Sandboxing under GoboLinux
The build system in GoboLinux uses sandboxing to ensure that all the filesystem writes during the software install phase are limited to an appropriate part of the filesystem. GoboLinux 016 ships with two different sandbox implementations.
UnionSandbox is a modern implementation which uses file system unions to achieve isolation. It is the default sandbox installer.
FiboSandbox is a fallback method used when a union-filesystem implementation
is not available in the running kernel. It sets up an isolated environment and
commands are run by a special user (named fibo) without root privileges.
During the installation phase of the software build process, most build systems
call the install program to copy files to their destination directories with
the proper ownership and attributes. install belongs to the CoreUtils
package.
Since user fibo lacks authority to change file ownership, the link at
/System/Index/bin/install points to a wrapper script in the Scripts package.
Under UnionSandbox, this wrapper script translates the superuser name if
necessary and calls real_install, a symlink to the CoreUtils install
utility, passing along the modified arguments.
Under FiboSandbox, the wrapper discards change-of-owner directives before
calling real_install.