404 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			404 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// +build !windows
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package oci
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import (
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	"context"
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	"encoding/json"
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	"fmt"
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	"os"
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	"path/filepath"
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	"strconv"
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	"strings"
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	"github.com/containerd/containerd/containers"
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	"github.com/containerd/containerd/content"
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	"github.com/containerd/containerd/images"
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	"github.com/containerd/containerd/mount"
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	"github.com/containerd/containerd/namespaces"
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	"github.com/containerd/continuity/fs"
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	"github.com/opencontainers/image-spec/specs-go/v1"
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	"github.com/opencontainers/runc/libcontainer/user"
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	specs "github.com/opencontainers/runtime-spec/specs-go"
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	"github.com/pkg/errors"
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	"github.com/syndtr/gocapability/capability"
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)
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// WithTTY sets the information on the spec as well as the environment variables for
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// using a TTY
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func WithTTY(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	s.Process.Terminal = true
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	s.Process.Env = append(s.Process.Env, "TERM=xterm")
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	return nil
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}
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// WithHostNamespace allows a task to run inside the host's linux namespace
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func WithHostNamespace(ns specs.LinuxNamespaceType) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		for i, n := range s.Linux.Namespaces {
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			if n.Type == ns {
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				s.Linux.Namespaces = append(s.Linux.Namespaces[:i], s.Linux.Namespaces[i+1:]...)
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				return nil
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			}
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		}
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		return nil
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	}
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}
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// WithLinuxNamespace uses the passed in namespace for the spec. If a namespace of the same type already exists in the
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// spec, the existing namespace is replaced by the one provided.
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func WithLinuxNamespace(ns specs.LinuxNamespace) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		for i, n := range s.Linux.Namespaces {
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			if n.Type == ns.Type {
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				before := s.Linux.Namespaces[:i]
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				after := s.Linux.Namespaces[i+1:]
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				s.Linux.Namespaces = append(before, ns)
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				s.Linux.Namespaces = append(s.Linux.Namespaces, after...)
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				return nil
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			}
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		}
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		s.Linux.Namespaces = append(s.Linux.Namespaces, ns)
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		return nil
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	}
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}
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// WithImageConfig configures the spec to from the configuration of an Image
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func WithImageConfig(image Image) SpecOpts {
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	return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) error {
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		ic, err := image.Config(ctx)
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		if err != nil {
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			return err
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		}
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		var (
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			ociimage v1.Image
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			config   v1.ImageConfig
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		)
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		switch ic.MediaType {
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		case v1.MediaTypeImageConfig, images.MediaTypeDockerSchema2Config:
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			p, err := content.ReadBlob(ctx, image.ContentStore(), ic.Digest)
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			if err != nil {
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				return err
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			}
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			if err := json.Unmarshal(p, &ociimage); err != nil {
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				return err
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			}
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			config = ociimage.Config
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		default:
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			return fmt.Errorf("unknown image config media type %s", ic.MediaType)
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		}
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		if s.Process == nil {
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			s.Process = &specs.Process{}
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		}
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		s.Process.Env = append(s.Process.Env, config.Env...)
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		cmd := config.Cmd
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		s.Process.Args = append(config.Entrypoint, cmd...)
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		cwd := config.WorkingDir
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		if cwd == "" {
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			cwd = "/"
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		}
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		s.Process.Cwd = cwd
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		if config.User != "" {
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			// According to OCI Image Spec v1.0.0, the following are valid for Linux:
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			//   user, uid, user:group, uid:gid, uid:group, user:gid
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			parts := strings.Split(config.User, ":")
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			switch len(parts) {
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			case 1:
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				v, err := strconv.Atoi(parts[0])
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				if err != nil {
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					// if we cannot parse as a uint they try to see if it is a username
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					return WithUsername(config.User)(ctx, client, c, s)
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				}
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				return WithUserID(uint32(v))(ctx, client, c, s)
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			case 2:
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				// TODO: support username and groupname
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				v, err := strconv.Atoi(parts[0])
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				if err != nil {
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					return errors.Wrapf(err, "parse uid %s", parts[0])
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				}
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				uid := uint32(v)
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				if v, err = strconv.Atoi(parts[1]); err != nil {
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					return errors.Wrapf(err, "parse gid %s", parts[1])
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				}
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				gid := uint32(v)
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				s.Process.User.UID, s.Process.User.GID = uid, gid
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			default:
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				return fmt.Errorf("invalid USER value %s", config.User)
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			}
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		}
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		return nil
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	}
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}
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// WithRootFSPath specifies unmanaged rootfs path.
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func WithRootFSPath(path string) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		if s.Root == nil {
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			s.Root = &specs.Root{}
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		}
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		s.Root.Path = path
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		// Entrypoint is not set here (it's up to caller)
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		return nil
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	}
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}
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// WithRootFSReadonly sets specs.Root.Readonly to true
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func WithRootFSReadonly() SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		if s.Root == nil {
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			s.Root = &specs.Root{}
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		}
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		s.Root.Readonly = true
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		return nil
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	}
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}
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// WithNoNewPrivileges sets no_new_privileges on the process for the container
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func WithNoNewPrivileges(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	s.Process.NoNewPrivileges = true
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	return nil
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}
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// WithHostHostsFile bind-mounts the host's /etc/hosts into the container as readonly
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func WithHostHostsFile(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	s.Mounts = append(s.Mounts, specs.Mount{
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		Destination: "/etc/hosts",
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		Type:        "bind",
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		Source:      "/etc/hosts",
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		Options:     []string{"rbind", "ro"},
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	})
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	return nil
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}
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// WithHostResolvconf bind-mounts the host's /etc/resolv.conf into the container as readonly
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func WithHostResolvconf(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	s.Mounts = append(s.Mounts, specs.Mount{
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		Destination: "/etc/resolv.conf",
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		Type:        "bind",
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		Source:      "/etc/resolv.conf",
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		Options:     []string{"rbind", "ro"},
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	})
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	return nil
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}
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// WithHostLocaltime bind-mounts the host's /etc/localtime into the container as readonly
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func WithHostLocaltime(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	s.Mounts = append(s.Mounts, specs.Mount{
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		Destination: "/etc/localtime",
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		Type:        "bind",
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		Source:      "/etc/localtime",
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		Options:     []string{"rbind", "ro"},
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	})
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	return nil
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}
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// WithUserNamespace sets the uid and gid mappings for the task
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// this can be called multiple times to add more mappings to the generated spec
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func WithUserNamespace(container, host, size uint32) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		var hasUserns bool
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		for _, ns := range s.Linux.Namespaces {
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			if ns.Type == specs.UserNamespace {
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				hasUserns = true
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				break
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			}
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		}
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		if !hasUserns {
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			s.Linux.Namespaces = append(s.Linux.Namespaces, specs.LinuxNamespace{
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				Type: specs.UserNamespace,
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			})
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		}
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		mapping := specs.LinuxIDMapping{
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			ContainerID: container,
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			HostID:      host,
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			Size:        size,
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		}
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		s.Linux.UIDMappings = append(s.Linux.UIDMappings, mapping)
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		s.Linux.GIDMappings = append(s.Linux.GIDMappings, mapping)
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		return nil
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	}
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}
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// WithCgroup sets the container's cgroup path
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func WithCgroup(path string) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		s.Linux.CgroupsPath = path
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		return nil
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	}
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}
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// WithNamespacedCgroup uses the namespace set on the context to create a
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// root directory for containers in the cgroup with the id as the subcgroup
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func WithNamespacedCgroup() SpecOpts {
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	return func(ctx context.Context, _ Client, c *containers.Container, s *specs.Spec) error {
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		namespace, err := namespaces.NamespaceRequired(ctx)
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		if err != nil {
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			return err
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		}
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		s.Linux.CgroupsPath = filepath.Join("/", namespace, c.ID)
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		return nil
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	}
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}
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// WithUIDGID allows the UID and GID for the Process to be set
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func WithUIDGID(uid, gid uint32) SpecOpts {
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	return func(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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		s.Process.User.UID = uid
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		s.Process.User.GID = gid
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		return nil
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	}
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}
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// WithUserID sets the correct UID and GID for the container based
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// on the image's /etc/passwd contents. If /etc/passwd does not exist,
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// or uid is not found in /etc/passwd, it sets gid to be the same with
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// uid, and not returns error.
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func WithUserID(uid uint32) SpecOpts {
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	return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) (err error) {
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		if c.Snapshotter == "" && c.SnapshotKey == "" {
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			if !isRootfsAbs(s.Root.Path) {
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				return errors.Errorf("rootfs absolute path is required")
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			}
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			uuid, ugid, err := getUIDGIDFromPath(s.Root.Path, func(u user.User) bool {
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				return u.Uid == int(uid)
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			})
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			if err != nil {
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				if os.IsNotExist(err) || err == errNoUsersFound {
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					s.Process.User.UID, s.Process.User.GID = uid, uid
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					return nil
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				}
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				return err
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			}
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			s.Process.User.UID, s.Process.User.GID = uuid, ugid
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			return nil
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		}
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		if c.Snapshotter == "" {
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			return errors.Errorf("no snapshotter set for container")
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		}
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		if c.SnapshotKey == "" {
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			return errors.Errorf("rootfs snapshot not created for container")
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		}
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		snapshotter := client.SnapshotService(c.Snapshotter)
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		mounts, err := snapshotter.Mounts(ctx, c.SnapshotKey)
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		if err != nil {
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			return err
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		}
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		return mount.WithTempMount(ctx, mounts, func(root string) error {
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			uuid, ugid, err := getUIDGIDFromPath(root, func(u user.User) bool {
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				return u.Uid == int(uid)
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			})
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			if err != nil {
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				if os.IsNotExist(err) || err == errNoUsersFound {
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					s.Process.User.UID, s.Process.User.GID = uid, uid
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					return nil
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				}
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				return err
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			}
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			s.Process.User.UID, s.Process.User.GID = uuid, ugid
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			return nil
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		})
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	}
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}
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// WithUsername sets the correct UID and GID for the container
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// based on the the image's /etc/passwd contents. If /etc/passwd
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// does not exist, or the username is not found in /etc/passwd,
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// it returns error.
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func WithUsername(username string) SpecOpts {
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	return func(ctx context.Context, client Client, c *containers.Container, s *specs.Spec) (err error) {
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		if c.Snapshotter == "" && c.SnapshotKey == "" {
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			if !isRootfsAbs(s.Root.Path) {
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				return errors.Errorf("rootfs absolute path is required")
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			}
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			uid, gid, err := getUIDGIDFromPath(s.Root.Path, func(u user.User) bool {
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				return u.Name == username
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			})
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			if err != nil {
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				return err
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			}
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			s.Process.User.UID, s.Process.User.GID = uid, gid
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			return nil
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		}
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		if c.Snapshotter == "" {
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			return errors.Errorf("no snapshotter set for container")
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		}
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		if c.SnapshotKey == "" {
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			return errors.Errorf("rootfs snapshot not created for container")
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		}
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		snapshotter := client.SnapshotService(c.Snapshotter)
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		mounts, err := snapshotter.Mounts(ctx, c.SnapshotKey)
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		if err != nil {
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			return err
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		}
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		return mount.WithTempMount(ctx, mounts, func(root string) error {
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			uid, gid, err := getUIDGIDFromPath(root, func(u user.User) bool {
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				return u.Name == username
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			})
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			if err != nil {
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				return err
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			}
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			s.Process.User.UID, s.Process.User.GID = uid, gid
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			return nil
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		})
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	}
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}
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// WithAllCapabilities set all linux capabilities for the process
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func WithAllCapabilities(_ context.Context, _ Client, _ *containers.Container, s *specs.Spec) error {
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	caps := getAllCapabilities()
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	s.Process.Capabilities.Bounding = caps
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	s.Process.Capabilities.Effective = caps
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	s.Process.Capabilities.Permitted = caps
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	s.Process.Capabilities.Inheritable = caps
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	return nil
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}
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func getAllCapabilities() []string {
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	last := capability.CAP_LAST_CAP
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	// hack for RHEL6 which has no /proc/sys/kernel/cap_last_cap
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	if last == capability.Cap(63) {
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		last = capability.CAP_BLOCK_SUSPEND
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	}
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	var caps []string
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	for _, cap := range capability.List() {
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		if cap > last {
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			continue
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		}
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		caps = append(caps, "CAP_"+strings.ToUpper(cap.String()))
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	}
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	return caps
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}
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var errNoUsersFound = errors.New("no users found")
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func getUIDGIDFromPath(root string, filter func(user.User) bool) (uid, gid uint32, err error) {
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	ppath, err := fs.RootPath(root, "/etc/passwd")
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	if err != nil {
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		return 0, 0, err
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	}
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	f, err := os.Open(ppath)
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	if err != nil {
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		return 0, 0, err
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	}
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	defer f.Close()
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	users, err := user.ParsePasswdFilter(f, filter)
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	if err != nil {
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		return 0, 0, err
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	}
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	if len(users) == 0 {
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		return 0, 0, errNoUsersFound
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	}
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	u := users[0]
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	return uint32(u.Uid), uint32(u.Gid), nil
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}
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func isRootfsAbs(root string) bool {
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	return filepath.IsAbs(root)
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}
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