Kate v0.25 (Spring 2024)#
The v0.25 is the spring experimental release of Kate. This release focuses on improving Kate’s stability, making it easier for players to play a game across multiple devices, and making it easier for developers to publish games for Kate.
New input proxy bridge#
This release includes a new input proxy bridge that allows one to specify a CSS selector for dispatching the events to, or keep dispatching them on the document/window. This is necessary because every engine out there decides to listen to events in a different place, so Ren’Py listens to window events, Bitsy to document events, and Godot to canvas events.
PRs: #33
New network proxy bridge#
The network proxy bridge was extended to allow specifying files that need to be loaded “synchronously” (which we do by pre-loading them at the time we create the process sandbox). This allows games that use workers and other features that require seemingly synchronous access to work in Kate without any changes to the source code, and expands Kate’s emulation support to engines like Godot and similar.
PRs: #41
Memory-friendly cartridge format#
Previously a Kate cartridge had to be fully loaded in memory in order to install it, which meant that some devices (e.g.: the Raspberry Pi 4) were limited to installing only cartridges smaller than 300 MB. This release introduces a new (not-backwards compatible) cartridge format that can be processed without loading it fully in memory, thus getting rid of the cartridge size restrictions for all devices.
- PRs: #37,
New file storage service#
Previous versions of Kate stored files (such as those extracted from cartridges) in its main database. This caused the database load to increase unreasonably, preventing the installation of large collections of games.
The new version has replaced this with an entirely new file storage service that leaves the database alone and is not subject to the same scalability concerns. The file storage service is also partitioned, meaning that cartridge files and other system files remain fully isolated — i.e.: cartridge A can never access files from cartridge B, or even from a different version of cartridge A.
The use of the file storage service gives us better stability, and helps us scale to large game collections, but it operates more sequentially and as such has lower raw write performance. This means that installing games with large amounts of files takes longer than before — optimisations here are possible, and will be looked at in future versions!
More stable process handling#
Important
SECURITY-SENSITIVE CHANGE: This patch fixes an issue with the previous cartridge sandboxing code that, with user cooperation, could lead to increased privileges for the cartridge.
The previous code for handling sandboxed processes in Kate was still in its proof-of-concept stage. This release includes a rewrite of the process handling to make it more stable and prepare for a future multi-process Kate.
Along with the changes, sandboxed processes are no longer using a Blob URL, and rather pass the HTML directly into the frame. This removes one avenue of privilege escalation where attackers could trick users to cooperate in opening the blob URL outside of the frame, and then having their code execute with the same privileges as Kate.
Note that this change does not yet address the issues with speculative side-channel attacks (Spectre, etc.), as Browsers do not offer any guarantee that a frame will be rendered in a separate process. The issue is however mitigated in Kate as sandboxed processes do not have network or navigation access.
- PRs: #34,
Cartridge signatures and key stores#
While not fully ready yet, this release prepares the ground-work for Kate’s decentralised game catalog by adding support for signed cartridges, as well as managing signing keys and verifying signatures. This comes with an early introduction of “Developer Profiles”, which will be the basis of Kate’s future developer tools.
New game engine recipes#
This release extends Kart (Kate’s official tool for creating game cartridges) with built-in recipe support for Godot (only version 3 for now), GameMaker, and RPG Maker MV. There’s a little bit of additional work to support other engines that will be done in the next iteration, but the changes introduced in this release should allow a fair amount of games to be loaded from a Kate cartridge with no code changes required!
Friendlier creation of cartridges#
This release includes the new Kate Publisher cartridge, a GUI Kate application that can generate and sign cartridges right from the console. It uses the same inputs as its command-line cousin Kart for now.
PRs: #42
Minor fixes and improvements#
The drop-installer indicator now shows up more reliably when dragging files over the console (b76b0ce);
Plugins are now fully disabled in sandboxed processes, which makes it harder for cartridges to escape their sandboxes (c070957);
Small performance improvements to loading and sending data in the cartridge’s process by avoiding copying when possible (f8eb02d);
Fixed an issue where overwriting a cartridge with the same version would not remove the previous cartridge’s files (fb030e8);
Many tweaks to the text and feel in some parts of the UI;
Support 1600x960 as a console resolution (808c3e7);
Added a “process log” which shows messages output by each process to standard outputs (#43);