Move shim package to pkg

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

pkg/shim/shim_unix.go

@@ -0,0 +1,113 @@
+//go:build !windows
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package shim
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/containerd/containerd/v2/pkg/sys/reaper"
+	"github.com/containerd/fifo"
+	"github.com/containerd/log"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// setupSignals creates a new signal handler for all signals and sets the shim as a
+// sub-reaper so that the container processes are reparented
+func setupSignals(config Config) (chan os.Signal, error) {
+	signals := make(chan os.Signal, 32)
+	smp := []os.Signal{unix.SIGTERM, unix.SIGINT, unix.SIGPIPE}
+	if !config.NoReaper {
+		smp = append(smp, unix.SIGCHLD)
+	}
+	signal.Notify(signals, smp...)
+	return signals, nil
+}
+
+func setupDumpStacks(dump chan<- os.Signal) {
+	signal.Notify(dump, syscall.SIGUSR1)
+}
+
+func serveListener(path string) (net.Listener, error) {
+	var (
+		l   net.Listener
+		err error
+	)
+	if path == "" {
+		l, err = net.FileListener(os.NewFile(3, "socket"))
+		path = "[inherited from parent]"
+	} else {
+		if len(path) > socketPathLimit {
+			return nil, fmt.Errorf("%q: unix socket path too long (> %d)", path, socketPathLimit)
+		}
+		l, err = net.Listen("unix", path)
+	}
+	if err != nil {
+		return nil, err
+	}
+	log.L.WithField("socket", path).Debug("serving api on socket")
+	return l, nil
+}
+
+func reap(ctx context.Context, logger *logrus.Entry, signals chan os.Signal) error {
+	logger.Debug("starting signal loop")
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case s := <-signals:
+			// Exit signals are handled separately from this loop
+			// They get registered with this channel so that we can ignore such signals for short-running actions (e.g. `delete`)
+			switch s {
+			case unix.SIGCHLD:
+				if err := reaper.Reap(); err != nil {
+					logger.WithError(err).Error("reap exit status")
+				}
+			case unix.SIGPIPE:
+			}
+		}
+	}
+}
+
+func handleExitSignals(ctx context.Context, logger *logrus.Entry, cancel context.CancelFunc) {
+	ch := make(chan os.Signal, 32)
+	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM)
+
+	for {
+		select {
+		case s := <-ch:
+			logger.WithField("signal", s).Debugf("Caught exit signal")
+			cancel()
+			return
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func openLog(ctx context.Context, _ string) (io.Writer, error) {
+	return fifo.OpenFifoDup2(ctx, "log", unix.O_WRONLY, 0700, int(os.Stderr.Fd()))
+}