gotosocial/vendor/go.uber.org/automaxprocs/internal/cgroups/mountpoint.go

172 lines
5 KiB
Go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//go:build linux
// +build linux
package cgroups
import (
"bufio"
"os"
"path/filepath"
"strconv"
"strings"
)
const (
_mountInfoSep = " "
_mountInfoOptsSep = ","
_mountInfoOptionalFieldsSep = "-"
)
const (
_miFieldIDMountID = iota
_miFieldIDParentID
_miFieldIDDeviceID
_miFieldIDRoot
_miFieldIDMountPoint
_miFieldIDOptions
_miFieldIDOptionalFields
_miFieldCountFirstHalf
)
const (
_miFieldOffsetFSType = iota
_miFieldOffsetMountSource
_miFieldOffsetSuperOptions
_miFieldCountSecondHalf
)
const _miFieldCountMin = _miFieldCountFirstHalf + _miFieldCountSecondHalf
// MountPoint is the data structure for the mount points in
// `/proc/$PID/mountinfo`. See also proc(5) for more information.
type MountPoint struct {
MountID int
ParentID int
DeviceID string
Root string
MountPoint string
Options []string
OptionalFields []string
FSType string
MountSource string
SuperOptions []string
}
// NewMountPointFromLine parses a line read from `/proc/$PID/mountinfo` and
// returns a new *MountPoint.
func NewMountPointFromLine(line string) (*MountPoint, error) {
fields := strings.Split(line, _mountInfoSep)
if len(fields) < _miFieldCountMin {
return nil, mountPointFormatInvalidError{line}
}
mountID, err := strconv.Atoi(fields[_miFieldIDMountID])
if err != nil {
return nil, err
}
parentID, err := strconv.Atoi(fields[_miFieldIDParentID])
if err != nil {
return nil, err
}
for i, field := range fields[_miFieldIDOptionalFields:] {
if field == _mountInfoOptionalFieldsSep {
// End of optional fields.
fsTypeStart := _miFieldIDOptionalFields + i + 1
// Now we know where the optional fields end, split the line again with a
// limit to avoid issues with spaces in super options as present on WSL.
fields = strings.SplitN(line, _mountInfoSep, fsTypeStart+_miFieldCountSecondHalf)
if len(fields) != fsTypeStart+_miFieldCountSecondHalf {
return nil, mountPointFormatInvalidError{line}
}
miFieldIDFSType := _miFieldOffsetFSType + fsTypeStart
miFieldIDMountSource := _miFieldOffsetMountSource + fsTypeStart
miFieldIDSuperOptions := _miFieldOffsetSuperOptions + fsTypeStart
return &MountPoint{
MountID: mountID,
ParentID: parentID,
DeviceID: fields[_miFieldIDDeviceID],
Root: fields[_miFieldIDRoot],
MountPoint: fields[_miFieldIDMountPoint],
Options: strings.Split(fields[_miFieldIDOptions], _mountInfoOptsSep),
OptionalFields: fields[_miFieldIDOptionalFields:(fsTypeStart - 1)],
FSType: fields[miFieldIDFSType],
MountSource: fields[miFieldIDMountSource],
SuperOptions: strings.Split(fields[miFieldIDSuperOptions], _mountInfoOptsSep),
}, nil
}
}
return nil, mountPointFormatInvalidError{line}
}
// Translate converts an absolute path inside the *MountPoint's file system to
// the host file system path in the mount namespace the *MountPoint belongs to.
func (mp *MountPoint) Translate(absPath string) (string, error) {
relPath, err := filepath.Rel(mp.Root, absPath)
if err != nil {
return "", err
}
if relPath == ".." || strings.HasPrefix(relPath, "../") {
return "", pathNotExposedFromMountPointError{
mountPoint: mp.MountPoint,
root: mp.Root,
path: absPath,
}
}
return filepath.Join(mp.MountPoint, relPath), nil
}
// parseMountInfo parses procPathMountInfo (usually at `/proc/$PID/mountinfo`)
// and yields parsed *MountPoint into newMountPoint.
func parseMountInfo(procPathMountInfo string, newMountPoint func(*MountPoint) error) error {
mountInfoFile, err := os.Open(procPathMountInfo)
if err != nil {
return err
}
defer mountInfoFile.Close()
scanner := bufio.NewScanner(mountInfoFile)
for scanner.Scan() {
mountPoint, err := NewMountPointFromLine(scanner.Text())
if err != nil {
return err
}
if err := newMountPoint(mountPoint); err != nil {
return err
}
}
return scanner.Err()
}