDecal( entry, SV_PEntityOfEntIndex( entry->entityIndex, true ), false ))
 			continue;
 
 		decalIndex = pfnDecalIndex( entry->name );
@@ -3350,24 +3365,21 @@ pfnPEntityOfEntIndex
 
 =============
 */
-edict_t *pfnPEntityOfEntIndex( int iEntIndex )
+static edict_t *pfnPEntityOfEntIndex( int iEntIndex )
 {
-	if( iEntIndex >= 0 && iEntIndex < GI->max_edicts )
-	{
-		edict_t	*pEdict = EDICT_NUM( iEntIndex );
-
-		if( !iEntIndex || FBitSet( host.features, ENGINE_QUAKE_COMPATIBLE ))
-			return pEdict; // just get access to array
-
-		if( SV_IsValidEdict( pEdict ) && pEdict->pvPrivateData )
-			return pEdict;
+	// have to be bug-compatible with GoldSrc in this function
+	return SV_PEntityOfEntIndex( iEntIndex, false );
+}
 
-		// g-cont: world and clients can be acessed even without private data!
-		if( SV_IsValidEdict( pEdict ) && SV_IsPlayerIndex( iEntIndex ))
-			return pEdict;
-	}
+/*
+=============
+pfnPEntityOfEntIndexAllEntities
 
-	return NULL;
+=============
+*/
+static edict_t *pfnPEntityOfEntIndexAllEntities( int iEntIndex )
+{
+	return SV_PEntityOfEntIndex( iEntIndex, true );
 }
 
 /*
@@ -4740,6 +4752,7 @@ static enginefuncs_t gEngfuncs =
 	pfnQueryClientCvarValue,
 	pfnQueryClientCvarValue2,
 	COM_CheckParm,
+	pfnPEntityOfEntIndexAllEntities,
 };
 
 /*