543 lines
13 KiB
Go
543 lines
13 KiB
Go
package shim
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"os/exec"
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"path/filepath"
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"strconv"
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"strings"
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"sync"
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"syscall"
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"time"
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"github.com/Sirupsen/logrus"
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"github.com/docker/containerd"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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"golang.org/x/sys/unix"
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)
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var (
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ErrContainerStartTimeout = errors.New("shim: container did not start before the specified timeout")
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ErrContainerNotStarted = errors.New("shim: container not started")
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ErrProcessNotExited = errors.New("containerd: process has not exited")
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ErrShimExited = errors.New("containerd: shim exited before container process was started")
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errInvalidPidInt = errors.New("shim: process pid is invalid")
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)
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const UnknownStatus = 255
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type processOpts struct {
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root string
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noPivotRoot bool
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checkpoint string
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c *containerd.Container
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cmd *exec.Cmd
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exec bool
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spec specs.Process
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stdin io.Reader
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stdout io.Writer
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stderr io.Writer
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}
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func newProcess(opts processOpts) (*process, error) {
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var (
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spec = opts.c.Spec()
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stdin, stdout, stderr string
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)
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uid, gid, err := getRootIDs(spec)
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if err != nil {
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return nil, err
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}
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for _, t := range []struct {
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path *string
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v interface{}
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}{
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{
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path: &stdin,
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v: opts.stdin,
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},
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{
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path: &stdout,
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v: opts.stdout,
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},
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{
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path: &stderr,
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v: opts.stderr,
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},
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} {
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p, err := getFifoPath(t.v)
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if err != nil {
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return nil, err
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}
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*t.path = p
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}
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p := &process{
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root: opts.root,
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cmd: opts.cmd,
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done: make(chan struct{}),
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spec: opts.spec,
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exec: opts.exec,
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rootUid: uid,
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rootGid: gid,
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noPivotRoot: opts.noPivotRoot,
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checkpoint: opts.checkpoint,
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stdin: stdin,
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stdout: stdout,
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stderr: stderr,
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}
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f, err := os.Create(filepath.Join(opts.root, "process.json"))
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if err != nil {
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return nil, err
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}
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err = json.NewEncoder(f).Encode(p)
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f.Close()
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if err != nil {
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return nil, err
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}
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exit, err := getExitPipe(filepath.Join(opts.root, "exit"))
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if err != nil {
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return nil, err
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}
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control, err := getControlPipe(filepath.Join(opts.root, "control"))
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if err != nil {
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return nil, err
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}
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p.exit, p.control = exit, control
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return p, nil
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}
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type process struct {
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root string
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cmd *exec.Cmd
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done chan struct{}
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success bool
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startTime string
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mu sync.Mutex
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pid int
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exit *os.File
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control *os.File
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spec specs.Process
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noPivotRoot bool
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exec bool
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rootUid int
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rootGid int
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checkpoint string
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stdin string
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stdout string
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stderr string
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}
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type processState struct {
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specs.Process
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Exec bool `json:"exec"`
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RootUID int `json:"rootUID"`
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RootGID int `json:"rootGID"`
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Checkpoint string `json:"checkpoint"`
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NoPivotRoot bool `json:"noPivotRoot"`
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RuntimeArgs []string `json:"runtimeArgs"`
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Root string `json:"root"`
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StartTime string `json:"startTime"`
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// Stdin fifo filepath
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Stdin string `json:"stdin"`
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// Stdout fifo filepath
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Stdout string `json:"stdout"`
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// Stderr fifo filepath
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Stderr string `json:"stderr"`
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}
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func (p *process) MarshalJSON() ([]byte, error) {
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ps := processState{
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Process: p.spec,
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NoPivotRoot: p.noPivotRoot,
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Checkpoint: p.checkpoint,
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RootUID: p.rootUid,
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RootGID: p.rootGid,
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Exec: p.exec,
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Stdin: p.stdin,
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Stdout: p.stdout,
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Stderr: p.stderr,
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Root: p.root,
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StartTime: p.startTime,
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}
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return json.Marshal(ps)
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}
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func (p *process) UnmarshalJSON(b []byte) error {
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var ps processState
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if err := json.Unmarshal(b, &ps); err != nil {
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return err
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}
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p.spec = ps.Process
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p.noPivotRoot = ps.NoPivotRoot
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p.rootGid = ps.RootGID
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p.rootUid = ps.RootUID
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p.checkpoint = ps.Checkpoint
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p.exec = ps.Exec
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p.stdin = ps.Stdin
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p.stdout = ps.Stdout
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p.stderr = ps.Stderr
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p.root = ps.Root
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p.startTime = ps.StartTime
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p.done = make(chan struct{})
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pid, err := readPid(filepath.Join(p.root, "pid"))
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if err != nil {
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return err
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}
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p.pid = pid
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exit, err := getExitPipe(filepath.Join(p.root, "exit"))
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if err != nil {
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return err
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}
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control, err := getControlPipe(filepath.Join(p.root, "control"))
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if err != nil {
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return err
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}
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p.exit, p.control = exit, control
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return nil
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}
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func (p *process) Pid() int {
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return p.pid
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}
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func (p *process) FD() int {
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return int(p.exit.Fd())
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}
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func (p *process) Close() error {
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return p.exit.Close()
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}
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func (p *process) Remove() bool {
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return true
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}
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func (p *process) Wait() (rst uint32, rerr error) {
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<-p.done
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data, err := ioutil.ReadFile(filepath.Join(p.root, "exitStatus"))
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defer func() {
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if rerr != nil {
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rst, rerr = p.handleSigkilledShim(rst, rerr)
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}
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}()
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if err != nil {
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if os.IsNotExist(err) {
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return UnknownStatus, ErrProcessNotExited
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}
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return UnknownStatus, err
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}
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if len(data) == 0 {
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return UnknownStatus, ErrProcessNotExited
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}
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i, err := strconv.ParseUint(string(data), 10, 32)
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return uint32(i), err
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}
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func (p *process) Signal(s os.Signal) error {
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_, err := fmt.Fprintf(p.control, "%d %d %d\n", 2, s, 0)
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return err
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}
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// same checks if the process is the same process originally launched
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func (p *process) same() (bool, error) {
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/// for backwards compat assume true if it is not set
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p.mu.Lock()
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defer p.mu.Unlock()
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if p.startTime == "" {
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return true, nil
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}
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pid, err := readPid(filepath.Join(p.root, "pid"))
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if err != nil {
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return false, nil
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}
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started, err := readProcessStartTime(pid)
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if err != nil {
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return false, err
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}
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return p.startTime == started, nil
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}
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func (p *process) checkExited() {
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err := p.cmd.Wait()
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if err == nil {
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p.mu.Lock()
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if p.success {
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p.mu.Unlock()
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return
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}
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p.success = true
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p.mu.Unlock()
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}
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if same, _ := p.same(); same && p.hasPid() {
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// The process changed its PR_SET_PDEATHSIG, so force kill it
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logrus.Infof("containerd: (pid %v) has become an orphan, killing it", p.pid)
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if err := unix.Kill(p.pid, syscall.SIGKILL); err != nil && err != syscall.ESRCH {
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logrus.Errorf("containerd: unable to SIGKILL (pid %v): %v", p.pid, err)
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return
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}
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// wait for the container process to exit
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for {
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if err := unix.Kill(p.pid, 0); err != nil {
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break
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}
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time.Sleep(5 * time.Millisecond)
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}
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}
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}
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func (p *process) hasPid() bool {
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p.mu.Lock()
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r := p.pid > 0
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p.mu.Unlock()
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return r
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}
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type pidResponse struct {
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pid int
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err error
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}
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func (p *process) waitForCreate(timeout time.Duration) error {
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r := make(chan pidResponse, 1)
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go p.readContainerPid(r)
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select {
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case resp := <-r:
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if resp.err != nil {
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return resp.err
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}
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p.mu.Lock()
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p.pid = resp.pid
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started, err := readProcessStartTime(resp.pid)
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if err != nil {
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if os.IsNotExist(err) {
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// process already exited
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p.success = true
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p.mu.Unlock()
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return nil
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}
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logrus.Warnf("shim: unable to save starttime: %v", err)
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}
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p.startTime = started
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f, err := os.Create(filepath.Join(p.root, "process.json"))
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if err != nil {
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logrus.Warnf("shim: unable to create process.json: %v", err)
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p.mu.Unlock()
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return nil
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}
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defer f.Close()
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if err := json.NewEncoder(f).Encode(p); err != nil {
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logrus.Warnf("shim: unable to encode process: %v", err)
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}
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p.mu.Unlock()
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return nil
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case <-time.After(timeout):
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p.cmd.Process.Kill()
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p.cmd.Wait()
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return ErrContainerStartTimeout
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}
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}
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func (p *process) readContainerPid(r chan pidResponse) {
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pidFile := filepath.Join(p.root, "pid")
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for {
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pid, err := readPid(pidFile)
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if err != nil {
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if os.IsNotExist(err) || err == errInvalidPidInt {
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if serr := checkErrorLogs(p.cmd,
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filepath.Join(p.root, "shim-log.json"),
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filepath.Join(p.root, "log.json")); serr != nil && !os.IsNotExist(serr) {
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r <- pidResponse{
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err: serr,
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}
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break
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}
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time.Sleep(15 * time.Millisecond)
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continue
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}
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r <- pidResponse{
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err: err,
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}
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break
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}
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r <- pidResponse{
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pid: pid,
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}
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break
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}
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}
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func (p *process) handleSigkilledShim(rst uint32, rerr error) (uint32, error) {
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if err := unix.Kill(p.pid, 0); err == syscall.ESRCH {
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logrus.Warnf("containerd: (pid %d) does not exist", p.pid)
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// The process died while containerd was down (probably of
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// SIGKILL, but no way to be sure)
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return UnknownStatus, writeExitStatus(filepath.Join(p.root, "exitStatus"), UnknownStatus)
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}
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// If it's not the same process, just mark it stopped and set
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// the status to the UnknownStatus value (i.e. 255)
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if same, _ := p.same(); !same {
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// Create the file so we get the exit event generated once monitor kicks in
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// without having to go through all this process again
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return UnknownStatus, writeExitStatus(filepath.Join(p.root, "exitStatus"), UnknownStatus)
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}
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ppid, err := readProcStatField(p.pid, 4)
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if err != nil {
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return rst, fmt.Errorf("could not check process ppid: %v (%v)", err, rerr)
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}
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if ppid == "1" {
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if err := unix.Kill(p.pid, syscall.SIGKILL); err != nil && err != syscall.ESRCH {
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return UnknownStatus, fmt.Errorf(
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"containerd: unable to SIGKILL (pid %v): %v", p.pid, err)
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}
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// wait for the process to die
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for {
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if err := unix.Kill(p.pid, 0); err == syscall.ESRCH {
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break
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}
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time.Sleep(5 * time.Millisecond)
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}
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// Create the file so we get the exit event generated once monitor kicks in
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// without having to go through all this process again
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status := 128 + uint32(syscall.SIGKILL)
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return status, writeExitStatus(filepath.Join(p.root, "exitStatus"), status)
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}
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return rst, rerr
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}
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func checkErrorLogs(cmd *exec.Cmd, shimLogPath, runtimeLogPath string) error {
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alive, err := isAlive(cmd)
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if err != nil {
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return err
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}
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if !alive {
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// runc could have failed to run the container so lets get the error
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// out of the logs or the shim could have encountered an error
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messages, err := readLogMessages(shimLogPath)
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if err != nil {
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return err
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}
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for _, m := range messages {
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if m.Level == "error" {
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return fmt.Errorf("shim error: %v", m.Msg)
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}
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}
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// no errors reported back from shim, check for runc/runtime errors
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messages, err = readLogMessages(runtimeLogPath)
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if err != nil {
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if os.IsNotExist(err) {
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err = ErrContainerNotStarted
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}
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return err
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}
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for _, m := range messages {
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if m.Level == "error" {
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return fmt.Errorf("oci runtime error: %v", m.Msg)
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}
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}
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return ErrContainerNotStarted
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}
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return nil
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}
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func readProcessStartTime(pid int) (string, error) {
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return readProcStatField(pid, 22)
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}
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func readProcStatField(pid int, field int) (string, error) {
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data, err := ioutil.ReadFile(filepath.Join(string(filepath.Separator), "proc", strconv.Itoa(pid), "stat"))
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if err != nil {
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return "", err
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}
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if field > 2 {
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// First, split out the name since he could contains spaces.
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parts := strings.Split(string(data), ") ")
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// Now split out the rest, we end up with 2 fields less
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parts = strings.Split(parts[1], " ")
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return parts[field-2-1], nil // field count start at 1 in manual
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}
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parts := strings.Split(string(data), " (")
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if field == 1 {
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return parts[0], nil
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}
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return strings.Split(parts[1], ") ")[0], nil
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}
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func readPid(pidFile string) (int, error) {
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data, err := ioutil.ReadFile(pidFile)
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if err != nil {
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return -1, err
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}
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i, err := strconv.Atoi(string(data))
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if err != nil {
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return -1, errInvalidPidInt
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}
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return i, nil
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}
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// isAlive checks if the shim that launched the container is still alive
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func isAlive(cmd *exec.Cmd) (bool, error) {
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if _, err := syscall.Wait4(cmd.Process.Pid, nil, syscall.WNOHANG, nil); err == nil {
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return true, nil
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}
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if err := syscall.Kill(cmd.Process.Pid, 0); err != nil {
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if err == syscall.ESRCH {
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return false, nil
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}
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return false, err
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}
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return true, nil
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}
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type message struct {
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Level string `json:"level"`
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Msg string `json:"msg"`
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}
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func readLogMessages(path string) ([]message, error) {
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var out []message
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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dec := json.NewDecoder(f)
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for {
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var m message
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if err := dec.Decode(&m); err != nil {
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if err == io.EOF {
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break
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}
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return nil, err
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}
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out = append(out, m)
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}
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return out, nil
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}
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func getExitPipe(path string) (*os.File, error) {
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if err := unix.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
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return nil, err
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}
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// add NONBLOCK in case the other side has already closed or else
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// this function would never return
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return os.OpenFile(path, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
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}
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func getControlPipe(path string) (*os.File, error) {
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if err := unix.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
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return nil, err
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}
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return os.OpenFile(path, syscall.O_RDWR|syscall.O_NONBLOCK, 0)
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}
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func writeExitStatus(path string, status uint32) error {
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return ioutil.WriteFile(path, []byte(fmt.Sprintf("%u", status)), 0644)
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}
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