engine: turn old pfnGetGameDir behavior into a bugcomp flag get_game_dir_full

This function is kinda nasty, some mods (like old RCBot builds) expect a slash,
some newer mods (like Sandbot) doesn't. To preserve compatibility with both old
and new mods, just add it as bug compatibility flag.

Documentation/bug-compatibility.md

@@ -13,5 +13,6 @@ When `-bugcomp` is specified with argument, it interpreted as flags separated wi
 | Flag    | Description | Games that require this flag |
 | ------- | ----------- | ---------------------------- |
 | `peoei` | Reverts `pfnPEntityOfEntIndex` behavior to GoldSrc, where it returns NULL for last player due to incorrect player index comparison | * Counter-Strike: Condition Zero - Deleted Scenes |
-| `gsmrf` | Rewrites message at the moment when Game DLL attempts to write an internal engine message, usually specific to GoldSrc protocol. Right now only supports `svc_spawnstaticsound`, more messages added by request. | * MetaMod/AMXModX based mods |
+| `gsmrf` | Rewrites message at the moment when Game DLL attempts to write an internal engine message, usually specific to GoldSrc protocol.<br>Right now only supports `svc_spawnstaticsound`, more messages added by request. | * MetaMod/AMXModX based mods |
 | `sp_attn_none` | Makes sounds with attenuation zero spatialized, i.e. have a stereo effect. | Possibly, every game that was made for GoldSrc. |
+| `get_game_dir_full` | Makes server return full path in server's `pfnGetGameDir` API function | Mods targetting engine before HL 1.1.1.1, according to MetaMod [documentation](http://metamod.org/engine_notes.html#GetGameDir) |

engine/common/common.h

@@ -282,6 +282,9 @@ typedef enum bugcomp_e
 
 	// makes sound with no attenuation spatialized, like in GoldSrc
 	BUGCOMP_SPATIALIZE_SOUND_WITH_ATTN_NONE = BIT( 2 ),
+
+	// returns full path to the game directory in server's pfnGetGameDir call
+	BUGCOMP_GET_GAME_DIR_FULL_PATH = BIT( 3 ),
 } bugcomp_t;
 
 typedef struct host_parm_s

engine/common/host.c

@@ -75,6 +75,7 @@ static const feature_message_t bugcomp_features[] =
 { BUGCOMP_PENTITYOFENTINDEX_FLAG, "pfnPEntityOfEntIndex bugfix revert", "peoei" },
 { BUGCOMP_MESSAGE_REWRITE_FACILITY_FLAG, "GoldSrc Message Rewrite Facility", "gsmrf" },
 { BUGCOMP_SPATIALIZE_SOUND_WITH_ATTN_NONE, "spatialize sounds with zero attenuation", "sp_attn_none" },
+{ BUGCOMP_GET_GAME_DIR_FULL_PATH, "Return full path in GET_GAME_DIR()", "get_game_dir_full" }
 };
 
 static const feature_message_t engine_features[] =

engine/server/sv_game.c

@@ -4638,14 +4638,21 @@ static void GAME_EXPORT pfnGetGameDir( char *out )
 	if( !out )
 		return;
 
-	// in GoldSrc, it's a full path to game directory, limited by 256 characters
+	if( !FBitSet( host.bugcomp, BUGCOMP_GET_GAME_DIR_FULL_PATH ))
-	// however the full path might easily overflow that limitation
-	// here we check if it would overflow and just return game folder in that case
-	if( !g_fsapi.GetRootDirectory( rootdir, sizeof( rootdir ))
-		|| Q_snprintf( out, 256, "%s/%s", rootdir, GI->gamefolder ) < 0 )
 	{
 		Q_strncpy( out, GI->gamefolder, 256 );
 	}
+	else
+	{
+		// in GoldSrc pre-1.1.1.1, it's a full path to game directory, limited by 256 characters
+		// however the full path might easily overflow that limitation
+		// here we check if it would overflow and just return game folder in that case
+		if( !g_fsapi.GetRootDirectory( rootdir, sizeof( rootdir ))
+			|| Q_snprintf( out, 256, "%s/%s", rootdir, GI->gamefolder ) < 0 )
+		{
+			Q_strncpy( out, GI->gamefolder, 256 );
+		}
+	}
 }
 
 // engine callbacks