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xemulxemul
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lib: Add simple Go wrappers for swrk mode
We'll need some docs :) bu the API is criu := MakeCriu() criu.Dump(opts, notify) criu.Restore(opts, notify) criu.PreDump(opts, notify) criu.StartPageServer(opts) where opts is the object from rpc.proto, Go has almost native support for those, so caller should - compile .proto file - export it and golang/protobuf/proto - create and initialize the CriuOpts struct and notify is an interface with callbacks that correspond to criu notification messages. A stupid dump/restore tool in src/test/main.go demonstrates the above. Changes since v1: * Added keep_open mode for pre-dumps. Do use it one needs to call criu.Prepare() right after creation and criu.Cleanup() right after .Dump() * Report resp.cr_errmsg string on request error. Further TODO: - docs - code comments travis-ci: success for libphaul (rev2) Signed-off-by: Pavel Emelyanov <[email protected]>
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5 files changed

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‎lib/go/.gitignore

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src/rpc/rpc.pb.go

‎lib/go/Makefile

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all: test
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test: rpc
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GOPATH=$(shell pwd):/usr/share/gocode go build -o test test
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rpc:
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mkdir -p src/rpc/
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protoc --go_out=src/rpc/ --proto_path=../../images/ ../../images/rpc.proto

‎lib/go/src/criu/main.go

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package criu
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import (
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"errors"
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"fmt"
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"github.com/golang/protobuf/proto"
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"os"
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"os/exec"
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"rpc"
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"strconv"
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"syscall"
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)
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type Criu struct {
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swrk_cmd *exec.Cmd
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swrk_sk *os.File
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}
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func MakeCriu() *Criu {
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return &Criu{}
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}
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func (c *Criu) Prepare() error {
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fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_SEQPACKET, 0)
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if err != nil {
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return err
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}
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cln := os.NewFile(uintptr(fds[0]), "criu-xprt-cln")
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syscall.CloseOnExec(fds[0])
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srv := os.NewFile(uintptr(fds[1]), "criu-xprt-srv")
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defer srv.Close()
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args := []string{"swrk", strconv.Itoa(fds[1])}
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cmd := exec.Command("criu", args...)
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err = cmd.Start()
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if err != nil {
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cln.Close()
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return err
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}
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c.swrk_cmd = cmd
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c.swrk_sk = cln
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return nil
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}
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func (c *Criu) Cleanup() {
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if c.swrk_cmd != nil {
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c.swrk_sk.Close()
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c.swrk_sk = nil
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c.swrk_cmd.Wait()
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c.swrk_cmd = nil
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}
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}
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func (c *Criu) sendAndRecv(req_b []byte) ([]byte, int, error) {
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cln := c.swrk_sk
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_, err := cln.Write(req_b)
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if err != nil {
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return nil, 0, err
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}
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resp_b := make([]byte, 2*4096)
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n, err := cln.Read(resp_b)
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if err != nil {
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return nil, 0, err
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}
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return resp_b, n, nil
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}
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func (c *Criu) doSwrk(req_type rpc.CriuReqType, opts *rpc.CriuOpts, nfy CriuNotify) error {
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req := rpc.CriuReq{
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Type: &req_type,
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Opts: opts,
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}
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if nfy != nil {
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opts.NotifyScripts = proto.Bool(true)
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}
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if c.swrk_cmd == nil {
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err := c.Prepare()
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if err != nil {
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return err
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}
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defer c.Cleanup()
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}
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for {
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req_b, err := proto.Marshal(&req)
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if err != nil {
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return err
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}
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resp_b, resp_s, err := c.sendAndRecv(req_b)
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if err != nil {
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return err
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}
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resp := &rpc.CriuResp{}
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err = proto.Unmarshal(resp_b[:resp_s], resp)
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if err != nil {
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return err
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}
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if !resp.GetSuccess() {
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return fmt.Errorf("operation failed (msg:%s err:%d)",
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resp.GetCrErrmsg(), resp.GetCrErrno())
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}
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resp_type := resp.GetType()
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if resp_type == req_type {
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break
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}
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if resp_type != rpc.CriuReqType_NOTIFY {
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return errors.New("unexpected responce")
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}
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if nfy == nil {
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return errors.New("unexpected notify")
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}
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notify := resp.GetNotify()
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switch notify.GetScript() {
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case "pre-dump":
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err = nfy.PreDump()
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case "post-dump":
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err = nfy.PostDump()
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case "pre-restore":
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err = nfy.PreRestore()
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case "post-restore":
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err = nfy.PostRestore(notify.GetPid())
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case "network-lock":
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err = nfy.NetworkLock()
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case "network-unlock":
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err = nfy.NetworkUnlock()
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case "setup-namespaces":
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err = nfy.SetupNamespaces(notify.GetPid())
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case "post-setup-namespaces":
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err = nfy.PostSetupNamespaces()
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case "post-resume":
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err = nfy.PostResume()
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default:
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err = nil
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}
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if err != nil {
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return err
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}
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req = rpc.CriuReq{
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Type: &resp_type,
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NotifySuccess: proto.Bool(true),
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}
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}
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return nil
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}
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func (c *Criu) Dump(opts rpc.CriuOpts, nfy CriuNotify) error {
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return c.doSwrk(rpc.CriuReqType_DUMP, &opts, nfy)
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}
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func (c *Criu) Restore(opts rpc.CriuOpts, nfy CriuNotify) error {
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return c.doSwrk(rpc.CriuReqType_RESTORE, &opts, nfy)
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}
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func (c *Criu) PreDump(opts rpc.CriuOpts, nfy CriuNotify) error {
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return c.doSwrk(rpc.CriuReqType_PRE_DUMP, &opts, nfy)
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}
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func (c *Criu) StartPageServer(opts rpc.CriuOpts) error {
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return c.doSwrk(rpc.CriuReqType_PAGE_SERVER, &opts, nil)
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}

‎lib/go/src/criu/notify.go

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package criu
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type CriuNotify interface {
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PreDump() error
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PostDump() error
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PreRestore() error
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PostRestore(pid int32) error
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NetworkLock() error
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NetworkUnlock() error
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SetupNamespaces(pid int32) error
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PostSetupNamespaces() error
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PostResume() error
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}
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type CriuNoNotify struct {
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}
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func (c CriuNoNotify) PreDump() error {
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return nil
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}
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func (c CriuNoNotify) PostDump() error {
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return nil
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}
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func (c CriuNoNotify) PreRestore() error {
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return nil
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}
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func (c CriuNoNotify) PostRestore(pid int32) error {
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return nil
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}
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func (c CriuNoNotify) NetworkLock() error {
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return nil
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}
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func (c CriuNoNotify) NetworkUnlock() error {
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return nil
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}
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func (c CriuNoNotify) SetupNamespaces(pid int32) error {
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return nil
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}
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func (c CriuNoNotify) PostSetupNamespaces() error {
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return nil
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}
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func (c CriuNoNotify) PostResume() error {
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return nil
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}

‎lib/go/src/test/main.go

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package main
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import (
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"criu"
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"fmt"
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"github.com/golang/protobuf/proto"
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"os"
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"rpc"
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"strconv"
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)
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type TestNfy struct {
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criu.CriuNoNotify
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}
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func (c TestNfy) PreDump() error {
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fmt.Printf("TEST PRE DUMP\n")
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return nil
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}
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func doDump(c *criu.Criu, pid_s string, img_dir string, pre bool, prev_img string) error {
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fmt.Printf("Dumping\n")
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pid, _ := strconv.Atoi(pid_s)
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img, err := os.Open(img_dir)
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if err != nil {
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return fmt.Errorf("can't open image dir (%s)", err)
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}
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defer img.Close()
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opts := rpc.CriuOpts{
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Pid: proto.Int32(int32(pid)),
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ImagesDirFd: proto.Int32(int32(img.Fd())),
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LogLevel: proto.Int32(4),
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LogFile: proto.String("dump.log"),
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}
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if prev_img != "" {
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opts.ParentImg = proto.String(prev_img)
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opts.TrackMem = proto.Bool(true)
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}
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if pre {
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err = c.PreDump(opts, TestNfy{})
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} else {
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err = c.Dump(opts, TestNfy{})
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}
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if err != nil {
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return fmt.Errorf("dump fail (%s)", err)
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}
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return nil
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}
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// Usage: test $act $pid $images_dir
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func main() {
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c := criu.MakeCriu()
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act := os.Args[1]
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switch act {
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case "dump":
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err := doDump(c, os.Args[2], os.Args[3], false, "")
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if err != nil {
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fmt.Print(err)
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os.Exit(1)
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}
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case "dump2":
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err := c.Prepare()
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if err != nil {
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fmt.Print(err)
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os.Exit(1)
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}
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err = doDump(c, os.Args[2], os.Args[3]+"/pre", true, "")
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if err != nil {
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fmt.Printf("pre-dump failed")
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fmt.Print(err)
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os.Exit(1)
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}
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err = doDump(c, os.Args[2], os.Args[3], false, "./pre")
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if err != nil {
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fmt.Printf("dump failed")
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fmt.Print(err)
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os.Exit(1)
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}
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c.Cleanup()
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case "restore":
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fmt.Printf("Restoring\n")
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img, err := os.Open(os.Args[2])
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if err != nil {
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fmt.Printf("can't open image dir")
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os.Exit(1)
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}
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defer img.Close()
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opts := rpc.CriuOpts{
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ImagesDirFd: proto.Int32(int32(img.Fd())),
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LogLevel: proto.Int32(4),
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LogFile: proto.String("restore.log"),
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}
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err = c.Restore(opts, nil)
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if err != nil {
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fmt.Printf("Error:")
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fmt.Print(err)
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fmt.Printf("\n")
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os.Exit(1)
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}
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default:
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fmt.Printf("unknown action\n")
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os.Exit(1)
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}
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fmt.Printf("Success\n")
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}

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