ChorusOS 4.0 Introduction

Actor Context

The precise context of an actor depends on how the system is configured. An extended actor has a file context similar to the file context of a UNIX process: it has a root directory as well as a current directory. It may also create, open, close, read and write files or sockets.

An extended actor runs on behalf of a user who is identified by means of a credentials structure. The actor credentials include: the identifier of the user, the identifier of the group of the user as well as a possibly empty list of identifiers of supplementary groups. Readers familiar with the concept of credentials in UNIX should note that the ChorusOS operating system concept of credentials is simpler than the UNIX one. ChorusOS 4.0 does not differentiate between real or effective user/group identification as it is not supported.

These actor credentials are used for file access. They are also used when the ChorusOS operating system runs in secured mode to check the validity of an operation. For example, in secured mode only the superuser, whose user identifier is 0, may load supervisor actors.