mirror of
https://github.com/genuinetools/reg.git
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277 lines
6.6 KiB
Go
277 lines
6.6 KiB
Go
// +build linux
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package copy // import "github.com/docker/docker/daemon/graphdriver/copy"
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/*
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#include <linux/fs.h>
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#ifndef FICLONE
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#define FICLONE _IOW(0x94, 9, int)
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#endif
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*/
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import "C"
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import (
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"container/list"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"syscall"
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"time"
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"github.com/docker/docker/pkg/pools"
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"github.com/docker/docker/pkg/system"
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rsystem "github.com/opencontainers/runc/libcontainer/system"
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"golang.org/x/sys/unix"
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)
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// Mode indicates whether to use hardlink or copy content
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type Mode int
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const (
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// Content creates a new file, and copies the content of the file
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Content Mode = iota
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// Hardlink creates a new hardlink to the existing file
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Hardlink
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)
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func copyRegular(srcPath, dstPath string, fileinfo os.FileInfo, copyWithFileRange, copyWithFileClone *bool) error {
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srcFile, err := os.Open(srcPath)
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if err != nil {
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return err
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}
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defer srcFile.Close()
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// If the destination file already exists, we shouldn't blow it away
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dstFile, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, fileinfo.Mode())
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if err != nil {
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return err
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}
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defer dstFile.Close()
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if *copyWithFileClone {
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_, _, err = unix.Syscall(unix.SYS_IOCTL, dstFile.Fd(), C.FICLONE, srcFile.Fd())
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if err == nil {
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return nil
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}
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*copyWithFileClone = false
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if err == unix.EXDEV {
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*copyWithFileRange = false
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}
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}
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if *copyWithFileRange {
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err = doCopyWithFileRange(srcFile, dstFile, fileinfo)
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// Trying the file_clone may not have caught the exdev case
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// as the ioctl may not have been available (therefore EINVAL)
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if err == unix.EXDEV || err == unix.ENOSYS {
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*copyWithFileRange = false
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} else {
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return err
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}
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}
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return legacyCopy(srcFile, dstFile)
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}
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func doCopyWithFileRange(srcFile, dstFile *os.File, fileinfo os.FileInfo) error {
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amountLeftToCopy := fileinfo.Size()
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for amountLeftToCopy > 0 {
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n, err := unix.CopyFileRange(int(srcFile.Fd()), nil, int(dstFile.Fd()), nil, int(amountLeftToCopy), 0)
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if err != nil {
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return err
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}
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amountLeftToCopy = amountLeftToCopy - int64(n)
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}
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return nil
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}
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func legacyCopy(srcFile io.Reader, dstFile io.Writer) error {
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_, err := pools.Copy(dstFile, srcFile)
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return err
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}
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func copyXattr(srcPath, dstPath, attr string) error {
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data, err := system.Lgetxattr(srcPath, attr)
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if err != nil {
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return err
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}
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if data != nil {
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if err := system.Lsetxattr(dstPath, attr, data, 0); 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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type fileID struct {
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dev uint64
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ino uint64
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}
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type dirMtimeInfo struct {
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dstPath *string
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stat *syscall.Stat_t
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}
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// DirCopy copies or hardlinks the contents of one directory to another,
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// properly handling xattrs, and soft links
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//
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// Copying xattrs can be opted out of by passing false for copyXattrs.
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func DirCopy(srcDir, dstDir string, copyMode Mode, copyXattrs bool) error {
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copyWithFileRange := true
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copyWithFileClone := true
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// This is a map of source file inodes to dst file paths
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copiedFiles := make(map[fileID]string)
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dirsToSetMtimes := list.New()
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err := filepath.Walk(srcDir, func(srcPath 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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relPath, err := filepath.Rel(srcDir, srcPath)
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if err != nil {
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return err
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}
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dstPath := filepath.Join(dstDir, relPath)
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if err != nil {
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return err
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}
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stat, ok := f.Sys().(*syscall.Stat_t)
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if !ok {
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return fmt.Errorf("Unable to get raw syscall.Stat_t data for %s", srcPath)
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}
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isHardlink := false
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switch f.Mode() & os.ModeType {
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case 0: // Regular file
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id := fileID{dev: stat.Dev, ino: stat.Ino}
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if copyMode == Hardlink {
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isHardlink = true
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if err2 := os.Link(srcPath, dstPath); err2 != nil {
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return err2
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}
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} else if hardLinkDstPath, ok := copiedFiles[id]; ok {
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if err2 := os.Link(hardLinkDstPath, dstPath); err2 != nil {
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return err2
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}
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} else {
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if err2 := copyRegular(srcPath, dstPath, f, ©WithFileRange, ©WithFileClone); err2 != nil {
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return err2
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}
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copiedFiles[id] = dstPath
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}
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case os.ModeDir:
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if err := os.Mkdir(dstPath, f.Mode()); err != nil && !os.IsExist(err) {
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return err
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}
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case os.ModeSymlink:
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link, err := os.Readlink(srcPath)
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if err != nil {
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return err
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}
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if err := os.Symlink(link, dstPath); err != nil {
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return err
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}
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case os.ModeNamedPipe:
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fallthrough
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case os.ModeSocket:
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if rsystem.RunningInUserNS() {
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// cannot create a device if running in user namespace
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return nil
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}
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if err := unix.Mkfifo(dstPath, stat.Mode); err != nil {
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return err
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}
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case os.ModeDevice:
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if err := unix.Mknod(dstPath, stat.Mode, int(stat.Rdev)); err != nil {
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return err
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}
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default:
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return fmt.Errorf("unknown file type for %s", srcPath)
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}
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// Everything below is copying metadata from src to dst. All this metadata
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// already shares an inode for hardlinks.
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if isHardlink {
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return nil
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}
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if err := os.Lchown(dstPath, int(stat.Uid), int(stat.Gid)); err != nil {
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return err
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}
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if copyXattrs {
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if err := doCopyXattrs(srcPath, dstPath); err != nil {
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return err
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}
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}
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isSymlink := f.Mode()&os.ModeSymlink != 0
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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 !isSymlink {
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if err := os.Chmod(dstPath, f.Mode()); err != nil {
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return err
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}
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}
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// system.Chtimes doesn't support a NOFOLLOW flag atm
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// nolint: unconvert
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if f.IsDir() {
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dirsToSetMtimes.PushFront(&dirMtimeInfo{dstPath: &dstPath, stat: stat})
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} else if !isSymlink {
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aTime := time.Unix(int64(stat.Atim.Sec), int64(stat.Atim.Nsec))
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mTime := time.Unix(int64(stat.Mtim.Sec), int64(stat.Mtim.Nsec))
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if err := system.Chtimes(dstPath, aTime, mTime); err != nil {
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return err
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}
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} else {
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ts := []syscall.Timespec{stat.Atim, stat.Mtim}
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if err := system.LUtimesNano(dstPath, ts); 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 e := dirsToSetMtimes.Front(); e != nil; e = e.Next() {
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mtimeInfo := e.Value.(*dirMtimeInfo)
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ts := []syscall.Timespec{mtimeInfo.stat.Atim, mtimeInfo.stat.Mtim}
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if err := system.LUtimesNano(*mtimeInfo.dstPath, ts); 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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func doCopyXattrs(srcPath, dstPath string) error {
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if err := copyXattr(srcPath, dstPath, "security.capability"); err != nil {
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return err
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}
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// We need to copy this attribute if it appears in an overlay upper layer, as
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// this function is used to copy those. It is set by overlay if a directory
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// is removed and then re-created and should not inherit anything from the
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// same dir in the lower dir.
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return copyXattr(srcPath, dstPath, "trusted.overlay.opaque")
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}
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