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1009e6a40b
Fixes case sensitivity issue Signed-off-by: Derek McGowan <derek@mcgstyle.net>
441 lines
12 KiB
Go
441 lines
12 KiB
Go
package archive
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import (
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"archive/tar"
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"bytes"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"sort"
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"strings"
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"syscall"
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"time"
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"github.com/docker/docker/pkg/idtools"
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"github.com/docker/docker/pkg/pools"
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"github.com/docker/docker/pkg/system"
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"github.com/sirupsen/logrus"
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)
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// ChangeType represents the change type.
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type ChangeType int
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const (
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// ChangeModify represents the modify operation.
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ChangeModify = iota
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// ChangeAdd represents the add operation.
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ChangeAdd
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// ChangeDelete represents the delete operation.
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ChangeDelete
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)
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func (c ChangeType) String() string {
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switch c {
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case ChangeModify:
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return "C"
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case ChangeAdd:
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return "A"
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case ChangeDelete:
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return "D"
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}
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return ""
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}
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// Change represents a change, it wraps the change type and path.
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// It describes changes of the files in the path respect to the
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// parent layers. The change could be modify, add, delete.
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// This is used for layer diff.
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type Change struct {
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Path string
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Kind ChangeType
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}
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func (change *Change) String() string {
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return fmt.Sprintf("%s %s", change.Kind, change.Path)
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}
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// for sort.Sort
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type changesByPath []Change
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func (c changesByPath) Less(i, j int) bool { return c[i].Path < c[j].Path }
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func (c changesByPath) Len() int { return len(c) }
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func (c changesByPath) Swap(i, j int) { c[j], c[i] = c[i], c[j] }
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// Gnu tar and the go tar writer don't have sub-second mtime
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// precision, which is problematic when we apply changes via tar
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// files, we handle this by comparing for exact times, *or* same
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// second count and either a or b having exactly 0 nanoseconds
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func sameFsTime(a, b time.Time) bool {
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return a == b ||
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(a.Unix() == b.Unix() &&
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(a.Nanosecond() == 0 || b.Nanosecond() == 0))
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}
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func sameFsTimeSpec(a, b syscall.Timespec) bool {
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return a.Sec == b.Sec &&
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(a.Nsec == b.Nsec || a.Nsec == 0 || b.Nsec == 0)
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}
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// Changes walks the path rw and determines changes for the files in the path,
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// with respect to the parent layers
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func Changes(layers []string, rw string) ([]Change, error) {
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return changes(layers, rw, aufsDeletedFile, aufsMetadataSkip)
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}
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func aufsMetadataSkip(path string) (skip bool, err error) {
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skip, err = filepath.Match(string(os.PathSeparator)+WhiteoutMetaPrefix+"*", path)
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if err != nil {
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skip = true
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}
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return
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}
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func aufsDeletedFile(root, path string, fi os.FileInfo) (string, error) {
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f := filepath.Base(path)
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// If there is a whiteout, then the file was removed
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if strings.HasPrefix(f, WhiteoutPrefix) {
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originalFile := f[len(WhiteoutPrefix):]
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return filepath.Join(filepath.Dir(path), originalFile), nil
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}
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return "", nil
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}
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type skipChange func(string) (bool, error)
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type deleteChange func(string, string, os.FileInfo) (string, error)
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func changes(layers []string, rw string, dc deleteChange, sc skipChange) ([]Change, error) {
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var (
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changes []Change
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changedDirs = make(map[string]struct{})
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)
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err := filepath.Walk(rw, func(path string, f os.FileInfo, err error) error {
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if err != nil {
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return err
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}
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// Rebase path
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path, err = filepath.Rel(rw, path)
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if err != nil {
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return err
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}
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// As this runs on the daemon side, file paths are OS specific.
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path = filepath.Join(string(os.PathSeparator), path)
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// Skip root
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if path == string(os.PathSeparator) {
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return nil
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}
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if sc != nil {
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if skip, err := sc(path); skip {
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return err
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}
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}
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change := Change{
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Path: path,
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}
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deletedFile, err := dc(rw, path, f)
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if err != nil {
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return err
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}
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// Find out what kind of modification happened
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if deletedFile != "" {
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change.Path = deletedFile
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change.Kind = ChangeDelete
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} else {
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// Otherwise, the file was added
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change.Kind = ChangeAdd
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// ...Unless it already existed in a top layer, in which case, it's a modification
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for _, layer := range layers {
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stat, err := os.Stat(filepath.Join(layer, path))
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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if err == nil {
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// The file existed in the top layer, so that's a modification
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// However, if it's a directory, maybe it wasn't actually modified.
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// If you modify /foo/bar/baz, then /foo will be part of the changed files only because it's the parent of bar
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if stat.IsDir() && f.IsDir() {
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if f.Size() == stat.Size() && f.Mode() == stat.Mode() && sameFsTime(f.ModTime(), stat.ModTime()) {
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// Both directories are the same, don't record the change
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return nil
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}
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}
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change.Kind = ChangeModify
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break
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}
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}
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}
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// If /foo/bar/file.txt is modified, then /foo/bar must be part of the changed files.
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// This block is here to ensure the change is recorded even if the
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// modify time, mode and size of the parent directory in the rw and ro layers are all equal.
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// Check https://github.com/docker/docker/pull/13590 for details.
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if f.IsDir() {
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changedDirs[path] = struct{}{}
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}
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if change.Kind == ChangeAdd || change.Kind == ChangeDelete {
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parent := filepath.Dir(path)
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if _, ok := changedDirs[parent]; !ok && parent != "/" {
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changes = append(changes, Change{Path: parent, Kind: ChangeModify})
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changedDirs[parent] = struct{}{}
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}
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}
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// Record change
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changes = append(changes, change)
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return nil
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})
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if err != nil && !os.IsNotExist(err) {
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return nil, err
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}
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return changes, nil
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}
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// FileInfo describes the information of a file.
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type FileInfo struct {
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parent *FileInfo
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name string
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stat *system.StatT
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children map[string]*FileInfo
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capability []byte
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added bool
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}
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// LookUp looks up the file information of a file.
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func (info *FileInfo) LookUp(path string) *FileInfo {
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// As this runs on the daemon side, file paths are OS specific.
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parent := info
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if path == string(os.PathSeparator) {
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return info
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}
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pathElements := strings.Split(path, string(os.PathSeparator))
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for _, elem := range pathElements {
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if elem != "" {
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child := parent.children[elem]
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if child == nil {
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return nil
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}
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parent = child
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}
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}
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return parent
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}
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func (info *FileInfo) path() string {
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if info.parent == nil {
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// As this runs on the daemon side, file paths are OS specific.
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return string(os.PathSeparator)
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}
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return filepath.Join(info.parent.path(), info.name)
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}
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func (info *FileInfo) addChanges(oldInfo *FileInfo, changes *[]Change) {
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sizeAtEntry := len(*changes)
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if oldInfo == nil {
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// add
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change := Change{
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Path: info.path(),
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Kind: ChangeAdd,
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}
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*changes = append(*changes, change)
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info.added = true
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}
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// We make a copy so we can modify it to detect additions
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// also, we only recurse on the old dir if the new info is a directory
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// otherwise any previous delete/change is considered recursive
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oldChildren := make(map[string]*FileInfo)
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if oldInfo != nil && info.isDir() {
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for k, v := range oldInfo.children {
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oldChildren[k] = v
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}
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}
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for name, newChild := range info.children {
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oldChild := oldChildren[name]
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if oldChild != nil {
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// change?
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oldStat := oldChild.stat
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newStat := newChild.stat
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// Note: We can't compare inode or ctime or blocksize here, because these change
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// when copying a file into a container. However, that is not generally a problem
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// because any content change will change mtime, and any status change should
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// be visible when actually comparing the stat fields. The only time this
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// breaks down is if some code intentionally hides a change by setting
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// back mtime
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if statDifferent(oldStat, newStat) ||
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!bytes.Equal(oldChild.capability, newChild.capability) {
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change := Change{
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Path: newChild.path(),
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Kind: ChangeModify,
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}
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*changes = append(*changes, change)
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newChild.added = true
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}
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// Remove from copy so we can detect deletions
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delete(oldChildren, name)
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}
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newChild.addChanges(oldChild, changes)
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}
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for _, oldChild := range oldChildren {
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// delete
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change := Change{
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Path: oldChild.path(),
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Kind: ChangeDelete,
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}
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*changes = append(*changes, change)
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}
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// If there were changes inside this directory, we need to add it, even if the directory
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// itself wasn't changed. This is needed to properly save and restore filesystem permissions.
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// As this runs on the daemon side, file paths are OS specific.
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if len(*changes) > sizeAtEntry && info.isDir() && !info.added && info.path() != string(os.PathSeparator) {
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change := Change{
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Path: info.path(),
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Kind: ChangeModify,
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}
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// Let's insert the directory entry before the recently added entries located inside this dir
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*changes = append(*changes, change) // just to resize the slice, will be overwritten
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copy((*changes)[sizeAtEntry+1:], (*changes)[sizeAtEntry:])
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(*changes)[sizeAtEntry] = change
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}
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}
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// Changes add changes to file information.
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func (info *FileInfo) Changes(oldInfo *FileInfo) []Change {
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var changes []Change
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info.addChanges(oldInfo, &changes)
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return changes
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}
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func newRootFileInfo() *FileInfo {
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// As this runs on the daemon side, file paths are OS specific.
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root := &FileInfo{
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name: string(os.PathSeparator),
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children: make(map[string]*FileInfo),
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}
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return root
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}
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// ChangesDirs compares two directories and generates an array of Change objects describing the changes.
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// If oldDir is "", then all files in newDir will be Add-Changes.
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func ChangesDirs(newDir, oldDir string) ([]Change, error) {
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var (
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oldRoot, newRoot *FileInfo
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)
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if oldDir == "" {
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emptyDir, err := ioutil.TempDir("", "empty")
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if err != nil {
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return nil, err
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}
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defer os.Remove(emptyDir)
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oldDir = emptyDir
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}
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oldRoot, newRoot, err := collectFileInfoForChanges(oldDir, newDir)
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if err != nil {
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return nil, err
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}
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return newRoot.Changes(oldRoot), nil
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}
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// ChangesSize calculates the size in bytes of the provided changes, based on newDir.
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func ChangesSize(newDir string, changes []Change) int64 {
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var (
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size int64
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sf = make(map[uint64]struct{})
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)
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for _, change := range changes {
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if change.Kind == ChangeModify || change.Kind == ChangeAdd {
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file := filepath.Join(newDir, change.Path)
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fileInfo, err := os.Lstat(file)
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if err != nil {
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logrus.Errorf("Can not stat %q: %s", file, err)
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continue
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}
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if fileInfo != nil && !fileInfo.IsDir() {
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if hasHardlinks(fileInfo) {
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inode := getIno(fileInfo)
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if _, ok := sf[inode]; !ok {
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size += fileInfo.Size()
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sf[inode] = struct{}{}
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}
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} else {
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size += fileInfo.Size()
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}
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}
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}
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}
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return size
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}
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// ExportChanges produces an Archive from the provided changes, relative to dir.
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func ExportChanges(dir string, changes []Change, uidMaps, gidMaps []idtools.IDMap) (io.ReadCloser, error) {
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reader, writer := io.Pipe()
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go func() {
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ta := newTarAppender(idtools.NewIDMappingsFromMaps(uidMaps, gidMaps), writer)
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// this buffer is needed for the duration of this piped stream
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defer pools.BufioWriter32KPool.Put(ta.Buffer)
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sort.Sort(changesByPath(changes))
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// In general we log errors here but ignore them because
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// during e.g. a diff operation the container can continue
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// mutating the filesystem and we can see transient errors
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// from this
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for _, change := range changes {
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if change.Kind == ChangeDelete {
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whiteOutDir := filepath.Dir(change.Path)
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whiteOutBase := filepath.Base(change.Path)
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whiteOut := filepath.Join(whiteOutDir, WhiteoutPrefix+whiteOutBase)
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timestamp := time.Now()
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hdr := &tar.Header{
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Name: whiteOut[1:],
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Size: 0,
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ModTime: timestamp,
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AccessTime: timestamp,
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ChangeTime: timestamp,
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}
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if err := ta.TarWriter.WriteHeader(hdr); err != nil {
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logrus.Debugf("Can't write whiteout header: %s", err)
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}
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} else {
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path := filepath.Join(dir, change.Path)
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if err := ta.addTarFile(path, change.Path[1:]); err != nil {
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logrus.Debugf("Can't add file %s to tar: %s", path, err)
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}
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}
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}
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// Make sure to check the error on Close.
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if err := ta.TarWriter.Close(); err != nil {
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logrus.Debugf("Can't close layer: %s", err)
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}
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if err := writer.Close(); err != nil {
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logrus.Debugf("failed close Changes writer: %s", err)
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}
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}()
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return reader, nil
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}
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