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mount.go
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mount.go
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package mount
import (
"fmt"
"os"
"path/filepath"
"syscall"
"github.com/docker/docker/pkg/symlink"
"github.com/docker/libcontainer/label"
)
type Mount struct {
Type string `json:"type,omitempty"`
Source string `json:"source,omitempty"` // Source path, in the host namespace
Destination string `json:"destination,omitempty"` // Destination path, in the container
Writable bool `json:"writable,omitempty"`
Relabel string `json:"relabel,omitempty"` // Relabel source if set, "z" indicates shared, "Z" indicates unshared
Private bool `json:"private,omitempty"`
Slave bool `json:"slave,omitempty"`
}
func (m *Mount) Mount(rootfs, mountLabel string) error {
switch m.Type {
case "bind":
return m.bindMount(rootfs, mountLabel)
case "tmpfs":
return m.tmpfsMount(rootfs, mountLabel)
default:
return fmt.Errorf("unsupported mount type %s for %s", m.Type, m.Destination)
}
}
func (m *Mount) bindMount(rootfs, mountLabel string) error {
var (
flags = syscall.MS_BIND | syscall.MS_REC
dest = filepath.Join(rootfs, m.Destination)
)
if !m.Writable {
flags = flags | syscall.MS_RDONLY
}
if m.Slave {
flags = flags | syscall.MS_SLAVE
}
stat, err := os.Stat(m.Source)
if err != nil {
return err
}
// FIXME: (crosbymichael) This does not belong here and should be done a layer above
dest, err = symlink.FollowSymlinkInScope(dest, rootfs)
if err != nil {
return err
}
if err := createIfNotExists(dest, stat.IsDir()); err != nil {
return fmt.Errorf("creating new bind mount target %s", err)
}
if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags), ""); err != nil {
return fmt.Errorf("mounting %s into %s %s", m.Source, dest, err)
}
if !m.Writable {
if err := syscall.Mount(m.Source, dest, "bind", uintptr(flags|syscall.MS_REMOUNT), ""); err != nil {
return fmt.Errorf("remounting %s into %s %s", m.Source, dest, err)
}
}
if m.Relabel != "" {
if err := label.Relabel(m.Source, mountLabel, m.Relabel); err != nil {
return fmt.Errorf("relabeling %s to %s %s", m.Source, mountLabel, err)
}
}
if m.Private {
if err := syscall.Mount("", dest, "none", uintptr(syscall.MS_PRIVATE), ""); err != nil {
return fmt.Errorf("mounting %s private %s", dest, err)
}
}
return nil
}
func (m *Mount) tmpfsMount(rootfs, mountLabel string) error {
var (
err error
l = label.FormatMountLabel("", mountLabel)
dest = filepath.Join(rootfs, m.Destination)
)
// FIXME: (crosbymichael) This does not belong here and should be done a layer above
if dest, err = symlink.FollowSymlinkInScope(dest, rootfs); err != nil {
return err
}
if err := createIfNotExists(dest, true); err != nil {
return fmt.Errorf("creating new tmpfs mount target %s", err)
}
if err := syscall.Mount("tmpfs", dest, "tmpfs", uintptr(defaultMountFlags), l); err != nil {
return fmt.Errorf("%s mounting %s in tmpfs", err, dest)
}
return nil
}