| // +build !windows |
| |
| package fs |
| |
| import ( |
| "bytes" |
| "os" |
| "path/filepath" |
| "strings" |
| "syscall" |
| |
| "github.com/containerd/continuity/sysx" |
| "github.com/pkg/errors" |
| ) |
| |
| // whiteouts are files with a special meaning for the layered filesystem. |
| // Docker uses AUFS whiteout files inside exported archives. In other |
| // filesystems these files are generated/handled on tar creation/extraction. |
| |
| // whiteoutPrefix prefix means file is a whiteout. If this is followed by a |
| // filename this means that file has been removed from the base layer. |
| const whiteoutPrefix = ".wh." |
| |
| // whiteoutMetaPrefix prefix means whiteout has a special meaning and is not |
| // for removing an actual file. Normally these files are excluded from exported |
| // archives. |
| const whiteoutMetaPrefix = whiteoutPrefix + whiteoutPrefix |
| |
| // whiteoutLinkDir is a directory AUFS uses for storing hardlink links to other |
| // layers. Normally these should not go into exported archives and all changed |
| // hardlinks should be copied to the top layer. |
| const whiteoutLinkDir = whiteoutMetaPrefix + "plnk" |
| |
| // whiteoutOpaqueDir file means directory has been made opaque - meaning |
| // readdir calls to this directory do not follow to lower layers. |
| const whiteoutOpaqueDir = whiteoutMetaPrefix + ".opq" |
| |
| // detectDirDiff returns diff dir options if a directory could |
| // be found in the mount info for upper which is the direct |
| // diff with the provided lower directory |
| func detectDirDiff(upper, lower string) *diffDirOptions { |
| // TODO: get mount options for upper |
| // TODO: detect AUFS |
| // TODO: detect overlay |
| return nil |
| } |
| |
| func aufsMetadataSkip(path string) (skip bool, err error) { |
| skip, err = filepath.Match(string(os.PathSeparator)+whiteoutMetaPrefix+"*", path) |
| if err != nil { |
| skip = true |
| } |
| return |
| } |
| |
| 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 |
| } |
| |
| // compareSysStat returns whether the stats are equivalent, |
| // whether the files are considered the same file, and |
| // an error |
| func compareSysStat(s1, s2 interface{}) (bool, error) { |
| ls1, ok := s1.(*syscall.Stat_t) |
| if !ok { |
| return false, nil |
| } |
| ls2, ok := s2.(*syscall.Stat_t) |
| if !ok { |
| return false, nil |
| } |
| |
| return ls1.Mode == ls2.Mode && ls1.Uid == ls2.Uid && ls1.Gid == ls2.Gid && ls1.Rdev == ls2.Rdev, nil |
| } |
| |
| func compareCapabilities(p1, p2 string) (bool, error) { |
| c1, err := sysx.LGetxattr(p1, "security.capability") |
| if err != nil && err != sysx.ENODATA { |
| return false, errors.Wrapf(err, "failed to get xattr for %s", p1) |
| } |
| c2, err := sysx.LGetxattr(p2, "security.capability") |
| if err != nil && err != sysx.ENODATA { |
| return false, errors.Wrapf(err, "failed to get xattr for %s", p2) |
| } |
| return bytes.Equal(c1, c2), nil |
| } |
| |
| func isLinked(f os.FileInfo) bool { |
| s, ok := f.Sys().(*syscall.Stat_t) |
| if !ok { |
| return false |
| } |
| return !f.IsDir() && s.Nlink > 1 |
| } |