mirror of
https://github.com/ceph/ceph-csi.git
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251 lines
7.4 KiB
Go
251 lines
7.4 KiB
Go
//go:build !windows
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// +build !windows
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/*
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Copyright 2019 The Kubernetes 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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package mount
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import (
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"bytes"
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"errors"
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"fmt"
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"io/fs"
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"os"
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"strconv"
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"strings"
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"sync"
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"syscall"
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"golang.org/x/sys/unix"
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"k8s.io/klog/v2"
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utilio "k8s.io/utils/io"
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)
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const (
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// At least number of fields per line in /proc/<pid>/mountinfo.
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expectedAtLeastNumFieldsPerMountInfo = 10
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// How many times to retry for a consistent read of /proc/mounts.
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maxListTries = 10
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)
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// IsCorruptedMnt return true if err is about corrupted mount point
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func IsCorruptedMnt(err error) bool {
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if err == nil {
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return false
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}
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var underlyingError error
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switch pe := err.(type) {
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case nil:
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return false
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case *os.PathError:
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underlyingError = pe.Err
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case *os.LinkError:
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underlyingError = pe.Err
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case *os.SyscallError:
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underlyingError = pe.Err
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case syscall.Errno:
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underlyingError = err
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}
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return underlyingError == syscall.ENOTCONN || underlyingError == syscall.ESTALE || underlyingError == syscall.EIO || underlyingError == syscall.EACCES || underlyingError == syscall.EHOSTDOWN || underlyingError == syscall.EWOULDBLOCK
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}
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// MountInfo represents a single line in /proc/<pid>/mountinfo.
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type MountInfo struct { // nolint: golint
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// Unique ID for the mount (maybe reused after umount).
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ID int
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// The ID of the parent mount (or of self for the root of this mount namespace's mount tree).
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ParentID int
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// Major indicates one half of the device ID which identifies the device class
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// (parsed from `st_dev` for files on this filesystem).
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Major int
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// Minor indicates one half of the device ID which identifies a specific
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// instance of device (parsed from `st_dev` for files on this filesystem).
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Minor int
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// The pathname of the directory in the filesystem which forms the root of this mount.
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Root string
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// Mount source, filesystem-specific information. e.g. device, tmpfs name.
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Source string
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// Mount point, the pathname of the mount point.
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MountPoint string
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// Optional fieds, zero or more fields of the form "tag[:value]".
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OptionalFields []string
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// The filesystem type in the form "type[.subtype]".
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FsType string
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// Per-mount options.
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MountOptions []string
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// Per-superblock options.
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SuperOptions []string
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}
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// ParseMountInfo parses /proc/xxx/mountinfo.
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func ParseMountInfo(filename string) ([]MountInfo, error) {
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content, err := readMountInfo(filename)
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if err != nil {
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return []MountInfo{}, err
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}
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contentStr := string(content)
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infos := []MountInfo{}
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for _, line := range strings.Split(contentStr, "\n") {
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if line == "" {
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// the last split() item is empty string following the last \n
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continue
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}
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// See `man proc` for authoritative description of format of the file.
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fields := strings.Fields(line)
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if len(fields) < expectedAtLeastNumFieldsPerMountInfo {
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return nil, fmt.Errorf("wrong number of fields in (expected at least %d, got %d): %s", expectedAtLeastNumFieldsPerMountInfo, len(fields), line)
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}
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id, err := strconv.Atoi(fields[0])
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if err != nil {
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return nil, err
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}
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parentID, err := strconv.Atoi(fields[1])
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if err != nil {
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return nil, err
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}
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mm := strings.Split(fields[2], ":")
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if len(mm) != 2 {
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return nil, fmt.Errorf("parsing '%s' failed: unexpected minor:major pair %s", line, mm)
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}
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major, err := strconv.Atoi(mm[0])
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if err != nil {
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return nil, fmt.Errorf("parsing '%s' failed: unable to parse major device id, err:%v", mm[0], err)
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}
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minor, err := strconv.Atoi(mm[1])
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if err != nil {
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return nil, fmt.Errorf("parsing '%s' failed: unable to parse minor device id, err:%v", mm[1], err)
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}
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info := MountInfo{
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ID: id,
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ParentID: parentID,
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Major: major,
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Minor: minor,
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Root: fields[3],
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MountPoint: fields[4],
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MountOptions: splitMountOptions(fields[5]),
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}
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// All fields until "-" are "optional fields".
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i := 6
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for ; i < len(fields) && fields[i] != "-"; i++ {
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info.OptionalFields = append(info.OptionalFields, fields[i])
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}
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// Parse the rest 3 fields.
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i++
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if len(fields)-i < 3 {
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return nil, fmt.Errorf("expect 3 fields in %s, got %d", line, len(fields)-i)
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}
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info.FsType = fields[i]
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info.Source = fields[i+1]
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info.SuperOptions = splitMountOptions(fields[i+2])
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infos = append(infos, info)
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}
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return infos, nil
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}
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// splitMountOptions parses comma-separated list of mount options into an array.
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// It respects double quotes - commas in them are not considered as the option separator.
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func splitMountOptions(s string) []string {
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inQuotes := false
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list := strings.FieldsFunc(s, func(r rune) bool {
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if r == '"' {
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inQuotes = !inQuotes
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}
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// Report a new field only when outside of double quotes.
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return r == ',' && !inQuotes
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})
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return list
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}
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// isMountPointMatch returns true if the path in mp is the same as dir.
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// Handles case where mountpoint dir has been renamed due to stale NFS mount.
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func isMountPointMatch(mp MountPoint, dir string) bool {
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return strings.TrimSuffix(mp.Path, "\\040(deleted)") == dir
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}
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// PathExists returns true if the specified path exists.
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// TODO: clean this up to use pkg/util/file/FileExists
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func PathExists(path string) (bool, error) {
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_, err := os.Stat(path)
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if err == nil {
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return true, nil
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} else if errors.Is(err, fs.ErrNotExist) {
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err = syscall.Access(path, syscall.F_OK)
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if err == nil {
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// The access syscall says the file exists, the stat syscall says it
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// doesn't. This was observed on CIFS when the path was removed at
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// the server somehow. POSIX calls this a stale file handle, let's fake
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// that error and treat the path as existing but corrupted.
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klog.Warningf("Potential stale file handle detected: %s", path)
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return true, syscall.ESTALE
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}
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return false, nil
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} else if IsCorruptedMnt(err) {
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return true, err
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}
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return false, err
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}
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// These variables are used solely by kernelHasMountinfoBug.
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var (
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hasMountinfoBug bool
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checkMountinfoBugOnce sync.Once
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)
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// kernelHasMountinfoBug checks if the kernel bug that can lead to incomplete
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// mountinfo being read is fixed. It does so by checking the kernel version.
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//
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// The bug was fixed by the kernel commit 9f6c61f96f2d97 (since Linux 5.8).
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// Alas, there is no better way to check if the bug is fixed other than to
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// rely on the kernel version returned by uname.
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func kernelHasMountinfoBug() bool {
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checkMountinfoBugOnce.Do(func() {
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// Assume old kernel.
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hasMountinfoBug = true
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uname := unix.Utsname{}
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err := unix.Uname(&uname)
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if err != nil {
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return
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}
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end := bytes.IndexByte(uname.Release[:], 0)
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v := bytes.SplitN(uname.Release[:end], []byte{'.'}, 3)
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if len(v) != 3 {
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return
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}
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major, _ := strconv.Atoi(string(v[0]))
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minor, _ := strconv.Atoi(string(v[1]))
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if major > 5 || (major == 5 && minor >= 8) {
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hasMountinfoBug = false
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}
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})
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return hasMountinfoBug
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}
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func readMountInfo(path string) ([]byte, error) {
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if kernelHasMountinfoBug() {
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return utilio.ConsistentRead(path, maxListTries)
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}
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return os.ReadFile(path)
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}
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