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moby--moby/daemon/volumes.go

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package daemon
import (
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"github.com/docker/docker/pkg/chrootarchive"
"github.com/docker/docker/pkg/system"
"github.com/docker/docker/volume"
)
// ErrVolumeReadonly is used to signal an error when trying to copy data into
// a volume mount that is not writable.
var ErrVolumeReadonly = errors.New("mounted volume is marked read-only")
// mountPoint is the intersection point between a volume and a container. It
// specifies which volume is to be used and where inside a container it should
// be mounted.
type mountPoint struct {
Name string
Destination string
Driver string
RW bool
Volume volume.Volume `json:"-"`
Source string
Mode string `json:"Relabel"` // Originally field was `Relabel`"
}
// Setup sets up a mount point by either mounting the volume if it is
// configured, or creating the source directory if supplied.
func (m *mountPoint) Setup() (string, error) {
if m.Volume != nil {
return m.Volume.Mount()
}
if len(m.Source) > 0 {
if _, err := os.Stat(m.Source); err != nil {
if !os.IsNotExist(err) {
return "", err
}
if err := system.MkdirAll(m.Source, 0755); err != nil {
return "", err
}
}
return m.Source, nil
}
return "", fmt.Errorf("Unable to setup mount point, neither source nor volume defined")
}
// hasResource checks whether the given absolute path for a container is in
// this mount point. If the relative path starts with `../` then the resource
// is outside of this mount point, but we can't simply check for this prefix
// because it misses `..` which is also outside of the mount, so check both.
func (m *mountPoint) hasResource(absolutePath string) bool {
relPath, err := filepath.Rel(m.Destination, absolutePath)
return err == nil && relPath != ".." && !strings.HasPrefix(relPath, fmt.Sprintf("..%c", filepath.Separator))
}
// Path returns the path of a volume in a mount point.
func (m *mountPoint) Path() string {
if m.Volume != nil {
return m.Volume.Path()
}
return m.Source
}
// copyExistingContents copies from the source to the destination and
// ensures the ownership is appropriately set.
func copyExistingContents(source, destination string) error {
volList, err := ioutil.ReadDir(source)
if err != nil {
return err
}
if len(volList) > 0 {
srcList, err := ioutil.ReadDir(destination)
if err != nil {
return err
}
if len(srcList) == 0 {
// If the source volume is empty copy files from the root into the volume
if err := chrootarchive.CopyWithTar(source, destination); err != nil {
return err
}
}
}
return copyOwnership(source, destination)
}