107 lines
2.7 KiB
Go
107 lines
2.7 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cgroups
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import (
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"errors"
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"fmt"
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"path/filepath"
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)
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type Path func(subsystem Name) (string, error)
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func RootPath(subsystem Name) (string, error) {
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return "/", nil
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}
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// StaticPath returns a static path to use for all cgroups
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func StaticPath(path string) Path {
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return func(_ Name) (string, error) {
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return path, nil
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}
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}
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// NestedPath will nest the cgroups based on the calling processes cgroup
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// placing its child processes inside its own path
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func NestedPath(suffix string) Path {
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paths, err := ParseCgroupFile("/proc/self/cgroup")
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if err != nil {
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return errorPath(err)
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}
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return existingPath(paths, suffix)
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}
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// PidPath will return the correct cgroup paths for an existing process running inside a cgroup
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// This is commonly used for the Load function to restore an existing container
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func PidPath(pid int) Path {
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p := fmt.Sprintf("/proc/%d/cgroup", pid)
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paths, err := ParseCgroupFile(p)
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if err != nil {
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return errorPath(fmt.Errorf("parse cgroup file %s: %w", p, err))
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}
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return existingPath(paths, "")
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}
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// ErrControllerNotActive is returned when a controller is not supported or enabled
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var ErrControllerNotActive = errors.New("controller is not supported")
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func existingPath(paths map[string]string, suffix string) Path {
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// localize the paths based on the root mount dest for nested cgroups
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for n, p := range paths {
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dest, err := getCgroupDestination(n)
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if err != nil {
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return errorPath(err)
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}
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rel, err := filepath.Rel(dest, p)
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if err != nil {
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return errorPath(err)
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}
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if rel == "." {
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rel = dest
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}
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paths[n] = filepath.Join("/", rel)
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}
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return func(name Name) (string, error) {
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root, ok := paths[string(name)]
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if !ok {
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if root, ok = paths["name="+string(name)]; !ok {
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return "", ErrControllerNotActive
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}
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}
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if suffix != "" {
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return filepath.Join(root, suffix), nil
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}
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return root, nil
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}
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}
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func subPath(path Path, subName string) Path {
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return func(name Name) (string, error) {
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p, err := path(name)
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if err != nil {
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return "", err
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}
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return filepath.Join(p, subName), nil
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}
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}
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func errorPath(err error) Path {
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return func(_ Name) (string, error) {
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return "", err
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}
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}
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