By Katie Marsal

Published: 07:00 PM EST

According to sources privy to pre-release builds of Apple's Mac OS X 10.4 "Tiger" operating system, the release will feature "Fast Logout and Autosave" technology and support for Access Control Lists file-based permissions, AppleInsider has learned.

Fast Logout and Autosave

Fast logout and autosave is a performance-related feature designed to improve the user experience of Mac OS X Tiger.

Presently, closing windows in Mac OS X an expensive operation, especially if the application must prompt the user about unsaved changes for each document window. Tiger's fast logout and autosave feature will improve logout, shutdown, and restart operations by reducing the number of confirmation dialogs presented to the user, all the while protecting the user's unsaved data in open applications.

During a logout, shutdown, or restart operation, Tiger will determine whether an application should post a confirmation dialog for unsaved changes or perform an auto-save event. If the application performs an auto-save event, data will be saved to a special location on the system and the user will be logged out of Mac OS X. The next time the user logs in, the system relaunches each application with auto-saved documents and reconstructs the documents as their state immediately before the last logout.

According to sources, most of the applications that will ship with Tiger will already support Fast Logout and Autosave. On the other hand, third party developers will need to update their applications to gain the benefits of the new feature.

Access Control Lists

Tiger will also introduce support for Access Control Lists (ACLs)—a robust system for implementing file-based permissions that offer many improvements over the existing BSD permissions currently used by the Mac OS X file systems.

Among the improvements delivered by ACL's is support for ownership of files and directories by a group, enhanced interoperability with Samba and Windows, and support for multiple owners of a file or directory, each with potentially different permissions.

Additionally, ACL's will add support for static inheritance of file permissions from a parent directory and provide more control over a file than just read/write/execute permissions.
ACLs are a common feature of enterprise computing because they provide flexible and highly configurable rights management for servers. The technology also removes many of the limitations of the existing BSD permissions by allowing access to files and directories by multiple groups and users. In addition, it lets the system administrator grant specific rights to each user and group without requiring the creation of special new groups.