cubefs

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// Copyright 2019 The Prometheus 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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package procfs
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import (
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	"bufio"
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	"bytes"
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	"fmt"
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	"regexp"
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	"github.com/prometheus/procfs/internal/util"
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)
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var (
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	rPos          = regexp.MustCompile(`^pos:\s+(\d+)$`)
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	rFlags        = regexp.MustCompile(`^flags:\s+(\d+)$`)
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	rMntID        = regexp.MustCompile(`^mnt_id:\s+(\d+)$`)
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	rInotify      = regexp.MustCompile(`^inotify`)
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	rInotifyParts = regexp.MustCompile(`^inotify\s+wd:([0-9a-f]+)\s+ino:([0-9a-f]+)\s+sdev:([0-9a-f]+)(?:\s+mask:([0-9a-f]+))?`)
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)
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// ProcFDInfo contains represents file descriptor information.
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type ProcFDInfo struct {
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	// File descriptor
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	FD string
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	// File offset
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	Pos string
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	// File access mode and status flags
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	Flags string
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	// Mount point ID
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	MntID string
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	// List of inotify lines (structured) in the fdinfo file (kernel 3.8+ only)
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	InotifyInfos []InotifyInfo
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}
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// FDInfo constructor. On kernels older than 3.8, InotifyInfos will always be empty.
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func (p Proc) FDInfo(fd string) (*ProcFDInfo, error) {
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	data, err := util.ReadFileNoStat(p.path("fdinfo", fd))
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	if err != nil {
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		return nil, err
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	}
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	var text, pos, flags, mntid string
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	var inotify []InotifyInfo
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	scanner := bufio.NewScanner(bytes.NewReader(data))
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	for scanner.Scan() {
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		text = scanner.Text()
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		if rPos.MatchString(text) {
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			pos = rPos.FindStringSubmatch(text)[1]
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		} else if rFlags.MatchString(text) {
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			flags = rFlags.FindStringSubmatch(text)[1]
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		} else if rMntID.MatchString(text) {
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			mntid = rMntID.FindStringSubmatch(text)[1]
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		} else if rInotify.MatchString(text) {
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			newInotify, err := parseInotifyInfo(text)
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			if err != nil {
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				return nil, err
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			}
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			inotify = append(inotify, *newInotify)
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		}
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	}
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	i := &ProcFDInfo{
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		FD:           fd,
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		Pos:          pos,
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		Flags:        flags,
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		MntID:        mntid,
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		InotifyInfos: inotify,
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	}
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	return i, nil
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}
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// InotifyInfo represents a single inotify line in the fdinfo file.
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type InotifyInfo struct {
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	// Watch descriptor number
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	WD string
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	// Inode number
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	Ino string
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	// Device ID
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	Sdev string
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	// Mask of events being monitored
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	Mask string
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}
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// InotifyInfo constructor. Only available on kernel 3.8+.
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func parseInotifyInfo(line string) (*InotifyInfo, error) {
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	m := rInotifyParts.FindStringSubmatch(line)
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	if len(m) >= 4 {
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		var mask string
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		if len(m) == 5 {
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			mask = m[4]
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		}
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		i := &InotifyInfo{
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			WD:   m[1],
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			Ino:  m[2],
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			Sdev: m[3],
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			Mask: mask,
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		}
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		return i, nil
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	}
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	return nil, fmt.Errorf("invalid inode entry: %q", line)
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}
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// ProcFDInfos represents a list of ProcFDInfo structs.
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type ProcFDInfos []ProcFDInfo
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func (p ProcFDInfos) Len() int           { return len(p) }
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func (p ProcFDInfos) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
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func (p ProcFDInfos) Less(i, j int) bool { return p[i].FD < p[j].FD }
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// InotifyWatchLen returns the total number of inotify watches.
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func (p ProcFDInfos) InotifyWatchLen() (int, error) {
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	length := 0
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	for _, f := range p {
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		length += len(f.InotifyInfos)
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	}
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	return length, nil
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}
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