// The expected cgroup format is "hierarchy-ID:controller-list:cgroup-path", and
// this function will return an error if every cgroup does not meet that format.
//
// For more information, see:
//   - http://man7.org/linux/man-pages/man7/cgroups.7.html
//   - https://www.kernel.org/doc/Documentation/cgroup-v2.txt
func GetCgroups(procCgroupData bytes.Buffer) ([]Cgroup, error) {
	reader := bytes.NewReader(procCgroupData.Bytes())
	var cgroups []Cgroup