79 lines
2 KiB
Go
79 lines
2 KiB
Go
// +build linux
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package main
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import (
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"os"
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"os/signal"
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"syscall"
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"github.com/Sirupsen/logrus"
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"github.com/docker/containerd"
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"github.com/opencontainers/runc/libcontainer/utils"
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)
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// http://man7.org/linux/man-pages/man2/prctl.2.html
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//
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// If arg2 is nonzero, set the "child subreaper" attribute of the
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// calling process; if arg2 is zero, unset the attribute. When a
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// process is marked as a child subreaper, all of the children
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// that it creates, and their descendants, will be marked as
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// having a subreaper. In effect, a subreaper fulfills the role
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// of init(1) for its descendant processes. Upon termination of
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// a process that is orphaned (i.e., its immediate parent has
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// already terminated) and marked as having a subreaper, the
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// nearest still living ancestor subreaper will receive a SIGCHLD
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// signal and be able to wait(2) on the process to discover its
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// termination status.
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const PR_SET_CHILD_SUBREAPER = 36
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func startSignalHandler(supervisor *containerd.Supervisor, bufferSize int) {
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logrus.Debug("containerd: starting signal handler")
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signals := make(chan os.Signal, bufferSize)
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signal.Notify(signals)
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for s := range signals {
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switch s {
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case syscall.SIGTERM, syscall.SIGINT:
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supervisor.Close()
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os.Exit(0)
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case syscall.SIGCHLD:
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exits, err := reap()
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if err != nil {
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logrus.WithField("error", err).Error("containerd: reaping child processes")
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}
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for _, e := range exits {
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supervisor.SendEvent(e)
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}
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}
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}
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}
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func reap() (exits []*containerd.Event, err error) {
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var (
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ws syscall.WaitStatus
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rus syscall.Rusage
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)
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for {
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pid, err := syscall.Wait4(-1, &ws, syscall.WNOHANG, &rus)
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if err != nil {
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if err == syscall.ECHILD {
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return exits, nil
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}
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return exits, err
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}
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if pid <= 0 {
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return exits, nil
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}
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e := containerd.NewEvent(containerd.ExitEventType)
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e.Pid = pid
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e.Status = utils.ExitStatus(ws)
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exits = append(exits, e)
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}
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}
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func setSubReaper() error {
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if _, _, err := syscall.RawSyscall(syscall.SYS_PRCTL, PR_SET_CHILD_SUBREAPER, 1, 0); err != 0 {
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return err
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}
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return nil
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}
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