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• Approaches To Modifying Game Resource Files

  16 août 2016, par Multimedia Mike — Game Hacking

  I have been assisting The Translator in the translation of another mid-1990s adventure game. This one isn’t quite as multimedia-heavy as the last title, and the challenges are a bit different. I wanted to compose this post in order to describe my thought process and mental model in approaching this problem. Hopefully, this will help some others understand my approach since what I’m doing here often appears as magic to some of my correspondents.

  High Level Model
  At the highest level, it is valuable to understand the code and the data at play. The code is the game’s engine and the data refers to the collection of resources that comprise the game’s graphics, sound, text, and other assets.

  
  
  Simplistic high-level game engine model
  

  Ideally, we want to change the data in such a way that the original game engine adopts it as its own because it has the same format as the original data. It is very undesirable to have to modify the binary engine executable in any way.

  Modifying The Game Data Directly
  How to modify the data ? If we modify the text strings for the sake of language translation, one approach might be to search for strings within the game data files and change them directly. This model assumes that the text strings are stored in a plain, uncompressed format. Some games might store these strings in a text format which can be easily edited with any text editor. Other games will store them as binary data.
  

  In the latter situation, a game hacker can scan through data files with utilities like Unix ‘strings’ to find the resources with the desired strings. Then, use a hex editor to edit the strings directly. For example, change “Original String”…

  0098F800   00 00 00 00  00 00 00 4F  72 69 67 69  6E 61 6C 20  .......Original 
  0098F810   53 74 72 69  6E 67 00 00  00 00 00 00  00 00 00 00  String..........
  

  …to “Short String” and pad the difference in string lengths using spaces (0x20) :

  0098F800   00 00 00 00  00 00 00 53  68 6F 72 74  20 53 74 72  .......Short Str
  0098F810   69 6E 67 20  20 20 00 00  00 00 00 00  00 00 00 00  ing   ..........
  

  This has some obvious problems. First, translated strings need to be of equal our smaller length compared to the original. What if we want to encode “Much Longer String” ?

  0098F800   00 00 00 00  00 00 00 4D  75 63 68 20  4C 6F 6E 67  .......Much Long
  0098F810   65 72 20 53  74 72 00 00  00 00 00 00  00 00 00 00  er Str..........
  

  It won’t fit. The second problem pertains to character set limitations. If the font in use was only designed for ASCII, it’s going to be inadequate for expressing nearly any other language.

  So a better approach is needed.

  Understanding The Data Structures
  An alternative to the approach outlined above is to understand the game’s resources so they can be modified at a deeper level. Here’s a model to motivate this investigation :

  
  
  Model of the game resource archive format
  

  This is a very common layout for such formats : there is a file header, a sequence of resource blocks, and a trailing index which describes the locations and types of the foregoing blocks.

  What use is understanding the data structures ? In doing so, it becomes possible to write new utilities that disassemble the data into individual pieces, modify the necessary pieces, and then reassemble them into a form that the original game engine likes.

  It’s important to take a careful, experimental approach to this since mistakes can be ruthlessly difficult to debug (unless you relish the thought of debugging the control flow through an opaque DOS executable). Thus, the very first goal in all of this is to create a program that can disassemble and reassemble the resource, thus creating an identical resource file. This diagram illustrates this complex initial process :

  
  
  Rewriting the game resource file
  

  So, yeah, this is one of the most complicated “copy file” operations that I can possibly code. But it forms an important basis, since the next step is to carefully replace one piece at a time.

  
  
  Modifying a specific game resource
  

  This diagram shows a simplistic model of a resource block that contains a series of message strings. The header contains pointers to each of the strings within the block. Instead of copying this particular resource block directly to the new file, a proposed modification utility will intercept it and rewrite the entire thing, writing new strings of arbitrary length and creating an adjusted header which will correctly point to the start of each new string. Thus, translated strings can be longer than the original strings.

  Further Work
  Exploiting this same approach, we can intercept and modify other game resources including fonts, images, and anything else that might need to be translated. I will explore specific examples in a later blog post.

  Followup

  • Translating Return to Ringworld, in which I apply the ideas expressed in this post.

• [Aug-Sept 2013] Piwik 2.0 Development Update !

  3 octobre 2013, par Fabian Becker — Development

  This Development Update is the first in a new series of posts we’ll be writing to keep you, our loyal users, informed of our efforts. We hope these updates keep you excited about Piwik’s future, and if you’re a developer, we hope they inspire and challenge you to accomplish more yourself !

  Despite this being our first update, it will probably be one of our biggest. We’ve gotten a lot done as we race towards the Piwik 2.0 release ! Just see for yourself :

  What we’ve accomplished

  Theming

  Piwik now supports theming, a feature that was requested often in the past. Because of our switch to the Twig template engine and other major code changes it is now possible to change the way Piwik looks. Additionally, developers can use the dynamic stylesheet language LESS, instead of CSS. Piwik will automatically transform the LESS code into CSS.

  Piwik 2.0 will ship with a new dark theme called PleineLune (french for Full Moon) that makes use of the new theming feature. Another theme with a left-aligned menu was created during the Piwik Meetup in Paris. Both of these themes were created by Thomas Zilliox, a very talented designer and CSS expert.

  

  PHP 5.3 Namespaces

  For Piwik 2.0 we decided to make use of namespaces, a feature introduced in PHP 5.3. The usage of namespaces makes our code more readable and allows us to better modularize the platform. This is in part why we are raising the required minimum PHP version to 5.3 for Piwik 2.0. (Remember to update your server !)

  Translations in JSON

  All translations are now stored in JSON files which makes storing translations in Piwik a lot cleaner that the giant PHP array we previously used.

  Side note : if you’d like to make Piwik available to more languages, please sign up at translations.piwik.org. We’d love to have your help !

  UI Tests

  We now use UI tests to make sure that changes to the code don’t break the UI. UI tests use PhantomJS and CutyCapt and are automatically executed on Travis CI. Whenever an integration test fails the script produces a screenshot diff that shows the difference. Learn more.

  

  AnonymizeIP supports IPv6

  The AnonymizeIP plugin now masks IPv6 addresses. The concept of the config option ‘ip_address_mask_length’ has now changed to reflect the level of masking that should be applied to the IP. With a masking level of 1 Piwik will mask the last octet of an IPv4 address and the last 80 bits of an IPv6 address.

  All Websites Dashboard usable with 20,000+ Websites

  The All Websites Dashboard is now usable even if you track many thousands of websites in your Piwik instance. We rewrote parts of the archiving process in order to make this possible. Making Piwik fast and memory efficient is a constant concern for core developers.

  Plugins can now add new Visualizations

  Piwik Plugins and Themes can now create new visualizations for your report data. They can also specify their own ViewDataTable footer icons or modify existing ones. This will allow plugin developers to create new ways for you to view your data, customize existing reports so they look great in new visualizations and provide extra analytics functionality accessible in each of your reports.

  The new TreemapVisualization plugin makes use of this feature to let you view your reports as treemaps. It serves as an example of this new functionality.

  Piwik Marketplace

  The Piwik Marketplace is a new platform developers can use to publish their plugins and themes so all Piwik users can easily access them. The marketplace is hosted at plugins.piwik.org and is currently in an early development state, but we’re already able to host plugins !

  Developers can easily publish their plugins by adding a commit hook to their Github repositories. Every time you push a new tag, the marketplace will make a new version of your plugin available. The marketplace will provide a centralized platform to search for plugins and also provide statistics on plugin usage.

  Install Plugins and Themes in one click from within Piwik

  Piwik has offered since the beginning the much-loved “one click update” feature. We are bringing the same functionnality to the Marketplace : you will be able to install Plugins and Themes in one click directly within the Piwik interface ! Similarly to WordPress or Firefox, Piwik will let you extend the functionnality of your analytics platform.

  Conclusion

  In Piwik 2.0 you will be able to install plugins and themes from the marketplace. And, if you’re so inclined, you will be able to create and host your own plugins/themes on the marketplace so everyone can use them. This is by far the accomplishment we are most excited by… the possibilities it opens up for Piwik’s future are truly unlimited. We hope you share our excitement !

  Au revoir, until next time !

  PS : our mission is to liberate web analytics ; thank you for sharing the word about Piwik 2.0 !

• How to publish your plugin or theme on the Piwik Marketplace – Introducing the Piwik Platform

  25 septembre 2014, par Thomas Steur — Community, Development

  This is the next post of our blog series where we introduce the capabilities of the Piwik platform. Over the last weeks we have already introduced you to some of the basics on how to create plugins and themes. This time you’ll learn how to publish a plugin or theme on the Piwik Marketplace to share it with all Piwik users.

  What is the Piwik Marketplace ?

  The Marketplace is a showcase for all plugins and themes that can be used in Piwik. You can browse them either on a standalone website or in Piwik itself by going to Settings => Marketplace. There you can install and update them with just one click. Easy as that ! While some of those plugins are provided by Piwik or Piwik PRO most of them are created and maintained by our community. Everyone is very welcome to distribute plugins or themes on the Marketplace.

  Prerequisites

  To publish your plugin on the Marketplace you simply need to meet these requirements :

  • The plugin name is not already taken by another plugin
  • The code of the plugin is hosted in a public GitHub repository
  • The GitHub service “Piwik plugins” for this repository is enabled (Repository Settings => Webhooks & Services => Add Service)
  • Push permission for this repository
  • The plugin is free (as in not paid)
  • The license must be compatible with the GNU General Public License v3 or any later version

  There is also list of Rules for plugins.

  Best practices

  Before actually distributing your plugin we recommend to follow a couple of best practices to make sure your plugin looks good on the Marketplace and provides useful information for your future users. If you have used the console to generate a plugin the needed files were already created for you.

  Provide a good description

  Make sure there is a file named README.md in the root of your plugin. When preparing your plugin for the Marketplace we will search for four sections in this file : Description, FAQ, Changelog and Support. Each of those is optional but it is good practice to provide at least a section Description and Support by prefixing them with ## . Any content of your readme outside of those sections will not be displayed on the Marketplace.

  # Piwik Plugin Name
  
  
  
  ## Description
  
  
  
  Add your plugin description here.
  
  
  
  ## Support
  
  
  
  Please direct any feedback to hello@piwik.org. 
  
  If you experience any issues feel free to file an issue at https://github.com/piwik/piwik/issues .

  A good example can be seen in the README.md of the CustomAlerts plugin and the related CustomAlerts plugin page.

  Provide screenshots

  This will improve your appearance in the Marketplace a lot and users will be more likely install your plugin. It is as easy as placing “png” or “jpg” files in a folder named screenshots. The filename of each image will be shown in the UI with underscores replaced by a whitespace. This way you can provide a nice description. Have a look at the CustomAlerts plugin to see how it works.

  Provide contact details

  Your contact details are specified in the plugin.json file of your plugin root folder. Providing at least one author and a link to your homepage is required. If you do not have a website you can use a link to your GitHub profile. This helps your users contact you in case they want to thank you for your great work or if they have any problem with it. An example plugin.json looks like this :

  {
  
      "name": "MyPluginName",
  
      "homepage": "http://piwik.org",
  
      "authors": [
  
          {
  
              "name": "Piwik",
  
              "email": "hello@piwik.org",
  
              "homepage": "http://piwik.org"
  
          }
  
      ],
  
      "support": {
  
        "email": "hello@piwik.org",
  
        "issues": "https://github.com/piwik/piwik/issues",
  
        "forum": "http://forum.piwik.org",
  
        "wiki": "https://github.com/piwik/piwik/wiki",
  
        "irc": "#piwik-dev"
  
      } 
  
  }

  Choose a license

  Choosing the right license that works best for you and your users is important. To distribute a plugin via the Piwik Marketplace the license must be compatible with the GNU General Public License v3 or any later version. If you do not specify a license anywhere in your plugin, it is assumed your plugin uses GPLv3 or later. The license must be specified in the plugin.json file using the property license :

  {
  
      "name": "MyPluginName",
  
      "license": "GPL v3+"
  
  }

  Provide donation links

  You can define a donation link or email for PayPal, Flattr and Bitcoin in the plugin.json file. Users that love your work will then be able to donate you money directly from the plugin page.

  {
  
      "name": "MyPluginName"
  
      "donate": {
  
          "paypal": "sponsor@piwik.org",
  
          "flattr": "https://flattr.com/profile/piwik",
  
          "bitcoin": "1234567890"
  
      }
  
  }

  How to publish the first version of your plugin

  We are trying to make it as easy as possible for you to publish your plugin on the Marketplace. That’s why we don’t require any logins or packaging. To publish your plugin you only have to create a new tag of your plugin and within a minute your plugin will be ready to be installed on hundreds of thousands of Piwik installations.

  To tag your plugin you can use one of the following two suggestions :

  Using the command line

  git tag 0.1.0 && git push --tags

  Where “0.1.0” is the name of the tag. While you can use any tag name it is best practice to use the current version number as defined in the plugin.json file.

  Using GitHub UI

  To tag a new version via GitHub click on Releases => Draft a new release.

  

  Now you can enter a tag name (version) and press “Publish release” as shown in this screen. That’s it !

  

  How to provide an update for your plugin

  To provide an update you only have to increase the version number in the file plugin.json and create another tag as explained in the previous section. Your new Plugin update will be visible on the Marketplace within a minute or so. It might take a bit longer until the update appears in Piwik itself as each Piwik server only checks for updates every few hours.

  For a complete list of information go to our Distributing Your Plugin guide in the Piwik Developer Zone.

  If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to let us know.