Add basic spec and mounts for Darwin

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

pkg/cri/opts/spec_darwin_opts.go

@@ -0,0 +1,119 @@
+/*
+   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 opts
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+
+	runtimespec "github.com/opencontainers/runtime-spec/specs-go"
+	runtime "k8s.io/cri-api/pkg/apis/runtime/v1"
+
+	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/oci"
+	osinterface "github.com/containerd/containerd/pkg/os"
+)
+
+// WithDarwinMounts adds mounts from CRI's container config + extra mounts.
+func WithDarwinMounts(osi osinterface.OS, config *runtime.ContainerConfig, extra []*runtime.Mount) oci.SpecOpts {
+	return func(ctx context.Context, client oci.Client, container *containers.Container, s *oci.Spec) error {
+		// mergeMounts merge CRI mounts with extra mounts. If a mount destination
+		// is mounted by both a CRI mount and an extra mount, the CRI mount will
+		// be kept.
+		var (
+			criMounts = config.GetMounts()
+			mounts    = append([]*runtime.Mount{}, criMounts...)
+		)
+
+		// Copy all mounts from extra mounts, except for mounts overridden by CRI.
+		for _, e := range extra {
+			found := false
+			for _, c := range criMounts {
+				if cleanMount(e.ContainerPath) == cleanMount(c.ContainerPath) {
+					found = true
+					break
+				}
+			}
+			if !found {
+				mounts = append(mounts, e)
+			}
+		}
+
+		// Sort mounts in number of parts. This ensures that high level mounts don't
+		// shadow other mounts.
+		sort.Sort(orderedMounts(mounts))
+
+		// Copy all mounts from default mounts, except for
+		// - mounts overridden by supplied mount;
+		mountSet := make(map[string]struct{})
+		for _, m := range mounts {
+			mountSet[filepath.Clean(m.ContainerPath)] = struct{}{}
+		}
+
+		defaultMounts := s.Mounts
+		s.Mounts = nil
+
+		for _, m := range defaultMounts {
+			dst := cleanMount(m.Destination)
+			if _, ok := mountSet[dst]; ok {
+				// filter out mount overridden by a supplied mount
+				continue
+			}
+			s.Mounts = append(s.Mounts, m)
+		}
+
+		for _, mount := range mounts {
+			var (
+				dst = mount.GetContainerPath()
+				src = mount.GetHostPath()
+			)
+
+			// Create the host path if it doesn't exist.
+			if _, err := osi.Stat(src); err != nil {
+				if !os.IsNotExist(err) {
+					return fmt.Errorf("failed to stat %q: %w", src, err)
+				}
+				if err := osi.MkdirAll(src, 0755); err != nil {
+					return fmt.Errorf("failed to mkdir %q: %w", src, err)
+				}
+			}
+
+			src, err := osi.ResolveSymbolicLink(src)
+			if err != nil {
+				return fmt.Errorf("failed to resolve symlink %q: %w", src, err)
+			}
+
+			var options []string
+			if mount.GetReadonly() {
+				options = append(options, "ro")
+			} else {
+				options = append(options, "rw")
+			}
+
+			s.Mounts = append(s.Mounts, runtimespec.Mount{
+				Source:      src,
+				Destination: dst,
+				Type:        "bind",
+				Options:     options,
+			})
+		}
+		return nil
+	}
+}