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|
package cgroups
import (
"fmt"
"path/filepath"
"github.com/pkg/errors"
)
type Path func(subsystem Name) (string, error)
func RootPath(subsysem Name) (string, error) {
return "/", nil
}
// StaticPath returns a static path to use for all cgroups
func StaticPath(path string) Path {
return func(_ Name) (string, error) {
return path, nil
}
}
// NestedPath will nest the cgroups based on the calling processes cgroup
// placing its child processes inside its own path
func NestedPath(suffix string) Path {
paths, err := parseCgroupFile("/proc/self/cgroup")
if err != nil {
return errorPath(err)
}
return existingPath(paths, suffix)
}
// PidPath will return the correct cgroup paths for an existing process running inside a cgroup
// This is commonly used for the Load function to restore an existing container
func PidPath(pid int) Path {
p := fmt.Sprintf("/proc/%d/cgroup", pid)
paths, err := parseCgroupFile(p)
if err != nil {
return errorPath(errors.Wrapf(err, "parse cgroup file %s", p))
}
return existingPath(paths, "")
}
func existingPath(paths map[string]string, suffix string) Path {
// localize the paths based on the root mount dest for nested cgroups
for n, p := range paths {
dest, err := getCgroupDestination(string(n))
if err != nil {
return errorPath(err)
}
rel, err := filepath.Rel(dest, p)
if err != nil {
return errorPath(err)
}
if rel == "." {
rel = dest
}
paths[n] = filepath.Join("/", rel)
}
return func(name Name) (string, error) {
root, ok := paths[string(name)]
if !ok {
if root, ok = paths[fmt.Sprintf("name=%s", name)]; !ok {
return "", fmt.Errorf("unable to find %q in controller set", name)
}
}
if suffix != "" {
return filepath.Join(root, suffix), nil
}
return root, nil
}
}
func subPath(path Path, subName string) Path {
return func(name Name) (string, error) {
p, err := path(name)
if err != nil {
return "", err
}
return filepath.Join(p, subName), nil
}
}
func errorPath(err error) Path {
return func(_ Name) (string, error) {
return "", err
}
}
|
