filesystem: allow acquiring C interface through CreateInterface export

filesystem/VFileSystem009.cpp

@@ -492,6 +492,18 @@ extern "C" void EXPORT *CreateInterface( const char *interface, int *retval )
 		return &g_VFileSystem009;
 	}
 
+	if( !Q_strcmp( interface, FS_API_CREATEINTERFACE_TAG ))
+	{
+		// return a copy, to disallow overriding
+		static fs_api_t copy = { 0 };
+
+		if( !copy.InitStdio )
+			memcpy( &copy, &g_api, sizeof( copy ));
+
+		if( retval ) *retval = 0;
+		return ©
+	}
+
 	if( retval ) *retval = 1;
 	return NULL;
 }

filesystem/filesystem.c

@@ -2868,7 +2868,7 @@ static qboolean FS_InitInterface( int version, fs_interface_t *engfuncs )
 	return true;
 }
 
-static fs_api_t g_api =
+fs_api_t g_api =
 {
 	FS_InitStdio,
 	FS_ShutdownStdio,

filesystem/filesystem.h

@@ -29,6 +29,7 @@ extern "C"
 #endif // __cplusplus
 
 #define FS_API_VERSION 1 // not stable yet!
+#define FS_API_CREATEINTERFACE_TAG "XashFileSystem001" // follow FS_API_VERSION!!!
 
 // search path flags
 enum

filesystem/filesystem_internal.h

@@ -86,6 +86,7 @@ extern qboolean      fs_ext_path;
 extern char          fs_rodir[MAX_SYSPATH];
 extern char          fs_rootdir[MAX_SYSPATH];
 extern char          fs_writedir[MAX_SYSPATH];
+extern fs_api_t      g_api;
 
 #define GI FI.GameInfo