github.com/dougm/docker@v1.5.0/pkg/mount/mountinfo_linux.go (about)

     1  // +build linux
     2  
     3  package mount
     4  
     5  import (
     6  	"bufio"
     7  	"fmt"
     8  	"io"
     9  	"os"
    10  	"strings"
    11  )
    12  
    13  const (
    14  	/* 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
    15  	   (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
    16  
    17  	   (1) mount ID:  unique identifier of the mount (may be reused after umount)
    18  	   (2) parent ID:  ID of parent (or of self for the top of the mount tree)
    19  	   (3) major:minor:  value of st_dev for files on filesystem
    20  	   (4) root:  root of the mount within the filesystem
    21  	   (5) mount point:  mount point relative to the process's root
    22  	   (6) mount options:  per mount options
    23  	   (7) optional fields:  zero or more fields of the form "tag[:value]"
    24  	   (8) separator:  marks the end of the optional fields
    25  	   (9) filesystem type:  name of filesystem of the form "type[.subtype]"
    26  	   (10) mount source:  filesystem specific information or "none"
    27  	   (11) super options:  per super block options*/
    28  	mountinfoFormat = "%d %d %d:%d %s %s %s %s"
    29  )
    30  
    31  // Parse /proc/self/mountinfo because comparing Dev and ino does not work from bind mounts
    32  func parseMountTable() ([]*MountInfo, error) {
    33  	f, err := os.Open("/proc/self/mountinfo")
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  	defer f.Close()
    38  
    39  	return parseInfoFile(f)
    40  }
    41  
    42  func parseInfoFile(r io.Reader) ([]*MountInfo, error) {
    43  	var (
    44  		s   = bufio.NewScanner(r)
    45  		out = []*MountInfo{}
    46  	)
    47  
    48  	for s.Scan() {
    49  		if err := s.Err(); err != nil {
    50  			return nil, err
    51  		}
    52  
    53  		var (
    54  			p              = &MountInfo{}
    55  			text           = s.Text()
    56  			optionalFields string
    57  		)
    58  
    59  		if _, err := fmt.Sscanf(text, mountinfoFormat,
    60  			&p.Id, &p.Parent, &p.Major, &p.Minor,
    61  			&p.Root, &p.Mountpoint, &p.Opts, &optionalFields); err != nil {
    62  			return nil, fmt.Errorf("Scanning '%s' failed: %s", text, err)
    63  		}
    64  		// Safe as mountinfo encodes mountpoints with spaces as \040.
    65  		index := strings.Index(text, " - ")
    66  		postSeparatorFields := strings.Fields(text[index+3:])
    67  		if len(postSeparatorFields) < 3 {
    68  			return nil, fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
    69  		}
    70  
    71  		if optionalFields != "-" {
    72  			p.Optional = optionalFields
    73  		}
    74  
    75  		p.Fstype = postSeparatorFields[0]
    76  		p.Source = postSeparatorFields[1]
    77  		p.VfsOpts = strings.Join(postSeparatorFields[2:], " ")
    78  		out = append(out, p)
    79  	}
    80  	return out, nil
    81  }
    82  
    83  // PidMountInfo collects the mounts for a specific Pid
    84  func PidMountInfo(pid int) ([]*MountInfo, error) {
    85  	f, err := os.Open(fmt.Sprintf("/proc/%d/mountinfo", pid))
    86  	if err != nil {
    87  		return nil, err
    88  	}
    89  	defer f.Close()
    90  
    91  	return parseInfoFile(f)
    92  }