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/
mountinfo.go
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/
mountinfo.go
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// Copyright 2016 The rkt 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 mountinfo
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"sort"
"strconv"
"strings"
"github.com/hashicorp/errwrap"
)
// HasPrefix returns a FilterFunc which returns true if
// the mountpoint of a given mount has prefix p, else false.
func HasPrefix(p string) FilterFunc {
return FilterFunc(func(m *Mount) bool {
return strings.HasPrefix(m.MountPoint, p)
})
}
// ParseMounts returns all mountpoints associated with a process mount namespace.
// The special value 0 as pid argument is used to specify the current process.
func ParseMounts(pid uint) (Mounts, error) {
var procPath string
if pid == 0 {
procPath = "/proc/self/mountinfo"
} else {
procPath = fmt.Sprintf("/proc/%d/mountinfo", pid)
}
mi, err := os.Open(procPath)
if err != nil {
return nil, err
}
defer mi.Close()
return parseMountinfo(mi)
}
// parseMountinfo parses mi (/proc/<pid>/mountinfo) and returns mounts information
// according to https://www.kernel.org/doc/Documentation/filesystems/proc.txt
func parseMountinfo(mi io.Reader) (Mounts, error) {
var podMounts Mounts
sc := bufio.NewScanner(mi)
var (
mountID int
parentID int
major int
minor int
root string
mountPoint string
opt map[string]struct{}
)
for sc.Scan() {
line := sc.Text()
columns := strings.Split(line, " ")
if len(columns) < 7 {
return nil, fmt.Errorf("Not enough fields from line %q: %+v", line, columns)
}
opt = map[string]struct{}{}
for i, col := range columns {
if col == "-" {
// separator: a single hyphen "-" marks the end of "optional fields"
break
}
var err error
switch i {
case 0:
mountID, err = strconv.Atoi(col)
case 1:
parentID, err = strconv.Atoi(col)
case 2:
split := strings.Split(col, ":")
if len(split) != 2 {
err = fmt.Errorf("found unexpected key:value field with more than two colons: %s", col)
break
}
major, err = strconv.Atoi(split[0])
if err != nil {
break
}
minor, err = strconv.Atoi(split[1])
if err != nil {
break
}
case 3:
root = col
case 4:
mountPoint = col
default:
split := strings.Split(col, ":")
switch len(split) {
case 1:
// we ignore modes like rw, relatime, etc.
case 2:
opt[split[0]] = struct{}{}
default:
err = fmt.Errorf("found unexpected key:value field with more than two colons: %s", col)
}
}
if err != nil {
return nil, errwrap.Wrap(fmt.Errorf("could not parse mountinfo line %q", line), err)
}
}
mnt := &Mount{
ID: mountID,
Parent: parentID,
Major: major,
Minor: minor,
Root: root,
MountPoint: mountPoint,
Opts: opt,
}
podMounts = append(podMounts, mnt)
}
if err := sc.Err(); err != nil {
return nil, errwrap.Wrap(errors.New("problem parsing mountinfo"), err)
}
sort.Sort(podMounts)
return podMounts, nil
}