Source: proc_fdinfo.go in package github.com/prometheus/procfs

Copyright 2019 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"
	"regexp"

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

Regexp variables

var (
	rPos     = regexp.MustCompile(`^pos:\s+(\d+)$`)
	rFlags   = regexp.MustCompile(`^flags:\s+(\d+)$`)
	rMntID   = regexp.MustCompile(`^mnt_id:\s+(\d+)$`)
	rInotify = regexp.MustCompile(`^inotify`)
)

ProcFDInfo contains represents file descriptor information.

File descriptor

File offset

File access mode and status flags

Mount point ID

List of inotify lines (structed) in the fdinfo file (kernel 3.8+ only)

	InotifyInfos []InotifyInfo
}

FDInfo constructor. On kernels older than 3.8, InotifyInfos will always be empty.

func (p Proc) FDInfo(fd string) (*ProcFDInfo, error) {
	data, err := util.ReadFileNoStat(p.path("fdinfo", fd))
	if err != nil {
		return nil, err
	}

	var text, pos, flags, mntid string
	var inotify []InotifyInfo

	scanner := bufio.NewScanner(bytes.NewReader(data))
	for scanner.Scan() {
		text = scanner.Text()
		if rPos.MatchString(text) {
			pos = rPos.FindStringSubmatch(text)[1]
		} else if rFlags.MatchString(text) {
			flags = rFlags.FindStringSubmatch(text)[1]
		} else if rMntID.MatchString(text) {
			mntid = rMntID.FindStringSubmatch(text)[1]
		} else if rInotify.MatchString(text) {
			newInotify, err := parseInotifyInfo(text)
			if err != nil {
				return nil, err
			}
			inotify = append(inotify, *newInotify)
		}
	}

	i := &ProcFDInfo{
		FD:           fd,
		Pos:          pos,
		Flags:        flags,
		MntID:        mntid,
		InotifyInfos: inotify,
	}

	return i, nil
}

InotifyInfo represents a single inotify line in the fdinfo file.

Watch descriptor number

Inode number

Device ID

Mask of events being monitored

	Mask string
}

InotifyInfo constructor. Only available on kernel 3.8+.

func parseInotifyInfo(line string) (*InotifyInfo, error) {
	r := regexp.MustCompile(`^inotify\s+wd:([0-9a-f]+)\s+ino:([0-9a-f]+)\s+sdev:([0-9a-f]+)\s+mask:([0-9a-f]+)`)
	m := r.FindStringSubmatch(line)
	i := &InotifyInfo{
		WD:   m[1],
		Ino:  m[2],
		Sdev: m[3],
		Mask: m[4],
	}
	return i, nil
}

ProcFDInfos represents a list of ProcFDInfo structs.

type ProcFDInfos []ProcFDInfo

func (p ProcFDInfos) Len() int           { return len(p) }
func (p ProcFDInfos) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
func (p ProcFDInfos) Less(i, j int) bool { return p[i].FD < p[j].FD }

InotifyWatchLen returns the total number of inotify watches

func (p ProcFDInfos) InotifyWatchLen() (int, error) {
	length := 0
	for _, f := range p {
		length += len(f.InotifyInfos)
	}

	return length, nil