dotcloud/docker

package container

import (
    "context"
    "net"
    "syscall"

    "github.com/containerd/log"
    "github.com/docker/docker/internal/unix_noeintr"
    "golang.org/x/sys/unix"
)

func notifyClosed(ctx context.Context, conn net.Conn, notify func()) {
    sc, ok := conn.(syscall.Conn)
    if !ok {
        log.G(ctx).Debug("notifyClosed: conn does not support close notifications")
        return
    }

    rc, err := sc.SyscallConn()
    if err != nil {
        log.G(ctx).WithError(err).Warn("notifyClosed: failed get raw conn for close notifications")
        return
    }

    epFd, err := unix_noeintr.EpollCreate()
    if err != nil {
        log.G(ctx).WithError(err).Warn("notifyClosed: failed to create epoll fd")
        return
    }
    defer unix.Close(epFd)

    err = rc.Control(func(fd uintptr) {
        err := unix_noeintr.EpollCtl(epFd, unix.EPOLL_CTL_ADD, int(fd), &unix.EpollEvent{
            Events: unix.EPOLLHUP,
            Fd:     int32(fd),
        })
        if err != nil {
            log.G(ctx).WithError(err).Warn("notifyClosed: failed to register fd for close notifications")
            return
        }

        events := make([]unix.EpollEvent, 1)
        if _, err := unix_noeintr.EpollWait(epFd, events, -1); err != nil {
            log.G(ctx).WithError(err).Warn("notifyClosed: failed to wait for close notifications")
            return
        }
        notify()
    })
    if err != nil {
        log.G(ctx).WithError(err).Warn("notifyClosed: failed to register for close notifications")
        return
    }
}