GetContainerGroups uses securejoin to get a list of numerical groupids from a container.

GetGroup takes a containermount path and a group name or ID and returns a match Group struct from /etc/group.

GetUser takes a containermount path and user name or ID and returns a matching User structure from /etc/passwd.

GetUserGroupInfo takes string forms of the the container's mount path and the container user and returns a ExecUser with uid, gid, sgids, and home.

Overrides allows you to override defaults in GetUserGroupInfo.