source: code/trunk/vendor/github.com/prometheus/procfs/proc_cgroups.go@ 822

// Copyright 2021 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package procfs

import (
        "bufio"
        "bytes"
        "fmt"
        "strconv"
        "strings"

        "github.com/prometheus/procfs/internal/util"
)

// CgroupSummary models one line from /proc/cgroups.
// This file contains information about the controllers that are compiled into the kernel.
//
// Also see http://man7.org/linux/man-pages/man7/cgroups.7.html
type CgroupSummary struct {
        // The name of the controller. controller is also known as subsystem.
        SubsysName string
        // The unique ID of the cgroup hierarchy on which this controller is mounted.
        Hierarchy int
        // The number of control groups in this hierarchy using this controller.
        Cgroups int
        // This field contains the value 1 if this controller is enabled, or 0 if it has been disabled
        Enabled int
}

// parseCgroupSummary parses each line of the /proc/cgroup file
// Line format is `subsys_name  hierarchy       num_cgroups     enabled`.
func parseCgroupSummaryString(CgroupSummaryStr string) (*CgroupSummary, error) {
        var err error

        fields := strings.Fields(CgroupSummaryStr)
        // require at least 4 fields
        if len(fields) < 4 {
                return nil, fmt.Errorf("at least 4 fields required, found %d fields in cgroup info string: %s", len(fields), CgroupSummaryStr)
        }

        CgroupSummary := &CgroupSummary{
                SubsysName: fields[0],
        }
        CgroupSummary.Hierarchy, err = strconv.Atoi(fields[1])
        if err != nil {
                return nil, fmt.Errorf("failed to parse hierarchy ID")
        }
        CgroupSummary.Cgroups, err = strconv.Atoi(fields[2])
        if err != nil {
                return nil, fmt.Errorf("failed to parse Cgroup Num")
        }
        CgroupSummary.Enabled, err = strconv.Atoi(fields[3])
        if err != nil {
                return nil, fmt.Errorf("failed to parse Enabled")
        }
        return CgroupSummary, nil
}

// parseCgroupSummary reads each line of the /proc/cgroup file.
func parseCgroupSummary(data []byte) ([]CgroupSummary, error) {
        var CgroupSummarys []CgroupSummary
        scanner := bufio.NewScanner(bytes.NewReader(data))
        for scanner.Scan() {
                CgroupSummaryString := scanner.Text()
                // ignore comment lines
                if strings.HasPrefix(CgroupSummaryString, "#") {
                        continue
                }
                CgroupSummary, err := parseCgroupSummaryString(CgroupSummaryString)
                if err != nil {
                        return nil, err
                }
                CgroupSummarys = append(CgroupSummarys, *CgroupSummary)
        }

        err := scanner.Err()
        return CgroupSummarys, err
}

// CgroupSummarys returns information about current /proc/cgroups.
func (fs FS) CgroupSummarys() ([]CgroupSummary, error) {
        data, err := util.ReadFileNoStat(fs.proc.Path("cgroups"))
        if err != nil {
                return nil, err
        }
        return parseCgroupSummary(data)
}