github.com/rkt/rkt@v1.30.1-0.20200224141603-171c416fac02/common/cgroup/v2/cgroup.go (about)

     1  // Copyright 2016 The rkt Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  //+build linux
    16  
    17  package v2
    18  
    19  import (
    20  	"bufio"
    21  	"errors"
    22  	"fmt"
    23  	"os"
    24  	"strings"
    25  
    26  	"github.com/hashicorp/errwrap"
    27  )
    28  
    29  // GetEnabledControllers returns a list of enabled cgroup controllers
    30  func GetEnabledControllers() ([]string, error) {
    31  	controllersFile, err := os.Open("/sys/fs/cgroup/cgroup.controllers")
    32  	if err != nil {
    33  		return nil, err
    34  	}
    35  	defer controllersFile.Close()
    36  
    37  	sc := bufio.NewScanner(controllersFile)
    38  
    39  	sc.Scan()
    40  	if err := sc.Err(); err != nil {
    41  		return nil, err
    42  	}
    43  
    44  	return strings.Split(sc.Text(), " "), nil
    45  }
    46  
    47  func parseProcCgroupInfo(procCgroupInfoPath string) (string, error) {
    48  	cg, err := os.Open(procCgroupInfoPath)
    49  	if err != nil {
    50  		return "", errwrap.Wrap(errors.New("error opening /proc/self/cgroup"), err)
    51  	}
    52  	defer cg.Close()
    53  
    54  	s := bufio.NewScanner(cg)
    55  	s.Scan()
    56  	parts := strings.SplitN(s.Text(), ":", 3)
    57  	if len(parts) < 3 {
    58  		return "", fmt.Errorf("error parsing /proc/self/cgroup")
    59  	}
    60  
    61  	return parts[2], nil
    62  }
    63  
    64  // GetOwnCgroupPath returns the cgroup path of this process
    65  func GetOwnCgroupPath() (string, error) {
    66  	return parseProcCgroupInfo("/proc/self/cgroup")
    67  }
    68  
    69  // GetCgroupPathByPid returns the cgroup path of the process
    70  func GetCgroupPathByPid(pid int) (string, error) {
    71  	return parseProcCgroupInfo(fmt.Sprintf("/proc/%d/cgroup", pid))
    72  }