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|
package namespaces
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"github.com/docker/libcontainer"
)
// SyncPipe allows communication to and from the child processes
// to it's parent and allows the two independent processes to
// syncronize their state.
type SyncPipe struct {
parent, child *os.File
}
func NewSyncPipe() (s *SyncPipe, err error) {
s = &SyncPipe{}
s.child, s.parent, err = os.Pipe()
if err != nil {
return nil, err
}
return s, nil
}
func NewSyncPipeFromFd(parendFd, childFd uintptr) (*SyncPipe, error) {
s := &SyncPipe{}
if parendFd > 0 {
s.parent = os.NewFile(parendFd, "parendPipe")
} else if childFd > 0 {
s.child = os.NewFile(childFd, "childPipe")
} else {
return nil, fmt.Errorf("no valid sync pipe fd specified")
}
return s, nil
}
func (s *SyncPipe) Child() *os.File {
return s.child
}
func (s *SyncPipe) Parent() *os.File {
return s.parent
}
func (s *SyncPipe) SendToChild(context libcontainer.Context) error {
data, err := json.Marshal(context)
if err != nil {
return err
}
s.parent.Write(data)
return nil
}
func (s *SyncPipe) ReadFromParent() (libcontainer.Context, error) {
data, err := ioutil.ReadAll(s.child)
if err != nil {
return nil, fmt.Errorf("error reading from sync pipe %s", err)
}
var context libcontainer.Context
if len(data) > 0 {
if err := json.Unmarshal(data, &context); err != nil {
return nil, err
}
}
return context, nil
}
func (s *SyncPipe) Close() error {
if s.parent != nil {
s.parent.Close()
}
if s.child != nil {
s.child.Close()
}
return nil
}
|
