Don't fix the size of the ExternalDescriptors array

In a future we may want to have more external descriptors.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

container.go

@@ -51,7 +51,7 @@ type State struct {
 	Config configs.Config `json:"config"`
 
 	// Container's standard descriptors (std{in,out,err}), needed for checkpoint and restore
-	ExternalDescriptors [3]string `json:"external_descriptors,omitempty"`
+	ExternalDescriptors []string `json:"external_descriptors,omitempty"`
 }
 
 // A libcontainer container object.

process_linux.go

@@ -34,9 +34,9 @@ type parentProcess interface {
 
 	signal(os.Signal) error
 
-	externalDescriptors() [3]string
+	externalDescriptors() []string
 
-	setExternalDescriptors(fds [3]string)
+	setExternalDescriptors(fds []string)
 }
 
 type setnsProcess struct {
@@ -45,7 +45,7 @@ type setnsProcess struct {
 	childPipe   *os.File
 	cgroupPaths map[string]string
 	config      *initConfig
-	fds         [3]string
+	fds         []string
 }
 
 func (p *setnsProcess) startTime() (string, error) {
@@ -149,11 +149,11 @@ func (p *setnsProcess) pid() int {
 	return p.cmd.Process.Pid
 }
 
-func (p *setnsProcess) externalDescriptors() [3]string {
+func (p *setnsProcess) externalDescriptors() []string {
 	return p.fds
 }
 
-func (p *setnsProcess) setExternalDescriptors(newFds [3]string) {
+func (p *setnsProcess) setExternalDescriptors(newFds []string) {
 	p.fds = newFds
 }
 
@@ -164,14 +164,14 @@ type initProcess struct {
 	config     *initConfig
 	manager    cgroups.Manager
 	container  *linuxContainer
-	fds        [3]string
+	fds        []string
 }
 
 func (p *initProcess) pid() int {
 	return p.cmd.Process.Pid
 }
 
-func (p *initProcess) externalDescriptors() [3]string {
+func (p *initProcess) externalDescriptors() []string {
 	return p.fds
 }
 
@@ -281,12 +281,14 @@ func (p *initProcess) signal(sig os.Signal) error {
 	return syscall.Kill(p.cmd.Process.Pid, s)
 }
 
-func (p *initProcess) setExternalDescriptors(newFds [3]string) {
+func (p *initProcess) setExternalDescriptors(newFds []string) {
 	p.fds = newFds
 }
 
-func getPipeFds(pid int) ([3]string, error) {
-	var fds [3]string;
+func getPipeFds(pid int) ([]string, error) {
+	var fds []string
+
+	fds = make([]string, 3)
 
 	dirPath := filepath.Join("/proc", strconv.Itoa(pid), "/fd")
 	for i := 0; i < 3; i++ {

restored_process.go

@@ -9,7 +9,7 @@ import (
 	"github.com/docker/libcontainer/system"
 )
 
-func newRestoredProcess(pid int, fds [3]string) (*restoredProcess, error) {
+func newRestoredProcess(pid int, fds []string) (*restoredProcess, error) {
 	var (
 		err error
 	)
@@ -31,7 +31,7 @@ func newRestoredProcess(pid int, fds [3]string) (*restoredProcess, error) {
 type restoredProcess struct {
 	proc             *os.Process
 	processStartTime string
-	fds              [3]string
+	fds              []string
 }
 
 func (p *restoredProcess) start() error {
@@ -68,11 +68,11 @@ func (p *restoredProcess) signal(s os.Signal) error {
 	return p.proc.Signal(s)
 }
 
-func (p *restoredProcess) externalDescriptors() [3]string {
+func (p *restoredProcess) externalDescriptors() []string {
 	return p.fds
 }
 
-func (p *restoredProcess) setExternalDescriptors(newFds [3]string) {
+func (p *restoredProcess) setExternalDescriptors(newFds []string) {
 	p.fds = newFds
 }
 
@@ -82,7 +82,7 @@ func (p *restoredProcess) setExternalDescriptors(newFds [3]string) {
 type nonChildProcess struct {
 	processPid       int
 	processStartTime string
-	fds              [3]string
+	fds              []string
 }
 
 func (p *nonChildProcess) start() error {
@@ -109,10 +109,10 @@ func (p *nonChildProcess) signal(s os.Signal) error {
 	return newGenericError(fmt.Errorf("restored process cannot be signaled"), SystemError)
 }
 
-func (p *nonChildProcess) externalDescriptors() [3]string {
+func (p *nonChildProcess) externalDescriptors() []string {
 	return p.fds
 }
 
-func (p *nonChildProcess) setExternalDescriptors(newFds [3]string) {
+func (p *nonChildProcess) setExternalDescriptors(newFds []string) {
 	p.fds = newFds
 }