Core client: file structure

The core client runs in a BOINC home directory. An account file (accounts.xml) must be present in this directory. The core client creates and uses the following files and directories within the BOINC home directory:

• client_state.xml: this is an description of the files, application, workunits and results present on this client.
• Each project has a project subdirectory whose name is the project's base URL. This subdirectory contains all files (inputs, outputs, executables) related to the project.
• slots: this directory contains one subdirectory for each CPU "slot" (normally there are as many slots as the host has CPUs). The subdirectories are named 0, 1, ... N-1.

Each result executes in particular slot. The core client creates symbolic links (UNIX) or .lnk files (Windows) in the slot directory, linking the input, output and executable files to the appropriate files in the project directory. On UNIX, the core client uses chroot() so that the application sees the slot directory as the root of its filesystem, and cannot create or access files outside of it.