migrate to github.com/moby/go-archive module

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/moby/go-archive/changes.go

@@ -0,0 +1,430 @@
+package archive
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/containerd/log"
+	"github.com/moby/sys/user"
+)
+
+// ChangeType represents the change type.
+type ChangeType int
+
+const (
+	ChangeModify = 0 // ChangeModify represents the modify operation.
+	ChangeAdd    = 1 // ChangeAdd represents the add operation.
+	ChangeDelete = 2 // ChangeDelete represents the delete operation.
+)
+
+func (c ChangeType) String() string {
+	switch c {
+	case ChangeModify:
+		return "C"
+	case ChangeAdd:
+		return "A"
+	case ChangeDelete:
+		return "D"
+	}
+	return ""
+}
+
+// Change represents a change, it wraps the change type and path.
+// It describes changes of the files in the path respect to the
+// parent layers. The change could be modify, add, delete.
+// This is used for layer diff.
+type Change struct {
+	Path string
+	Kind ChangeType
+}
+
+func (change *Change) String() string {
+	return fmt.Sprintf("%s %s", change.Kind, change.Path)
+}
+
+// for sort.Sort
+type changesByPath []Change
+
+func (c changesByPath) Less(i, j int) bool { return c[i].Path < c[j].Path }
+func (c changesByPath) Len() int           { return len(c) }
+func (c changesByPath) Swap(i, j int)      { c[j], c[i] = c[i], c[j] }
+
+// Gnu tar doesn't have sub-second mtime precision. The go tar
+// writer (1.10+) does when using PAX format, but we round times to seconds
+// to ensure archives have the same hashes for backwards compatibility.
+// See https://github.com/moby/moby/pull/35739/commits/fb170206ba12752214630b269a40ac7be6115ed4.
+//
+// Non-sub-second is problematic when we apply changes via tar
+// files. We handle this by comparing for exact times, *or* same
+// second count and either a or b having exactly 0 nanoseconds
+func sameFsTime(a, b time.Time) bool {
+	return a.Equal(b) ||
+		(a.Unix() == b.Unix() &&
+			(a.Nanosecond() == 0 || b.Nanosecond() == 0))
+}
+
+// Changes walks the path rw and determines changes for the files in the path,
+// with respect to the parent layers
+func Changes(layers []string, rw string) ([]Change, error) {
+	return changes(layers, rw, aufsDeletedFile, aufsMetadataSkip)
+}
+
+func aufsMetadataSkip(path string) (skip bool, err error) {
+	skip, err = filepath.Match(string(os.PathSeparator)+WhiteoutMetaPrefix+"*", path)
+	if err != nil {
+		skip = true
+	}
+	return skip, err
+}
+
+func aufsDeletedFile(root, path string, fi os.FileInfo) (string, error) {
+	f := filepath.Base(path)
+
+	// If there is a whiteout, then the file was removed
+	if strings.HasPrefix(f, WhiteoutPrefix) {
+		originalFile := f[len(WhiteoutPrefix):]
+		return filepath.Join(filepath.Dir(path), originalFile), nil
+	}
+
+	return "", nil
+}
+
+type (
+	skipChange   func(string) (bool, error)
+	deleteChange func(string, string, os.FileInfo) (string, error)
+)
+
+func changes(layers []string, rw string, dc deleteChange, sc skipChange) ([]Change, error) {
+	var (
+		changes     []Change
+		changedDirs = make(map[string]struct{})
+	)
+
+	err := filepath.Walk(rw, func(path string, f os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Rebase path
+		path, err = filepath.Rel(rw, path)
+		if err != nil {
+			return err
+		}
+
+		// As this runs on the daemon side, file paths are OS specific.
+		path = filepath.Join(string(os.PathSeparator), path)
+
+		// Skip root
+		if path == string(os.PathSeparator) {
+			return nil
+		}
+
+		if sc != nil {
+			if skip, err := sc(path); skip {
+				return err
+			}
+		}
+
+		change := Change{
+			Path: path,
+		}
+
+		deletedFile, err := dc(rw, path, f)
+		if err != nil {
+			return err
+		}
+
+		// Find out what kind of modification happened
+		if deletedFile != "" {
+			change.Path = deletedFile
+			change.Kind = ChangeDelete
+		} else {
+			// Otherwise, the file was added
+			change.Kind = ChangeAdd
+
+			// ...Unless it already existed in a top layer, in which case, it's a modification
+			for _, layer := range layers {
+				stat, err := os.Stat(filepath.Join(layer, path))
+				if err != nil && !os.IsNotExist(err) {
+					return err
+				}
+				if err == nil {
+					// The file existed in the top layer, so that's a modification
+
+					// However, if it's a directory, maybe it wasn't actually modified.
+					// If you modify /foo/bar/baz, then /foo will be part of the changed files only because it's the parent of bar
+					if stat.IsDir() && f.IsDir() {
+						if f.Size() == stat.Size() && f.Mode() == stat.Mode() && sameFsTime(f.ModTime(), stat.ModTime()) {
+							// Both directories are the same, don't record the change
+							return nil
+						}
+					}
+					change.Kind = ChangeModify
+					break
+				}
+			}
+		}
+
+		// If /foo/bar/file.txt is modified, then /foo/bar must be part of the changed files.
+		// This block is here to ensure the change is recorded even if the
+		// modify time, mode and size of the parent directory in the rw and ro layers are all equal.
+		// Check https://github.com/docker/docker/pull/13590 for details.
+		if f.IsDir() {
+			changedDirs[path] = struct{}{}
+		}
+		if change.Kind == ChangeAdd || change.Kind == ChangeDelete {
+			parent := filepath.Dir(path)
+			if _, ok := changedDirs[parent]; !ok && parent != "/" {
+				changes = append(changes, Change{Path: parent, Kind: ChangeModify})
+				changedDirs[parent] = struct{}{}
+			}
+		}
+
+		// Record change
+		changes = append(changes, change)
+		return nil
+	})
+	if err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+	return changes, nil
+}
+
+// FileInfo describes the information of a file.
+type FileInfo struct {
+	parent     *FileInfo
+	name       string
+	stat       fs.FileInfo
+	children   map[string]*FileInfo
+	capability []byte
+	added      bool
+}
+
+// LookUp looks up the file information of a file.
+func (info *FileInfo) LookUp(path string) *FileInfo {
+	// As this runs on the daemon side, file paths are OS specific.
+	parent := info
+	if path == string(os.PathSeparator) {
+		return info
+	}
+
+	pathElements := strings.Split(path, string(os.PathSeparator))
+	for _, elem := range pathElements {
+		if elem != "" {
+			child := parent.children[elem]
+			if child == nil {
+				return nil
+			}
+			parent = child
+		}
+	}
+	return parent
+}
+
+func (info *FileInfo) path() string {
+	if info.parent == nil {
+		// As this runs on the daemon side, file paths are OS specific.
+		return string(os.PathSeparator)
+	}
+	return filepath.Join(info.parent.path(), info.name)
+}
+
+func (info *FileInfo) addChanges(oldInfo *FileInfo, changes *[]Change) {
+	sizeAtEntry := len(*changes)
+
+	if oldInfo == nil {
+		// add
+		change := Change{
+			Path: info.path(),
+			Kind: ChangeAdd,
+		}
+		*changes = append(*changes, change)
+		info.added = true
+	}
+
+	// We make a copy so we can modify it to detect additions
+	// also, we only recurse on the old dir if the new info is a directory
+	// otherwise any previous delete/change is considered recursive
+	oldChildren := make(map[string]*FileInfo)
+	if oldInfo != nil && info.isDir() {
+		for k, v := range oldInfo.children {
+			oldChildren[k] = v
+		}
+	}
+
+	for name, newChild := range info.children {
+		oldChild := oldChildren[name]
+		if oldChild != nil {
+			// change?
+			oldStat := oldChild.stat
+			newStat := newChild.stat
+			// Note: We can't compare inode or ctime or blocksize here, because these change
+			// when copying a file into a container. However, that is not generally a problem
+			// because any content change will change mtime, and any status change should
+			// be visible when actually comparing the stat fields. The only time this
+			// breaks down is if some code intentionally hides a change by setting
+			// back mtime
+			if statDifferent(oldStat, newStat) ||
+				!bytes.Equal(oldChild.capability, newChild.capability) {
+				change := Change{
+					Path: newChild.path(),
+					Kind: ChangeModify,
+				}
+				*changes = append(*changes, change)
+				newChild.added = true
+			}
+
+			// Remove from copy so we can detect deletions
+			delete(oldChildren, name)
+		}
+
+		newChild.addChanges(oldChild, changes)
+	}
+	for _, oldChild := range oldChildren {
+		// delete
+		change := Change{
+			Path: oldChild.path(),
+			Kind: ChangeDelete,
+		}
+		*changes = append(*changes, change)
+	}
+
+	// If there were changes inside this directory, we need to add it, even if the directory
+	// itself wasn't changed. This is needed to properly save and restore filesystem permissions.
+	// As this runs on the daemon side, file paths are OS specific.
+	if len(*changes) > sizeAtEntry && info.isDir() && !info.added && info.path() != string(os.PathSeparator) {
+		change := Change{
+			Path: info.path(),
+			Kind: ChangeModify,
+		}
+		// Let's insert the directory entry before the recently added entries located inside this dir
+		*changes = append(*changes, change) // just to resize the slice, will be overwritten
+		copy((*changes)[sizeAtEntry+1:], (*changes)[sizeAtEntry:])
+		(*changes)[sizeAtEntry] = change
+	}
+}
+
+// Changes add changes to file information.
+func (info *FileInfo) Changes(oldInfo *FileInfo) []Change {
+	var changes []Change
+
+	info.addChanges(oldInfo, &changes)
+
+	return changes
+}
+
+func newRootFileInfo() *FileInfo {
+	// As this runs on the daemon side, file paths are OS specific.
+	root := &FileInfo{
+		name:     string(os.PathSeparator),
+		children: make(map[string]*FileInfo),
+	}
+	return root
+}
+
+// ChangesDirs compares two directories and generates an array of Change objects describing the changes.
+// If oldDir is "", then all files in newDir will be Add-Changes.
+func ChangesDirs(newDir, oldDir string) ([]Change, error) {
+	var oldRoot, newRoot *FileInfo
+	if oldDir == "" {
+		emptyDir, err := os.MkdirTemp("", "empty")
+		if err != nil {
+			return nil, err
+		}
+		defer os.Remove(emptyDir)
+		oldDir = emptyDir
+	}
+	oldRoot, newRoot, err := collectFileInfoForChanges(oldDir, newDir)
+	if err != nil {
+		return nil, err
+	}
+
+	return newRoot.Changes(oldRoot), nil
+}
+
+// ChangesSize calculates the size in bytes of the provided changes, based on newDir.
+func ChangesSize(newDir string, changes []Change) int64 {
+	var (
+		size int64
+		sf   = make(map[uint64]struct{})
+	)
+	for _, change := range changes {
+		if change.Kind == ChangeModify || change.Kind == ChangeAdd {
+			file := filepath.Join(newDir, change.Path)
+			fileInfo, err := os.Lstat(file)
+			if err != nil {
+				log.G(context.TODO()).Errorf("Can not stat %q: %s", file, err)
+				continue
+			}
+
+			if fileInfo != nil && !fileInfo.IsDir() {
+				if hasHardlinks(fileInfo) {
+					inode := getIno(fileInfo)
+					if _, ok := sf[inode]; !ok {
+						size += fileInfo.Size()
+						sf[inode] = struct{}{}
+					}
+				} else {
+					size += fileInfo.Size()
+				}
+			}
+		}
+	}
+	return size
+}
+
+// ExportChanges produces an Archive from the provided changes, relative to dir.
+func ExportChanges(dir string, changes []Change, idMap user.IdentityMapping) (io.ReadCloser, error) {
+	reader, writer := io.Pipe()
+	go func() {
+		ta := newTarAppender(idMap, writer, nil)
+
+		sort.Sort(changesByPath(changes))
+
+		// In general we log errors here but ignore them because
+		// during e.g. a diff operation the container can continue
+		// mutating the filesystem and we can see transient errors
+		// from this
+		for _, change := range changes {
+			if change.Kind == ChangeDelete {
+				whiteOutDir := filepath.Dir(change.Path)
+				whiteOutBase := filepath.Base(change.Path)
+				whiteOut := filepath.Join(whiteOutDir, WhiteoutPrefix+whiteOutBase)
+				timestamp := time.Now()
+				hdr := &tar.Header{
+					Name:       whiteOut[1:],
+					Size:       0,
+					ModTime:    timestamp,
+					AccessTime: timestamp,
+					ChangeTime: timestamp,
+				}
+				if err := ta.TarWriter.WriteHeader(hdr); err != nil {
+					log.G(context.TODO()).Debugf("Can't write whiteout header: %s", err)
+				}
+			} else {
+				path := filepath.Join(dir, change.Path)
+				if err := ta.addTarFile(path, change.Path[1:]); err != nil {
+					log.G(context.TODO()).Debugf("Can't add file %s to tar: %s", path, err)
+				}
+			}
+		}
+
+		// Make sure to check the error on Close.
+		if err := ta.TarWriter.Close(); err != nil {
+			log.G(context.TODO()).Debugf("Can't close layer: %s", err)
+		}
+		if err := writer.Close(); err != nil {
+			log.G(context.TODO()).Debugf("failed close Changes writer: %s", err)
+		}
+	}()
+	return reader, nil
+}