mirror of
https://github.com/moby/moby.git
synced 2022-11-09 12:21:53 -05:00
archive: Implement ApplyLayer directly
Rather than calling out to tar we use the golang tar parser to directly extract the tar files. This has two major advantages: 1) We're able to replace an existing directory with a file in the new layer. This currently breaks with the external tar, since it refuses to recursively remove the destination directory in this case, and there are no options to make it do that. 2) We avoid extracting the whiteout files just to later remove them.
This commit is contained in:
Alexander Larsson
parent
5a89c6f6df
commit
818c249bae
3 changed files with 171 additions and 71 deletions
215
archive/diff.go
215
archive/diff.go
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@ -1,6 +1,9 @@
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package archive
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import (
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"archive/tar"
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"github.com/dotcloud/docker/utils"
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"io"
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"os"
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"path/filepath"
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"strings"
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@ -8,87 +11,159 @@ import (
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"time"
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)
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// Linux device nodes are a bit weird due to backwards compat with 16 bit device nodes
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// The lower 8 bit is the lower 8 bit in the minor, the following 12 bits are the major,
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// and then there is the top 12 bits of then minor
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func mkdev(major int64, minor int64) uint32 {
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return uint32(((minor & 0xfff00) << 12) | ((major & 0xfff) << 8) | (minor & 0xff))
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}
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func timeToTimespec(time time.Time) (ts syscall.Timespec) {
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if time.IsZero() {
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// Return UTIME_OMIT special value
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ts.Sec = 0
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ts.Nsec = ((1 << 30) - 2)
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return
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}
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return syscall.NsecToTimespec(time.UnixNano())
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}
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// ApplyLayer parses a diff in the standard layer format from `layer`, and
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// applies it to the directory `dest`.
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func ApplyLayer(dest string, layer Archive) error {
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// Poor man's diff applyer in 2 steps:
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// We need to be able to set any perms
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oldmask := syscall.Umask(0)
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defer syscall.Umask(oldmask)
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// Step 1: untar everything in place
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if err := Untar(layer, dest, nil); err != nil {
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return err
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}
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tr := tar.NewReader(layer)
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modifiedDirs := make(map[string]*syscall.Stat_t)
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addDir := func(file string) {
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d := filepath.Dir(file)
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if _, exists := modifiedDirs[d]; !exists {
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if s, err := os.Lstat(d); err == nil {
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if sys := s.Sys(); sys != nil {
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if stat, ok := sys.(*syscall.Stat_t); ok {
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modifiedDirs[d] = stat
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var dirs []*tar.Header
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// Iterate through the files in the archive.
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for {
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hdr, err := tr.Next()
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if err == io.EOF {
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// end of tar archive
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break
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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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// Skip AUFS metadata dirs
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if strings.HasPrefix(hdr.Name, ".wh..wh.") {
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continue
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}
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path := filepath.Join(dest, hdr.Name)
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base := filepath.Base(path)
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if strings.HasPrefix(base, ".wh.") {
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originalBase := base[len(".wh."):]
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originalPath := filepath.Join(filepath.Dir(path), originalBase)
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if err := os.RemoveAll(originalPath); err != nil {
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return err
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}
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} else {
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// If path exits we almost always just want to remove and replace it
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// The only exception is when it is a directory *and* the file from
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// the layer is also a directory. Then we want to merge them (i.e.
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// just apply the metadata from the layer).
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hasDir := false
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if fi, err := os.Lstat(path); err == nil {
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if fi.IsDir() && hdr.Typeflag == tar.TypeDir {
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hasDir = true
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} else {
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if err := os.RemoveAll(path); err != nil {
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return err
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}
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}
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}
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switch hdr.Typeflag {
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case tar.TypeDir:
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if !hasDir {
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err = os.Mkdir(path, os.FileMode(hdr.Mode))
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if err != nil {
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return err
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}
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}
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dirs = append(dirs, hdr)
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case tar.TypeReg, tar.TypeRegA:
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// Source is regular file
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file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, os.FileMode(hdr.Mode))
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if err != nil {
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return err
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}
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if _, err := io.Copy(file, tr); err != nil {
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file.Close()
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return err
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}
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file.Close()
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case tar.TypeBlock, tar.TypeChar, tar.TypeFifo:
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mode := uint32(hdr.Mode & 07777)
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switch hdr.Typeflag {
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case tar.TypeBlock:
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mode |= syscall.S_IFBLK
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case tar.TypeChar:
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mode |= syscall.S_IFCHR
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case tar.TypeFifo:
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mode |= syscall.S_IFIFO
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}
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if err := syscall.Mknod(path, mode, int(mkdev(hdr.Devmajor, hdr.Devminor))); err != nil {
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return err
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}
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case tar.TypeLink:
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if err := os.Link(filepath.Join(dest, hdr.Linkname), path); err != nil {
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return err
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}
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case tar.TypeSymlink:
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if err := os.Symlink(hdr.Linkname, path); err != nil {
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return err
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}
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default:
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utils.Debugf("unhandled type %d\n", hdr.Typeflag)
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}
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if err = syscall.Lchown(path, hdr.Uid, hdr.Gid); err != nil {
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return err
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}
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// There is no LChmod, so ignore mode for symlink. Also, this
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// must happen after chown, as that can modify the file mode
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if hdr.Typeflag != tar.TypeSymlink {
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err = syscall.Chmod(path, uint32(hdr.Mode&07777))
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if err != nil {
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return err
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}
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}
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// Directories must be handled at the end to avoid further
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// file creation in them to modify the mtime
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if hdr.Typeflag != tar.TypeDir {
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ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)}
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// syscall.UtimesNano doesn't support a NOFOLLOW flag atm, and
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if hdr.Typeflag != tar.TypeSymlink {
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if err := syscall.UtimesNano(path, ts); err != nil {
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return err
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}
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} else {
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if err := LUtimesNano(path, ts); err != nil {
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return err
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}
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}
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}
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}
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}
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// Step 2: walk for whiteouts and apply them, removing them in the process
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err := filepath.Walk(dest, func(fullPath string, f os.FileInfo, err error) error {
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if err != nil {
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if os.IsNotExist(err) {
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// This happens in the case of whiteouts in parent dir removing a directory
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// We just ignore it
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return filepath.SkipDir
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}
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return err
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}
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// Rebase path
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path, err := filepath.Rel(dest, fullPath)
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if err != nil {
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return err
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}
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path = filepath.Join("/", path)
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// Skip AUFS metadata
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if matched, err := filepath.Match("/.wh..wh.*", path); err != nil {
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return err
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} else if matched {
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addDir(fullPath)
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if err := os.RemoveAll(fullPath); err != nil {
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return err
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}
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}
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filename := filepath.Base(path)
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if strings.HasPrefix(filename, ".wh.") {
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rmTargetName := filename[len(".wh."):]
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rmTargetPath := filepath.Join(filepath.Dir(fullPath), rmTargetName)
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// Remove the file targeted by the whiteout
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addDir(rmTargetPath)
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if err := os.RemoveAll(rmTargetPath); err != nil {
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return err
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}
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// Remove the whiteout itself
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addDir(fullPath)
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if err := os.RemoveAll(fullPath); err != nil {
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return err
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}
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}
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return nil
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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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for k, v := range modifiedDirs {
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lastAccess := getLastAccess(v)
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lastModification := getLastModification(v)
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aTime := time.Unix(lastAccess.Unix())
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mTime := time.Unix(lastModification.Unix())
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if err := os.Chtimes(k, aTime, mTime); err != nil {
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for _, hdr := range dirs {
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path := filepath.Join(dest, hdr.Name)
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ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)}
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if err := syscall.UtimesNano(path, ts); err != nil {
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return err
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}
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}
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@ -9,3 +9,7 @@ func getLastAccess(stat *syscall.Stat_t) syscall.Timespec {
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func getLastModification(stat *syscall.Stat_t) syscall.Timespec {
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return stat.Mtimespec
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}
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func LUtimesNano(path string, ts []syscall.Timespec) error {
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return nil
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}
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@ -1,6 +1,9 @@
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package archive
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import "syscall"
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import (
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"syscall"
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"unsafe"
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)
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func getLastAccess(stat *syscall.Stat_t) syscall.Timespec {
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return stat.Atim
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@ -9,3 +12,21 @@ func getLastAccess(stat *syscall.Stat_t) syscall.Timespec {
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func getLastModification(stat *syscall.Stat_t) syscall.Timespec {
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return stat.Mtim
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}
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func LUtimesNano(path string, ts []syscall.Timespec) error {
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// These are not currently availible in syscall
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AT_FDCWD := -100
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AT_SYMLINK_NOFOLLOW := 0x100
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var _path *byte
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_path, err := syscall.BytePtrFromString(path)
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if err != nil {
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return err
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}
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if _, _, err := syscall.Syscall6(syscall.SYS_UTIMENSAT, uintptr(AT_FDCWD), uintptr(unsafe.Pointer(_path)), uintptr(unsafe.Pointer(&ts[0])), uintptr(AT_SYMLINK_NOFOLLOW), 0, 0); err != 0 && err != syscall.ENOSYS {
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return err
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}
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return nil
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}
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