containerd/archive/tar_unix.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 archive

import (
	"archive/tar"
	"context"
	"os"
	"sync"
	"syscall"

	"github.com/containerd/continuity/sysx"
	"github.com/opencontainers/runc/libcontainer/system"
	"github.com/pkg/errors"
	"golang.org/x/sys/unix"
)

func tarName(p string) (string, error) {
	return p, nil
}

func chmodTarEntry(perm os.FileMode) os.FileMode {
	return perm
}

func setHeaderForSpecialDevice(hdr *tar.Header, name string, fi os.FileInfo) error {
	s, ok := fi.Sys().(*syscall.Stat_t)
	if !ok {
		return errors.New("unsupported stat type")
	}

	// Rdev is int32 on darwin/bsd, int64 on linux/solaris
	rdev := uint64(s.Rdev) // nolint: unconvert

	// Currently go does not fill in the major/minors
	if s.Mode&syscall.S_IFBLK != 0 ||
		s.Mode&syscall.S_IFCHR != 0 {
		hdr.Devmajor = int64(unix.Major(rdev))
		hdr.Devminor = int64(unix.Minor(rdev))
	}

	return nil
}

func open(p string) (*os.File, error) {
	return os.Open(p)
}

func openFile(name string, flag int, perm os.FileMode) (*os.File, error) {
	f, err := os.OpenFile(name, flag, perm)
	if err != nil {
		return nil, err
	}
	// Call chmod to avoid permission mask
	if err := os.Chmod(name, perm); err != nil {
		return nil, err
	}
	return f, err
}

func mkdirAll(path string, perm os.FileMode) error {
	return os.MkdirAll(path, perm)
}

func mkdir(path string, perm os.FileMode) error {
	if err := os.Mkdir(path, perm); err != nil {
		return err
	}
	// Only final created directory gets explicit permission
	// call to avoid permission mask
	return os.Chmod(path, perm)
}

var (
	inUserNS bool
	nsOnce   sync.Once
)

func setInUserNS() {
	inUserNS = system.RunningInUserNS()
}

func skipFile(hdr *tar.Header) bool {
	switch hdr.Typeflag {
	case tar.TypeBlock, tar.TypeChar:
		// cannot create a device if running in user namespace
		nsOnce.Do(setInUserNS)
		return inUserNS
	default:
		return false
	}
}

// handleTarTypeBlockCharFifo is an OS-specific helper function used by
// createTarFile to handle the following types of header: Block; Char; Fifo.
// This function must not be called for Block and Char when running in userns.
// (skipFile() should return true for them.)
func handleTarTypeBlockCharFifo(hdr *tar.Header, path string) error {
	mode := uint32(hdr.Mode & 07777)
	switch hdr.Typeflag {
	case tar.TypeBlock:
		mode |= unix.S_IFBLK
	case tar.TypeChar:
		mode |= unix.S_IFCHR
	case tar.TypeFifo:
		mode |= unix.S_IFIFO
	}

	return unix.Mknod(path, mode, int(unix.Mkdev(uint32(hdr.Devmajor), uint32(hdr.Devminor))))
}

func handleLChmod(hdr *tar.Header, path string, hdrInfo os.FileInfo) error {
	if hdr.Typeflag == tar.TypeLink {
		if fi, err := os.Lstat(hdr.Linkname); err == nil && (fi.Mode()&os.ModeSymlink == 0) {
			if err := os.Chmod(path, hdrInfo.Mode()); err != nil {
				return err
			}
		}
	} else if hdr.Typeflag != tar.TypeSymlink {
		if err := os.Chmod(path, hdrInfo.Mode()); err != nil {
			return err
		}
	}
	return nil
}

func getxattr(path, attr string) ([]byte, error) {
	b, err := sysx.LGetxattr(path, attr)
	if err == unix.ENOTSUP || err == sysx.ENODATA {
		return nil, nil
	}
	return b, err
}

func setxattr(path, key, value string) error {
	return sysx.LSetxattr(path, key, []byte(value), 0)
}

// apply applies a tar stream of an OCI style diff tar.
// See https://github.com/opencontainers/image-spec/blob/master/layer.md#applying-changesets
func apply(ctx context.Context, root string, tr *tar.Reader, options ApplyOptions) (size int64, err error) {
	return applyNaive(ctx, root, tr, options)
}