buildkit/snapshot/localmounter.go

73 lines
1.4 KiB
Go

package snapshot
import (
"io/ioutil"
"os"
"sync"
"github.com/containerd/containerd/mount"
"github.com/pkg/errors"
)
type Mounter interface {
Mount() (string, error)
Unmount() error
}
// LocalMounter is a helper for mounting mountfactory to temporary path. In
// addition it can mount binds without privileges
func LocalMounter(mountable Mountable) Mounter {
return &localMounter{mountable: mountable}
}
// LocalMounterWithMounts is a helper for mounting to temporary path. In
// addition it can mount binds without privileges
func LocalMounterWithMounts(mounts []mount.Mount) Mounter {
return &localMounter{mounts: mounts}
}
type localMounter struct {
mu sync.Mutex
mounts []mount.Mount
mountable Mountable
target string
}
func (lm *localMounter) Mount() (string, error) {
lm.mu.Lock()
defer lm.mu.Unlock()
if lm.mounts == nil {
mounts, err := lm.mountable.Mount()
if err != nil {
return "", err
}
lm.mounts = mounts
}
if len(lm.mounts) == 1 && (lm.mounts[0].Type == "bind" || lm.mounts[0].Type == "rbind") {
ro := false
for _, opt := range lm.mounts[0].Options {
if opt == "ro" {
ro = true
break
}
}
if !ro {
return lm.mounts[0].Source, nil
}
}
dir, err := ioutil.TempDir("", "buildkit-mount")
if err != nil {
return "", errors.Wrap(err, "failed to create temp dir")
}
if err := mount.All(lm.mounts, dir); err != nil {
os.RemoveAll(dir)
return "", err
}
lm.target = dir
return dir, nil
}