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

// 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"
        "fmt"
        "regexp"

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

var (
        rPos          = regexp.MustCompile(`^pos:\s+(\d+)$`)
        rFlags        = regexp.MustCompile(`^flags:\s+(\d+)$`)
        rMntID        = regexp.MustCompile(`^mnt_id:\s+(\d+)$`)
        rInotify      = regexp.MustCompile(`^inotify`)
        rInotifyParts = regexp.MustCompile(`^inotify\s+wd:([0-9a-f]+)\s+ino:([0-9a-f]+)\s+sdev:([0-9a-f]+)(?:\s+mask:([0-9a-f]+))?`)
)

// ProcFDInfo contains represents file descriptor information.
type ProcFDInfo struct {
        // File descriptor
        FD string
        // File offset
        Pos string
        // File access mode and status flags
        Flags string
        // Mount point ID
        MntID string
        // List of inotify lines (structured) 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.
type InotifyInfo struct {
        // Watch descriptor number
        WD string
        // Inode number
        Ino string
        // Device ID
        Sdev string
        // Mask of events being monitored
        Mask string
}

// InotifyInfo constructor. Only available on kernel 3.8+.
func parseInotifyInfo(line string) (*InotifyInfo, error) {
        m := rInotifyParts.FindStringSubmatch(line)
        if len(m) >= 4 {
                var mask string
                if len(m) == 5 {
                        mask = m[4]
                }
                i := &InotifyInfo{
                        WD:   m[1],
                        Ino:  m[2],
                        Sdev: m[3],
                        Mask: mask,
                }
                return i, nil
        }
        return nil, fmt.Errorf("invalid inode entry: %q", line)
}

// 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
}