seaweedfs/weed/command/mount_linux.go
2022-02-27 03:03:19 -08:00

150 lines
3.9 KiB
Go

package command
import (
"bufio"
"fmt"
"io"
"os"
"strings"
)
const (
/* 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
(1) mount ID: unique identifier of the mount (may be reused after umount)
(2) parent ID: ID of parent (or of self for the top of the mount tree)
(3) major:minor: value of st_dev for files on filesystem
(4) root: root of the mount within the filesystem
(5) mount point: mount point relative to the process's root
(6) mount options: per mount options
(7) optional fields: zero or more fields of the form "tag[:value]"
(8) separator: marks the end of the optional fields
(9) filesystem type: name of filesystem of the form "type[.subtype]"
(10) mount source: filesystem specific information or "none"
(11) super options: per super block options*/
mountinfoFormat = "%d %d %d:%d %s %s %s %s"
)
// Info reveals information about a particular mounted filesystem. This
// struct is populated from the content in the /proc/<pid>/mountinfo file.
type Info struct {
// ID is a unique identifier of the mount (may be reused after umount).
ID int
// Parent indicates the ID of the mount parent (or of self for the top of the
// mount tree).
Parent int
// Major indicates one half of the device ID which identifies the device class.
Major int
// Minor indicates one half of the device ID which identifies a specific
// instance of device.
Minor int
// Root of the mount within the filesystem.
Root string
// Mountpoint indicates the mount point relative to the process's root.
Mountpoint string
// Opts represents mount-specific options.
Opts string
// Optional represents optional fields.
Optional string
// Fstype indicates the type of filesystem, such as EXT3.
Fstype string
// Source indicates filesystem specific information or "none".
Source string
// VfsOpts represents per super block options.
VfsOpts string
}
// Mounted determines if a specified mountpoint has been mounted.
// On Linux it looks at /proc/self/mountinfo and on Solaris at mnttab.
func mounted(mountPoint string) (bool, error) {
entries, err := parseMountTable()
if err != nil {
return false, err
}
// Search the table for the mountPoint
for _, e := range entries {
if e.Mountpoint == mountPoint {
return true, nil
}
}
return false, nil
}
// Parse /proc/self/mountinfo because comparing Dev and ino does not work from
// bind mounts
func parseMountTable() ([]*Info, error) {
f, err := os.Open("/proc/self/mountinfo")
if err != nil {
return nil, err
}
defer f.Close()
return parseInfoFile(f)
}
func parseInfoFile(r io.Reader) ([]*Info, error) {
var (
s = bufio.NewScanner(r)
out []*Info
)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
var (
p = &Info{}
text = s.Text()
optionalFields string
)
if _, err := fmt.Sscanf(text, mountinfoFormat,
&p.ID, &p.Parent, &p.Major, &p.Minor,
&p.Root, &p.Mountpoint, &p.Opts, &optionalFields); err != nil {
return nil, fmt.Errorf("Scanning '%s' failed: %s", text, err)
}
// Safe as mountinfo encodes mountpoints with spaces as \040.
index := strings.Index(text, " - ")
postSeparatorFields := strings.Fields(text[index+3:])
if len(postSeparatorFields) < 3 {
return nil, fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
}
if optionalFields != "-" {
p.Optional = optionalFields
}
p.Fstype = postSeparatorFields[0]
p.Source = postSeparatorFields[1]
p.VfsOpts = strings.Join(postSeparatorFields[2:], " ")
out = append(out, p)
}
return out, nil
}
func checkMountPointAvailable(dir string) bool {
mountPoint := dir
if mountPoint != "/" && strings.HasSuffix(mountPoint, "/") {
mountPoint = mountPoint[0 : len(mountPoint)-1]
}
if mounted, err := mounted(mountPoint); err != nil || mounted {
return false
}
return true
}